Synthesis of l -Ribose from d -Ribose by a Stereoconversion through Sequential Lactonization as the Key Transformation

Article abstract of DOI:10.1055/s-0036-1588857

l -Ribose, a key precursor of various l -nucleosides can only be synthesized from other sugars or other non-sugar precursors. Herein, the study involves the synthesis of naturally rare l -ribose from readily available d -ribose. Though, many synthetic strategies are developed to meet the increasing demands of l -ribose, seeking innovation, a synthesis employing sequential lactonization as the key transformation was explored. This novel conversion involves protection, oxidation, sequential lactonization, reduction with DIBAL-H, and deprotection..

Full text of DOI:10.1055/s-0036-1588857

SYNTHESIS
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X
©
Georg Thieme Verlag Stuttgart · New York
2017, 49, A–D
paper
A
en
Synthesis
J. Ban et al.
Paper
Synthesis of L-Ribose from D-Ribose by a Stereoconversion
through Sequential Lactonization as the Key Transformation
Jaeyoung Bana‡
Saira Shabbirb‡
Minkyung Lima
Byunghoon Leec
Hakjune Rhee*a,c
Sequential lactonization
O
O
O
O
O
OH
O
HO
HO
O
HO
OH
OH
HO
OH
O
O
HO
OH
i, ii, iii
HO
OH
D-Ribose
L-Ribose
a
Department of Bionanotechnology, Hanyang University,
5
1
5 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do
5588, South Korea
+
i. Amberlyst 15(H ), H2O, 70 °C
ii. NaBH4, 0 °C
34.3% overall yield
b
c
Department of Chemistry, Quaid-i-Azam University,
Islamabad 45320, Pakistan
Department of Applied Chemistry, Hanyang University, 55
Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do
+
iii. Amberlyst 15(H ), i-PrOH, reflux
15588, South Korea
hrhee@hanyang.ac.kr
‡
These authors contributed equally to this work.
Received: 14.04.2017
Accepted after revision: 08.05.2017
Published online: 20.06.2017
worldwide. L-Ribose can be synthesized by chemical trans-
8
9
formation from other sugars such as L-arabinose, L-xylose,
1
0
11
12
DOI: 10.1055/s-0036-1588857; Art ID: ss-2017-f0254-op
D-ribose, D-mannono-1,4-lactone, D-glucose, D-galac-
tose,13 D-fructose or by chemical synthesis as asymmetric
chain elongation with non-sugar compounds. Despite all
14
Abstract L-Ribose, a key precursor of various L-nucleosides can only be
synthesized from other sugars or other non-sugar precursors. Herein,
the study involves the synthesis of naturally rare L-ribose from readily
available D-ribose. Though, many synthetic strategies are developed to
meet the increasing demands of L-ribose, seeking innovation, a synthe-
sis employing sequential lactonization as the key transformation was
explored. This novel conversion involves protection, oxidation, sequen-
tial lactonization, reduction with DIBAL-H, and deprotection.
15
these efforts, L-ribose is still considered an expensive and
highly in demand sugar for the synthesis of many biologi-
cally significant antiviral active pharmaceuticals. Therefore,
we focused our study with an emphasis on the use of inex-
pensive starting materials and reagents, simple workup
procedures, and minimal use of purification techniques.
Previously reported methods used expensive reagents,
while we have accomplished a practical synthesis of L-ri-
bose using commercially available D-ribose as the starting
material. In addition, in the current study, separation steps
Key words L-ribose, D-ribose, sugar, lactonization, DIBAL-H, reduction
In contrast to D-ribose, which is found in all almost liv-
ing cells, L-ribose is naturally non-existent. The accounts of
1
L-ribose dates back to the early 20th century but correla-
tion of naturally occurring D-nucleosides with the synthe-
sized L-nucleosides was not studied until the end of centu-
ry. Fortunately, such studies led to a new world of develop-
H
N
O
O
O
2
O
O
N
N
HN
OH
OH
ments in the pharmaceutical industry.
O
Recently, L-ribose has received recognition as the main
precursor and basic structural component of several biolog-
ically active L-nucleosides, glycoproteins, glycolipids, and
OH
F
OH
Telbivudine
Clevudine
3
oligonucleotides. L-Nucleoside-based drugs have received
Cl
Cl
O
a great deal of attention around the globe because of their
potential to interact with the viral nucleoside synthesis-
H2N
N
replication process. Telbivudine, Clevudine, Levovirin,6
2
a
4
5
N
O
N
O
N
N
OH
7
and Maribavir, as shown in Figure 1, are well-known ex-
OH
HO
OH
NH
amples of L-ribose related antiviral agents used for the
treatment of hepatitis, AIDS, and other diseases such as im-
munological disorders. As a result of the emerging impor-
tance and high demands of L-ribose, the commercial pro-
duction as well as laboratory syntheses have been explored
OH
HO
Levovirin
Maribavir
Figure 1 L-Ribose related antiviral agents
©
Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–D

