General methods for the synthesis of glycopyranosyluronic acid azides

Article abstract of DOI:10.1016/S0008-6215(03)00042-9

Per-O-acetylated D-glycopyranoses derived from both mono- and disaccharides were first converted to glycosyl iodides and subsequently reacted with an azide source to achieve the stereoselective synthesis of β-D-glycosyl azides after deacetylation. Low-temperature (4°C) TEMPO oxidation of the monosaccharides provided the corresponding uronic acids, which were purified as the free acids. Oxidation of the lactosyl- and cellobiosyl azides resulted in diacid formation. However, 4′,6′-O-benzylidene protection enabled selective oxidation of the C-6 hydroxyl. 2-Acetamido-2-deoxy-D-glycopyranosyl azides were also prepared and converted to uronic acids completing the library synthesis.

Full text of DOI:10.1016/S0008-6215(03)00042-9

Carbohydrate Research 338 (2003) 835–841
www.elsevier.com/locate/carres
General methods for the synthesis of glycopyranosyluronic acid
azides
Laiqiang Ying, Jacquelyn Gervay-Hague*
Department of Chemistry, Uni6ersity of California, One Shields A6enue, Da6is, CA 95616, USA
Received 23 September 2002; accepted 15 January 2003
Abstract
Per-O-acetylated
D
-glycopyranoses derived from both mono- and disaccharides were first converted to glycosyl iodides and
-glycosyl azides after deacetylation.
subsequently reacted with an azide source to achieve the stereoselective synthesis of b-
Low-temperature (4 °C) TEMPO oxidation of the monosaccharides provided the corresponding uronic acids, which were purified
D
as the free acids. Oxidation of the lactosyl- and cellobiosyl azides resulted in diacid formation. However, 4%,6%-O-benzylidene
protection enabled selective oxidation of the C-6 hydroxyl. 2-Acetamido-2-deoxy-D-glycopyranosyl azides were also prepared and
converted to uronic acids completing the library synthesis. © 2003 Elsevier Science Ltd. All rights reserved.
Keywords: Glycosyl azides; TEMPO oxidation; Uronic acid azides, unprotected
1. Introduction
ily by the sequence of events. Most often per-O-acety-
lated glycopyranoses are converted to glycosyl azides
and then deprotected to the free sugars, which are
subsequently subjected to selective oxidation of the
primary hydroxyl groups. Alternatively, esters of per-
O-acetylated uronic acids can be converted to glycosyl
azides. Gyo¨rgydea´k and Thiem demonstrated the feasi-
bility of these methods on a number of monomeric
sugars.4 However, due to the formation of salts in the
oxidation step, the unprotected hydroxy acids were not
isolated. Instead, after oxidation of the glycopyranosyl
azide, the acid was converted to a methyl ester, and the
resulting compound was acetylated for purification.
Since we required unprotected azido acids for the
incorporation into solid-phase oligomer synthesis, we
decided to re-examine the Gyo¨rgydea´k approach with
the goal of establishing methods for the purification of
the free glycopyranosyl azide uronic acids. We also
sought to extend the Gyo¨rgydea´k protocol to include
the preparation of disaccharides containing two gly-
curonic acids as well as singly oxidized analogs. Finally,
to increase diversity in the sugar acid azide library,
The design and synthesis of novel molecular scaffolds
with unique structural and biological properties is an
increasingly active area of chemical research.1 In many
of these studies, carbohydrates containing both car-
boxylic acid and amine functionalities have been used
as building blocks for the construction of amide-linked
oligomers.2 We have found solid-phase synthesis to be
an efficient method for coupling the monomer units,
and in most cases the hydroxyl groups do not require
protection. As we expand our studies to include diverse
combinations of carbohydrate units, it has become
important to develop general methods for the synthesis
of appropriately functionalized precursors. Since com-
pounds containing carboxylic acid and azide function-
alities can be directly incorporated into solid-phase
strategies,3 we have targeted the synthesis of these
important carbohydrate analogs.
