Scholarly article on (5S)-1,2,5-tri-O-acetyl-3-O-benzyl-5-C-vinyl-L-arabino-pentofuranose 628281-10-7 from European Journal of Organic Chemistry p. 3603

FULL PAPER

Efficient Preparation of Three Building Blocks for the Synthesis of Heparan

Sulfate Fragments: Towards the Combinatorial Synthesis of Oligosaccharides

from Hypervariable Regions

[b]

[a]

´

¨

Ollivier Gavard, Yael Hersant, Jocelyne Alais, Veronique Duverger, Anna Dilhas,

[c]

[a]

´

Alison Bascou, and David Bonnaffe*

Keywords: Combinatorial chemistry / Glycosaminoglycans / Heparan sulfate / Heparin / Oligosaccharides / Carbohydrates

New, multigram routes to suitably protected

L-iduronyl

a combinatorial approach toward the synthesis of heparan

monosaccharide donors 4 and 5 and 2-azidoglucose ac- sulfate fragments representative of the heterogeneous re-

ceptors 6 and 7 are described. The

L-iduronyl and

D-glucu-

gions of this polysaccharide.

ronyl disaccharides 1−3 were then prepared from these com-

pounds, by means of efficient and regioselective protective

group manipulations. These disaccharides form the basis of

( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,

Germany, 2003)Introduction

Introduction

ponentially with the polymer length, giving 2304 possible

tetrasaccharides, 110,592 hexasaccharides, and more than

5·10⁶octasaccharides.

Heparan sulfate (HS) is a member of the family of glycos-

aminoglycans (GAGs). It is a linear, sulfated polysaccharide

in which a basic disaccharide, composed of a uronic acid

1Ϫ4 linked to a 2-deoxy-2-aminoglucose, is repeated

throughout the sequence. HS chains, either at cell surfaces

or in the extracellular matrix, interact and regulate the ac-

tivity of numerous proteins, such as growth factors, cyto-

kines, chemokines, viral proteins, coagulation factors.^[1,2]

There is growing evidence that the formation of different

HS structures is tightly controlled during biosynthesis, with

the presumed goal of generating sequences with biological

specificity.^[3]HS is one of the most heterogeneous biopoly-

mers, since various epimerisation and sulfation patterns

(sulfoforms) may occur along the chain.^[4Ϫ6]The uronic

acid may be either -glucuronic or -iduronic, while O-sulf-

ation may occur on position 2 of the uronic acid and on

positions 3 and/or 6 of the amino sugar. The glucosamine

nitrogen may be sulfated, acetylated or, less frequently, un-

modified (Figure 1), thus resulting in 48 possible disacchar-

ides. From current knowledge of HS biosynthesis, all the

theoretical structures cannot be expressed, but 23 of them

have already been characterised.^[7]The diversity grows ex-

Figure 1. Theoretical molecular diversity found in HS

The polymer, typically composed of 50Ϫ200 disaccharide

units (25Ϫ100 kD), is not fully heterogeneous. Fairly reg-

ular N-acetylated (NA) regions, mainly composed of glucu-

ronic acid and N-acetylated glucosamine, separate hyper-

variable N-sulfated (NS) domains. The latter, typically

hexa- to hexadecasaccharides, are expressed dynamically

and specifically at the cell surface^[3,8]and are responsible

for specific interactions with various proteins.^[1]New drugs,

capable of modulating the activity of a target protein, may

emerge from the identification of a HS fragment able to

bind selectively and with high affinity to this protein. How-

ever, the isolation of NS fragments by enzymatic or chemi-

cal degradation of the polymer is impeded by their low level

of occurrence. Moreover, HS fragments purified by size ex-

[a]

Laboratoire de Chimie Organique Multifunctionnelle, UMR

´

8614 ‘‘Glycochimie Moleculaire’’, Bat. 420, Universite Paris

Sud,

91405 Orsay Cedex, France

Fax: (internat.) ϩ33-1-69154715

E-mail: david.bonnaffe@icmo.u-psud.fr

Cerise Chemtech,

[b]

[c]

Rue de Strasbourg 5, 1140 Bruxelles, Belgium

Ethypharm,

194 Bureaux de la Colline, 92213 Saint Cloud Cedex, France

Eur. J. Org. Chem. 2003, 3603Ϫ3620

DOI: 10.1002/ejoc.200300254

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D. Bonnaffe et al.

FULL PAPER

clusion and ion-exchange chromatography after depolym-

erisation are often found to be non-homogeneous by PAGE

electrophoresis.^[9]Total synthesis of HS fragments, although

still difficult (in spite of impressive improvements in recent

decades^[10Ϫ16]) is therefore the most efficient way to access

structurally defined HS fragments in sufficient amounts for

structure-activity studies. Indeed, chemical synthesis has

proved to be a valuable tool in the establishment as a drug

lead of a pentasaccharide binding to antithrombin and re-

sponsible for the anti Xa properties of heparin.^[10]This re-

sulted in the development of Arixtra^, an FDA- and

EMEA-approved drug against deep vein thrombosis, and

of mimetics with enhanced anti IIa properties.^[11]

For proteins other than antithrombin, however, the epi-

merisation and sulfation patterns responsible for the selec-

tive binding of a given protein are generally unknown. Syn-

thetic targets are therefore difficult to define, and a combi-

natorial approach to access the molecular diversity of

GAGs seems most appropriate. We have indeed shown, a

few years ago, that combinatorial synthesis was an ideal

tool with which to generate all the sulfo forms of the basic

disaccharides of chondroitin sulfate (another GAG),^[17]and

since then, developments of building blocks for the modular

synthesis of HS fragments have been published by other

groups.^[18,19]In the meantime, we have started to develop a

combinatorial approach for the preparation of HS frag-

ments in order to find compounds able to bind the chemok-

ine SDF-1α selectively and with high affinity.^[20]Biochemi-

cal studies have shown that the smallest HS fragments to

inhibit the interaction between heparin and SDF-1α is an

octasaccharide.^[21]As shown above, the synthesis of all the

HS octasaccharides is unrealistic. However, the SDF-1α

binding site on HS chains should be found in the most het-

erogeneous regions, which are located in the NS or mixed

NA/NS domains. We thus decided to restrict the diversity

Figure 2. Three disaccharide building blocks for the generation of

four HS basic disaccharide

with the benzyl ethers, by hydrogenolysis at the last step of

the synthesis, or selectively, by oxidation or acidic treat-

ment, to furnish a disaccharide acceptor for chain elong-

ation. The anomeric positions are protected by an allyl

group, which can be removed to give, after activation of the

anomeric position, a disaccharide donor. The orthogonality

of the p-methoxybenzyl and allyl groups can then be used

for further elongation of the chain by recurrent deprotec-

tion and activation steps.^[24]

Results and Discussion

We explored different preparations of the disaccharides

to highly N-sulfated octasaccharides, but the diversity 1Ϫ3 from the restricted number of monosaccharide build-

would still remain tremendous. We therefore considered the ing blocks 4Ϫ8 (Figure 3). Since our final goal will require

combination of four disaccharides that are of great occur- important quantities of disaccharide building blocks, we

Ϫ

rence in the NS or mixed NA/NS regions: -2-OSO₃

-

optimized the preparations of compounds 4Ϫ7 on multig-

Ϫ

IdoUA-6-OSO₃^Ϫ-GlcNSO₃

-

(A),

-2-OSO₃^Ϫ-IdoUA- ram scales with the minimum of silica gel chromatography

GlcNSO₃^Ϫ- (B), -GlcUA-GlcNSO₃^Ϫ- (C), and -GlcUA- and then followed two strategies for disaccharide prep-

GlcNAc- (D) (Figure 2). The three building blocks 1,^[22]2, aration. On one hand, monosaccharide building blocks 4

and 3 are the precursors of disaccharide domains AϪD and and 6, containing all the protecting groups in the right posi-

should allow a fully divergent synthesis of HS octasacchar- tion, were condensed to give the disaccharide 1 directly. Do-

ides. Here we report efficient routes to these three building nor 4 was prepared from compound 9, in which an alkenic

blocks.

moiety, used as precursor for the carboxymethyl function,

The three building blocks 1Ϫ3 already contain the -glu- facilitated the introduction of the protecting groups without

curonic or -iduronic moieties protected as methyl esters in the limitations often encountered with -iduronic deriva-

order to avoid oxidation steps that could be troublesome tives, which are prone to β-eliminations, epimerisation, or

on elaborated material at the end of the synthesis. In order 2,6-lactone formation. On the other hand, we have also de-

to avoid tedious deprotection schemes, we chose a protec- veloped the most efficient route so far reported to the less

tive group pattern making clear distinction between the po- functionalised -iduronyl donor 5^[25](72% yield from com-

sitions to be sulfated and those remaining as free hydroxy mercial diacetone glucose). This compound was condensed

groups. Acetates protect the positions to be sulfated, while onto acceptors 6 and 7, giving disaccharides in which the

benzyl ethers are used for permanent protection. A p-meth- 4Ј positions were differentiated from positions 6 and 2Ј by

oxybenzyl group at the 4Ј positions avoids the need to pre- regioselective acetylations. The disaccharide 3, containing

pare a special building block for capping of the non-reduc- a -glucuronyl moiety, was prepared in a similar way, by

ing end.^[23]This group should be removable either together condensation of acetobromoglucose 8^[26]and acceptor 7,

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Eur. J. Org. Chem. 2003, 3603Ϫ3620

Building Blocks for the Synthesis of Heparan Sulfate Fragments

FULL PAPER

followed by regioselective protecting group manipulation pounds. We then turned to the use of lipases as selective

and oxidation at the 6Ј position (Figure 3).

deacetylating catalyst, following a methodology successfully

used in this laboratory.^[33]The α/β mixture 11 was thus

treated with Amano AP6 lipase supported on Celite 545 in

butan-2-ol, but no conversion could be detected even after

prolonged heating at 60 °C. Pig Pancreatic Lipase (PPL),

used in phosphate buffer with 10% acetone,^[34]proved to be

a better catalyst, giving 12 without degradation or excessive

deacetylation. Monitoring of the reaction was difficult due

to the lack of solubility of 11 and 12 in the aqueous buffer

and thus the reaction was not reproducible. To dissolve

both compounds, while keeping the PPL catalytically active,

we turned to a reverse-micelle emulsion composed of

HEPES buffer pH 10, nBuOH, octane, and cetyltrimethyl-

ammonium bromide (CTAB).^[35]Under these conditions,

the reaction could easily be followed by TLC, which indi-

cated slow conversion of the β anomer, while transform-

ation of the α anomer was hardly detected. We generally

stopped the reaction at around 90% conversion of 11β.

After treatment and purification we obtained 12 (74%), ac-

companied by a 1:1 α/β mixture of the starting material

(25%), which could be recycled (Scheme 1). Hemiacetal 12

was then further converted into the anomeric chloride, by

use of Vilsmeier reagent,^[36,37]and into the 1,2-orthoester,

by use of DMF dimethyl acetal and Bu₄NBr,^[38]giving 13

Figure 3. Retrosynthetic analysis for the preparation of the disac-

charide building blocks 1Ϫ3

Preparation of the Monosaccharide Building Blocks 4؊7

Synthesis of Iduronyl Donor 4

We recently showed that the -idose derivative 10 could in 90% overall yield (Scheme 1). The rate-limiting step in

easily be prepared from aldehyde 9 by addition of vinylmag- this procedure for the preparation of 13 from 9 is the anom-

nesium bromide (Scheme 1).^[27]Compound 10 is an inter- eric deacetylation, which proceeds very slowly (12 days to

esting starting material for the synthesis of iduronyl donors, reach 90% conversion in 11β). We thus decided to perform a

since the alkenic moiety may be efficiently converted into a direct conversion of peracetate 11 into an anomeric halide.

carboxymethyl group. Moreover, as discussed above, there Classical conditions with HBr in acetic acid, tin or titanium

is no risk of side reactions under basic conditions with such tetrachloride,^[39]as well as dichloromethoxymethane/

vinylic derivatives, thus facilitating the differentiation of po- BF₃·Et₂O,^[40]all failed to convert 11 into the corresponding

sitions 1, 2, and 4. Compound 10 was first converted into halide, giving mostly decomposition products. Fortunately,

the acetylated pyrano derivative 11 by a standard two-step the use of TMSBr as brominating agent^[41,42]gave the ex-

procedure. The 1,2-isopropylidene moiety was cleaved by pected anomeric bromide, which was directly converted into

use of aqueous acetic acid at 80 °C and the resulting triol the orthoester 13 in a 96% overall yield (Scheme 1). Reac-

was acetylated in pyridine with Ac₂O, giving 75% of pyrano tions between TMSBr and peracetylated sugars are gener-

derivatives 11 together with 25% of furano derivatives ally performed at 80 °C or require the presence of bis-

(Scheme 1). These were separated by chromatography, and muth() salts to catalyse the reaction.^[43]In the current

the furano derivatives were recycled by deacetylation and case, however, the transformation of 11 or its -gluco dia-

reacetylation, giving a combined yield of 80% for 11α/11β stereomer (data not shown) is complete after 2 h at room

as a 15:85 mixture. Formation of 11β as the major anomer temp., revealing a greater reactivity of 6-C-vinylic deriva-

is consistent with results obtained previously in the acety- tives such as 11 with respect to their 6-O-acetylated

lation of 18 and is further supported by NMR spectro- counterparts. The synthesis of 4 was then further completed

scopic data.^[28]We then opted for the formation of a 1,2- in a few high-yielding steps. The orthoester 13 was first de-

´

orthoester to perform the differentiation of position 4 from acetylated under Zemplen conditions, and the resulting al-

1 and 2 (Scheme 1). Our first strategy was based on the cohol was alkylated with NaH and p-methoxybenzyl bro-

preparation of hemiacetal 12 and its conversion into an an- mide, giving orthoester 14 in quantitative yield (Scheme 1).

omeric halide. Unexpectedly, the selective anomeric de- The vinylic moiety in 13 allowed the use of these standard,

acetylation of 11 proved to be problematic: the classical and high-yielding, alkylation conditions, which, had uronic

methods with use of hydrazine acetate^[29]or benzylamine^[30]derivatives been used, would have resulted in β-eliminations

resulted in the formation of the expected hemiacetal 12, and epimerisation. In such a case, alkylation with Ag₂O or

which degraded before completion of the reaction with for- under acidic conditions should be used. The latter con-

mation of excessively deacetylated product, hydrazone or ditions are incompatible with orthoester protection, while

Schiff base. More unusual methods, such as sodium me- the use of expensive Ag₂O is prohibitive with multigram

thoxide in THF^[31]or guanidine in methanol,^[32]also re- preparations of building blocks. Compound 14 was then

sulted in the formation of excessively deacetylated com- treated with ozone and NaOH in a CH₂Cl₂/MeOH mixture

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hyde 9, we have studied the addition of various carboxylate

precursors and shown that the addition of tris-phenylthi-

omethyllithium to 9 exclusively affords the -ido stereo-

isomer 16 (Scheme 2).^[27]This reaction is easily scalable to

100 g and allowed us to devise the most efficient route yet

described to the known iduronyl bromide 5.^[25]The tris-

[47,48]

phenylthioorthoester 16 was treated with CuO/CuCl₂

in a MeOH/H₂O/CH₂Cl₂mixture to give the known ester

17^[25]in 94% yield (Scheme 2). This reaction has been scaled

up to 39 g with comparable yields. In the earlier synthesis

of bromide 5 from 17,^[25]the 1,2-isopropylidene was cleaved

quantitatively with trifluoroacetic acid and the resulting

mixture was acetylated with Ac₂O in pyridine. Unfortu-

nately, this procedure afforded 40% of furanose derivatives,

which had to be separated from the pyrano compounds

19α/β by tedious chromatography. We have solved this prob-

lem by showing that the β-pyrano crystalline form of 18

may be trapped by acetylation if a solvent in which the crys-

tals are only sparingly soluble is used.^[49]Thus, on con-

ducting the reaction in dichloromethane at Ϫ40 °C, with

AcCl as acylating agent, pyridine as base, and DMAP as

catalyst, pure 19β was isolated in 83% yield by simple crys-

tallisation, while 9% additional α/β mixture could be reco-

vered by flash chromatography of the mother liquor

(Scheme 2). Thanks to its high isolated yield of pyrano de-

rivatives 19α/β (92%) and the simplicity of the workup pro-

cedure, this procedure is very attractive for large-scale syn-

thesis. Nearly quantitative conversion of 19α/β into anom-

eric bromide 5 was then performed with TiBr₄, as de-

scribed.^[25]The overall yield of this new synthesis is 72%

from commercial diacetone glucose, making this strategy

the most attractive route to the useful -iduronyl synthon 5

yet reported.

Scheme 1. a) H₂CϭCHMgBr, Et₂O, room temp., -Ido/-Glc

60:40, 93%; b) i. AcOH/H₂O 7:3, 80 °C; ii. Ac₂O, pyridine; 80%

after one recycling of the furano derivatives; c) PPL, nBuOH/

octane/HEPES pH 10, 0.2  CTAB; 74%; d) i. DMF, (COCl)₂,

CH₂Cl₂; ii. DMF dimethyl acetal, Bu₄NBr, CH₂Cl₂, reflux; 92%;

e) i. TMSBr, CH₂Cl₂; ii. DMF dimethyl acetal, CH₂Cl₂, reflux;

96%; f) i. MeONa, MeOH; ii. p-MeOPhCH₂-Br, NaH, DMF; qu-

ant; g) i. O₃, NaOH, MeOH/CH₂Cl₂, Ϫ78 °C; ii. AcOH/H₂O 9:1;

73%; h) i. O₃, Me₂S, CH₂Cl₂, Ϫ78 °C; ii. mCPBA, H₂O pH 7.3;

iii. pH 2; iv. CH₂N₂; 68%; i) Cl₃CCN, K₂CO₃, CH₂Cl₂; 92%

at Ϫ78 °C,^[44]giving the desired methyl ester with neither

β-elimination nor epimerisation. The 1,2-orthoester was

opened by use of a 90% aqueous AcOH solution, giving

hemiacetal 15 in a 73% overall yield (Scheme 1). Alterna-

tively, ozonolysis followed by a reductive workup with

Me₂S was performed on 14, giving an aldehyde that was

oxidized to the corresponding acid with mCPBA in aqueous

media at pH 7.^[27]The 1,2-orthoester was then opened by

reduction of the pH to 2, followed by esterification with

diazomethane, giving compound 15 in a 68% yield for the

four steps. Although this yield is slightly lower than that

obtained by the first method, it did establish the use of

mCPBA in water as an interesting reagent for the oxidation

of aldehydes to carboxylic acids, even on highly func-

tionalized molecules.^[45]The α/β mixture of hemiacetals 15

was then converted into imidate 4 in 92% yield (Scheme 1).

In this reaction, the kinetic β anomer appeared first, fol-

lowed by the α anomer and further equilibration to a 1:1

ratio. NMR further confirmed this attribution of the α and

β configuration.^[46]We have thus shown that the synthesis

of the iduronyl donor 4, in eight steps from the vinyl deriva-

tive 9, is efficient (52% global yield) and we have carried it

out routinely on 3Ϫ4 g scales.

Preparation of 2-Azidoglucosamine Acceptors 6 and 7

We devised a first access to the acceptors 6 and 7 from

α-allyl derivative 21, which was obtained in 88% isolated

Synthesis of Iduronyl Donor 5

The approach described above allows the preparation of

an iduronyl donor in which all the protecting groups needed

in the -iduronyl moiety of disaccharide building blocks 1

and 2, are already present. The preparation of the vinylic

precursor 9, however, suffers from low diastereoselectivity.