B
Synthesis
J. Ban et al.
Paper
such as column chromatography are minimized, and an
efficient stereoconversion is achieved without using an
expensive chiral auxiliary.
oxylic acid 3 also involved TEMPO catalysis but was assisted
by trichloroisocyanuric acid (TCCA).21 In contrast to sodium
chlorite and bleach, TCCA is nontoxic and a less expensive
reagent. Once again, the reaction proceeded well; however,
the product appeared to dissolve in water, which made it
difficult to remove TCCA from the reaction mixture. Hence,
we returned to the first set of reagents, but utilized step-
Previously, some reports on L-ribose synthesis have in-
16
10c,g
volved Mitsunobu reaction or Swern oxidation,
which
have drawbacks such as the use of expensive reagents, re-
moval of by-products, and low reaction temperature at oxi-
dation step. In contrast, 2,2,6,6-tetramethylpiperidine 1-
oxyl (TEMPO)-catalyzed oxidation employed in the current
study is not only nontoxic but also cheap. It has been used
as a mild oxidizing agent with or without a combination of
wise addition of NaOCl and NaClO to lower the risk factor
2
(Table 1, entry 3).22
Table 1 Optimization Studies for Oxidation of Compound 2
17
different additives like trichloroacetic acid. The oxidation
can also be conducted at room temperature and a combina-
tion of TEMPO with NaOCl were employed here for mild ox-
idizing conditions.1 Another highlight of this synthesis is
that the key transformation combines hydrolysis, reduc-
tion, and lactonization together into a ‘sequential lactoniza-
tion’ that simplifies the process.
Entry
1
Reagents and conditions
Yield (%)
quant
(i) TEMPO, phosphate buffer (pH 6.7), MeCN
8
(
(
ii) NaClO
iii) NaOH (pH 8), 35 °C, 12 h
2
, NaOCl, r.t.
2
3
(i) NaHCO , NaBr, TEMPO, acetone, r.t.
3
90
(
ii) TCCA, r.t., 4 h
The synthesis of L-ribose commenced with the selective
protection of hydroxyl groups of D-ribose, as shown in
Scheme 1. The protection of syn-diol as well as the anomer-
ic hydroxyl group with sulfuric acid in acetone and MeOH
at room temperature afforded the desired product in satis-
(i) EtOAc, TEMPO, KBr, H
2
O, r.t.
quant
(
(
ii) NaOCl (12%), r.t.
iii) NaClO (25%), r.t.
2
(iv) concd HCl, r.t., 8 h
19
factory result.
Next, carboxylic acid 3 was transformed into the key
skeleton of L-ribose, as shown in Scheme 1, through crucial
modifications at C-1 and C-5. Some major changes for the
stereoconversion including reduction of the C-1 carbonyl,
lactonization, and hydroxyl protection were carried out in a
four-step sequence by simple filtration without column
chromatography (Scheme 2; path c in Scheme 1). This se-
quential lactonization began with the deprotection of hy-
droxyl groups with Amberlyst 15 (H ) catalyst. Following
deprotection, selective reduction of the formyl group to hy-
droxyl was carried out by adding NaBH4 to the reaction
mixture, followed by lactonization assisted by Amberlyst
resin. The use of Amberlyst resin has several advantages to
HO
HO
O
HO
O
O
O
HO
(a)
(b)
(c)
O
O
O
O
HO
OH
O
O
1
2
3
O
OH
OH
+
23
TBDMSO
TBDMSO
HO
O
O
O
(
d)
(e)
TBDMSO
TBDMSO
HO
TBDMSO
TBDMSO
HO
7
8
9
+
traditional sources of H like HCl, such as ease of reaction
Scheme 1 Synthesis of L-ribose. Reagents and conditions: (a) H SO , ac-
monitoring, simple separation by filtration, and the absence
of counter-ions. After separating the solid residue from the
reaction vessel, the reaction contents were treated with
tert-butyldimethylsilyl chloride (TBDMSCl) using imidazole
as base, which led to protection of all three hydroxyl
groups. The stereo-inversion during the sequential lacton-
ization was confirmed by X-ray crystallographic analysis. X-
ray crystallographic ORTEP plots of compound 3 and 7 are
shown in Figure 224 (for details, see Supporting Informa-
tion).
2
4
etone, MeOH, r.t., 48 h, 90%; (b) KBr, TEMPO, NaOCl, NaClO , EtOAc,
2
+
r.t., 8 h, 99.9%; (c) i) Amberlyst 15 (H ), H O, 70 °C, 5 h, ii) NaBH , 0 °C,
h, iii) Amberlyst 15 (H ), i-PrOH, reflux, 12 h, iv) TBDMSCl, imidazole,
2
4
+
1
DMF, 50 °C, 12 h, 67%; (d) DIBAL-H, CH Cl , –70 °C, 1.5 h, 77%; (e) CsF,
2
2
MeOH, r.t., 24 h, 74%.
Protection of alcohols was followed by oxidation of the
exposed primary hydroxyl to carboxyl group. Three sets of
reaction conditions were found to show promising results,
as shown in Table 1. The best productivity was observed us-
The synthesis of L-ribose was completed by DIBAL-H re-
20
25
ing the reaction protocol reported by Zhao et al. for the
oxidation catalyzed by TEMPO and subsequent treatment
with sodium chlorite and bleach. Despite the quantitative
product yield, the reaction conditions were anticipated to
be risky on large scale due to the dangers associated with
using sodium chlorite and bleach together. Another such at-
tempt to oxidize the alcohol 2 to the corresponding carb-
duction of lactone 7 to lactol 8 followed by desilylation
using a typical fluoride to give L-ribose (Scheme 1).
In summary, we have accomplished an efficient and
practical synthesis of L-ribose on gram scale with an overall
34.3% yield using commercially available D-ribose as the
starting material. The synthetic strategy employed in the
current study made use of inexpensive reagents, mild reac-
©
Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–D