There are two general strategies for the synthesis of
glycopyranosyluronic acid azides, which differ primar-
* Corresponding author. Tel.: +1-530-7549577; fax: +1-
530-7528995
E-mail address: gervay@chem.ucdavis.edu (J. Gervay-
Hague).
preparation of 2-acetamido-2-deoxy-
D-gluco-,
D-
galacto- and
targeted.
D-mannopyranosyluronic azides was
0008-6215/03/$ - see front matter © 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0008-6215(03)00042-9

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L. Ying, J. Ger6ay-Hague / Carbohydrate Research 338 (2003) 835–841
2. Results and discussion
Initially, our work focused on developing a convenient
glycosyl azides. Classically, per-O-acetylated glycosyl
chlorides and bromides have been reacted with metal
azides (lithium, sodium, or silver) to afford good to
moderate yields of glycosyl azides, but typically high
and stereoselective method for the preparation of b-D-
Table 1
Conversion of per-O-acetylated sugars to b-D-glycopyranosyl azides

L. Ying, J. Ger6ay-Hague / Carbohydrate Research 338 (2003) 835–841
837
Table 2
Oxidation of
uronic acids
acetate generated in the reaction was easily removed by
evaporation, yielding pure per-O-acetylated glycosyl io-
dides, which were quite stable and could even be chro-
matographed. More typically, the crude iodide donors
were directly reacted with tetrabutylammonium azide
(TBAN3) or tetramethylguanidinum azide (TMGA)8 in
CH2Cl2 to afford the per-O-acetyl glycosyl azides. The
results from the above experiments appear in Table 1.
The yields represent a one-pot, two-step process involv-
ing glycosyl iodide generation and azide displacement
D-glycopyranosyl azides to the corresponding
to give the b-
-glycosyl azides (7–12).9
D
We next turned our attention to the oxidation step.
The glycopyranosyl azides were first deprotected using
catalytic amounts of sodium methoxide in methanol.4
When TLC indicated that the reaction was complete,
the methanolic solution was acidified with Dowex 50
(H+) resin and evaporated to dryness. The crude
glycopyranosyl azides were dissolved in saturated
sodium bicarbonate solution, and KBr (5 mol%) and
TEMPO (6 mol%) were added. The oxidant (NaOCl
1.3 M in H2O, 3 equiv) was added slowly in portions,
making certain that the reaction mixture remained cold.
In preliminary studies, we observed that over-oxidation
occurred when the substrates were reacted at room
temperature, but this problem could be overcome by
performing the oxidation at 4 °C. Due to salt forma-
tion, it was difficult to follow the reaction by TLC, but
the progress of the reaction could be monitored by
working up a small amount of the reaction mixture. In
general, the reactions were carried out for 48 h at 4 °C
to insure that the reaction was complete.
When the reaction was complete, any solids that had
formed were removed by filtration, and the aqueous
solution was washed with CH2Cl2 to remove the
TEMPO byproducts. The aqueous layer was carefully
acidified to pH 2.0, making sure that the mixture
remained cold. The resulting yellow solution was con-
centrated on the rotary evaporator until it became
clear, after which time it was lyophilized to afford a
white powder. The white powder was dissolved in
methanol, the salts were filtered, and the methanol was
removed by evaporation. This process was repeated
three times, and the resulting solid was purified using
reversed-phase (RP) HPLC. Salts eluted first from the
column with the desired salt free uronic acids eluting
several minutes later. Typically, the salt-containing
fractions were analyzed for the presence of carbohy-
drate, which was evidenced by the blue color produced
upon charring a TLC spot of the fraction with molyb-
date. If carbohydrate was present, the fraction was
acidified with HCl and resubjected to RP-HPLC. As
shown in Table 2, high yields of the glucosyl (13),
galactosyl (14), and melibiosyl (18) uronic acid azides
were obtained for the two-step process. Similarly, the
cellobiosyl and lactosyl azides were efficiently oxidized
to the diacids 16 and 17. The yield of the mannosyl-
Method A: NaOMe, MeOH; dilute product in aq NaHCO3,
add TEMPO and KBr, then add NaOCl in portions. Stir at
4 °C for 48 h. Method B: Same as method A only Ca(OCl)2
was used as oxidant.
boiling polar solvents such as HMPA or DMF and
heating are required.5 Alternatively, per-O-acetylated
sugars can be activated with a Lewis acid in the pres-
ence of azidotrimethylsilane to give the 1,2-trans
product.6 However, in the case of mannosyl azides,
only the a anomer has been prepared efficiently. In
view of our recent studies on the use of glycosyl iodides
in organic synthesis,7 we decided to probe the potential
of these donors in the preparation of glycosyl azides.