In order to improve the proportion of -ido derivative

Scheme 2. a) (PhS)₃CLi, THF, Ϫ78 °C, 92%; b) i. CuO, CuCl₂,

MeOH/H₂O/CH₂Cl₂, 94%; c) 9:1 CF₃COOH/H₂O then crystallis-

ation from EtOAc, 80Ϫ100%; d) AcCl, pyridine, DMAP, CH₂Cl₂,

formed in the addition of organometallic reagent to alde- Ϫ40 °C, 92%; e) TiBr₄, CH₂Cl₂, 95%

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yield from hemiacetal 20 by α-stereoselective anomeric al-

kylation^[50](Scheme 3). Compound 21 was N- and O-deace-

tylated by heating at reflux with aqueous Ba(OH)₂,^[51]giv-

ing the ammonium salt 22 after neutralisation with aqueous

sulfuric acid. Further treatment with the triflyl azide re-

agent^[52,53]gave 23, which was not isolated at this step, but

was converted into the 4,6-O-benzylidene derivative 24 in

70% isolated overall yield from 21 (Scheme 3). This first

preparation of 24 from 20 is efficient and may be applied

on several gram scales. However the synthesis of hemiacetal

20 requires chromatographic purifications, which became

unpractical on scales larger than 10 g. We thus turned to a

more classical Fischer glycosylation in order to prepare α-

allyl glucosaminyl starting material in larger quantities

(Scheme 4). The hydrochloride 25 was N-acetylated in water

and further allylated, as described previously, by use of allyl

alcohol and BF₃·Et₂O.^[54,55]This glycosylation is quantitat-

ive and may be scaled up to 1 kg.^[55]In our hands, unfortu-

nately, the diastereoselectivity of the reaction was only

90:10 in favour of the α anomer 26α. Moreover, although

several later intermediates in the synthesis of 6 and 7 are

crystalline, it was impossible to separate the β anomer. We

solved this problem by performing a kinetic resolution of

the α and β anomers of 26, taking advantage of the greater

reactivity of β anomers toward hydrolysis. Treatment of the

26α/β mixture with H^ϩresin in water at 70 °C allowed the

total hydrolysis of the β anomer, along with only minor

conversion of the α one. The remaining 26α was then N-

deacetylated with Ba(OH)₂, transformed into the azido de-

rivative 23 as described above, and directly converted into

the 4,6-O-benzylidene derivative 24, which was isolated in

50% overall yield from glucosamine hydrochloride 25. It is

worth noting that all the purifications throughout the whole

procedure could be performed by use of ion-exchange re-

sins, simple filtration on silica gel pads or crystallisation,

which allowed us to carry out this procedure on batches of

up to 80 g hydrochloride 25.^[56]Benzylation of compound

24 was then performed quantitatively by standard pro-

Scheme 3. a) AllBr, NaH, Bu₄NBr, CH₂Cl₂, Ϫ20 °C, 98:2 α/β, 88%

isolated α; b) i. Ba(OH)₂, H₂O, reflux; then neutralisation with

H₂SO₄; c) TfN₃, CuSO₄, CH₂Cl₂/MeOH/H₂O; d) PhCH(OMe)₂,

TsOH, CH₃CN; 70% from 21

Scheme 4. a) i. Ac₂O, NaHCO₃, H₂O; ii. AllOH, BF₃·Et₂O, reflux;

b) Dowex H^ϩ, H₂O, 70 °C; c) i. Ba(OH)₂, H₂O, reflux; then neu-

tralisation with H₂SO₄; ii. TfN₃, CuSO₄, CH₂Cl₂/MeOH/H₂O; ii-

i. PhCH(OMe)₂, TsOH, CH₃CN; 50% from glucosamine hydro-

chloride 25; d) BnBr, NaH, DMF, 99%; e) Dowex H^ϩ, MeOH, 40

°C, 99%; f) AcCl, pyridine, 0 °C; 95%; g) NaBH₃CN, HCl, Et₂O,

96%

cedures to give 28, which can be isolated by simple crystal- mation of a 1Ј,2Ј-trans glycoside was confirmed by the

lisation (Scheme 4). Compound 28 was then converted into measurement of an 1Ј-H/CЈ-1 J¹coupling constant of

acceptor 6 in two steps in 95% yield: first transacetalation 169 Hz in the non-decoupled ¹³C NMR spectra of disac-

of the benzylidene moiety in methanol with H^ϩresin as charide 1. Such a value is characteristic of the presence of

catalyst, to give the diol 29, then regioselective acetylation an equatorial hydrogen at the anomeric position of a pyran-

at C-6, with AcCl in pyridine at 0 °C.^[57]Alternatively 28 ose compound, and thus of an α configuration for an -

was converted into the benzylated acceptor 7 in 96% yield iduronyl glycoside.^[60]In addition, treatment of 1 with DDQ

by a regioselective reductive opening of the 4,6-O-benzylid- gave disaccharide 34, in which a hydrogen bond between

1

ene with HCl in Et₂O and NaBH₃CN.^[58][59]This reaction OH at CЈ-4 and OЈ-2 promotes a C₄conformation. The

can be scaled up to 10 g of 28 with comparable and repro- ¹H NMR spectrum of 34 (Scheme 6) reveals the presence

ducible yields.

of a J⁴W coupling constant of 1.0 Hz between 1Ј-H and

3Ј-H, which can only exist if the iduronyl moiety is α linked

to the 2-azidoglucose.

Preparation of L-Iduronyl Disaccharides 1 and 2

As shown above, the preparations of building blocks 4Ϫ7

Alternatively, coupling of the bromide 5 onto acceptors

have been optimized on multigram scales. We then studied 6 and 7 in CH₂Cl₂with AgOTf as catalyst gave disacchar-

condensation reactions between the iduronyl donors 4 and ides 30 and 31 in 75 and 81% yields, respectively^[61]

5 and the acceptors 6 and 7 (Scheme 5). The condensation (Scheme 5). Confirmation of the α stereochemistry of the

of the fully protected donor 4 onto acceptor 6 was per- newly created glycosidic linkages was acquired at a later

formed in CH₂Cl₂with TMSOTf as a catalyst, giving the stage in the synthesis. Like compound 1, disaccharide 30

target disaccharide building block 1 in 60% yield. The for- may be transformed into compound 34 (Scheme 6), the α

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conditions, the monoacetate 35 was obtained in 70% yield

after one recycling step (Scheme 6).^[65]The last step in these

syntheses is the introduction of the p-methoxybenzyl group

at the 4Ј position, but the presence of an uronic moiety

prevented us from performing this alkylation with NaH and

p-methoxybenzyl bromide. We thus turned to an acid-cata-

lysed alkylation through the use of p-methoxybenzyl trich-

loroacetimidate and BF₃·Et₂O.^[66][67]Although several sets

of reaction conditions were studied for this last step, it was

not possible to bring the reaction to completion without

degradation of the starting material. If, however, the reac-

tions were stopped around 65% conversion, disaccharides 1

˚

Scheme 5. a) TMSOTf, molecular sieves (4 A), CH₂Cl₂, 60%; b) Ag- and 2 were isolated in 63Ϫ65% yields and the unchanged

˚

OTf, molecular sieves (4 A), CH₂Cl₂, 0 °C, 75% for 30 and 81%

34 and 35 were recovered nearly quantitatively (Scheme 6).

It is worth noting that these incomplete reactions are not a

for 31

major disadvantage in the perspective of the preparation of

longer HS oligosaccharides, since 34 and 35 are disacchar-

ide acceptors for the formation of tetrasaccharides.

Preparation of Glucuronyl Disaccharide 3

The easily available acetobromoglucose 8 was condensed

with acceptor 7 in the presence of AgOTf in CH₂Cl₂at Ϫ40

°C, affording the disaccharide 36, which was deacetylated

´

under Zemplen conditions to give the disaccharide 37 in

80% overall yield (Scheme 7). The deacetylation step, per-

formed directly after extractive workup of the glycosylation

reaction, simplified the purifications, through the conver-

sion of the acetobromoglucose into water-soluble deriva-

tives, and allowed us to perform this reaction routinely on

10 g acceptor 7. As expected, the occurrence of a 7.5 Hz

coupling constant between 1Ј-H and 2Ј-H in the spectrum

of 36 confirmed the formation of a β glycoside. A 4Ј,6Ј-O-

Scheme 6. a) K₂CO₃, MeOH; b) i. Bu₂SnO, benzene, reflux;

ii. AcCl, NEt₃; c) pMBnOTCA, BF₃·Et₂O, Ϫ20 °C

configuration of which was discussed above. The disacchar- p-methoxybenzylidene moiety was then introduced in 89%

ide 31 may also be converted into disaccharide 35 yield, by use of p-anisaldehyde dimethyl acetal and catalytic

1

(Scheme 6), the H NMR spectrum of which also revealed camphorsulfonic acid, giving disaccharide 38, which was

the presence of a J⁴W coupling constant of 1.0 Hz between then benzylated quantitatively to give disaccharide 39

1Ј-H and 3Ј-H, indicating an α configuration for the idu- (Scheme 7). A regioselective reductive opening of the 4Ј,6Ј-

ronyl moiety. Further transformation of disaccharides 30 O-p-methoxybenzylidene was then used as the key step to

and 31 into the disaccharide building blocks 1 and 2 re- differentiate position 6Ј and 4Ј. PhBCl₂has recently been

quired similar protecting group manipulations (Scheme 6). introduced as a bulky Lewis acid for the coordination of

Both compounds were deacetylated under classical con- the C-6 oxygen of a benzylidene ring, to afford, with Et₃SiH

ditions, giving disaccharides 32 and 33 in 90% isolated as hydride donor, the regioisomer alkylated in the most

yields. To differentiate between position 4Ј and 2Ј, we sterically hindered position.^[68]In CH₂Cl₂and with a p-

turned to stannylene chemistry.^[62][63]Treatment of disac- methoxybenzylidene group, however, along with the ex-

charide 32 with Bu₂SnO and azeotropic removal of water pected 40 (38%), we also obtained the product 41 (39%)

resulted in the formation of a 2Ј,4Ј-stannylene, which al- resulting from the cleavage of the p-methoxybenzylidene

lowed 2Ј-regioselective acylation with AcCl. To perform group. In order to stabilize reactive charged intermediates,

acetylation of position 6 at the same time, 2.5 equiv. of we used a more polar solvent,^[69]conducting the reaction in

AcCl were used and NEt₃was added to maintain the pH Et₂O at Ϫ40 °C. Under these conditions, the disaccharide

as slightly basic. Under these conditions, the diacetate 34 40 was obtained in 91% yield (Scheme 7). The regioselectiv-

was formed as the major product, together with its 4Ј re- ity of the reductive opening of the p-methoxybenzylidene

gioisomer and triacetylated product. The by-products were group under this conditions was confirmed by the presence

deacetylated and reacetylated under the same conditions, of a triplet, corresponding to an exchangeable proton cou-

1

giving a combined yield of 75% for 34 (Scheme 6), the H pled to 6Ј-H^aand 6Ј-H^b, in the ¹H NMR spectrum of com-

NMR spectrum of which confirmed the regioselectivity of pound 40. The last step of the synthesis was performed by

the reaction.^[64]A similar procedure was used for the selec- a two-step methodology that we had already successfully

tive acetylation of diol 33, but in this case, only 1.2 equiv. used for the combinatorial preparation of a chondroitin sul-

of AcCl and no triethylamine were needed. Under these fate disaccharide library.^[17]The disaccharide 40 was oxid-

3608

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Eur. J. Org. Chem. 2003, 3603Ϫ3620

Building Blocks for the Synthesis of Heparan Sulfate Fragments

FULL PAPER

Gel 60 A.C.C. (6Ϫ35 µ). Melting points were determined with a

Büchi capillary apparatus and are uncorrected. Optical rotations

were measured on a Jasco DIP 370 digital polarimeter. NMR spec-

tra were recorded at room temp. with Bruker AC 200, AC 250, AM

250, AM 360, or DRX 400 spectrometers. Chemical shifts δ are

given in parts per million (ppm) relative to internal Me₄Si reference,

solvent signals (CDCl₃¹³C δ ϭ 77.0 ppm, [D₆]DMSO: ¹H δ ϭ

2.49 ppm, ¹³C δ ϭ 39.5 ppm) or acetone in D₂O (¹H δ ϭ 2.225 ppm

and ¹³C δ ϭ 30.5 ppm). The allyl group carbons are numbered in

the following way: ϪOϪC^aH₂ϪC^bHϭC^cH₂, the two protons on C-

c were numbered H-cc for the one cis to H-b, and H-ct for the one

ized, by Swern oxidation, to the corresponding aldehyde,

which was not isolated. The NMR of the crude mixture

after extraction revealed the presence of a single compound

with signals corresponding to an aldehyde proton (δ ϭ

8.95 ppm, d, J ϭ 1.5 Hz) and carbon (δ ϭ 196.9 ppm). This

product was then directly oxidized to the methyl ester with

I₂and methanolic KOH,^[17][70]giving disaccharide 3 in 79%

yield (Scheme 7). The synthesis of disaccharide building

block 3 was thus completed in 54% global yield from ac-

ceptor 7 and acetobromoglucose 8.

1

trans to H-b. For H spectra of iduronyl derivatives, apodisations

with Gaussian functions (LB ϭ Ϫ1 to Ϫ2 Hz and GB ϭ 50%) were

used, allowing measurement of coupling constants. COSY, gradient

enhanced COSY and HMQC were performed by recording 256

FIDs with 1024 complex data points by use of the standard Bruker

programs. Prior to Fourier transformation, the data were zero filled

in the t₁dimension to 1024 points and multiplied with a non-

shifted sinebell function in both dimensions for COSY; for HMQC,

a non-shifted sinebell function in t₂dimension and a non-shifted

squared sinebell function in the t₁dimension were used. MS spectra

were recorded in the positive mode on a Finnigan MAT 95 S by

electrospray ionization. Infrared spectra were recorded on a Four-

ier transform Bruker IFS66 apparatus. Elemental analyses were

performed at the CNRS (Gif sur Yvette, France).

Large-Scale Preparation of 3-O-Benzyl-1,2-O-isopropylidene-α-D-

xylo-dialdose (9): NaH (60% in oil, 13 g, 0.33 mol, 1.65 equiv.) was

added in portions to a cooled solution (0 °C) of commercial diace-

tone glucose (52 g, 0.20 mol) and benzyl bromide (35 mL, 0.30 mol,

1.50 equiv.) in DMF (500 mL). The temperature was then raised to

room temp. and the mixture was stirred for 2 h. The temperature

was then lowered to 0 °C and the reaction was quenched by ad-

dition of iPrOH (20 mL), followed by water (400 mL). The re-

sulting solution was extracted with Et₂O (3 ϫ 200 mL) and the

combined organic layers were washed with HCl (0.1 , 2 ϫ

100 mL), water (2 ϫ 100 mL), satd. aqueous NaHCO₃(2 ϫ

100 mL), and then water (2 ϫ 100 mL). The organic phase was

filtered through a silicon-treated filter and concentrated. Acetic

acid (60 mL) and water (60 mL) were added to the residue and the

mixture was stirred for 2 h at 50 °C. The solvents were then evapo-

rated, the remaining traces of acetic acid were removed by coevap-

oration with toluene, and the residue was purified by chromatogra-

˚

Scheme 7. a) AgOTf, molecular sieves (4 A), CH₂Cl₂, Ϫ40 °C;

b) MeONa, MeOH; 80% from 7; c) pMeOPhCH(OMe)₂, TsOH,

CH₃CN, 89%; d) BnBr, NaH, DMF, 97%; e) PhBCl₂, Et₃SiH,

CH₂Cl, Ϫ40 °C, 38% of 40 and 39% of 41; f) PhBCl₂, Et₃SiH,

Et₂O, Ϫ40 °C, 91% of 40; g) i. (COCl)₂, DMSO, CH₂Cl₂, Ϫ78 °C;

then NEt₃, Ϫ78 to Ϫ20 °C; ii. I₂, KOH, MeOH; 79%

Conclusion

We have designed and developed the preparation of the

monosaccharide building blocks 4Ϫ7 in multigram scale

syntheses. These compounds were used to optimize efficient phy (petroleum ether/EtOAc, 9:1 to 3:7) to give 3-O-benzyl-1,2-O-

isopropylidene-α--glucofuranose (60.7 g, 98% for the two steps).

This compound (0.196 mol) was dissolved in CH₂Cl₂(400 mL),

and water (300 mL) was then added, followed by NaHCO₃(5.04 g,

0.03 mol, 0.3 equiv.) and Bu₄NHSO₄(6.7 g, 0.02 mol, 0.1 equiv.).

The resulting mixture was cooled (0 °C) and NaIO₄(88 g, 0.4 mol,

2 equiv.) was added in portions over 30 min with vigorous mechan-

ical stirring. The temperature was raised to room temp. and, after

3 h stirring, the mixture was decanted. The aqueous phase was ex-

tracted with CH₂Cl₂(3 ϫ 100 mL), the combined organic layers

were filtered and concentrated, and the residue was dissolved in

1 L Et₂O. The resulting solution was washed with water (4 ϫ

500 mL), dried (MgSO₄), filtered, and concentrated, giving 9

(51.7 g, 95%) which was used without further purification. IR (thin

film, cm^Ϫ1): ν˜ ϭ 1735 (ν_CϭO), 1450, 1372. ¹H NMR (250 MHz,

CDCl₃, ppm): δ ϭ 9.64 (d, J_CHO,5ϭ 1.5 Hz, 1 H, CHO), 7.24Ϫ7.30

synthesis of disaccharides 1Ϫ3, which are essential building

blocks for the combinatorial synthesis of HS fragments we

are currently developing. In this context, we have already

prepared oligosaccharides from the heparin regular region

up to the hexadecasaccharide from disaccharide 1,^[24]while

oligomerisations of the building blocks 2 and 3 are cur-

rently under investigation and will be reported in due co-

urse.

Experimental Section

General Remarks: All moisture-sensitive reactions were performed

under argon atmospheres in oven-dried glassware. All solvents were

dried over standard drying agents^[71]and freshly distilled prior to

use. Evaporations were performed under reduced pressure. Reac-

tions were monitored by TLC on glass Silica Gel 60 F₂₅₄plates

with detection by UV at 254 nm and by charring with 5% ethanolic

H₂SO₄. Flash column chromatography was performed on Silica

(m, 5 H, Ph), 6.11 (d, J_1,2ϭ 4.0 Hz, 1 H, 1-H), 4.64 (d, J_2,1

ϭ

4.0 Hz, 1 H, 2-H), 4.60 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.59 (d, J ϭ

12.0 Hz, 1 H, CH₂Ph), 4.50Ϫ4.63 (m, 4-H), 4.33 (d, J_3,4ϭ 4.0 Hz,

1 H, 3-H), 1.45 and 1.30 (2 s, 2 ϫ 3 H, CH₃). C₁₅H₁₈O₅(278.3 g/

mol).

Eur. J. Org. Chem. 2003, 3603Ϫ3620

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3609

´

D. Bonnaffe et al.

FULL PAPER

1,2,4-Tri-O-acetyl-3-O-benzyl-6,7-dideoxy-α,β-

L

-ido-hepta-6-eno-

CH₃OAc). ¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 170.3, 170.0

(CϭO), 137.0 (C_{quaternary,arom}), 132.9 (C-6), 128.3, 128.0, 127.5 (C_a-

_rom), 117.8 (C-7), 91.6 (C-1), 73.8, 73.3, 72.7 (CH₂Bn), 68.1, 20.7,

20.6 (CH₃OAc). C₁₈H₂₂O₇(350.4 g/mol): calcd. C 61.71, H 6.33,

O 31.96; found C 61.72, H 6.41, O 32.18.

pyranose (11): Compound 10^[27,72](6.30 g, 29.1 mmol) was dis-

solved in aqueous AcOH (70%, 75 mL), and the solution was

heated for 12 h at 80 °C and concentrated. Acetic anhydride

(50 mL) was then added to a cooled (0 °C) solution of the residue

in pyridine (50 mL). After 16 h stirring at room temp., the mixture

was concentrated, residual volatile materials were coevaporated

with toluene, and the residue was dissolved in CH₂Cl₂(200 mL).

The solution was washed with HCl (0.1 , 2 ϫ 100 mL), water (2

ϫ 100 mL), satd. aqueous NaHCO₃(2 ϫ 100 mL), and again water

(2 ϫ 100 mL). The organic phase was filtered through a silicon-

treated filter and concentrated. Flash chromatography of the resi-

due (CH₂Cl₂/Et₂O, 99:1 to 9:1) gave 11 (7.67 g), as a 15:85 α/β

mixture, together with (5S)-1,2,5-tri-O-acetyl-3-O-benzyl-5-C-vi-

4-O-Acetyl-3-O-benzyl-6,7-dideoxy-1,2-(1-methoxyethylidene)-β-L-

ido-hepta-6-enopyranose (13). Synthesis from Hemiacetal 12: DMF

(2.6 mL, 32 mmol, 3.0 equiv.) was added to a solution of com-

pound 12 (3.90 g, 11.1 mmol) in CH₂Cl₂(100 mL), followed by

oxalyl chloride (9.7 mL, 111 mmol, 10 equiv.). After 14 h stirring

at room temp., the solution was poured into a mixture of Et₂O

(500 mL), satd. aqueous NaHCO₃(300 mL), and crushed ice

(100 g), and the aqueous phase was quickly extracted with ice-cold

Et₂O (100 mL). The combined organic phases were washed with

ice-cold water (2 ϫ 100 mL), dried (MgSO₄), filtered, concentrated,

and the residual water was coevaporated with toluene. DMF di-

methyl acetal (7.3 mL, 55 mmol, 5 equiv.) and Bu₄NBr (3.6 g,

11.1 mmol, 1 equiv.) were then added to a solution of the resulting

chloride in CH₂Cl₂(100 mL). After 20 h at reflux, the reaction mix-

ture was diluted with Et₂O (500 mL), washed successively with

satd. aqueous NaHCO₃(200 mL) and water (2 ϫ 200 mL), dried

(MgSO₄), filtered, and concentrated. The residue was generally

used directly in the next step, but could be purified by flash chro-

matography of the residue (petroleum ether/EtOAc, 95:5 to 85:15,

0.5% NEt₃) to give 13 (3.65 g, 90%) as one stereoisomer (presum-

nyl--arabino-pentofuranose (2.56 g).

A catalytic amount of

MeONa was added to a solution of the furano derivatives in

MeOH (30 mL). After 2 h at room temp., the reaction mixture was

neutralised with Dowex 50X8 200 H^ϩ, the resin was filtered off,

and the filtrate was concentrated and acetylated as described above,

giving another crop of 11 (1.46 g, combined yield 80%). IR (thin

film, cm^Ϫ1): ν˜ ϭ 3297 (ν_CϪH,arom.), 2098 (ν_CϪH,aliph.), 1745 (ν_CϭO),

1

1663 (ν_CϭC). H NMR of the major β anomer (250 MHz, CDCl₃,

ppm): δ ϭ 7.43Ϫ7.28 (m, 5 H, Ph), 6.14 (d J_1,2ϭ 2.0 Hz, 1 H, 1-

H), 5.83 (ddd, J_6,7tϭ 17.5, J_6,7cϭ 10.5, J_6,5ϭ 6.0 Hz, 1 H, 6-H),

5.38 (dt, J_7t,6ϭ 17.5, J_gemϭ J_7t,5ϭ 1.5 Hz, 1 H, 7-H^t), 5.25 (dt,

J_7c,6ϭ 10.5, J_gemϭ J_7c,5ϭ 1.5 Hz, 1 H, 7-H^c), 5.05 (ddd, J_2,3

ϭ

1

ably exo). H NMR (200 MHz, CDCl₃, ppm): δ ϭ 7.45Ϫ7.30 (m,

3.0, J_2,1ϭ 2.0, J_2,4ϭ 1.0 Hz, 1 H, 2-H), 4.88 (ddd, J_4,3ϭ 3.5,

J_4,5ϭ 2.0, J_4,2ϭ 1.0 Hz, 1 H, 4-H), 4.76 (d, J ϭ 12.5 Hz, 1 H,

CH₂Ph), 4.70 (d, J ϭ 12.5 Hz, 1 H, CH₂Ph), 4.65 (ddt, J_5,6ϭ 6.0,

J_5,4ϭ 2.0, J_5,7cϭ J_5,7tϭ 1.5 Hz, 1 H, 5-H), 3.89 (dd, J_3,4ϭ 3.5,

5 H, Ph), 5.80 (ddd, J_6,7tϭ 17.5, J_6,7cϭ 10.5, J_6,5ϭ 5.5 Hz, 1 H,

6-H), 5.55 (d, J_1,2ϭ 3.0 Hz, 1 H, 1-H), 5.37 (dt, J_7t,6ϭ 17.5, J_gemϭ

J_7t,5ϭ 1.5 Hz, 1 H, 7-H^t), 5.24 (dt, J_7c,6ϭ 10.5, J_gemϭ J_7c,5

ϭ

1.5 Hz, 1 H, 7-H^c), 4.84 (dt, J_4,3ϭ 3.0, J_4,5ϭ J_4,2ϭ 1.5 Hz, 1 H,

4-H), 4.78 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.66 (d, J ϭ 12.0 Hz, 1

H, CH₂Ph), 4.40 (dq, J_5,6ϭ 5.5, J_5,4ϭ J_5,7cϭ J_5,7tϭ 1.5 Hz, 1 H,

5-H), 4.08 (ddd, J_2,1ϭ 3.0, J_2,3ϭ 2.0, J_2,4ϭ 1.5 Hz, 1 H, 2-H),

4.04 (dd, J_3,4ϭ 3.0, J_3,2ϭ 2.0 Hz, 1 H, 3-H), 3.26 (s, 3 H, CH₃

OMe), 2.05 (s, 3 H, CH₃OAc), 1.73 (s, 3 H, CH₃orthoester). ¹³C

NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 170.6 (CϭO), 133.5 (C-6),

132.0 (C_{quaternary,arom}), 128.6, 128.2, 127.8 (C_arom), 123.8 (C quat.

orthoester), 117.7 (C-7), 96.5 (C-1), 76.2, 72.8, 72.2, 67.7, 49.0,

(CH₃OMe), 25.1 (CH₃orthoester), 20.8 (CH₃OAc). C₁₉H₂₄O₇

(364.4 g/mol).

J

_3,2ϭ 3.0 Hz, 1 H, 3-H), 2.13, 2.11, 2.06 (3 s, 3 ϫ 3 H, CH₃OAc).

¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 169.9, 169.8, 168.4 (Cϭ

O), 136.8 (C_{quaternary,arom}), 132.3 (C-6), 128.3, 128.0, 127.6 (C_arom),

118.5 (C-7), 90.0 (C-1) 74.8, 73.5, 72.8, 68.3, 66.6, 20.7, 20.6 (CH₃

OAc). C₂₀H₂₄O₈(392.4 g/mol): calcd. C 61.22, H 6.16, O 32.62;

found C 61.01, H 6.07, O 32.82.

2,4-Di-O-acetyl-3-O-benzyl-6,7-dideoxy-α,β-L-ido-Hepta-6-eno-

pyranose (12): HEPES buffer (50 m, pH 10, 7.5 mL) was added

to a solution of cetyltrimethylammonium bromide (0.2 , CTAB)

in octane/nBuOH, 8:2 (492.5 mL). Compound 11 (85:15 α:β mix-

ture, 9.79 g, 24.9 mmol) was dissolved in this reverse-micelle solu-

tion (400 mL) with the aid of an ultrasonic bath. An aqueous solu-

tion of PPL (250 mg/mL) was added in portions (3 mL) every 12

hours. After 6 days stirring on an orbital shaker, the precipitated

enzyme was filtered off with a paper filter and the reaction was

allowed to continue for an additional 6 days with periodical ad-

dition of PPL solution. The reaction mixture was then filtered

through a Celite 545 pad and concentrated. CTAB was precipitated

from the residue with acetonitrile and filtered off, and the filtrate

was concentrated. Flash chromatography of the residue (toluene/

Synthesis from Peracetate 11: TMSBr (13 mL, 111 mmol, 5 equiv.)

was added to a cooled (0 °C) solution of compound 11 (8.5 g,

22.1 mmol) in CH₂Cl₂(75 mL). After the mixture had been stirred

for 2 h at room temp., the solvent and excess reagent were evapo-

rated. DMF dimethyl acetal (14.8 mL, 111 mmol, 5 equiv.) was

then added to a solution of the crude bromide in CH₂Cl₂(200 mL).

The reaction mixture was heated at reflux for 12 hours, treated as

above and used directly in the next step.

3-O-Benzyl-6,7-dideoxy-4-O-(4-methoxybenzyl)-1,2-(1-methoxy-

EtOAc, 8:2 to 7:3) gave 12 (6.42 g, 74%) and a 1:1 α:β mixture of ethylidene)-β-

11 (2.42 g, 25%). A major anomer crystallised from Et₂O/petro- 0.57 mmol, 0.4 equiv.) was added to a solution of crude 13, ob-

leum (mp ϭ 123Ϫ125 °C). IR (thin film, cm^Ϫ1): ν˜ ϭ 3395, 3194

tained from 12 (1 g, 2.85 mmol), in methanol (10 mL). After 20 h

L-ido-hepta-6-enopyranose (14): MeONa (60 mg,

(3650Ϫ3050, ν_OϪH), 3030, 2982, 2954, 2929 (ν_CϪH), 1735 (ν_CϭO), stirring at room temp., the reaction mixture was concentrated, and

1455, 1374, 1227, 1158, 1037. ¹H NMR (crystalline anomer, the residual methanol was azeotropically removed with toluene.

250 MHz, CDCl₃, ppm): δ ϭ 7.45Ϫ7.25 (m, 5 H, Ph), 5.83 (ddd,

NaH (60% in oil, 240 mg, 6 mmol, 2.1 equiv.) was added to a co-

J

_6,7tϭ 17.0, J_6,7cϭ 10.5, J_6,5ϭ 5.5 Hz, 1 H, 6-H), 5.40 (dt, J_7t,6ϭ oled (0 °C) solution of the residue in DMF (10 mL). After the

17.0, J_gemϭ J_7t,5ϭ 1.5 Hz, 1 H, 7-H^t), 5.25 (dt, J_7c,6ϭ 10.5, J_gemϭ mixture had been stirred for 5 min at 0 °C, pMeOBnBr (1.04 g,

J_7c,5ϭ 1.5 Hz, 1 H, 7-H^c), 5.20 (dd, J_1,OHϭ 10.0, J_1,2ϭ 1.5 Hz, 1 5.2 mmol, 1.8 equiv.) was added and the reaction mixture was

H, 1-H), 4.92Ϫ4.83 (m, 2 H, 2-H, 4-H), 4.76 (d, J ϭ 12.0 Hz, 1 H, stirred for one hour at room temp. It was then quenched with iP-

CH₂Ph), 4.70 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.54 (dq, J_5,6ϭ 5.5, rOH (1 mL), followed by water (10 mL), and diluted with Et₂O

J_5,4ϭ J_5,7cϭ J_5,7tϭ 1.5 Hz, 1 H, 5-H), 3.91 (t, J_3,4ϭ J_3,2ϭ 3.0 Hz,

(100 mL). The organic phase was washed with water (3 ϫ 50 mL),

1 H, 3-H), 3.44 (d, J_OH,1ϭ 10.0 Hz, OH), 2.22, 2.02 (2 s, 2 ϫ 3 H,

dried (MgSO₄), filtered, and concentrated. Flash chromatography

3610

 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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Eur. J. Org. Chem. 2003, 3603Ϫ3620

Building Blocks for the Synthesis of Heparan Sulfate Fragments

FULL PAPER

of the residue (petroleum ether/EtOAc, 9:1 to 8:2, NEt₃0.5%) gave

14 (1.16 g, 92%) as one stereoisomer (presumably exo).

(t, J_3,2ϭ J_3,4ϭ 3.5 Hz, 0.4 H, H-3β), 3.90 (td, J_3,2ϭ J_3,4ϭ 4.0,

J_3,1ϭ 1.5 Hz, 0.6 H, H-3α), 3.87Ϫ3.70 (m, 7.4 H, including 2 s at

δ ϭ 3.79 and 3.74: 2 ϫ CH₃OMe), 2.03 (s, 1.2 H, CH₃OAc), 2.00

(s, 1.8 H, CH₃OAc). ¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ

170.8, 170.4, 169.8, 169.2 (CϭO), 159.1 (C-OMe, pMBn), 137.0,

136.7 (C_{quaternary,arom}), 134.4, 129.6, 129.5, 129.2, 129.1, 128.9,

128.5, 128.4, 128.2, 128.1, 128.0, 127.9 (C_arom), 113.5 (C_mpMBn),

93.1/91.8 (C-1), 74.1, 73.2, 72.9/72.5 (CH₂Bn or pMBn), 72.1 (CH₂

Bn or pMBn), 71.4, 71.2, 68.4, 67.9, 55.1 (CH₃, Ph-OMe), 52.2/52.1

(CH₃, COOMe), 20.9 (CH₃OAc). C₂₄H₂₈O₉(460.5 g/mol): calcd. C

62.60, H 6.13, O 31.21; found C 62.01, H 6.26, O 30.61.

Note: pMeOBnBr was prepared from pMeOBnOH (750 µL,

6 mmol) by treatment with HBr (33% in AcOH, 7.5 mL). After

30 min at room temp., the mixture was concentrated, and the resi-

due was diluted with toluene (50 mL), washed with satd. aqueous

NaHCO₃(10 mL) and water (10 mL), filtered through a silica gel

pad eluted with toluene, and concentrated to give pMeOBnBr

(1.04 g, 84%).

Data for 14: [α]³_D⁰ϭ Ϫ31 (c ϭ 1.0, toluene). IR (thin film, cm^Ϫ1):

ν˜ ϭ 3063, 3027 (ν_CϪH,arom.), 2998, 2940, 2911, 2836 (ν_CϪH,aliph.),

1612, 1586, 1514, 1455, 1431, 1384, 1317, 1303, 1250, 1208, 1173,

Alternative Preparation of 15 by Ozonolysis and Oxidation of the

Intermediate Aldehyde with mCPBA in Water: Ozone was bubbled

through a cooled (Ϫ78 °C) solution of orthoester 14 (177 mg,

0.4 mmol) in CH₂Cl₂(4 mL) until the colour tuned to a permanent

blue. The excess ozone was then eliminated by bubbling argon, and

dimethyl sulfide (300 µL, 4 mmol, 10 equiv.) was added. The tem-

perature was raised to room temp. over 3 h and the solvent was

evaporated. mCPBA (200 mg, 0.8 mmol, 2 equiv.) was then added

to a suspension of the residue in phosphate buffer (pH, 7.3, 1 ,

7 mL). After two hours under vigorous stirring, the reaction was

quenched with an aqueous Na₂S₂O₃solution (1 , 800 µL) and the

pH was lowered to 2 by careful addition of aqueous H₂SO₄(1 ).

The mixture was stirred for 15 min at room temp. and then ex-

tracted with EtOAc (3 ϫ 5 mL). The combined organic layers were

filtered through a silicon-treated filter and concentrated. A freshly

prepared ethereal solution of diazomethane (6 mL) was added to a

solution of the residue in Et₂O (2 mL). After destruction of the

excess diazomethane with AcOH, the solvent was evaporated and

the residue was purified as described above, giving 15 (126 mg,

68%).

1

1152. H NMR (250 MHz, CDCl₃, ppm): δ ϭ 7.40Ϫ7.25 (m, 5 H,

Ph), 7.21 (d, J ϭ 8.5 Hz, 2 H, Ph-OMe), 6.84 (d, J ϭ 8.5 Hz, 2 H,

Ph-OMe), 5.96 (ddd, J_6,7tϭ 17.0, J_6,7cϭ 10.5, J_6,5ϭ 6.0 Hz, 1 H,

6-H), 5.52 (d, J_1,2ϭ 3.0 Hz, 1 H, 1-H), 5.35 (dt, J_7t,6ϭ 17.0, J_gemϭ

J_7t,5ϭ 1.5 Hz, 1 H, 7-H^t), 5.23 (dt, J_7c,6ϭ 10.5, J_gemϭ J_7c,5

ϭ

1.5 Hz, 1 H, 7-H^c), 4.61 (d, J ϭ 11.5 Hz, 1 H, CH₂Ph), 4.55 (d,

ϭ 11.5 Hz, 1 H, CH₂Ph), 4.53 (d, J ϭ 11.5 Hz, 1 H,

CH₂PhOMe), 4.38 (d, J ϭ 11.5 Hz, 1 H, CH₂PhOMe), 4.24 (dq,

_5,6ϭ 6.0, J_5,4ϭ J_5,7cϭ J_5,7tϭ 1.5 Hz, 1 H, 5-H), 4.13 (ddd, J_2,1ϭ

J

3.0, J_2,3ϭ 2.0, J_2,4ϭ 1.0 Hz, 1 H, 2-H), 4.05 (dd, J_3,4ϭ 3.0, J_3,2ϭ

2.0 Hz, 1 H, 3-H), 3.80 (s, 3 H, CH₃OMe pMBn), 3.34 (ddd, J_4,3ϭ

3.0, J_4,5ϭ 1.5, J_4,2ϭ 1.0 Hz, 1 H, 4-H), 3.28 (s, 3 H, CH₃OMe

orthoester), 1.68 (s, 3 H, CH₃orthoester). ¹³C NMR (62.5 MHz,

CDCl₃, ppm): δ ϭ 159.1 (C-OMe, pMBn), 137.3 (C_{quaternary,arom}),

134.7 (C-6), 130.0, 129.1, 128.5, 128.0, 127.7 (C_arom), 123.8 (C quat.

orthoester), 117.1 (C-7), 113.5 (C_mpMBn), 96.7 (C-1), 76.5, 73.8,

72.5, 72.4 (CH₂Bn or pMBn), 72.1, 71.5 (CH₂Bn or pMBn), 55.1

(CH₃Ph-OMe), 48.9, (CH₃OMe orthoester), 25.0 (CH₃orthoes-

ter). C₂₅H₃₀O₇(442.5 g/mol): calcd. C 67.86, H 6.83; found C

68.11, H 6.92.

Methyl 2-O-Acetyl-3-O-benzyl-4-O-(4-methoxybenzyl)-α,β-

ranuronate Trichloroacetimidate (4): Trichloroacetonitrile (4.0 mL,

ronate (15): Ozone was bubbled through a cooled (Ϫ78 °C) solution 41 mmol, 6.0 equiv.) and K₂CO₃(1.67 g, 13.6 mmol, 2.0 equiv.)

L-idopy-

Methyl 2-O-Acetyl-3-O-benzyl-4-O-(4-methoxybenzyl)-L-idopyranu-

of orthoester 14 (2.7 g, 6.1 mmol) in a mixture of CH₂Cl₂(170 mL)

and methanolic NaOH (2.5 , 50 mL, 125 mmol, 20 equiv.).^[44]The

solution turned dark orange, which slowly faded and turned to

typical ozone blue after 4 h. TLC (toluene/EtOAc, 9:1, R_f14ϭ 0.60)

indicated that the intermediate aldehyde (R_fϭ 0.33) was formed

first, followed by the ester (R_f15ϭ 0.45). Ozone was bubbled

through the solution until completion of the reaction. A mixture of

aqueous KH₂PO₄solution (1 , 115 mL), satd. aqueous NaHCO₃

solution (20 mL) and satd. aqueous Na₂S₂O₃solution (50 mL) was

then poured onto the cold (Ϫ78 °C) reaction mixture. After warm-

were added to a solution of compound 15 (3.13 g, 6.9 mmol) in

CH₂Cl₂(12 mL). TLC (toluene/acetone, 8:2) showed that the β an-

omer (R_fϭ 0.73) appeared first, followed by the α anomer (R_fϭ

0.63). After 6 h stirring at room temp. the reaction mixture was

directly applied to the top of a flash chromatography column and

eluted (toluene/EtOAc, 95:5 to 8:2, 0.1% NEt₃), giving 4 (3.85 g,

92%) as a 1:1 α/β mixture. Data for the α anomer: ¹H NMR

(250 MHz, CDCl₃, ppm): δ ϭ 8.64 (s, 1 H, NH), 7.42Ϫ7.27 (m, 5

H, Ph), 7.10 (d, J ϭ 8.5 Hz, 2 H, Ph-OMe), 6.82 (d, J ϭ 8.5 Hz, 2

H, Ph-OMe), 6.40 (t, J_1,2ϭ J_1,3ϭ 1.3 Hz, 1 H, 1-H), 5.11 (dt,

ing to room temp., the aqueous phase was extracted with EtOAc J_2,3ϭ 3.0, J_2,1ϭ J_2,4ϭ 1.3 Hz, 1 H, 2-H), 4.94 (d, J ϭ 2.5 Hz, 1

(3 ϫ 200 mL). The combined organic phases were filtered through

a silicon-treated filter and concentrated. The resulting oil was dis-

H, 5-H), 4.74 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.57 (d, J ϭ 12.0 Hz,

1 H, CH₂Ph), 4.45 (d, J ϭ 11.5 Hz, 1 H, CH₂PhOMe), 4.36 (d,

solved in aqueous AcOH (90%, 150 mL) and the reaction mixture J ϭ 11.5 Hz, 1 H, CH₂PhOMe), 3.90 (ddd, J_3,4ϭ 3.5, J_3,2ϭ 3.0,

was stirred for 45 min at room temp. and concentrated. Flash chro- J_3,1ϭ 1.3 Hz, 1 H, 3-H), 3.81 (ddd, J_4,3ϭ 3.5, J_4,5ϭ 2.5, J_4,2

ϭ

matography of the residue (toluene/EtOAc, 75:25 to 60:40) gave 15

(2.06 g, 73%). Data for the 60:40 α/β mixture: ¹H NMR (250 MHz,

CDCl₃, ppm): δ ϭ 7.43Ϫ7.25 (m, 5 H, Ph), 7.07 and 7.04 (d, J ϭ

8.5 Hz, 2 H, Ph-OMe), 6.81 and 6.80 (d, J ϭ 8.5 Hz, 2 H, Ph-

1.3 Hz, 1 H, 4-H), 3.79 (s, 3 H, CH₃OMe), 3.73 (s, 3 H, CH₃

OMe), 2.06 (s, 3 H, CH₃OAc). ¹³C NMR (62.5 MHz, CDCl₃,

ppm): δ ϭ 169.8, 169.0 (CϭO), 160.0 (CϭNH), 159.3 (C-OMe,

pMBn), 137.2 (C_{quaternary,arom}), 130.1, 128.3, 127.8, 127.7 (C_arom),

OMe), 5.33 (dt, J_1,OHϭ 9.0, J_1,2ϭ J_1,3ϭ 1.5 Hz, 0.6 H, H-1α), 113.6 (C_mpMBn), 95.3 (C-1), 94.3 (CCl₃), 73.0, 72.0 (2 ϫ C), 70.2,

5.12 (dd, J_1,OHϭ 11.5, J_1,2ϭ 2.0 Hz, 0.4 H, H-1β), 4.86 (d, J_5,469.7, 65.3, 55.1 (CH₃OMe pMBn), 52.2 (CH₃OMe ester), 20.8

3.0 Hz, 0.6 H, H-5α), 4.82Ϫ4.78 (m, 1 H, 2-H α and β), 4.71 (d, (CH₃OAc). Data for the β anomer: H NMR (250 MHz, CDCl₃,

J ϭ 11.5 Hz, 0.6 H, CH₂Ph), 4.68 (d, J ϭ 11.5 Hz, 0.4 H, CH₂Ph), ppm): δ ϭ 8.66 (s, 1 H, NH), 7.43Ϫ7.28 (m, 5 H, Ph), 7.08 (d, J ϭ

4.63 (d, J ϭ 11.5 Hz, 0.6 H, CH₂Ph), 4.58 (d, J ϭ 11.5 Hz, 0.4 H, 8.5 Hz, 2 H, Ph-OMe), 6.81 (d, J ϭ 8.5 Hz, 2 H, Ph-OMe), 6.20

CH₂Ph), 4.57 (d, J_5,4ϭ 2.0 Hz, 0.4 H, H-5β), 4.37 (d, J ϭ 11.0 Hz, (d, J_1,2ϭ 2.0 Hz, 1 H, 1-H), 5.22 (ddd, J_2,3ϭ 3.5, J_2,1ϭ 2.0, J_2,4ϭ

0.6 H, CH₂PhOMe), 4.33 (d, J ϭ 11.5 Hz, 0.4 H, CH₂PhOMe), 1.0 Hz, 1 H, 2-H), 4.69 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.67 (d,

4.32 (d, J ϭ 11.0 Hz, 0.6 H, CH₂PhOMe), 4.27 (d, J ϭ 11.5 Hz, J_5,4ϭ 2.5 Hz, 1 H, 5-H), 4.59 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.41

0.4 H, CH₂PhOMe), 4.18 (d, J_OH,1ϭ 9.0 Hz, 0.6 H, OH α), 3.98 (d, J ϭ 11.5 Hz, 1 H, CH₂PhOMe), 4.33 (d, J ϭ 11.5 Hz, 1 H,

ϭ

1

Eur. J. Org. Chem. 2003, 3603Ϫ3620

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´

D. Bonnaffe et al.

FULL PAPER

CH₂PhOMe), 3.95 (t, J_3,2ϭ J_3,4ϭ 3.5, 1 H, 3-H), 3.81Ϫ3.75 (m

of the mother liquor followed by flash chromatography gave ad-

including s at δ ϭ 3.78, 4 H, 4-H and CH₃OMe), 3.72 (s, 3 H, ditional 19α/β (1:2) mixture (0.5 g, combined yield in 19α/β: 92%).