The glycosyl iodides were readily obtained from the
anomeric acetate upon treatment with iodotrimethylsi-
lane in refluxing CH2Cl2 for 30 min. The trimethylsilyl

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L. Ying, J. Ger6ay-Hague / Carbohydrate Research 338 (2003) 835–841
glucuronic acids 21 and 22 after the aforementioned
purification procedure (Scheme 1).
In order to add further diversification to our library
of glycopyranosyluronic acid azides, glycosyl azides10 of
2-acetamido-2-deoxy-D-glucose (23),
D-galactose (24),
and -mannose (25) were subjected to the oxidation
D
conditions. As can be seen in Scheme 2, 23 and 24
underwent efficient conversion to the uronic acids 26
and 27, respectively. In contrast, 25 gave poor yields of
28, just as was seen for b-
D
-mannopyranosyl azide. We
also attempted the oxidation of a-
D-mannopyranosyl
azide 29, and here again, the uronic acid (30) was
formed in only 10% yield, indicating that oxidation is
generally sluggish for substrates of the
D-manno
configuration.
Scheme 1.
3. Conclusions
Methods have been developed for the mild conversion
of per-O-acetylated sugars to b-glycopyranosyl azides
via glycosyl iodides and their subsequent oxidation to
the corresponding uronic acids. A protocol for desalt-
ing the unprotected hydroxy acids and purifying them
on RP-HPLC has been established providing carboxylic
acid azides ready for solid-phase oligomer synthesis.
Compounds derived from
azides were smoothly converted, whereas oxidation of
substrates with the -manno configuration did not pro-
D-gluco and D-galacto sugar
D
ceed to completion. Nevertheless, the mannuronic acids
could be separated from the starting material; and by
recycling the starting mannopyranosyl azides, multi-
gram quantities of both a- and b-D-mannopyran-
osyluronic acid azides and a-2-acetamido-2-deoxy-
mannopyranosyluronic acid azide could be prepared.
Scheme 2.
uronic acid (15) was only 8% using NaOCl as the
oxidant.† The reaction was slightly improved using
Ca(OCl)2 but even then only about 20% yield was
realized. However, the starting material could be re-
trieved from the reaction and re-subjected to the reac-
tion conditions. In this manner multigram quantities of
15 were produced. The disaccharide diacids (16 and 17)
are attractive compounds for generating branched
amide-linked oligomers; however, we also recognized
the need for single oxidation products. In order to
achieve that goal, 10 and 11 were deacetylated and
subsequently treated with a,a-dimethoxytoluene in the
presence of a catalytic amount p-toluenesulfonic acid to
provide the corresponding 4%,6%-O-benzylidene com-
pounds 19 (72%) and 20 (54%), respectively. Subse-
quent oxidation proceeded smoothly yielding the
4. Experimental
4.1. General methods
All chemicals were used as supplied without further
purification. Solvents (MeOH 99.8%, CH2Cl2 99.8%,
PhMe 99.8%) were purchased in anhydrous Sure/Seal™
bottles from Aldrich, used without further purification,
and stored under argon. TMSI was purchased from
Fluka (]98%) and used without purification unless the
color had changed to a dark brown shade, in which
case, it was discarded or distilled under an argon atmo-
sphere from quinoline. TMSI was stored at −15 °C
under a desiccated atmosphere. Dowex 50WX8 (200
mesh) acidic resin was purchased from Aldrich, washed
copiously with MeOH, and used without further purifi-
cation. NaOMe–MeOH (0.5 M) was purchased from
Aldrich. Glass-backed EM Science TLC plates (Silica
Gel 60 with a 254 nm fluorescent indicator) were pur-
† Low yields in the oxidation of mannopyranosyl azides
with NaOCl was also observed by Gyo¨rgydea´k and Thiem.