CH₃OMe), 2.05 (s, 3 H, CH₃OAc). ¹³C NMR (62.5 MHz, CDCl₃,

ppm): δ ϭ 170.5, 168.0 (CϭO), 160.3 (CϭNH), 159.3 (C-OMe,

pMBn), 136.8 (C_{quaternary,arom}), 129.5, 128.4, 128.1, 127.9 (C_arom),

113.6 (C_mpMBn), 94.2 (C-1), 90.4 (CCl₃), 74.8, 73.0, 72.6, 72.2,

71.8, 65.7, 55.1 (CH₃, Ph-OMe), 52.2 (CH₃, COOMe), 20.8 (CH₃

OAc). C₂₆H₂₈Cl₃NO (604.9 g/mol).

C₁₈H₂₁BrO₈(424.4 g/mol).

Methyl 2,4-Di-O-acetyl-3-O-benzyl-L-idofuranuronyl Bromide (5):

TiBr₄(4.4 g, 12.1 mmol, 1.28 equiv.) was added to a solution of 19

(4 g, 9.43 mmol) in CH₂Cl₂(90 mL). The resulting mixture was

stirred for 5 h at room temp., diluted with CH₂Cl₂(100 mL), and

washed with ice-cold water (100 mL). The organic layer was filtered

through a Celite 545 pad, and the filtrate was filtered through a

Tris(thiophenyl) 3-O-Benzyl-1,2-O-isopropylidene-β-L-orthoidofur-

anuronate (16): nBuLi (195 mL of a 1.2  soln. in hexane, 0.274 phase silicon-treated filter and concentrated, giving 5 (3.95 g), the

mol, 1.2 equiv.) was added to a cooled (Ϫ78 °C), mechanically

stirred solution of tris(thiophenyl)methane (93.2 g, 0.274 mol, 1.3

equiv.) in THF (400 mL). Upon addition of nBuLi the colour

changed to bright yellow and a yellow solid then precipitated. After

the mixture had been stirred for 1.5 h at this temperature, a solu-

tion of 9 (57 g, 0.205 mol) in THF (400 mL) was added dropwise.

The mixture was stirred for 1 h at the same temperature and was

then allowed to come to room temp. overnight. Satd. aqueous

NH₄Cl (500 mL) was then added, and the aqueous phase was ex-

tracted with Et₂O (3 ϫ 400 mL). The combined organic layers were

washed with water (2*100 mL), dried (MgSO₄), filtered, and con-

centrated. Flash chromatography of the residue (petroleum ether/

analytical data for which were identical to those described pre-

viously.^[25]This compound was used without further purification.

C₂₀H₂₄O₁₀(445.3 g/mol).

Allyl 2-Azido-4,6-O-benzylidene-2-deoxy-α-D-glucopyranoside (24):

Acetic anhydride (10.4 mL, 0.11 mol, 1.1 equiv.) was added drop-

wise to a solution of glucosamine hydrochloride 25 (21.6 g, 0.1 mol)

and NaHCO₃(20.2 g, 0.24 mol, 2.4 equiv.) in water (250 mL). After

90 min at room temp., the mixture was concentrated to 50 mL,

passed through a Dowex 50X8 200 H^ϩcolumn (500 mL) and col-

Ϫ

lected into a batch of Dowex IX8 200 HCO₃(500 mL). The resin

was filtered off, the solution was concentrated, and the residue was

dried over P₂O₅at 40 °C under vacuum, giving a quantitative yield

of N-acetyl-glucosamine. Allyl alcohol (250 mL, 3.7 mol, 37 equiv.)

and BF₃·Et₂O (3.7 mL, 25 mmol, 0.25 equiv.) were successively ad-

ded to the crude N-acetyl-glucosamine, and the mixture was heated

at reflux overnight.^[54,55]The solution was then concentrated and

1

EtOAc, 9:1 to 8:2) gave 16 (116.7 g, 92%) the H and ¹³C data for

which were identical to those previously reported.^[27]C₃₄H₃₄O₇S₃

(618.8 g/mol).

Methyl 3-O-Benzyl-1,2-O-isopropylidene-β-L-idofuranuronate (17):

Methanol (1.33 L), CuO (8.53 g, 106.6 mmol, 1.7 equiv.), CuCl₂dried over P₂O₅, giving a quantitative yield of 26α/β as an 90:10 α/

(32.0 g, 237.0 mmol, 3.8 equiv.), and water (115 mL) were success-

ively added to a solution of compound 16 (38.9 g, 63.4 mmol) in

β mixture. ¹³C NMR (62.9 MHz, D₂O, ppm): δ ϭ 174.6 (CϭO),

133.9 (C-b α), 133.6 (C-b β), 118.3 (C-c β), 118.1 (C-c α), 100.3 (C-

CH₂Cl₂(115 mL). The reaction mixture was vigorously shaken for 1 β), 96.3 (C-1 α), 76.1 (β), 74.1 (β), 72.1, 71.2, 70.6 (β), 70.2, 68.6,

2 h, filtered through a Celite 545 pad and concentrated without

warming above 30 °C. The residue was dissolved in CH₂Cl₂(1 L),

and water (500 mL) was added, giving a Cu salt precipitate that

was eliminated by filtration through a Celite 545 pad. After decan-

tation, the aqueous layer was extracted with CH₂Cl₂(2 ϫ 250 mL).

The combined organic layers were washed with a satd. aqueous

NaHCO₃solution (200 mL) and water (200 mL), filtered through

a silicon-treated filter, and concentrated. Flash chromatography of

the residue (toluene followed by petroleum ether/EtOAc, 7:3 to 1:1)

61.0, 60.8, 55.7 (C-2 β), 53.9 (C-2 α), 22.4 (CH₃, NHAc β), 22.1

(CH₃, NHAc α). C₁₁H₁₉NO₆(488.2 g/mol).

Dowex 50X8 200 H^ϩ(11 g) was added to a solution of crude 26α/

β in water (100 mL), and the mixture was heated at 70 °C. The

hydrolysis of the β anomer was followed by ¹³C NMR with refer-

ence to the β anomeric carbon signal at δ ϭ 100.1 ppm and was

complete after 15 h at 70 °C. The mixture was cooled to room

temp., the resin was filtered off, and the filtrate was neutralised

with Dowex IX8 200 HCO₃^Ϫ. The resin was filtered off and the

filtrate was concentrated to 400 mL, Ba(OH)₂·8H₂O (56.8 g, 0.18

mol, 1.8 equiv.) was then added, and the mixture was heated at

reflux overnight.^[51]The brown solution was cooled to 0 °C and

1

gave 17 (19 g, 89%), the H and ¹³C NMR spectra of which were

identical to those previously reported.^[25]C₁₇H₂₂O₇(338.4 g/mol).

Methyl 3-O-Benzyl-L-idofuranuronate (18): Compound 17 (15.4 g,

45.5 mmol) was dissolved in a mixture of trifluoroacetic acid neutralised with sulfuric acid (3 ), and the precipitated barium

(85.5 mL) and water (9.5 mL). After 20 min stirring at room temp.,

the solvents were evaporated and the resulting solution was coeva-

sulfate was removed by centrifugation. The collected supernatant

was concentrated, giving crude 22 as

a

brown oil. ¹H

porated with water (3 ϫ 30 mL). The residue was crystallised from NMR(250 MHz, D₂O, ppm): δ ϭ 5.99 (dddd, J_b,ctϭ 17.0, J_b,cc

ϭ

EtOAc, to which the minimum pyridine necessary to reach neu-

trality has been added, giving a quantitative yield of 18 (13.5 g),

the analytical data for which were identical to those described pre-

viously.^[25]C₁₄H₁₈O₇(298.3 g/mol).

10.5, J_b,aЈϭ 6.0, J_b,aϭ 5.0 Hz, 1 H, H-b), 5.37 (dq, J_ct,bϭ 17.0,

J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.27 (dq, J_cc,bϭ 10.5,

J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-cc), 4.92 (d, J_1,2 ϭ 3.5 Hz,

1 H, 1-H), 4.24 (ddt, J_gemϭ 13.0, J_a,bϭ 5.0, J_a,ccϭ J_a,ctϭ 1.5 Hz,

1 H, H-a), 4.05 (ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz,

Methyl 1,2,4-Tri-O-acetyl-3-O-benzyl-α,β-L-idofuranuronate (19):

1 H, H-aЈ), 3.90Ϫ3.65 (m, 3 H, 5-H, 6-H^a, 6-H^b), 3.55 (dd, J_3,2

ϭ

2,4-Dimethylaminopyridine (172 mg, 1.4 mmol, 0.1 equiv.), pyri-

dine (11.3 mL, 141 mmol, 10 equiv.) and acetyl chloride (6 mL,

84.6 mmol, 6 equiv.) were added to a cooled (Ϫ40 °C) suspension

of crystalline 18 (4.2 g, 14.1 mmol) in CH₂Cl₂(70 mL). After 10 h

stirring at this temperature, the mixture was diluted with dichloro-

methane (200 mL) and the resulting organic phase was washed with

saturated NaHCO₃solution (3 ϫ 50 mL), water (2 ϫ 50 mL),

10.0, J_3,4ϭ 9.5 Hz, 1 H, 3-H), 3.38 (t, J_4,3ϭ J_4,5ϭ 9.5 Hz, 1 H,

4-H), 2.72 (dd, J_2,3ϭ 10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H).

A solution of triflyl azide in CH₂Cl₂was prepared as de-

scribed,^[52,53]from NaN₃(65 g, 1 mol) and triflic anhydride (36 mL,

0.21 mol) [Caution: TfN₃is reported to be explosive when dry].

This solution was added dropwise, over 50 min, to a cooled (0 °C)

H₂SO₄(1 , 3 ϫ 50 mL), and water (3 ϫ 50 mL), filtered through solution of crude 22, K₂CO₃(20.7 g, 0.15 mol) and CuSO₄

a phase separator filter, and concentrated. The residue was crystal- (160 mg, 1 mmol) in water (100 mL) and MeOH (150 mL). MeOH

lised from Et₂O, giving 19β (5.0 g, 11.7 mmol, 83%). Evaporation (up to 250 mL) was added during the addition to keep the system

3612

 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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Eur. J. Org. Chem. 2003, 3603Ϫ3620

Building Blocks for the Synthesis of Heparan Sulfate Fragments

FULL PAPER

monophasic. The reaction mixture was then stirred overnight at Allyl 2-Azido-3-O-benzyl-4,6-O-benzylidene-2-deoxy-α-

D-glucopyr-

room temp. and BuNH₂(30 mL, 0.30 mol) was added. After three

hours stirring, the reaction mixture was adsorbed on silica gel

(70Ϫ200 µ, 130 mL) and filtered through a silica gel pad (600 mL,

EtOAc/MeOH, 98:2 to 50:50). The solvents were evaporated, the

anoside (28): Compound 24 (16.21 g, 48.7 mmol) was dried azeo-

tropically with toluene and dissolved in DMF (300 mL). NaH (60%

in oil, 3.12 g, 78.1 mmol, 1.6 equiv.) and benzyl bromide (8.7 mL,

73.2 mmol, 1.5 equiv.) were successively added to this cooled solu-

residue was eluted with water from a Dowex 50X8 200 H^ϩcolumn tion (0 °C). After 35 min stirring at this temperature, the reaction

(500 mL), and the fractions containing 23 were neutralised with

Dowex IX8 200 HCO₃^Ϫ. The resin was filtered off and the water

was evaporated, giving crude allyl 2-azido-2-deoxy-α--glucopyr-

mixture was quenched with iPrOH (10 mL), and water (10 mL) was

added. The solution was diluted with diethyl ether (500 mL) and

water (250 mL). The aqueous phase was further extracted with di-

anoside 23 (15.0 g). For purposes of characterisation, a small ethyl ether (2 ϫ 250 mL), and the combined organic layers were

amount of 23 was purified by flash chromatography (CH₂Cl₂/

washed with a 5% aqueous KH₂PO₄solution (250 mL) and water

MeOH, 9:1 to 8:2). [α]²_D⁹ϭ Ϫ124 (c ϭ 1.0, MeOH). IR (thin film, (2 ϫ 250 mL). The organic phase was dried (MgSO₄), filtered, and

cm^Ϫ1): ν˜ ϭ 3329 (3700Ϫ3000, ν_OϪH), 2924 (3750Ϫ3000, ν_CϪH), concentrated. Crystallisation from Et₂O/petroleum ether gave a

2099 (ν_N3), 1647, 1454, 1421, 1337. ¹H NMR (250 MHz, D₂O,

first crop of white crystals (16.0 g), and the mother liquor was con-

centrated. Flash chromatography of the residue (petroleum ether/

EtOAc, 95:5 to 8:2) followed by crystallisation gave an additional

ppm): δ ϭ 5.98 (dddd, J_b,ctϭ 17.5, J_b,ccϭ 10.5, J_b,aЈϭ 6.0, J_b,a

5.0 Hz, 1 H, H-b), 5.39 (dq, J_ct,bϭ 17.5, J_ct,aϭ J_ct,aЈϭ J_gem

1.5 Hz, 1 H, H-ct), 5.29 (dq, J_cc,bϭ 10.5, J_cc,aϭ J_cc,aЈϭ J_gem

ϭ

crop of 28 (4.3 g), giving a combined yield of 99%. m.p. 95 °C. [α]

29

1.5 Hz, 1 H, H-cc), 5.10 (d, J_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.24 (ddt,

_gemϭ 12.5, J_b,aϭ 5.0, J_cc,aϭ J_ct,aϭ 1.5 Hz, 1 H, H-a), 4.09 (ddt,

ϭ Ϫ67 (c ϭ 1.0, CH₂Cl₂). IR (KBr pellet, cm^Ϫ1): ν˜ ϭ 3096,

D

J

3070, 3037, 3012 (ν_CϪH,aliph), 2912, 2875 (ν_CϪH,aliph), 2107 (ν_N3),

J_gemϭ 12.5, J_b,aЈϭ 6.0, J_cc,aЈϭ J_ct,aЈϭ 1.5 Hz, 1 H, H-aЈ), 1497, 1453, 1371, 1308, 1233, 1214, 1175, 1127, 1088. ¹H NMR

3.91Ϫ3.65 (m, 4 H), 3.51 (dd, J_2,3ϭ 10.5, J_2,1ϭ 3.5 Hz, 1 H, 2-

(250 MHz, CDCl₃, ppm): δ ϭ 7.55Ϫ7.45 (m, 2 H, Ph), 7.45Ϫ7.25

H), 3.48 (t, J_3,2ϭ J_3,4ϭ 9.5 Hz, 1 H, 4-H). ¹³C NMR (62.9 MHz, (m, 8 H, Ph), 5.93 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.5, J_b,aЈϭ 6.0,

DMSO, ppm): δ ϭ 132.9 (C-b), 116.4 (C-c), 96.5 (C-1), 73.2, 70.9,

70.5, 67.1 (C-6), 63.0, 60.6 (C-2). C₉H₁₅N₃O₅(245.2 g/mol): calcd.

C 44.08, H 6.17, N 17.13; found C 44.57, H 6.32, N 16.52.

J_b,aϭ 5.0 Hz, 1 H, H-b), 5.59 (s, 1 H, CHPh), 5.35 (dq, J_ct,b

17.0, J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.25 (dq, J_cc,b

ϭ

10.5, J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-cc), 4.96 (d, J ϭ

11.0 Hz, 1 H, CH₂Ph), 4.94 (d, J_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.81 (d,

J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.28 (dd, J_6a,6bϭ 10.0, J_6a,5ϭ 4.5 Hz,

1 H, 6-H^a), 4.22 (ddt, J_gemϭ 13.0, J_a,bϭ 5.0, J_a,ccϭ J_a,ctϭ 1.5 Hz,

1 H, H-a), 4.11 (t, J_6b,6aϭ J_6b,5ϭ 10.0 Hz, 1 H, 6-H^b), 4.06 (ddt,

J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H, H-aЈ), 3.93

(td, J_5,6bϭ J_5,4ϭ 10.0, J_5,6aϭ 4.5 Hz, 1 H, 5-H), 3.76 (t, J ϭ

10.0 Hz, 1 H, 3-H or 4-H), 3.71 (t, J ϭ 10.0 Hz, 1 H, 3-H or 4-H),

3.41 (dd, J_2,3ϭ 10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H). ¹³C NMR

(62.5 MHz, CDCl₃, ppm): δ ϭ 137.8, 137.2 (2 C_{quaternary,arom}), 133.1

(C-b), 129.1, 128.5, 128.3, 128.2, 127.9, 126.0 (C_arom), 118.2 (C-c),

101.4 (CH-Ph), 97.4 (C-1), 82.8 (C-a), 76.2, 75.0, 68.8, 68.7, 63.0

(C-6), 62.8 (C-2). C₂₃H₂₅N₃O₅(423.5 g/mol): calcd. C 65.24, H

5.95, N 9.92, O 18.89; found C 64.95, H 5.96, N 9.98, O 18.63.

Benzaldehyde dimethyl acetal (13.7 mL, 91 mmol) and (Ϯ)-cam-

phorsulfonic acid (1.42 g, 6.1 mmol) were added successively to a

solution of crude compound 23 in acetonitrile (300 mL). The reac-

tion mixture was stirred for 8 hours and quenched by addition of

a satd. aqueous NaHCO₃solution (100 mL). The resulting solution

was then extracted with Et₂O (3 ϫ 200 mL), and the organic layers

were combined, washed with water (3 ϫ 150 mL), filtered through

a silicon-treated filter, dried (MgSO₄), filtered, and concentrated.

The residue was dissolved in the minimum of Et₂O, and crude 24

was precipitated by addition of petroleum ether. The solid reco-

vered after filtration (17.7 g) was dissolved in CH₂Cl₂, filtered

through a silica gel pad (petroleum ether/EtOAc/CH₂Cl₂, 75:15:10)

and concentrated. Crystallisation (Et₂O/petroleum ether) gave a Allyl 2-Azido-3-O-benzyl-2-deoxy-α-

first crop of 24 (14.3 g) as white crystals. Flash chromatography

50X8 200 H^ϩ(7.0 g) was added to a solution of compound 28

of the combined mother liquors (petroleum ether/EtOAc/CH₂Cl₂, (6.77 g, 16.0 mmol) in CH₂Cl₂(45 mL) and MeOH (190 mL). After

D-glucopyranoside (29): Dowex

90:5:5 to 75:15:10) and crystallisation gave another crop of 24

(2.3 g), thus corresponding to a combined yield of 50% from glu-

cosamine hydrochloride 25. m.p. 113 °C. [α]²_D⁸ϭ Ϫ117 (c ϭ 1.0,

24 h stirring at 40 °C, the mixture was filtered, neutralised with

solid NaHCO₃and again filtered, and the resulting solution was

concentrated. Flash chromatography of the residue (petroleum

CH₂Cl₂). IR (KBr pellet, cm^Ϫ1): ν˜ ϭ 3400 (3520Ϫ3100, ν_OϪH), ether/EtOAc, 8:2 to 1:1) gave compound 29 as an oil (5.27 g, qu-

3074, 3049, 3015, 2999, 2982 (ν_CϪH,arom), 2916, 2999, 2866 ant). [α]²_D⁹ϭ Ϫ112 (c ϭ 1.1, CH₂Cl₂). IR (thin film, cm^Ϫ1): ν˜ ϭ

(ν_CϪH,aliph), 2104 (ν_N3), 1452, 1427, 1373, 1327, 1309, 1269. ¹H 3411 (3600Ϫ3100, ν_OϪH), 3091, 3066, 3029 (ν_CϪH,aliph), 2924, 2874

NMR (250 MHz, CDCl₃, ppm): δ ϭ 7.55Ϫ7.45 (m, 2 H, Ph), (ν_CϪH,aliph), 2108 (ν_N3), 1497, 1454, 1408, 1349, 1333, 1259, 1209

1

7.45Ϫ7.35 (m, 3 H, Ph), 5.95 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.5, (ν_CϭC,arom). H NMR (250 MHz, CDCl₃, ppm): δ ϭ 7.35Ϫ7.30

J_b,aЈϭ 6.0, J_b,aϭ 5.0 Hz, 1 H, H-b), 5.56 (s, 1 H, CHPh), 5.37 (dq,

J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.27 (dq,

(m, 5 H, Ph), 5.94 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.5, J_b,aЈϭ 6.0,

J_b,aϭ 5.0 Hz, 1 H, H-b), 5.36 (dq, J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈ

ϭ

J_cc,bϭ 10.5, J_cc,aϭ J_cc,aЈ ϭ J_gemϭ 1.5 Hz, 1 H, H-cc), 4.98 (d, J_gemϭ 1.5 Hz, 1 H, H-ct), 5.25 (dq, J_cc,bϭ 10.5, J_cc,aϭ J_cc,aЈ

ϭ

J

_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.32Ϫ4.20 (m, 3 H, 6-H^a, 3-H, H-a), 4.07

J_gemϭ 1.5 Hz, 1 H, H-cc), 4.97 (d, J ϭ 11.5 Hz, 1 H, CH₂Ph), 4.96

(ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H, H-aЈ), (d, J_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.74 (d, J ϭ 11.5 Hz, 1 H, CH₂Ph),

3.91 (td, J_5,4ϭ J_5,6bϭ 9.5, J_5,6aϭ 4.5 Hz, 1 H, H-5), 3.74 (t, 4.22 (ddt, J_gemϭ 13.0, J_a,bϭ 5.0, J_a,ccϭ J_a,ctϭ 1.5 Hz, 1 H, H-

J_6b,5ϭ J_6b,6aϭ 9.5 Hz, 1 H, 6-H^b), 3.53 (t, J_4,3ϭ J_4,5ϭ 9.5 Hz, 1 a), 4.05 (ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H,

H, 4-H), 3.31 (dd, J_2,3ϭ 10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H), 2.66 (d,

H-aЈ), 3.92Ϫ3.75 (m, 3 H), 3.75Ϫ3.58 (m, 2 H), 3.31 (dd, J_2,3ϭ

J_OH,3ϭ 2.5 Hz, 1 H, OH). ¹³C NMR (62.5 MHz, CDCl₃, ppm): 10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H), 2.65 (br. s, 1 H, OH), 2.30 (br. s, 1

δ ϭ 136.8 (C_{quaternary,arom}), 133.0 (C-b), 129.3, 128.4, 126.2 (C_arom), H, OH). ¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 137.9 (C_quaternar-

118.1 (C-c), 102.0 (CHPh), 97.5 (C-1), 81.8 (C-a), 68.8 (C-3, C-4,

_y,arom), 133.1 (C-b), 128.6, 128.1 (C_arom), 118.1 (C-c), 96.9 (C-1),

C-5), 63.0 (C-6), 62.4 (C-2). C₁₆H₁₉N₃O₅(333.3 g/mol): calcd. C 80.0 (C-a), 75.1 (CH₂Ph), 71.3, 70.7, 68.5, 62.9 (C-6), 61.9 (C-2).

57.65, H 5.75, N 12.61, O 24.00; found C 57.58, H 5.69, N 12.74,

O 23.79.

C₁₆H₂₁N₃O₅(335.4 g/mol): calcd. C 57.38, H 6.31, N 12.53, O

23.85; found C 57.28, H 6.36, N 12.18, O 23.92.

Eur. J. Org. Chem. 2003, 3603Ϫ3620

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 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

3613

´

D. Bonnaffe et al.

FULL PAPER

Allyl 6-O-Acetyl-2-azido-3-O-benzyl-2-deoxy-α-

D

-glucopyranoside

(C-4), 70.2 (C-5), 69.3 (C-a), 68.1 (C-6), 62.5 (C-2). C₂₃H₂₇N₃O₅

(425.5 g/mol): calcd. C 64.93, H 6.49, N 9.88, O 18.90; found C

64.74, H 6.41, N 9.97, O 18.93.

(6): Diol 29 (6.90 g, 20.6 mmol) was azeotropically dried with tolu-

ene (200 mL). AcCl (1.64 mL, 23 mmol, 1.1 equiv.) was then added

dropwise to a cooled (0 °C) solution of this compound in pyridine

(100 mL). After overnight stirring at 0 °C, the reaction mixture was

quenched with MeOH (1 mL). The mixture was concentrated and

the residue was dissolved in Et₂O (500 mL). This solution was

washed with aqueous KH₂PO₄(2 , 100 mL), water (2 ϫ 100 mL),

satd. aqueous NaHCO₃(2 ϫ 100 mL), and finally water (2 ϫ

100 mL), dried (MgSO₄), filtered, and concentrated. Flash chroma-

tography of the residue (petroleum ether/EtOAc, 9:1 to 7:3) yielded

6 (7.34 g, 95%) as a colourless oil. [α]²_D⁹ϭ Ϫ121 (c ϭ 2.8, CH₂Cl₂).

IR (thin film, cm^Ϫ1): ν˜ ϭ 3431 (3600Ϫ3100, ν_OϪH), 3099, 3068,

3037 (ν_CϪH,arom), 2973, 2927, 2867 (ν_CϪH,aliph), 2109 (ν_N3), 1735,

Allyl [Methyl 2-O-acetyl-3-O-benzyl-4-O-(4-methoxybenzyl)-α-

idopyranosyluronate]-(1Ǟ4)-O-6-O-acetyl-2-azido-3-O-benzyl-2-

deoxy-α- -glucopyranoside (1). From 4 and 6: Imidate 4 (3.78 g,

L-

D

6.2 mmol) and acceptor 6 (4.7 g, 12.5 mmol, 2 equiv.) were azeo-

tropically dried with toluene and dissolved in CH₂Cl₂(15 mL).

˚

Powdered molecular sieve (4 A, 13.5 g) was added and the mixture

was then stirred for 30 min at room temp. TMSOTf (0.1  in

CH₂Cl₂, 9.4 mL, 0.94 mmol, 0.15 equiv.) was added and, after

5 min stirring, the reaction mixture was quenched with satd. aque-

ous NaHCO₃solution (20 mL), diluted with water (100 mL), and

extracted with EtOAc (3 ϫ 200 mL). The combined organic layers

were concentrated and the residue was purified by flash chromatog-

raphy (petroleum ether/CH₂Cl₂/EtOAc, 5:90:5 to 5:15:80), giving

compound 1 as a colourless oil (3.0 g, 60%), together with reco-

vered compound 6 (2 g). [α]²_D⁸ϭ 20 (c ϭ 1.0, CH₂Cl₂). IR (thin

film, cm^Ϫ1): ν˜ ϭ 3063, 3032 (ν_CϪH,arom), 2950, 2935 (ν_CϪH,aliph),

2109 (ν_N3), 1740 (ν_CϭO), 1613, 1514, 1455, 1439, 1373, 1303, 1244.

¹H NMR (400 MHz, CDCl₃, ppm): δ ϭ 7.52Ϫ7.36 (m, 10 H, Ph),

7.25 (d, J ϭ 8.5 Hz, 2 H, Ph-OMe), 6.96 (d, J ϭ 8.5 Hz, 2 H, Ph-

1

1658, 1455, 1376, 1257, 1146, 1091. H NMR (250 MHz, CDCl₃,

ppm): δ ϭ 7.45Ϫ7.30 (m, 5 H, Ph), 5.94 (dddd, J_b,ctϭ 17.0, J_b,ccϭ

10.5, J_b,aЈϭ 6.5, J_b,aϭ 5.5 Hz, 1 H, H-b), 5.35 (dq, J_ct,bϭ 17.0,

J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.25 (dq, J_cc,bϭ 10.5,

J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-cc), 4.96 (d, J_1,2ϭ 3.5 Hz, 1

H, 1-H), 4.93 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.82 (d, J ϭ 11.0 Hz,

1 H, CH₂Ph), 4.54 (dd, J_6a,6bϭ 12.5, J_6a,5ϭ 4.0 Hz, 1 H, 6-H^a),

4.21 (ddt, J_gemϭ 13.0, J_a,bϭ 5.5, J_a,ccϭ J_a,ctϭ 1.5 Hz, 1 H, H-

a), 4.17 (dd, J_6b,6aϭ 12.5, J_6b,5ϭ 2.5 Hz, 1 H, 6-H^b), 4.06 (ddt,

J_gemϭ 13.0, J_aЈ,bϭ 6.5, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H, H-aЈ), 3.87

(dd, J_3,2ϭ 10.0, J_3,4ϭ 8.5 Hz, 1 H, 3-H), 3.81 (ddd, J_5,4ϭ 10.0,

OMe), 6.06 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 11.0, J_b,aЈϭ 6.0, J_b,a

5.0 Hz, 1 H, H-b), 5.49 (dq, J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gem

1.5 Hz, 1 H, H-ct), 5.39 (dq, J_cc,bϭ 11.0, J_cc,aϭ J_cc,aЈϭ J_gem

ϭ

J_5,6aϭ 4.0, J_5,6bϭ 2.5 Hz, 1 H, 5-H), 3.48 (ddd, J_4,5ϭ 10.0, J_4,3ϭ

1.5 Hz, 1 H, H-cc), 5.38 (d, J_1Ј,2Јϭ 5.0 Hz, 1 H, 1Ј-H), 5.05 (d,

J_1,2ϭ 3.5 Hz, 1 H, 1-H), 5.02 (t, J_2Ј,3Јϭ J_2Ј,1Јϭ 5.0 Hz, 1 H, 2Ј-

H), 5.02 (d, J ϭ 10.5 Hz, 1 H, CH₂Ph), 4.83 (d, J ϭ 11.0 Hz, 1 H,

8.5, J_4,OHϭ 3.5 Hz, 1 H, 4-H), 3.34 (dd, J_2,3ϭ 10.0, J_2,1ϭ 3.5 Hz,

1 H, 2-H), 2.73 (d, J_OH,4ϭ 3.5 Hz, 1 H, OH), 2.12 (s, 3 H, CH₃

OAc). ¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 171.7 (CϭO),

137.8 (C_{quaternary,arom}), 133.0 (C-b), 128.6, 128.2, 128.1 (C_arom),

118.2 (C-c), 96.8 (C-1), 79.5 (C-a), 75.2 (CH₂Ph), 70.5, 70.0, 68.6,

62.8 (C-6, C-2), 20.8 (CH₃, OAc). C₁₈H₂₃N₃O₆(377.4 g/mol): calcd.

C 57.29, H 6.14, N 11.13; found C 56.96, H 6.15, N 10.71.

CH₂Ph), 4.82 (d, J ϭ 10.5 Hz, 1 H, CH₂Ph), 4.81 (d, J_5Ј,4Ј

ϭ

6.5 Hz, 1 H, 5Ј-H), 4.78 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.58 (d,

J ϭ 11.5 Hz, 1 H, CH₂PhOMe), 4.52 (d, J ϭ 11.5 Hz, 1 H,

CH₂PhOMe), 4.50 (dd, J_6a,6bϭ 12.5, J_6a,5ϭ 2.0 Hz, 1 H, 6-H^a),

4.36 (dd, J_6b,6aϭ 12.5, J_6b,5ϭ 3.5 Hz, 1 H, 6-H^b), 4.37 (ddt, J_gemϭ

Allyl 2-Azido-3,6-di-O-benzyl-2-deoxy-α-D-glucopyranoside (7):

13.0, J_a,bϭ 5.0, J_a,ccϭ J_a,ctϭ 1.5 Hz, 1 H, H-a), 4.17 (ddt, J_gem

ϭ

NaBH₃CN (1.196 g, 19.03 mmol, 8 equiv.) was added to a cooled

13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H, H-aЈ), 4.10 (dd, J_4,5ϭ

9.5, J_4,3ϭ 9.0, 1 H, 4-H), 4.02 (dd, J_3,2ϭ 10.0, J_3,4ϭ 9.0 Hz, 1

H, 3-H), 3.98 (ddd, J_5,4ϭ 9.5, J_5,6bϭ 3.5, J_5,6aϭ 2.0 Hz, 1 H, 5-

H), 3.95Ϫ3.90 (m, 4 H, containing s at δ ϭ 3.92, 4Ј-H and OMe),

3.88 (t, J_3Ј,2Јϭ J_3Ј,4Јϭ 5.0, 1 H, 3Ј-H), 3.66 (s, 3 H, OMe), 3.54

(dd, J_2,3ϭ 10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H), 2.20 (s, 3 H, CH₃OAc),

2.18 (s, 3 H, CH₃OAc). ¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ

170.7, 170.0, 169.8 (CϭO), 159.3 (C-OMe, pMBn), 137.9, 137.7

(C_{quaternary,arom}), 133.0 (C-b), 129.5, 129.3, 128.4, 128.1, 127.9,

127.8, 127.4 (C_arom), 118.2 (C-c), 113.7 (C_mpMBn), 97.9 (CЈ-1),

96.5 (C-1), 78.2 (C-3), 75.7 (C-4), 74.9 (CH₂Ph), 74.7 (CЈ-3), 74.4

(CЈ-4), 73.0 (CH₂Ph), 72.4 (CH₂pMBn), 70.5 (CЈ-5), 70.1 (CЈ-2),

69.1 (C-5), 68.6 (C-a), 63.1 (C-2), 62.0 (C-2), 55.2 (CH₃OMe

pMBn), 51.7 (CH₃, COOMe), 20.9, 20.7 (CH₃, OAc). C₄₂H₄₉N₃O₁₄

(819.9 g/mol): calcd. C 61.53, H 6.02, N 5.13, O 27.32; found C

61.22, H 5.96, N 4.97, O 27.04.

(0 °C) suspension of compound 28 (4.67 g, 11.3 mmol), molecular

˚

sieves (4 A, 12 g) and a spatula tip of methyl orange in THF (40

m L). A satd. ethereal HCl solution (ഠ 75 mL) was then added to

the reaction mixture until the solution became a persistent pink.

After 10 minutes at 0 °C, the reaction was quenched with a satd.

aqueous NaHCO₃solution (100 mL) and diluted with diethyl ether

(250 mL). The aqueous phase was extracted with Et₂O (100 mL)

and the combined organic layers were washed twice with water

(100 mL), dried (MgSO₄), filtered, and concentrated. Flash chro-

matography of the residue (petroleum ether/EtOAc, 8:2 to 6:4) gave

compound 7 (4.33 g, 90%) as a colourless oil. [α]²_D⁹ϭ 79 (c ϭ 1.1,

CH₂Cl₂). IR (thin film, cm^Ϫ1): ν˜ ϭ 3457 (3600Ϫ3200, ν_OϪH), 3086,

3062, 3032 (ν_CϪH,arom), 2916, 2868 (ν_CϪH,aliph), 2111 (ν_N3), 1496,

1

1453, 1363, 1332, 1262, 1051. H NMR (250 MHz, CDCl₃, ppm):

δ ϭ 7.50Ϫ7.28 (m, 10 H, Ph), 5.94 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.5,

J_b,aЈϭ 6.5, J_b,aϭ 5.0 Hz, 1 H, H-b), 5.34 (dq, J_ct,bϭ 17.0, J_ct,a

J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.24 (dq, J_cc,bϭ 10.5, J_cc,a

J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-cc), 4.95 (d, J_1,2ϭ 3.5 Hz, 1 H, 1-

ϭ

Allyl (Methyl 2,4-di-O-acetyl-3-O-benzyl-α-

(1Ǟ4)-O-6-O-acetyl-2-azido-3-O-benzyl-2-deoxy-α-

H), 4.93 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.80 (d, J ϭ 11.0 Hz, 1 H, ranoside (30): Bromide donor 5 (1.0 g, 2.2 mmol) and acceptor 6

L

-idopyranosyluronate)-

D

-glucopy-

CH₂Ph), 4.62 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.54 (d, J ϭ 12.0 Hz,

1 H, CH₂Ph), 4.22 (ddt, J_gemϭ 13.0, J_a,bϭ 5.0, J_a,ccϭ J_a,ct

1.5 Hz, 1 H, H-a), 4.05 (ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.5, J_aЈ,ccϭ J_aЈ,ctϭ

(1.2 g, 3.1 mmol, 1.4 equiv.) were azeotropically dried with toluene.