See Ref. 4.

L. Ying, J. Ger6ay-Hague / Carbohydrate Research 338 (2003) 835–841
839
chased from VWR International, cut into 2×5-cm
strips, used without further manipulation, and stored
over dessicant. Developed TLC plates were visualized
under a short-wave UV lamp, stained with a cerium–
molybdate solution and charred. Column chromatogra-
phy was conducted using flash silica gel (32–63 mm)
available from Scientific Adsorbents, and solvents were
purchased from EM Science. NMR experiments (1D
and 2D) were conducted on Inova 400 MHz and/or
Bruker DRX500 MHz spectrometers at 298 K. Optical
data were taken on a JASCO DIP-370 Digital Polar-
imeter. RP-HPLC preparative separations were carried
out on Dynamax-60A C18 column. Solvents: (A)
H2O+0.1% TFA; and (B) H2O–CH3CN gradient
100% to 50% H2O, with UV detection at 190 and 220
nm.
mg) and TEMPO (10 mg), after which solid Ca(OCl)2
(200 mg) was added in portions at 0 °C. The mixture
was stirred for 2 days at 4 °C, then the mixture was
filtered and washed with CH2Cl2 to remove TEMPO
byproduct. The aqueous layer was acidified to pH 1–2
by 4 N HCl. The yellow solution was concentrated until
it became clear, after which time it was lyophilized to
afford a white powder. The white powder was extracted
with MeOH, the salts were filtered, and the MeOH was
removed by evaporation. This process was repeated
three times, and the resulting solid was purified by
RP-HPLC.
4.5. b-D-Glucopyranosyluronic acid azide (13)
Prepared in 76% yield using TEMPO oxidation method
A. Purified by RP-HPLC using solvent system A. [h]D26
1
4.2. General procedure for the synthesis of per-O-ace-
−22.5° (c 1.1, H2O); H NMR (D2O): l 4.84 (d, 1 H,
tyl glycosyl azides
J 8.5 Hz, H-1), 4.09 (d, 1 H, J 9.0 Hz, H-5), 3.54–3.61
(m, 2 H, H-3, H-4), 3.32 (applt, 1 H, J 8.5 Hz, H-2);
13C NMR (D2O): l 177.0 (C-6), 92.2 (C-1), 79.6 (C-5),
77.7, 74.8 (C-2), 73.6; ESIMS: m/z 241.9 [M+Na]+.
To a solution of per-O-acetyl pyranoses (1.0 mmol) in
dry CH2Cl2 (0.5 M solution) was added TMSI (1.1
mmol) under argon. The solution was refluxed under
argon for 30 min and concentrated in vacuo. The
resulting residue was azeotroped with dry toluene twice
to afford the crude glycosyl iodide, which was redis-
solved in dry CH2Cl2, before adding TBAN3 or TMGA
(1.5 mmol). The solution was stirred under argon for 10
min, CH2Cl2 (20 mL) and water (20 mL) were added to
the reaction mixture successively, and the organic layer
washed with 10% Na2S2O3, 10% NaHCO3, water, brine,
and dried (anhyd Na2SO4) and evaporated. The residue
was purified by column chromatography to give the
corresponding per-O-acetyl glycosyl azide.
4.6. b-D-Galactopyranosyluronic acid azide (14)
Prepared in 71% yield using TEMPO oxidation method
A. Purified by RP-HPLC using solvent system A. [h]D26
1
−31.9° (c 0.8, H2O); H NMR (D2O): l 4.83 (d, 1 H,
J 9.0 Hz, H-1), 4.37 (d, 1 H, J 3.0 Hz, H-4), 4.35 (s, 1
H, H-5), 3.88 (dd, 1 H, J 10.0, 3.5 Hz, H-3), 3.63 (applt,
1 H, J 9.5 Hz, H-2); 13C NMR (D2O): l 174.2 (C-6),
90.6 (C-1), 77.2 (C-5), 73.0 (C-3), 70.3 (C-2, C-4);
ESIMS: m/z 242.0 [M+Na]+.
4.7. b-D-Mannopyranosyluronic acid azide (15)
4.3. General procedure (A) for TEMPO oxidation
Prepared in 20% yield using TEMPO oxidation proce-
To a solution of the unprotected glycosyl azides (1.0
mmol) in satd aq NaHCO3 (5 mL) were added KBr (12
mg) and TEMPO (10 mg), after which a solution of
NaOCl (2.4 mL, 1.3 M) was added dropwise at 0 °C.
The mixture was stirred for 2 days at 4 °C, then the
mixture was washed with CH2Cl2 to remove TEMPO
byproducts. The aq layer was acidified to pH 1–2 using
4 N HCl. The yellow solution was concentrated until it
became clear, after which time it was lyophilized to
afford a white powder. The white powder was extracted
with MeOH, the salts were filtered, and the MeOH was
removed by evaporation. This process was repeated
three times and the resulting solid was purified by
RP-HPLC.
dure B. Purified by RP-HPLC using solvent system A.
1
[h]2D6 −70.8° (c 1.0, H2O); H NMR (D2O): l 4.94 (s, 1
H, H-1), 4.01 (d, 1 H, J 3.0 Hz, H-2), 3.96 (d, 1 H, J 9.5
Hz, H-5), 3.80 (applt, 1 H, J 9.5 Hz, H-4), 3.67 (dd, 1
H, J 3.0, 9.5 Hz, H-3); 13C NMR (D2O): l 176.3 (C-6),
87.9 (C-1), 78.6, 73.3 (C-3), 71.6 (C-2), 69.0; ESIMS:
m/z 242.0 [M+Na]+.
4.8. b-Cellobiosyldiuronic acid azide (16)
Prepared in 76% yield using TEMPO oxidation proce-
dure B. Purified by RP-HPLC using solvent system A.
1H NMR (D2O): l 4.91 (d, 1 H, J 9.0 Hz, H-1), 4.61 (d,
1 H, J 7.5 Hz, H-1%), 4.23 (d, 1 H, J 9.5 Hz, H-5), 4.06
(d, 1 H, J 9.5 Hz, H-5%), 3.88 (applt, 1 H, J 9.0 Hz,
H-4), 3.75 (applt, 1 H, J 9.0 Hz, H-3), 3.64 (applt, 1 H,
J 9.0 Hz, H-4%), 3.58 (applt, 1 H, J 9.5 Hz, H-3%),
3.42–3.37 (m, 2 H, H-2, H-2%); 13C NMR (D2O): l
172.7, 171.8, 102.4 (C-1%), 90.38 (C-1), 79.7 (C-4), 75.5
4.4. General procedure (B) for TEMPO oxidation
To a solution of the unprotected glycosyl azides (1.0
mmol) in satd aq NaHCO3 (5 mL) were added KBr (12

840
L. Ying, J. Ger6ay-Hague / Carbohydrate Research 338 (2003) 835–841
(C-5), 75.4 (C-3%), 74.6 (C-5%), 74.2 (C-3), 73.0, 72.6,
71.5 (C-4%); ESIMS: m/z 418.0 [M+Na]+.
4.12. 4%,6%-O-Benzylidene-b-lactopyranosyl azide (20)
To a solution of lactosyl azide (11) (1.0 mmol) in dry
DMF (5 mL) were added a,a-dimethoxytoluene (1.5
mmol) and p-toluenesulfonic acid (10 mg). The mixture
was stirred at 40 °C in a vacuum. After 2 h, more DMF
(4 mL), dimethoxytoluene (1.5 mmol) and p-toluenesul-
fonic acid (10 mg) were added, and stirring was continued
for an additional 2 h. The solution was concentrated, and
the residue was purified by column chromatography to
4.9. b-Lactosyldiuronic acid azide (17)
Prepared in 71% yield using TEMPO oxidation proce-
dure B. Purified by RP-HPLC using solvent system A.