ϭ

Compound 4 was dissolved in CH₂Cl₂(20 mL) and transferred to

˚

a reaction flask containing 6 and powdered molecular sieves (4 A,

1.5 Hz, 1 H, H-aЈ), 3.92Ϫ3.66 (m, 4 H, 3-H, 4-H, 5-H, 6-H^a), 3.66 900 mg). The resulting mixture was stirred for 30 min at room

(dd, J_6b,6aϭ 10.0, J_6b,5ϭ 4.0 Hz, 1 H, 6-H^b), 3.36 (dd, J_2,3ϭ 10.0, temp. and then cooled to 0 °C, and AgOTf (203 mg, 792 mmol, 1.2

J_2,1ϭ 3.5 Hz, 1 H, 2-H), 2.48 (d, J_OH,4ϭ 2.5 Hz, 1 H, OH). ¹³C

NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 137.9, 137.5 (2 C_{quaternary,a-}

equiv.) was added. After 1.5 h stirring at this temperature, the reac-

tion mixture was diluted with CH₂Cl₂(50 mL), filtered through a

_rom), 133.1 (C-b), 128.5, 128.2, 127.6, 127.5, 127.1 (C_arom), 117.6 Celite 545 pad and concentrated. Flash chromatography of the resi-

(C-c), 96.6 (C-1), 79.6 (C-3), 74.6 (CH₂Ph), 73.3 (CH₂Ph), 71.6 due (petroleum ether/EtOAc, 7:3 to 3:7) gave disaccharide 30 (1.1 g,

3614

 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjoc.org

Eur. J. Org. Chem. 2003, 3603Ϫ3620

Building Blocks for the Synthesis of Heparan Sulfate Fragments

FULL PAPER

65%), together with recovered acceptor 6 (520 mg). [α]²_D⁹ϭ 19 (c ϭ

87%). [α]³_D⁰ϭ 47 (c ϭ 1.3, CH₂Cl₂). IR (thin film, cm^Ϫ1): ν˜ ϭ 3460

5.8, CH₂Cl₂). IR (thin film, cm^Ϫ1): ν˜ ϭ 3064, 3033 (ν_CϪH,arom), (3600Ϫ3100, ν_OϪH), 3087, 3065, 3032 (ν_CϪH,arom), 2949, 2926, 2856

2952, 2929, 2874 (ν_CϪH,aliph), 2110 (ν_N3), 1747 (ν_CϭO), 1455, 1438, (ν_CϪH,aliph), 2108 (ν_N3), 1741 (ν_CϭO), 1497, 1455, 1366, 1263, 1216,

1373, 1228. ¹H NMR (250 MHz, CDCl₃, ppm): δ ϭ 7.45Ϫ7.10 (m,

1154, 1105, 1043. ¹H NMR (250 MHz, CDCl₃, ppm): δ ϭ

7.45Ϫ7.10 (m, 10 H, Ph), 5.96 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.0,

10 H, Ph), 5.95 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.0, J_b,aЈϭ 6.0, J_b,a

5.0 Hz, 1 H, H-b), 5.37 (dq, J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gem

1.5 Hz, 1 H, H-ct), 5.28 (dq, J_cc,bϭ 10.0, J_cc,aϭ J_cc,aЈϭ J_gem

ϭ

J_b,aЈϭ 6.0, J_b,aϭ 5.0 Hz, 1 H, H-b), 5.37 (dq, J_ct,bϭ 17.0, J_ct,a

J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.26 (dq, J_cc,bϭ 10.0, J_cc,a

ϭ

1.5 Hz, 1 H, H-cc), 5.14 (d, J_1Ј,2Јϭ 2.0 Hz, 1 H, 1Ј-H), 5.06 (dd, J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-cc), 5.17 (br. s, 1 H, 1Ј-H), 4.96 (d,

J_4Ј,5Јϭ 3.0, J_4Ј,3Јϭ 2.5 Hz, 1 H, 4Ј-H), 4.96 (d, J_1,2ϭ 3.5 Hz, 1 H, J_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.78 (br. s, 1 H, 5Ј-H), 4.70 (d, J ϭ

1-H), 4.92 (d, J_5Ј,4Јϭ 3.0 Hz, 1 H, 5Ј-H), 4.88 (dd, J_2Ј,3Јϭ 2.5, 11.5 Hz, 1 H, CH₂Ph), 4.63 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.60 (d,

J_2Ј,1Јϭ 2.0 Hz, 1 H, 2Ј-H), 4.75 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), J ϭ 11.5 Hz, 1 H, CH₂Ph), 4.56 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph),

4.70 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.70 (d, J ϭ 10.0 Hz, 1 H,

CH₂Ph), 4.65 (d, J ϭ 10.0 Hz, 1 H, CH₂Ph), 4.45 (dd, J_6a,6b

12.0, J_6a,5ϭ 1.5 Hz, 1 H, 6-H^a), 4.28Ϫ4.16 (m, 2 H, 6-H^band H-

4.21 (ddt, J_gemϭ 13.0, J_a,bϭ 5.0, J_a,ccϭ J_a,ctϭ 1.5 Hz, 1 H, H-

a), 4.04 (ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H,

ϭ

H-aЈ), 4.03Ϫ3.91 (m, 4 H), 4.87Ϫ3.70 (m, 4 H), 3.40 (dd, J_2,3

a), 4.06 (ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H, 10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H), 3.38 (s, 3 H, OMe). ¹³C NMR

H-aЈ), 3.95Ϫ3.75 (m, 4 H, 3-H, 4-H, 5-H and 3Ј-H), 3.43 (dd, (62.5 MHz, CDCl₃, ppm): δ ϭ 170.8 (CϭO), 137.9, 137.6 (C_quater-

J_2,3ϭ 10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H), 3.42 (s, 3 H, OMe), 2.11 (s, _nary,arom), 133.2 (C-b), 128.4, 128.1, 128.0, 127.3, 127.1 (C_arom),

ϭ

3 H, CH₃OAc), 2.02 (s, 3 H, CH₃OAc), 1.95 (s, 3 H, CH₃OAc).

118.0 (C-c), 99.9 (CЈ-1), 96.7 (C-1), 78.5, 74.9, 74.4 (CH₂Ph), 73.9,

72.1 (CH₂Ph), 71.6, 68.6, 68.5 (C-a), 66.1, 63.6 (C-2), 60.7 (C-6),

¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 170.6, 169.9, 169.8, 168.7

(CϭO), 137.7, 137.2 (C_{quaternary,arom}), 133.1 (C-b), 128.5, 128.0, 52.0 (CH₃, COOMe). C₃₀H₃₇N₃O₁₁(657.7 g/mol): calcd. C 58.53,

127.5, 127.4 (C_arom), 118.4 (C-c), 97.5 (CЈ-1), 96.5 (C-1), 78.4, 74.8,

74.7 (CH₂Ph), 72.6 (CH₂Ph), 72.8, 69.3, 68.7 (C-a), 68.0, 67.6, 67.0,

63.4 (C-2), 62.0 (C-6), 52.2 (CH₃, COOMe), 20.9, 20.8, 20.7 (CH₃,

OAc). C₃₆H₄₃N₃O₁₄(741.7 g/mol): calcd. C 58.29, H 5.84, N 5.66,

O 30.20; found C 58.01, H 5.81, N 5.44, O 30.12.

H 6.06, N 6.83, O 28.59; found C 57.94, H 6.25, N 6.07, O 28.51.

ESI MS calcd. for C₃₀H₃₇N₃NaO₁₁[M ϩ Na]: 638.2; found 638.2.

Allyl (Methyl 3-O-benzyl-α-

L-idopyranosyluronate)-(1Ǟ4)-O-2-az-

ido-3,6-di-O-benzyl-2-deoxy-α-

D-glucopyranoside (33): Disaccharide

31 (335 mg, 0.450 mmol) was treated as in the case of compound

30. Flash chromatography (petroleum ether/EtOAc/MeOH, 1:9:0.5)

gave disaccharide 33 (280 mg, 90%). IR (thin film, cm^Ϫ1): ν˜ ϭ 3448

(3600Ϫ3100, ν_OϪH), 3085, 3064, 3031 (ν_CϪH,arom), 2955, 2924, 2854

(ν_CϪH,aliph), 2107 (ν_N3), 1740 (ν_CϭO), 1497, 1457, 1376, 1220, 1162.

Allyl (Methyl 2,4-di-O-acetyl-3-O-benzyl-α-

L-idopyranosyluronate)-

(1Ǟ4)-O-2-azido-3,6-di-O-benzyl-2-deoxy-α-

D

-glucopyranoside

(31): Acceptor 7 (300 mg; 0.67 mmol) and donor 5 (400 mg,

0.94 mmol, 1.4 equiv.) were treated as described above, giving di-

saccharide 31 (425 mg, 81%), together with recovered acceptor 7 ¹H NMR (250 MHz, CDCl₃, ppm): δ ϭ 7.40Ϫ7.20 (m, 15 H, Ph),

(170 mg). [α]²_D⁷ϭ 12 (c ϭ 3.3, CH₂Cl₂). IR (thin film, cm^Ϫ1): ν˜ ϭ

3077, 3061, 3030 (ν_CϪH,arom), 2952, 2921, 2874, 2858 (ν_CϪH,aliph),

5.95 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.0, J_b,aЈϭ 6.0, J_b,aϭ 5.0 Hz, 1

H, H-b), 5.36 (dq, J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H,

2102 (ν_N3), 1736 (ν_CϭO), 1497, 1455, 1439, 1373, 1226, 1253, 1222. H-ct), 5.25 (dq, J_cc,bϭ 10.0, J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H,

¹H NMR (200 MHz, CDCl₃, ppm): δ ϭ 7.45Ϫ7.15 (m, 10 H, Ph), H-cc), 5.06 (br. d, J_1Ј,2Јϭ 2.0 Hz, 1 H, 1Ј-H), 4.97 (d, J_1,2ϭ 3.5 Hz,

5.95 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.5, J_b,aЈϭ 6.0, J_b,aϭ 5.0 Hz, 1

1 H, 1-H), 4.73 (d, J_5Ј,4Јϭ 2.5 Hz, 1 H, 5Ј-H), 4.72 (d, J ϭ 10.5 Hz,

H, H-b), 5.35 (dq, J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, 1 H, CH₂Ph), 4.67 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.64 (d, J ϭ

H-ct), 5.25 (dq, J_cc,bϭ 10.5, J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, 10.5 Hz, 1 H, CH₂Ph), 4.62 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.60 (d,

H-cc), 5.20 (br. s, 1 H, 1Ј-H), 5.04 (dd, J_4Ј,3Јϭ 3.0, J_4Ј,5Јϭ 2.5 Hz,

1 H, 4Ј-H), 4.97 (d, J_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.94 (d, J_5Ј,4Ј

J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.53 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph),

4.21 (ddt, J_gemϭ 13.0, J_a,bϭ 5.0, J_a,ccϭ J_a,ctϭ 1.5 Hz, 1 H, H-

ϭ

2.5 Hz, 1 H, 5Ј-H), 4.92Ϫ4.87 (m, 1 H, 2Ј-H), 4.73 (s, 2 H, CH₂Ph), a), 4.05 (ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H,

4.63 (s, 2 H, CH₂Ph), 4.61 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.51 (d, H-aЈ), 4.00 (t, J_4,3ϭ J_4,5ϭ 9.5 Hz, 1 H, 4-H), 4.00Ϫ3.92 (m, 1 H),

J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.21 (ddt, J_gemϭ 13.0, J_a,bϭ 5.0, J_a,ccϭ

3.90Ϫ3.78 (m, 2 H), 3.72 (dd, J_6a,6bϭ 11.0, J_6a,5ϭ 3.0 Hz, 1 H,

J

_a,ctϭ 1.5 Hz, 1 H, H-a), 4.04 (ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ 6-H^a), 3.72Ϫ3.63 (m, 2 H), 3.63 (dd, J_6b,6aϭ 11.0, J_6b,5ϭ 2.5 Hz,

J_aЈ,ctϭ 1.5 Hz, 1 H, H-aЈ), 4.04 (dd, J_6a,6bϭ 9.0, J_6a,5ϭ 1.0 Hz, 1 1 H, 6-H^b), 3.43 (dd, J_2,3ϭ 10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H), 3.42 (s,

H, 6-H^a), 3.89Ϫ3.74 (m, 4 H, 3-H, 4-H, 5-H and 3Ј-H), 3.65 (dd, 3 H, OMe). ¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 170.5 (Cϭ

J

_6b,6aϭ 9.0, J_6b,5ϭ 3.0 Hz, 1 H, 6-H^b), 3.45 (dd, J_2,3ϭ 10.0, J_2,1ϭ O), 138.0, 137.7, 137.6 (C_{quaternary,arom}), 133.3 (C-b), 128.5, 128.4,

3.5 Hz, 1 H, 2-H), 3.35 (s, 3 H, OMe), 2.00 (s, 3 H, CH₃OAc),

128.1, 128.0, 127.8, 127.4, 127.2 (C_arom), 118.0 (C-c), 100.7 (CЈ-

1), 96.7 (C-1), 78.5, 76.1, 75.5, 74.3 (CH₂Ph), 73.6 (CH₂Ph), 72.5

1.99 (s, 3 H, CH₃OAc). ¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ

169.9, 169.7, 168.4 (CϭO), 137.9, 137.8, 137.2 (C_{quaternary,arom}), (CH₂Ph), 70.8, 68.9, 68.7, 68.5/68.4 (C-a/C-6), 67.8, 63.4 (C-2), 52.0

133.2 (C-b), 128.4, 128.3, 128.1, 127.6, 127.5, 127.1 (C_arom), 118.0

(C-c), 97.1 (CЈ-1), 96.6 (C-1), 78.4, 74.4, 74.2, 73.1, 72.5, 72.2, 70.9,

68.5, 67.9, 67.1, 63.3, 63.5, 51.9 (CH₃, COOMe), 20.8, 20.7 (CH₃,

OAc). C₄₁H₄₇N₃O₁₃(789.8 g/mol): calcd. C 62.35, H 6.00, N 5.32,

O 26.33; found C 62.31, H 5.82, N 4.97, O 26.45.

(CH₃, COOMe). ESI HR-MS calcd. for C₃₇H₄₃N₃NaO₁₁[M ϩ

Na]: 728.27953; found 728.27941.

Allyl (Methyl 2-O-acetyl-3-O-benzyl-α-

L-idopyranosyluronate)-

(1Ǟ4)-O-6-O-acetyl-2-azido-3-O-benzyl-2-deoxy-α-

D

-glucopyra-

noside (34): A suspension of 32 (400 mg, 0.66 mmol) and Bu₂SnO

Allyl (Methyl 3-O-benzyl-α-

ido-3-O-benzyl-2-deoxy-α-

L

-idopyranosyluronate)-(1Ǟ4)-O-2-az-

(360 mg, 1.45 mmol, 2.2 equiv.) in benzene (9 mL) was heated at

D

-glucopyranoside (32): Dried K₂CO₃90 °C for 30 min. The temperature was then raised, and benzene

(16 mg, 0.11 mmol, 0.3 equiv.) was added to a solution of disac-

charide 30 (296 mg, 0.39 mmol) in MeOH (5 mL). The reaction

mixture was stirred at room temp. for one night, filtered, neutral-

(7 mL) was distilled off over 30 min (DeanϪStark apparatus). Ace-

tyl chloride (117 µL, 1.65 mmol, 2.5 equiv.) and enough triethyl-

amine to reach pH 8 (roughly 400 µL, 2.9 mmol, 4.4 equiv.) were

ised with Dowex 50X8 200 H^ϩand again filtered, and the methanol then added and the reaction mixture was stirred at room temp. for

was evaporated. Flash chromatography of the residue (petroleum

ether/EtOAc/MeOH, 1:9:0.5) gave the disaccharide 32 (210 mg,

1 h. TLC (petroleum ether/EtOAc, 2:8, R_f32ϭ 0.09) showed the

formation of the expected diacetate 34 (R_fϭ 0.39), its 4Ј-O-acetyl-

Eur. J. Org. Chem. 2003, 3603Ϫ3620

www.eurjoc.org

 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

3615

´

D. Bonnaffe et al.

FULL PAPER

ated regioisomer (R_fϭ 0.54) and a triacetylated compound (R_fϭ

0.60). The reaction mixture was directly placed on the top of a

flash chromatography column and eluted (petroleum ether/EtOAc,

8:2 to 6:4), giving 34 (277 mg, 60%). The regioisomer of 34 and the

triacetylated derivative were deacetylated as described for com-

pound 30 and reacetylated as described above, giving another crop

of 34 (69 mg), giving an overall yield of 75%. [α]²_D⁷ϭ 37 (c ϭ 1.0,

4.04 (t, J_4,5ϭ J_4,3ϭ 9.5 Hz, 1 H, 4-H), 3.93 (br. d, J_4Ј,OH

10.0 Hz, 1 H, became a ddd when an exchange with D₂O was per-

formed, J_4Ј,3Јϭ 2.5, J_4Ј,5Јϭ 2.0, J_4Ј,2Јϭ 1.0 Hz, 4Ј-H), 3.84 (dd,

ϭ

J_3,2ϭ 10.0, J_3,4ϭ 9.5 Hz, 1 H, 4-H), 3.83 (ddd, J_5,4ϭ 9.5, J_5Ϫ6aϭ

3.0, J_5,6bϭ 2.0 Hz, 1 H, 5-H), 3.76 (dd, J_6a,6bϭ 11.0, J_6a,5

ϭ

3.0 Hz, 1 H, 6-H^a), 3.73 (ddd, J_3Ј,2Јϭ 3.0, J_3Ј,4Јϭ 2.5, J_3Ј,1Ј

ϭ

1.0 Hz, 1 H, 3Ј-H), 3.65 (dd, J_6b,6aϭ 11.0, J_6b,5ϭ 2.0 Hz, 1 H, 6-

CH₂Cl₂). IR (thin film, cm^Ϫ1): ν˜ ϭ 3490 (3650Ϫ3250, ν_OϪH), 3086, H^b), 3.43 (dd, J_2,3ϭ 10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H), 3.38 (s, 3 H,

3064, 3031 (ν_CϪH,arom), 2956, 2919, 2867 (ν_CϪH,aliph), 2106 (ν_N3), OMe), 2.67 (d, J_OH,4Јϭ 10.0 Hz, 1 H, OH), 2.04 (s, 3 H, CH₃

1744 (ν_CϭO), 1497, 1455, 1438, 1371, 1237, 1156, 1105, 1068, 1039.

¹H NMR (250 MHz, CDCl₃, ppm): δ ϭ 7.42Ϫ7.22 (m, 10 H, Ph), O), 137.9, 137.8, 137.2 (C_{quaternary,arom}), 133.2 (C-b), 128.5, 128.3,

5.96 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.0, J_b,aЈϭ 6.0, J_b,aϭ 5.5 Hz, 1 128.1, 128.0, 127.5, 127.1 (C_arom), 118.0 (C-c), 97.6 (CЈ-1), 96.6 (C-

OAc). ¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 169.4, 169.2 (Cϭ

H, H-b), 5.37 (dq, J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, 1), 78.4, 74.7, 74.3, 74.1 (CH₂Ph), 73.2 (CH₂Ph), 72.1 (CH₂Ph),

H-ct), 5.28 (dq, J_cc,bϭ 10.0, J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, 70.9, 68.5 (C-a), 68.1, 67.8, 67.0 (C-6), 63.5 (C-2), 51.9 (CH₃, CO-

H-cc), 5.07 (br. s, 1 H, 1Ј-H), 4.96 (d, J_1,2ϭ 3.5 Hz, 1 H, 1-H),

OMe), 20.9 (CH₃, OAc). ESI HR-MS calcd. for C₃₉H₄₅N₃NaO₁₂

4.94 (dt, J_2Ј-3Јϭ 2.5, J_2Ј,1Јϭ J_2Ј,4Јϭ 1.0 Hz, 1 H, 2Ј-H), 4.90 (d, [M ϩ Na]: 770.29009; found 770.29063.

J_5Ј,4Јϭ 2.5 Hz, 1 H, 5Ј-H), 4.75 (d, J ϭ 11.5 Hz, 1 H, CH₂Ph),

Allyl (Methyl 2-O-acetyl-3-O-benzyl-4-O-(4-methoxybenzyl)-α-

idopyranosyluronate)-(1Ǟ4)-O-2-azido-3,6-di-O-benzyl-2-deoxy-α-

-glucopyranoside (2): 4-Methoxybenzyl trichloroacetimidate^[66]

L-

4.75 (d, J ϭ 10.5 Hz, 1 H, CH₂Ph), 4.66 (d, J ϭ 10.5 Hz, 1 H,

CH₂Ph), 4.63 (d, J ϭ 11.5 Hz, 1 H, CH₂Ph), 4.42 (dd, J_6a,6b

ϭ

11.5, J_6a,5ϭ 1.5 Hz, 1 H, 6-H^a), 4.23 (dd, J_6b,6aϭ 11.5, J_6b,5

ϭ

D

1.0 Hz, 1 H, 6-H^b), 4.22 (ddt, J_gemϭ 13.0, J_a,bϭ 5.5, J_a,ccϭ J_a,ctϭ

1.5 Hz, 1 H, H-a), 4.06 (ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ

1.5 Hz, 1 H, H-aЈ), 3.96 (br. d, J_4Ј,OHϭ 11.5 Hz, 1 H, 4Ј-H),

(161 mg, 0.57 mmol, 3.0 equiv.) and BF₃·Et₂O (0.8  in CH₂Cl₂,

14 µL, 0.011 mmol, 0.6 equiv.) were added successively to a cooled

(Ϫ30 °C) solution of 35 (142 mg, 1.19 mmol) in CH₂Cl₂(2 mL).

After one hour at Ϫ30 °C, the reaction mixture was quenched with

NEt₃(1  in CH₂Cl₂) and the solvent was evaporated. Flash chro-

matography of the residue gave 2 (107 mg, 65%), together with un-

changed 35 (45 mg, 32%). [α]²_D⁷ϭ 34 (c ϭ 1.0, CH₂Cl₂). IR (thin

film, cm^Ϫ1): ν˜ ϭ 3095, 3048, 3032, 3001 (ν_CϪH,arom), 2986, 2923,

2845 (ν_CϪH,aliph), 2108 (ν_N3), 1736 (ν_CϭO), 1613, 1582, 1514, 1497,

3.91Ϫ3.79 (m, 3 H, 3-H, 4-H, 5-H), 3.72 (ddd, J_3Ј,4Јϭ 3.5, J_3Ј,2Ј

ϭ

2.5, J_3Ј,1Јϭ 1.0 Hz, 1 H, 3Ј-H), 3.46 (s, 3 H, OMe), 3.40 (dd, J_2,3ϭ

10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H), 2.65 (d, J_OH,4Јϭ 11.5 Hz, 1 H,

OH), 2.10 (s, 3 H, CH₃OAc), 2.08 (s, 3 H, CH₃OAc). ¹³C NMR

(62.5 MHz, CDCl₃, ppm): δ ϭ 170.5, 169.4, 169.1 (CϭO), 137.7,

137.1 (C_{quaternary,arom}), 133.0 (C-b), 128.4, 128.1, 128.0, 127.4, 127.3

(C_arom), 118.3 (C-c), 97.9 (CЈ-1), 96.5 (C-1), 78.4, 75.0, 74.4

(CH₂Ph), 74.3, 72.3 (CH₂Ph), 69.1, 68.7 (C-a), 68.5, 67.6, 67.0, 63.5

(C-2), 62.1 (C-6), 52.0 (CH₃, COOMe), 20.8 (CH₃, OAc).

C₃₄H₄₁N₃O₁₃(699.7 g/mol): calcd. C 58.36, H 5.91, N 6.01, O

29.73; found C 58.39, H 5.93, N 5.66, O 30.11.