1
[h]2D6 −58.6° (c 0.5, H2O); H NMR (D2O): l 4.89 (d,
1 H, J 8.5 Hz, H-1), 4.50 (d, 1 H, J 8.0 Hz, H-1%), 4.45
(d, 1 H, J 0.5 Hz, H-5%), 4.29 (d, 1 H, J 2.0 Hz, H-4%),
4.24 (d, 1 H, J 10.0 Hz, H-5), 3.88 (applt, 1 H, J 9.0
Hz, H-4), 3.76 (applt, 1 H, J 8.5 Hz, H-3), 3.74 (dd, 1
H, J 8.0 Hz, 3.5 Hz, H-3%), 3.56 (applt, 1 H, J 8.0 Hz,
H-2%), 3.37 (applt, 1 H, J 8.5 Hz, H-2); 13C NMR
(D2O): l 171.7, 171.6, 102.7 (C-1%), 90.3 (C-1), 80.1
(C-4), 75.2 (C-5), 74.3 (C-5%), 74.2 (C-3), 72.3 (C-3%),
72.1 (C-2), 70.3 (C-2%), 69.6 (C-4%); ESIMS: m/z 418.0
[M+Na]+.
1
give 20 in 54% yield. H NMR (CD3OD): l 7.45 (m, 2
H, Ar), 7.27 (m, 3 H, Ar), 5.54 (s, 1 H, CHAr), 4.47 (d,
1 H, J 9.0 Hz, H-1), 4.40 (d, 1 H, J 7.0 Hz, H-1%),
4.13–4.08 (m, 3 H, H-4%, H-6¦, H-6§), 3.84 (m, 2 H, H-6,
H-6%), 3.60–3.54 (m, 4 H, H-2%, H-3%, H-4, H-5%), 3.49
(applt, 1 H, J 9.0 Hz, H-3), 3.43 (m, 1 H, H-5), 3.14
(applt, 1 H, J 9.0 Hz, H-2); 13C NMR (CD3OD): l 139.4,
129.9, 129.0, 127.4, 104.6 (C-1%), 102.18 (CHPh), 91.7
(C-1), 79.3 (C-5%), 78.5 (C-5), 77.2 (C-4%), 76.2 (C-3), 74.5
(C-2), 73.3 (C-3%), 71.7 (C-2%), 70.1 (C-6%), 68.3 (C-4), 61.4
(C-6). FABMS: m/z 478.1420 [M+Na]+.
4.10. b-Melibiopyranosyluronic acid azide (18)
Prepared in 64% yield using TEMPO oxidation proce-
4.13. 4%,6%-O-Benzylidene-b-cellobiopyranosyluronic acid
azide (21)
dure A. Purified by RP-HPLC using solvent system A.
1
[h]2D6 +49.5° (c 3.2, H2O); H NMR (D2O): l 5.02 (d,
Prepared in 37% yield using TEMPO oxidation proce-
1 H, J 3.5 Hz, H-1%), 4.73 (d, 1 H, J 9.0 Hz, H-1), 4.64
(s, 1 H, H-5%), 4.32 (d, 1 H, J 2.0 Hz, H-4%), 3.94–3.81
(m, 4 H, H-3%, H-6%, H-6, H-2%), 3.68 (m, 1 H, H-5),
3.50–3.41 (m, 2 H, H-3, H-4), 3.24 (applt, 1 H, J 9.0
Hz, H-2); 13C NMR (D2O): l 174.0 (C-6%), 98.7 (C-1%),
90.8 (C-1), 76.8 (C-5), 76.4, 73.3 (C-2), 71.4 (C-5%), 69.7
(C-3%), 69.6, 68.4 (C-2%), 66.7 (C-6); FABMS: m/z
404.0911 [M+Na]+.
dure A. Purified by RP-HPLC using solvent system B.
1
[h]2D6 −37.7° (c 0.8, H2O); H NMR (D2O): l 7.53 (m,
2 H, Ar), 7.46 (m, 3 H, Ar), 5.72 (s, 1 H, CHAr), 4.77
(d, 1 H, J 9.0 Hz, H-1), 4.60 (d, 1 H, J 8.3 Hz, H-1%),
4.36 (dd, 1 H, J 5.0, 10.5 Hz, H-6%), 3.93–3.85 (m, 2 H,
H-5, H-6), 3.78–3.60 (m, 5 H, H-3%, H-4%, H-4, H-5%,
H-3), 3.41 (applt, 1 H, J 8.3 Hz, H-2%), 3.32 (applt, 1 H,
J 9.0 Hz, H-2); 13C NMR (D2O): l 176.8 (C-6), 138.3,
132.1, 130.9, 128.5, 105.2 (C-1%), 103.9, 92.0 (C-1), 82.1
(C-4%), 82.0 (C-4), 79.4 (C-5), 76.4, 76.3, 74.6, 74.5, 70.0,
68.1; FABMS: m/z 470.1403 [M+H]+.
4.11. 4%,6%-O-Benzylidene-b-cellobiopyranosyl azide (19)
To a solution of cellobiosyl azide 10 (1.0 mmol) in dry
DMF (5 mL) were added a,a-dimethoxytoluene (1.5
mmol) and p-toluenesulfonic acid (10 mg). The mixture
was stirred at 40 °C in a vacuum. After 2 h, more DMF
(4 mL), dimethoxytoluene (1.5 mmol) and p-toluenesul-
fonic acid (10 mg) were added, and stirring was contin-
4.14. 4%,6%-O-Benzylidene-b-lactopyranosyluronic acid
azide (22)
Prepared in 42% yield using TEMPO oxidation procedure
A. Purified by RP-HPLC using solvent system B. [h]D26
1
−20.2° (c 0.6, H2O); H NMR (D2O): l 7.53 (m, 2 H,
ued for an additional
2 h. The solution was
Ar), 7.46 (m, 3 H, Ar), 5.74 (s, 1 H, CHAr), 4.85 (d, 1
H, J 9.0 Hz, H-1), 4.53 (d, 1 H, J 7.5 Hz, H-1%), 4.34 (d,
1 H, J 3.5 Hz, H-4%), 4.25 (m, 2 H, H-6, H-6%), 4.14 (d,
1 H, J 10.0 Hz, H-5), 3.84–3.73 (m, 5 H, H-2%, H-3%, H-5%,
H-3, H-4), 3.34 (applt, 1 H, J 9.0 Hz, H-2); 13C NMR
(D2O): l 172.5 (C-6), 137.0, 129.9, 128.8, 126.4, 102.9
(C-1%), 101.30 (CHPh), 90.3 (C-1), 79.6 (C-5%), 75.9 (C-5),
75.9 (C-4%), 74.2, 72.3 (C-2), 71.4, 70.5, 69. (C-6%), 66.9;
ESIMS: m/z 492.0 [M+Na]+.
concentrated, and the residue was purified by column
chromatography to give 19 in 72% yield. 1H NMR
(CD3OD): l 7.42 (m, 2 H, Ar), 7.27 (m, 3 H, Ar), 5.50
(s, 1 H, CHAr), 4.49 (d, 1 H, J 8.5 Hz, H-1), 4.47 (d,
1 H, J 8.5 Hz, H-1%), 4.23 (m, 1 H, H-6§), 3.87–3.80
(m, 2 H, H-6, H-6%), 3.71 (m, 1 H, H-6¦), 3.59 (applt, 1
H, J 9.0 Hz, H-3%), 3.55 (applt, 1 H, J 9.0 Hz, H-4%),
3.48–3.42 (m, 5 H, H-3, H-4, H-5, H-5%), 3.28 (applt, 1
H, J 8.5 Hz, H-2%), 3.15 (applt, 1 H, J 8.5 Hz, H-2); 13C
NMR (CD3OD): l 139.0, 129.9, 129.0, 127.5, 105.0
(C-1%), 102.9 (CHPh), 91.8 (C-1), 81.9 (C-5%), 80.0 (C-
4%), 78.5 (C-5), 76.1 (C-3), 75.8 (C-2), 74.5 (C-2), 74.5
(C-3%), 69.4 (C-6%), 67.7 (C-4), 61.5 (C-6). FABMS: m/z
456.1630 [M+H]+.