1

1455, 1433, 1372, 1254, 1120. H NMR (250 MHz, CDCl₃, ppm):

δ ϭ 7.40Ϫ7.21 (m, 15 H, Ph), 7.12 (d, J ϭ 8.5 Hz, 2 H, Ph-OMe),

6.80 (d, J ϭ 8.5 Hz, 2 H, Ph-OMe), 5.92 (dddd, J_b,ctϭ 17.0, J_b,ccϭ

10.0, J_b,aЈϭ 6.0, J_b,aϭ 5.0 Hz, 1 H, H-b), 5.33 (dq, J_ct,bϭ 17.0,

J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.30 (d, J_1Ј,2Јϭ 4.0 Hz,

1 H, 1Ј-H), 5.23 (dq, J_cc,bϭ 10.0, J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1

Allyl (Methyl 2-O-acetyl-3-O-benzyl-α-

L-idopyranosyluronate)-

H, H-cc), 4.94 (d, J_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.89 (t, J_2ЈϪ3Јϭ J_2Ј,1Ј

ϭ

(1Ǟ4)-O-2-azido-3,6-di-O-benzyl-2-deoxy-α-

D

-glucopyranoside

4.0 Hz, 1 H, 2Ј-H), 4.83 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.70 (d,

J ϭ 10.5 Hz, 1 H, CH₂Ph) 4.67 (d, J_5Ј,4Јϭ 2.5 Hz, 1 H, 5Ј-H), 4.67

(d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.64 (d, J ϭ 10.5 Hz, 1 H, CH₂Ph),

4.57 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.50 (d, J ϭ 12.0 Hz, 1 H,

CH₂Ph), 4.45 (d, J ϭ 11.5 Hz, 1 H, CH₂PhOMe), 4.39 (d, J ϭ

11.5 Hz, 1 H, CH₂PhOMe), 4.19 (ddt, J_gemϭ 13.0, J_a,ctϭ 5.0,

J_a,ccϭ J_a,ctϭ 1.5 Hz, 1 H, H-a), 4.04 (t, J_4,3ϭ J_4,5ϭ 9.0 Hz, 1 H,

4-H), 4.02 (ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1

H, H-aЈ), 3.85 (dd, J_3,2ϭ 10.0, J_3,4ϭ 9.0 Hz, 1 H, 3-H), 3.82Ϫ3.68

(m, 4 H, 5-H, 6-H^a, 3Ј-H, 4Ј-H), 3.78 (s, 3 H, PhOMe), 3.62 (dd,

J_6b,6aϭ 10.5, J_6b,5ϭ 2.0 Hz, 1 H, 6-H^b), 3.45 (s, 3 H, COOMe),

3.41 (dd, J_2,3ϭ 10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H), 1.94 (s, 3 H, CH₃

OAc). ¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 169.9, 169.6 (Cϭ

O), 159.3 (C-OMe, pMBn),138.1, 137.8, 137.7 (C_{quaternary,arom}),

133.2 (C-b), 129.5, 129.4, 128.4, 128.2, 128.0, 127.8, 127.7, 127.6,

127.5, 127.2 (C_arom), 118.0 (C-c), 113.6 (C_mpMBn), 97.7 (CЈ-1),

96.5 (C-1), 78.3, 75.4, 74.7, 74.5 (CH₂Ph), 74.0, 73.3 (CH₂Ph), 72.9

(CH₂Ph), 72.3 (CH₂Ph), 70.8, 69.9, 69.6, 68.4 (C-a), 67.8 (C-6),

63.2 (C-2), 55.2 (CH₃, Ph-OMe), 51.7 (CH₃, COOMe), 20.9 (CH₃,

OAc). C₄₇H₅₃N₃O₁₃(867.9 g/mol): calcd. C 65.04, H 6.15, N 4.84;

(35): Compound 33 (200 mg, 0.284 mmol) was treated as described

for 32, with Bu₂SnO (85 mg, 0.340 mmol, 1.2 equiv.) and then ace-

tyl chloride (24 µL, 0.340 mmol, 1.2 equiv.), without addition of

triethylamine. TLC (petroleum ether/EtOAc, 1:1) of the reaction

mixture after 1 h stirring at room temp. showed the complete disap-

pearance of compound 33 (R_fϭ 0.25) and the major formation

of the expected monoacetate 35 (R_fϭ 0.37), its 4Ј-O-acetylated

regioisomer and diacetylated compound (R_fϭ 0.53 and R_fϭ 0.58),

together with a tiny amount of a 4Ј-O-acetylated-2Ј,6Ј-lactone

(R_fϭ 0.73, ESI MS calcd. for C₃₈H₄₁N₃NaO₁₁[M ϩ Na]: 738.3;

found 738.3). Purification by flash chromatography (petroleum

ether/EtOAc, 1:1) and recycling as described above gave a 70%

combined yield of 35 (149 mg). IR (thin film, cm^Ϫ1): ν˜ ϭ 3569,

3503, 3348 (ν_OϪH), 3080, 3064, 3032 (ν_CϪH,arom), 2955, 2924, 2854

(ν_CϪH,aliph), 2108 (ν_N3), 1741 (ν_CϭO), 1498, 1456, 1376, 1216, 1159,

1104, 1042. ¹H NMR (360 MHz, CDCl₃, ppm): δ ϭ 7.42Ϫ7.25 (m,

10 H, Ph), 5.95 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.0, J_b,aЈϭ 6.0, J_b,a

5.0 Hz, 1 H, H-b), 5.35 (dq, J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gem

1.5 Hz, 1 H, H-ct), 5.25 (dq, J_cc,bϭ 10.0, J_cc,aϭ J_cc,aЈϭ J_gem

ϭ

1.5 Hz, 1 H, H-cc), 5.13 (br. s, 1 H, 1Ј-H), 4.98 (d, J_1,2ϭ 3.5 Hz,

1 H, 1-H), 4.96 (dt, J_2ЈϪ3Јϭ 3.0, J_2Ј,1Јϭ J_2Ј,4Јϭ 1.0 Hz, 1 H, 2Ј-

H), 4.91 (d, J_5Ј,4Јϭ 2.0 Hz, 1 H, 5Ј-H), 4.73 (d, J ϭ 11.5 Hz, 1 H,

CH₂Ph), 4.70 (d, J ϭ 11.5 Hz, 1 H, CH₂Ph), 4.64 (d, J ϭ 11.5 Hz,

found

C 65.28, H 6.55, N 4.39. ESI HR-MS calcd. for

C₄₇H₅₃N₃NaO₁₃[M ϩ Na]: 890.34761; found 890.34797.

Allyl 2,3,4,6-Tetra-O-acetyl-β-

D-glucopyranosyl-(1Ǟ4)-O-2-azido-

1 H, CH₂Ph), 4.63 (d, J ϭ 11.5 Hz, 1 H, CH₂Ph), 4.57 (d, J ϭ 3,6-di-O-benzyl-2-deoxy-α-

D-glucopyranoside (36): Acceptor

7

12.0 Hz, 1 H, CH₂Ph), 4.51 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.21 (10.47 g, 23.13 mmol) was azeotropically dried with toluene. Pow-

[26]

˚

(ddt, J_gemϭ 13.0, J_a,bϭ 5.0, J_a,ccϭ J_a,ctϭ 1.5 Hz, 1 H, H-a), 4.05

dered molecular sieves (4 A, 14.86 g) and acetobromoglucose 8

(ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H, H-aЈ), (23.78 g, 57.83 mmol, 2.5 equiv.) were then added, followed by

3616  2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.eurjoc.org

Eur. J. Org. Chem. 2003, 3603Ϫ3620

Building Blocks for the Synthesis of Heparan Sulfate Fragments

FULL PAPER

CH₂Cl₂(115 mL). After 30 min stirring at room temp., the solution

was cooled to Ϫ40 °C and silver triflate (14.86 g, 57.83, 2.5 mmol)

was added. The reaction was then quenched with satd. aqueous

J_6a,5ϭ 3.0 Hz, 1 H, 6-H^a), 3.95 (t, J_3,2ϭ J_3,4ϭ 9.5 Hz, 1 H, 3-H),

3.85 (ddd, J_5,4ϭ 9.5, J_5,6aϭ 3.0, J_5,6bϭ 2.0 Hz, 1 H, 5-H), 3.67

(dd, J_6b,6aϭ 11.5, J_6b,5ϭ 2.0 Hz, 1 H, 6-H^b), 3.59 (dd, J_6aЈ,6bЈ

ϭ

NaHCO₃(15 mL) after 2.5 hours at Ϫ40 °C. The reaction mixture 12.0, J_6aЈ,5Јϭ 3.0 Hz, 1 H, 6Ј-H^a), 3.44 (dd, J_2,3ϭ 9.5, J_2,1

was diluted with diethyl ether (500 mL) and filtered through a pad

3.5 Hz, 1 H, 2-H), 3.40 (dd, J_6bЈ,6aЈϭ 12.0, J_6bЈ,5Јϭ 4.0 Hz, 1 H,

of Celite 545. The organic layer was washed with water (2 ϫ 6Ј-H^b), 3.40 (t, J_4Ј,3Јϭ J_4Ј,5Јϭ 9.5 Hz, 1 H, 4Ј-H), 3.35Ϫ3.20 (m,

150 mL), dried (MgSO₄), filtered, and concentrated, giving a mix-

ture of disaccharide 36 and excess donor 8 (30.33 g), which was

generally directly deacetylated. An analytically pure sample of com-

pound 36 was obtained by flash chromatography (toluene/EtOAc,

9:1 to 8:2). IR (thin film, cm^Ϫ1): ν˜ ϭ 3090, 3066, 3032 (ν_CϪH,arom),

2 H, 3Ј-H, 2Ј-H), 3.02 (ddd, J_5Ј,4Јϭ 9.5, J_5Ј,6bЈϭ 4.0, J_5Ј,6aЈϭ

3.0 Hz, 1 H, 5Ј-H), without D₂O there were 4 additional br. s (1

H) at δ ϭ 3.35, 3.13, 3.00, and 2.83. ¹³C NMR (62.5 MHz, CDCl₃,

ppm): δ ϭ 138.1, 137.4 (2 C_{quaternary,arom}), 133.1 (C-b), 128.5, 128.4,

128.0, 127.3 (C_arom), 118.1 (C-c), 102.1 (CЈ-1), 96.7 (C-1), 78.7,

2941, 2900, 2867 (ν_CϪH,aliph), 2115 (ν_N3), 1771, 1746, 1723 (ν_CϭO), 76.8, 76.4, 75.5, 74.9 (CH₂Ph), 74.3, 73.6 (CH₂Ph), 70.5, 70.1, 68.6

1497, 1456, 1430, 1374, 1321, 1226, 1168. ¹H NMR (250 MHz,

CDCl₃, ppm): δ ϭ 7.45Ϫ7.15 (m, 10 H, Ph), 5.91 (dddd, J_b,ct

(C-a), 68.0 (C-6), 63.3 (C-2), 61.9 (CЈ-6). C₂₉H₃₇N₃O₁₀(587.6 g/

mol): calcd. C 59.27, H 6.35; found C 58.78, H 6.61.

ϭ

17.0, J_b,ccϭ 10.5, J_b,aЈϭ 6.0, J_b,aϭ 5.0 Hz, 1 H, H-b), 5.33 (dq,

J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.23 (dq,

Allyl [4,6-O-(4-Methoxybenzylidene)-β-

D-glucopyranosyl]-(1Ǟ4)-O-

2-azido-3,6-di-O-benzyl-2-deoxy-α- -glucopyranoside (38): Com-

D

J

_cc,bϭ 10.5, J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-cc), 5.07 (d, J ϭ

pound 37 (10.9 g, 18.50 mmol) was dried azeotropically with tolu-

ene and dissolved in acetonitrile (80 mL). 4-Methoxybenzaldehyde

dimethyl acetal (5.2 mL, 37.0 mmol, 2.0 equiv.) and catalytic cam-

phorsulfonic acid were then added. The reaction mixture was

stirred for 1 hour at room temp. and then quenched by addition of

a satd. aqueous NaHCO₃solution (15 mL). The resulting mixture

was diluted with EtOAc (500 mL) and washed with water (2 ϫ

100 mL), filtered through a silicon-treated filter, and concentrated.

Flash chromatography of the residue (petroleum ether/EtOAc, 7:3

to 1:1) gave 38 (12.50 g, 89%) as a colourless oil. [α]²_D⁹ϭ 103 (c ϭ

1, CH₂Cl₂). IR (thin film, cm^Ϫ1): ν˜ ϭ 3462 (3670Ϫ3270, ν_OϪH),

3089, 3065, 3033, 3009 (ν_CϪH,arom), 2936, 2904, 2872, 2840

(ν_CϪH,aliph), 2108 (ν_N3), 1617, 1584, 1519, 1497, 1455, 1383, 1366,

11.0 Hz, 1 H, CH₂Ph), 5.05Ϫ4.90 (m, 3 H, 2Ј-H, 3Ј-H, 4Ј-H), 4.94

(d, J_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.81 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph),

4.64 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.47 (d, J_1Ј,2Јϭ 7.5 Hz, 1 H,

1Ј-H), 4.43 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.18 (ddt, J_gemϭ 13.0,

J_a,bϭ 5.0, J_a,ccϭ J_a,ctϭ 1.5 Hz, 1 H, H-a), 4.14 (dd, J_6aЈ,6bЈ

ϭ

12.5, J_6aЈ,5Јϭ 4.0 Hz, 1 H, 6Ј-H^a), 4.03 (ddt, J_gemϭ 13.0, J_aЈ,b

ϭ

6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H, H-aЈ), 4.02 (t, J_4,5ϭ J_4,3ϭ 9.0 Hz,

1 H, 4-H), 3.88 (dd, J_6bЈ,6aЈϭ 12.5, J_6bЈ,5Јϭ 2.5 Hz, 1 H, 6Ј-H^b),

3.88 (dd, J_3,2ϭ 10.0, J_3,4ϭ 9.0 Hz, 1 H, 3-H), 3.81 (dd, J_6a,6b

ϭ

11.0, J_6a,5ϭ 2.5 Hz, 1 H, 6-H^a), 3.69 (ddd, J_5,4ϭ 9.0, J_5,6aϭ 2.5,

J_5,6bϭ 1.5 Hz, 1 H, 5-H), 3.63 (dd, J_6b,6aϭ 11.0, J_6b,5ϭ 1.5 Hz,

1 H, 6-H^b), 3.35 (dd, J_2,3ϭ 10.0, J_2,1ϭ 3.5 Hz, 1 H, 2-H), 3.31

(ddd, J_5Ј,4Јϭ 10.0, J_5Ј,6aЈϭ 4.0, J_5Ј,6bЈϭ 2.5 Hz, 1 H, 5Ј-H), 2.01

(s, 3 H, CH₃OAc), 1.99 (s, 3 H, CH₃OAc), 1.97 (s, 3 H, CH₃OAc),

1.94 (s, 3 H, CH₃OAc); NMR ¹³C (62.9 MHz, CDCl₃, ppm): δ

(ppm) 170.5, 170.1, 169.3, 168.9 (CϭO), 138.3, 137.3 (C_{quaternary,a-}

_rom), 133.0 (C_a), 128.9, 128.6, 128.3, 128.0, 127.6, 127.4 (C_arom),

118.0 (C-c), 99.8 (CЈ-1), 96.6 (C-1), 77.7, 77.0, 74.9 (CH₂Ph), 73.6

(CH₂Ph), 72.9, 71.6, 71.4, 70.2, 68.5 (C-a), 67.9, 67.0 (C-6 or CЈ-6),

62.7 (C-2), 61.5 (C-6 or CЈ-6), 20.6, 20.5 (CH₃OAc). C₃₇H₄₅N₃O₁₄

(755.8 g/mol): calcd. C 58.80, H 6.00, N 5.56, O 29.64; found C

58.77, H 6.07, N 5.69, O 29.59.

1

1305, 1251, 1210, 1172, 1046. H NMR (250 MHz, CDCl₃, 1 drop

D₂O, ppm): δ ϭ 7.44Ϫ7.28 (m, 12 H, Ph), 6.88 (d, J ϭ 8.5 Hz, 2

H, Ph-OMe), 5.91 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.5, J_b,aЈϭ 6.0,

J_b,aϭ 5.0 Hz, 1 H, H-b), 5.37 (s, 1 H, CH-PhOMe), 5.33 (dq,

J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.23 (dq,

J

_cc,bϭ 10.5, J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-cc), 4.96 (d, J ϭ

10.5 Hz, 1 H, CH₂Ph), 4.93 (d, J_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.76 (d,

J ϭ 10.5 Hz, 1 H, CH₂Ph), 4.69 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph),

4.49 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.48 (d, J_1Ј,2Јϭ 7.0 Hz, 1 H,

1Ј-H), 4.17 (ddt, J_gemϭ 13.0, J_a,bϭ 5.0, J_a,ccϭ J_a,ctϭ 1.5 Hz, 1

H, H-a), 4.12Ϫ3.96 (m, 4 H), 3.94 (t, J ϭ 9.0 Hz, 1 H), 3.84 (ddd,

J_5,4ϭ 10.0, J_5,6aϭ 3.0, J_5,6bϭ 1.5 Hz, 1 H, 5-H), 3.77 (s, 3 H,

OMe), 3.67 (dd, J_6b,6aϭ 11.0, J_6b,5ϭ 1.5 Hz, 1 H, 6-H^b), 3.53 (t,

Allyl β-D-Glucopyranosyl-(1Ǟ4)-O-2-azido-3,6-di-O-benzyl-2-de-

oxy-α- -glucopyranoside (37): MeONa (1.87 g, 35 mmol) was ad-

D

ded over 1 h to a solution of the crude mixture obtained above in

MeOH (200 mL). The reaction mixture was then neutralised with

Dowex 50X8 200 H^ϩ, filtered and concentrated. The residue was

diluted with EtOAc (300 mL) and washed with water (3 ϫ 50 mL).

Water was extracted with EtOAc (3 ϫ 50 mL) and the organic lay-

ers, containing nearly pure 37, were combined, filtered through a

silicon treated filter, and concentrated. Flash chromatography of

the residue (petroleum ether/EtOAc, 3:7 to 1:9) gave 37 (10.9 g,

80% from 7). [α]²_D⁹ϭ 111 (c ϭ 1, CH₂Cl₂). IR (thin film, cm^Ϫ1):

ν˜ ϭ 3419 (3670Ϫ3100, ν_OϪH), 3088, 3064, 3031 (ν_CϪH,arom), 2912,

2881 (ν_CϪH,aliph), 2108 (ν_N3), 1497, 1454, 1364, 1332, 1260, 1210,

J_6aЈ,6bЈϭ J_6aЈ,5Јϭ 9.5 Hz, 1 H, 6Ј-H^a), 3.42 (dd, J_2,3ϭ 9.5, J_2,1

3.5 Hz, 1 H, 2-H), 3.46Ϫ3.31 (m, 3 H), 3.06 (td, J_5Ј,4Јϭ J_5Ј,6aЈ

ϭ

9.5, J_5Ј,6bЈϭ 3.0 Hz, 1 H, 5Ј-H), without D₂O there were 2 ad-

ditional br. s (1 H) at δ ϭ 3.22 and 2.95. ¹³C NMR (62.5 MHz,

CDCl₃, ppm): δ ϭ 160.1 (C-OMe, pMBn), 138.2, 137.4 (C_quaternary,-

_arom), 133.0 (C-b), 129.3, 128.5, 128.2, 127.9, 127.6, 127.5, 127.4

(C_arom), 118.1 (C-c), 113.6 (C_mpMBn), 102.8 (O-CH-O or CЈ-1),

101.6 (O-CH-O or CЈ-1), 96.5 (C-1), 80.2, 78.7, 77.3, 74.9 (CH₂Ph),

73.4 (CH₂Ph), 73.0, 70.2, 68.4 (C-a), 68.3 (C-6), 67.8 (CЈ-6), 62.9

(C-2), 55.2 (CH₃, OMe). C₃₇H₄₃N₃O₁₁(705.8 g/mol): calcd. C

62.97, H 6.14, N 5.95; found C 62.58, H 6.24, N 5.95.