4.15. 2-Acetamido-2-deoxy-a-D-mannopyranosyl azide
(25)
Prepared in 85% yield using the published method.6 1
NMR (D2O): l 5.39 (s, 1 H, H-1), 4.23 (s, 1 H, H-2),
H

L. Ying, J. Ger6ay-Hague / Carbohydrate Research 338 (2003) 835–841
841
3.92–3.79 (m, 4 H, H-3, H-5, H-6, H-6%), 3.59 (applt, 1
H, J 9.5 Hz, H-4), 2.01 (s, 3 H, NHAc); 13C NMR
(CD3OD): l 174.0, 90.6, 76.5, 69.9, 67.8, 62.1, 53.9,
22.6. ESIMS: m/z 246.9 [M+H]+.
tion CHE-0196482. NSF CRIF program (CHE-
9808183), NSF Grant OSTI 97-24412, and NIH Grant
RR11973 provided funding for the NMR spectrometers
used on this project.
4.16. 2-Acetamido-2-deoxy-b-D-glucopyranosyluronic
acid azide (26)
References
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Prepared in 80% yield using TEMPO oxidation proce-
1
dure A. [h]2D6 −37.8° (c 1.5, H2O); H NMR (D2O): l
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H-5), 3.77 (applt, 1 H, J 9.5 Hz, H-2), 3.65–3.57 (m, 2
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177.0, 176.0, 90.8 (C-1), 79.1 (C-5), 75.5, 73.7, 56.9
(C-2), 24.2 (NHAc); FABMS: m/z 283.0649 [M+Na]+
.
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Prepared in 72% yield using TEMPO oxidation proce-
1
dure A. [h]2D6 −10.8° (c 0.9, H2O); H NMR (D2O): l
4.73 (d, 1 H, J 9.0 Hz, H-1), 4.31 (d, 1 H, J 2.0 Hz,
H-4), 4.18 (s, 1 H, H-5), 3.97 (applt, 1 H, J 9.5 Hz,
H-2), 3.87 (dd, 2 H, J 3.5, 10.5 Hz, H-3), 2.10 (s, 3 H,
NHAc); 13C NMR (D2O): l 175.6, 172.8, 89.3 (C-1),
76.5 (C-5), 70.8 (C-3), 69.2 (C-4), 51.7 (C-2), 22.8
(NHAc); FABMS: m/z 283.0647 [M+Na]+.
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4.18. 2-Acetamido-2-deoxy-a-D-mannopyranosyluronic
acid azide (28)
Prepared in 30% yield using TEMPO oxidation proce-
1
dure B. [h]2D6 +78.8° (c 1.1, H2O); H NMR (D2O): l
5.40 (d, 1 H, J 3.2 Hz, H-1), 4.23 (applt, 1 H, J 3.8 Hz,
H-2), 4.11 (d, 1 H, J 8.8 Hz, H-5), 3.92 (dd, 1 H, J 4.4,
8.8 Hz, H-3), 3.78 (t, 2 H, J 8.8 Hz, H-4), 2.04 (s, 3 H,
NHAc); 13C NMR (D2O): d 176.0, 174.7, 88.0 (C-1),
75.5, 69.1, 68.5, 51.4, 22.0 (NHAc); ESIMS: m/z 283.0
[M+Na]+.
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Prepared in 10% yield using TEMPO oxidation proce-
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dure B. [h]2D6 +128.4° (c 1.7, H2O); H NMR (D2O): l
5.44 (d, 1 H, J 3.5 Hz, H-1), 4.32 (d, 1 H, J 8.5 Hz,
H-5), 3.94 (applt, 1 H, J 8.5 Hz, H-4), 3.84 (applt, 1 H,
J 3.5 Hz, H-2), 3.79 (dd, 1 H, J 3.5, 8.5 Hz, H-3); 13C
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68.9; ESIMS: m/z 242.0 [M+Na]+.
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Acknowledgements
We appreciate helpful suggestions for optimizing the
TEMPO oxidation from Professor H.K. and Dr M.S.
This work was supported by National Science Founda-