1

1162, 1089, 1065, 1042. H NMR (250 MHz, CDCl₃, 1 drop D₂O,

ppm): δ ϭ 7.44Ϫ7.28 (m, 10 H, Ph), 5.92 (dddd, J_b,ctϭ 17.0, J_b,ccϭ

10.5, J_b,aЈϭ 6.5, J_b,aϭ 5.0 Hz, 1 H, H-b), 5.34 (dq, J_ct,bϭ 17.0,

J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.24 (dq, J_cc,bϭ 10.5, anosyl-(1Ǟ4)-O-2-azido-3,6-di-O-benzyl-2-deoxy-α-

Allyl 2,3-Di-O-benzyl-4,6-O-(4-methoxybenzylidene)-β-

-glucopyra-

J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-cc), 4.97 (d, J ϭ 11.0 Hz, 1 noside (39): NaH (60% in oil, 2.14 g, 53.5 mmol, 3.5 equiv.) was

H, CH₂Ph), 4.96 (d, J_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.81 (d, J ϭ 11.0 Hz, added in small portions to a cooled (0 °C) solution of compound

D-glucopyr-

D

1 H, CH₂Ph), 4.69 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.50 (d, J ϭ 38 (10.8 g, 15.3 mmol) in DMF (80 mL). After 10 min, benzyl bro-

12.0 Hz, 1 H, CH₂Ph), 4.41 (d, J_1Ј,2Јϭ 7.0 Hz, 1 H, 1Ј-H), 4.18 mide (5.5 mL, 45.9 mmol, 3.0 equiv.) was added dropwise. The mix-

(ddt, J_gemϭ 13.0, J_a,bϭ 5.0, J_a,ccϭ J_a,ctϭ 1.5 Hz, 1 H, H-a), 4.04

(ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.5, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H, H-aЈ), reaction. Isopropanol (15 mL) was carefully added at 0 °C, fol-

4.00 (t, J_4,3ϭ J_4,5ϭ 9.5 Hz, 1 H, 4-H), 3.95 (dd, J_6a,6bϭ 11.5, lowed by water (15 mL). The resulting mixture was diluted with

ture was then stirred at room temperature until completion of the

Eur. J. Org. Chem. 2003, 3603Ϫ3620

www.eurjoc.org

 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

3617

´

D. Bonnaffe et al.

FULL PAPER

Et₂O (500 mL) and washed with water (2 ϫ 100 mL). The organic

layer was dried (MgSO₄), filtered, and then concentrated. Flash

chromatography of the residue (petroleum ether/EtOAc, 95:5 to

1:1) afforded the benzylated product 39 (15.56 g, 97%), which was

crystallised from Et₂O/petroleum ether to give 13.01 g white crys-

tals (mp ϭ 119Ϫ120 °C). [α]²_D⁹ϭ 35 (c ϭ 1, CH₂Cl₂). IR (KBr

pellet, cm^Ϫ1): ν˜ ϭ 3087, 3066, 3032 (ν_CϪH,arom), 2909, 2868

4.79 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.75 (d, J ϭ 11.0 Hz, 1 H,

CH₂Ph), 4.71 (d, J ϭ 10.5 Hz, 1 H, CH₂Ph), 4.58 (d, J ϭ 12.0 Hz,

1 H, CH₂PhOMe), 4.49 (d, J ϭ 10.5 Hz, 1 H, CH₂Ph), 4.38 (d,

J ϭ 12.0 Hz, 1 H, CH₂PhOMe), 4.34 (d, J_1Ј,2Јϭ 8.0 Hz, 1 H, 1Ј-

H), 4.19 (ddt, J_gemϭ 13.0, J_a,bϭ 5.5, J_a,ccϭ J_a,ctϭ 1.5 Hz, 1 H,

H-a), 4.04 (ddt, J_gemϭ 13.0, J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1

H, H-aЈ), 3.99 (t, J_4,3ϭ J_4,5ϭ 9.5 Hz, 1 H, 4-H), 3.89 (t, J_3,2

ϭ

(ν_CϪH,aliph), 2110 (ν_N3), 1615, 1517, 1497, 1454, 1382, 1366, 1349, J_3,4ϭ 9.5 Hz, 1 H, 3-H), 3.82 (dd, J_6a,6bϭ 11.0, J_6a,5ϭ 2.0 Hz, 1

1304, 1250, 1211, 1172, 1129, 1085, 1039. ¹H NMR (250 MHz,

H, 6-H^a), 3.80 (s, 3 H, OMe), 3.69 (dt, J_5,4ϭ 9.5, J_5,6aϭ J_5,6b

ϭ

CDCl₃, ppm): δ ϭ 7.46Ϫ7.20 (m, 22 H, Ph), 6.91 (d, J ϭ 8.5 Hz, 2.0 Hz, 1 H, 5-H), 3.56 (ddd, J_6aЈ,6bЈϭ 12.0, J_6aЈ,OHϭ 7.0, J_6aЈ,5Ј

ϭ

2 H, Ph-OMe), 5.94 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.5, J_b,aЈϭ 6.0, 2.0 Hz, 1 H, simplified as a dd by exchange with D₂O, 6Ј-H^a), 3.47

J_b,aϭ 5.0 Hz, 1 H, H-b), 5.44 (s, 1 H, CH-PhOMe), 5.37 (dq,

(dd, J_6b,6aϭ 11.0, J_6b,5ϭ 2.0 Hz, 1 H, 6-H^b), 3.46 (t, J_3Ј,2Ј

J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.25 (dq, J_3Ј,4Јϭ 8.5 Hz, 1 H, 3Ј-H), 3.42 (dd, J_2,3ϭ 9.5, J_2,1ϭ 3.5 Hz, 1

_cc,bϭ 10.5, J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-cc), 5.01 (d, J ϭ H, 2-H), 3.38 (t, J_4Ј,3Јϭ J_4Ј,5Јϭ 8.5 Hz, 1 H, 4Ј-H), 3.33 (dd,

10.5 Hz, 1 H, CH₂Ph), 4.92 (d, J_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.89 (d, J_2Ј,3Јϭ 8.5, J_2Ј,1Јϭ 8.0 Hz, 1 H, 2Ј-H), 3.20 (ddd, J_6bЈ,6aЈϭ 12.0,

J ϭ 12.5 Hz, 1 H, CH₂Ph), 4.84 (d, J ϭ 11.5 Hz, 1 H, CH₂Ph), J_6bЈ,OHϭ 7.0, J_6bЈ,5ϭ 5.0 Hz, simplified as a dd by exchange with

ϭ

J

4.76 (d, J ϭ 12.5 Hz, 1 H, CH₂Ph), 4.75 (d, J ϭ 11.5 Hz, 1 H,

D₂O, 1 H, 6Ј-H^b), 3.08 (ddd, J_5Ј,4Јϭ 8.5, J_5Ј,6bЈϭ 5.0, J_5Ј,6aЈ

ϭ

CH₂Ph), 4.71 (d, J ϭ 10.5 Hz, 1 H, CH₂Ph), 4.60 (d, J ϭ 12.0 Hz, 2.0 Hz, 1 H, 5Ј-H), 1.32 (t, J_OH,6aЈϭ J_OH,6bЈϭ 7.0 Hz, OH). ¹³C

1 H, CH₂Ph), 4.37 (d, J_1Ј,2Јϭ 7.5 Hz, 1 H, 1Ј-H), 4.31 (d, J ϭ NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 159.3 (C-OMe, pMBn),

12.0 Hz, 1 H, CH₂Ph), 4.18 (ddt, J_gemϭ 13.0, J_a,bϭ 5.0, J_a,c_cϭ 138.4, 138.3, 138.2, 137.5 (C_{quaternary,arom}), 133.2 (C-b), 130.1,

J_a,ctϭ 1.5 Hz, 1 H, H-a), 4.13Ϫ3.98 (m, 3 H), 3.89 (t, J ϭ 9.5 Hz,

129.6, 128.4, 128.3, 128.2, 128.0, 127.8, 127.7, 127.6, 127.5, 127.1

1 H), 3.89 (dd, J_6b,6aϭ 11.0, J_6,5ϭ 2.0 Hz, 1 H, 6-H), 3.78 (s, 3 (C_arom), 118.0 (C-c), 113.8 (C_mpMBn), 102.5 (CЈ-1), 96.6 (C-1),

H, OMe), 3.67 (dt, J_5,4ϭ 10.0, J_5,6aϭ J_5,6bϭ 2.0 Hz, 1 H, 5-H), 84.6, 82.7, 78.2, 77.6, 76.9, 75.6 (CH₂Ph), 75.0 (CH₂Ph), 74.9, 74.8

3.61Ϫ3.50 (m, 2 H), 3.50Ϫ3.30 (m, 3 H), 3.42 (dd, J_2,3ϭ 10.0,

J_2,1ϭ 3.5 Hz, 1 H, 2-H), 3.08 (td, J_5Ј,4Јϭ J_5Ј,6aЈϭ 9.0, J_5Ј,6aЈ

(CH₂Ph), 74.4 (CH₂Ph), 73.3 (CH₂Ph), 70.6, 68.5 (C-a), 67.2 (C-

6), 62.9 (C-2), 61.8 (CЈ-6), 55.2 (CH₃, Ph-OMe). C₅₁H₅₇N₃O₁₁

ϭ

5.0 Hz, 1 H, 5Ј-H). ¹³C NMR (62.5 MHz, CDCl₃, ppm): δ ϭ 159.9 (888.0 g/mol): calcd. C 68.98, H 6.47, N 4.73; found C 69.08, H

(C-OMe, pMBn), 138.3, 138.2, 137.6 (C_{quaternary,arom}), 133.2 (C-b),

129.7, 128.4, 128.2, 128.1, 128.0, 127.9, 127.8, 127.7, 127.5, 127.2

(C_arom), 117.9 (C-c), 113.4 (C_mpMBn), 102.6 (O-CH-O or CЈ-1),

100.9 (O-CH-O or CЈ-1), 96.4 (C-1), 82.3, 81.5, 80.8, 78.1, 76.7,

75.4 (CH₂Ph), 75.0 (CH₂Ph), 74.7 (CH₂Ph), 73.2 (CH₂Ph), 70.5,

68.4 (C-a and C-6 or CЈ-6), 67.2 (C-6 or CЈ-6), 65.6, 62.5 (C-2),

55.1 (CH₃, Ph-OMe). C₅₁H₅₅N₃O₁₁(886.0 g/mol): calcd. C 69.14,

H 6.26, N 4.74, O 19.86; found C 69.25, H 6.36, N 4.57, O 19.62.

6.42, N 4.25.

Allyl [Methyl 2,3-Di-O-benzyl-4-O-(4-methoxybenzyl)-β-

ranosyluronate]-(1Ǟ4)-O-2-azido-3,6-di-O-benzyl-2-deoxy-α-

D

-glucopy-

D-glu-

copyranoside (3): DMSO (474 µL, 6.67 mmol, 12 equiv.) was added

dropwise to a cooled (Ϫ78 °C) solution of oxalyl chloride (160 µL,

1.67 mmol, 3 equiv.) in CH₂Cl₂(5 µL). After the mixture had been

kept for 15 min at Ϫ78 °C, a solution of compound 40 (474 mg,

0.56 mmol) in CH₂Cl₂(500 µL) was added and the mixture was

stirred for 45 minutes at Ϫ78 °C. NEt₃(930 µL, 6.67 mmol, 12

equiv.) was then added dropwise over 5 min. The reaction was

monitored by TLC (petroleum ether/EtOAc, 7:3. After dipping the

plates into an nBuNH₂solution (5% vol. in CH₂Cl₂) to allow differ-

entiation between 40 and the aldehyde). The reaction mixture was

slowly warmed to Ϫ20 °C over 1 hour and quenched with aqueous

KH₂PO₄(5%, 10 mL). The resulting mixture was then diluted with

Et₂O (100 mL) and decanted. The organic layer was washed with

water (2 ϫ 30 mL), dried (MgSO₄), filtered, and concentrated. The

¹H and ¹³C NMR spectra of the crude aldehyde contain signals

corresponding to the aldehyde proton (δ ϭ 8.95 ppm, d, J ϭ

1.5 Hz) and carbon (δ ϭ 196.9 ppm). Methanolic I₂(0.4 , 4.2 mL,

1.68 mmol, 3 equiv.) and methanolic KOH (0.8 , 4.2 mL,

3.36 mmol, 6 equiv.) were then added dropwise to a cooled (0 °C)

Allyl 2,3-Di-O-benzyl-4-O-(4-methoxybenzyl)-β-

(1Ǟ4)-O-2-azido-3,6-di-O-benzyl-2-deoxy-α-

D

-glucopyranosyl-

D

-glucopyranoside

(40): Triethylsilane (850 µL, 5.29 mmol, 5 equiv.) and molecular

˚

sieves (4 A, 400 mg) were added to a solution of 39 (938 mg,

1.06 mmol) in diethyl ether (10 mL). After 30 min stirring at room

temp., the solution was cooled down to Ϫ78 °C and dichlorophe-

nylborane (740 µL, 3.6 mmol, 3.4 equiv.) was added quickly, in or-

der to avoid freezing in the needle. The reaction mixture was

warmed up to Ϫ40 °C over one hour and stirred at this temperature

for one night. The reaction was then quenched at Ϫ40 °C by ad-

dition of NEt₃(1.15 mL, 7.8 equiv.) and MeOH (740 µL) followed

by a satd. aqueous NaHCO₃solution (6 mL). The resulting suspen-

sion was filtered through a Celite 545 pad. The organic layer was

then washed with an aqueous sodium hydroxide solution (0.5 , 2

ϫ 10 mL), aqueous 5% KH₂PO₄(10 mL), and water (2 ϫ 10 mL). solution of the crude aldehyde in MeOH (3 mL) as described.^[17][70]

The organic layer was dried (MgSO₄), filtered, and concentrated.

Flash chromatography of the residue (petroleum ether/EtOAc, 9:1

to 7:3) gave 40 (883 mg, 91%) as a colourless oil. [α]²_D⁹ϭ 63 (c ϭ

After 1 h stirring at 0 °C the reaction was neutralised with meth-

anolic AcOH (1 ), and a satd. aqueous Na₂S₂O₃solution was

then added until decolouration. The reaction mixture was diluted

1, CH₂Cl₂). IR (thin film, cm^Ϫ1): ν˜ ϭ 3583, 3466 (ν_OϪH), 3088, with diethyl ether (100 mL) and washed with a satd. aqueous

3064, 3031, 3014 (ν_CϪH,arom), 2909, 2859 (ν_CϪH,aliph), 2107 (ν_N3), NaHCO₃solution (30 mL) and water (2 ϫ 30 mL). The organic

1737, 1612, 1586, 1514, 1497, 1454, 1361, 1304, 1249, 1210, 1067.

layer was dried (MgSO₄), filtered, and concentrated. Flash chroma-

¹H NMR (250 MHz, CDCl₃, ppm): δ ϭ 7.42Ϫ7.21 (m, 20 H, Ph), tography of the residue (petroleum ether/EtOAc, 8:2 to 7:3) gave 3

7.17 (d, J ϭ 8.5 Hz, 2 H, Ph-OMe), 6.84 (d, J ϭ 8.5 Hz, 2 H, Ph- (405 mg, 79%) as a colourless oil. [α]²_D⁹ϭ 54 (c ϭ 1, CH₂Cl₂). IR

OMe), 5.94 (dddd, J_b,ctϭ 17.0, J_b,ccϭ 10.5, J_b,aЈϭ 6.0, J_b,a

5.5 Hz, 1 H, H-b), 5.36 (dq, J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gem

1.5 Hz, 1 H, H-ct), 5.25 (dq, J_cc,bϭ 10.5, J_cc,aϭ J_cc,aЈϭ J_gem

1.5 Hz, 1 H, H-cc), 5.01 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.94 (d,

J_1,2ϭ 3.5 Hz, 1 H, 1-H), 4.88 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.82

(d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.81 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph),

ϭ

(thin film, cm^Ϫ1): ν˜ ϭ 3089, 3064, 3031, 3006 (ν_CϪH,arom), 2955,

2913, 2863 (ν_CϪH,aliph), 2109 (ν_N3), 1751 (ν_CϭO), 1716, 1613, 1586,

1514, 1497, 1454, 1361, 1303, 1250, 1217. ¹H NMR (250 MHz,

CDCl₃, ppm): δ ϭ 7.50Ϫ7.20 (m, 20 H, Ph), 7.15 (d, J ϭ 8.5 Hz,

2 H, Ph-OMe), 6.84 (d, J ϭ 8.5 Hz, 2 H, Ph-OMe), 5.94 (dddd,

J_b,ctϭ 17.0, J_b,ccϭ 10.5, J_b,aЈϭ 6.0, J_b,aϭ 5.5 Hz, 1 H, H-b), 5.35

3618

 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjoc.org Eur. J. Org. Chem. 2003, 3603Ϫ3620

Building Blocks for the Synthesis of Heparan Sulfate Fragments

FULL PAPER

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[15]

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[17]

R. Ojeda, J. Angulo, P. M. Nieto, M. Martin-Lomas, Can. J.

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J. D. C. Codee, G. A. van der Marel, C. A. A. van Boeckel, J.

(dq, J_ct,bϭ 17.0, J_ct,aϭ J_ct,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-ct), 5.25

(dq, J_cc,bϭ 10.5, J_cc,aϭ J_cc,aЈϭ J_gemϭ 1.5 Hz, 1 H, H-cc), 5.13

(d, J ϭ 10.0 Hz, 1 H, CH₂Ph), 4.92 (d, J_1,2ϭ 3.5 Hz, 1 H, 1-H),

4.86 (d, J ϭ 11.0 Hz, 1 H, CH₂Ph), 4.80 (d, J ϭ 11.0 Hz, 1 H,

CH₂Ph), 4.77 (s, 2 H, CH₂Ph), 4.69 (d, J ϭ 10.5 Hz, 1 H, CH₂Ph),

4.62 (d, J ϭ 12.0 Hz, 1 H, CH₂Ph), 4.61 (d, J ϭ 10.0 Hz, 1 H,

´

H. van Boom, Eur. J. Org. Chem. 2002, 3954Ϫ3965.

L. Poleti, M. Fleischer, C. Vogel, M. Guerrini, G. Torri, L. Lay,

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A. Lubineau, D. Bonnaffe, Eur. J. Org. Chem. 1999,

CH₂PhOMe), 4.52 (d, J ϭ 10.5 Hz, 1 H, CH₂Ph), 4.41 (d, J_1Ј,2Ј

ϭ

2523Ϫ2532.

[18]

[19]

7.5 Hz, 1 H, 1Ј-H), 4.36 (d, J ϭ 12.0 Hz, 1 H, CH₂PhOMe), 4.17

(ddt, J_gemϭ 13.0, J_a,bϭ 5.5, J_a,ccϭ J_a,ctϭ 1.5 Hz, 1 H, H-a), 4.06

(dd, J_4,5ϭ 10.0, J_4,3ϭ 8.5 Hz, 1 H, 4-H), 4.03 (ddt, J_gemϭ 13.0,

M. F. Haller, G.-J. Boons, Eur. J. Org. Chem. 2002, 2033Ϫ2038.

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[20]

J_aЈ,bϭ 6.0, J_aЈ,ccϭ J_aЈ,ctϭ 1.5 Hz, 1 H, H-aЈ), 3.88 (dd, J_6a,6b

ϭ

11.0, J_6a,5ϭ 2.0 Hz, 1 H, 6-H^a), 3.87 (dd J_3,2ϭ 10.0, J_3,4ϭ 8.5 Hz,

1 H, 3-H), 3.81 (dd, J_4Ј,5Јϭ 10.0, J_4Ј,3Јϭ 9.0 Hz, 1 H, 4Ј-H), 3.78

(s, 3 H, PhOMe), 3.71 (dt, J_5Ј,4Јϭ 10.0, J_5Ј,6aЈϭ J_5Ј,6bЈϭ 2.0 Hz,

1 H, 5Ј-H), 3.65 (dt, J_5,4ϭ 10.0, J_5,6aϭ J_5,6bϭ 2.0 Hz, 1 H, 5-H),

3.57 (s, 3 H, COOMe), 3.47Ϫ3.37 (m, 3 H, 2Ј-H, 3Ј-H, 6-H^b), 3.37

(dd, J_2,3ϭ 10.0, J_2,1ϭ 3.5 Hz, 1 H, H-2). ¹³C NMR (62.5 MHz,

CDCl₃, ppm): δ ϭ 168.7 (CϭO), 159.2 (C-OMe, pMBn), 138.3,

138.2, 138.1, 137.6 (C_{quaternary,arom}), 133.3 (C-b), 130.0, 129.5,

128.5, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.8, 127.7, 127.6,

127.5 (C_arom), 117.9 (C-c), 113.7 (C_mpMBn), 102.7 (CЈ-1), 96.7 (C-

1), 83.8, 82.1, 79.2, 78.1, 77.1, 75.5 (CH₂Ph), 75.2 (CH₂Ph), 75.1,

74.5 (CH₂Ph), 74.3 (CH₂Ph), 73.3 (CH₂Ph), 70.5, 68.5 (C-a), 67.2

(C-6), 62.6 (C-2), 55.2 (CH₃, Ph-OMe), 52.3 (CH₃, COOMe).

C₅₂H₅₇N₃O₁₂(916.0 g/mol): calcd. C 68.18, H 6.27, N 4.59, O

20.96; found C 68.23, H 6.39, N 4.65, O 20.76.

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Acknowledgments

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1

In the H NMR spectrum of 4α there is a J⁴W coupling be-

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