C
Synthesis
J. Ban et al.
Paper
tion conditions, and simple separation techniques. It is es-
pecially noteworthy in this synthesis that a stereoconver-
sion is possible by sequential lactonization without the use
of an expensive chiral auxiliary.
product as a pale yellow oil; yield 24.4 g (90%); R = 0.2 (hexane/EtOAc
f
25
26
20
=
5:1, v/v); [α]D –80.00 (c 1.00, CHCl ) {Lit. [α]D –75.00 (c 1.00,
3
CHCl )}.
3
1
H NMR (CDCl , 400 MHz): δ = 4.97 (s, 1 H), 4.83 (d, J = 5.7 Hz, 1 H),
3
4
3
.58 (d, J = 6.0 Hz, 1 H), 4.42 (t, J = 2.7 Hz, 1 H), 3.56–3.72 (m, 2 H),
.43 (s, 3 H), 3.32 (dd, J = 10.0, 3.0 Hz, 1 H), 1.49 (s, 3 H), 1.32 (s, 3 H).
All solvents were dried and distilled by standard procedures. Com-
mercially available reagents were used without prior purification. Re-
actions were performed in flame-dried round-bottom flasks under an
argon atmosphere and monitored by TLC, visualized by an exposure
to UV light and/or by staining to ninhydrin, phosphomolybidic acid
ethanolic solution, I2 crystals, or KMnO4 solution. Crude products
were purified by flash column chromatography on silica gel (230–400
Methyl 2,3-O-Isopropylidene-D-ribofuranosiduronic Acid (3)27
KBr (1.70 g, 14.7 mmol) and TEMPO (0.383 g, 2.45 mmol) were added
to a solution of 2 (10.0 g, 49.0 mmol) in EtOAc (100 mL), followed by
dropwise addition of NaOCl (12%, 39.5 mL, 63.7 mmol) over 30 min at
0
°C. Then, the pH was adjusted to 2 by the addition of 35% HCl, fol-
lowed by the addition of 25% aq NaClO (5.76 g, 63.7 mmol) over 30
2
min maintaining r.t. Stirring was continued until completion of the
reaction after 7 h. After adjusting the pH to 2–3, the product was ex-
tracted with EtOAc. The combined organic phases were washed with
mesh). NMR spectra were recorded in CDCl on Bruker AV-400 MHz
3
1
13
(
H: 400 MHz; C: 100 MHz) spectrometer. Chemical shifts are re-
ported relative to TMS as an internal standard. Optical rotations were
measured using PerkinElmer-343 instrument.
brine, dried (MgSO ), filtered, and the solvent was removed in vacuo
4
to give the crude product. Recrystallization from hot CH Cl2 with n-
2
hexane gave a white solid; yield: 10.68 g (quant.); mp 128.5–129.5 °C
Methyl 2,3-O-Isopropylidene-D-ribofuranoside (2)26
27b
20.5
(Lit. mp 129–131 °C); [α]D
–67.29 (c 2.47, CHCl3).
To a suspension of D-ribose (1; 20.0 g, 133.2 mmol) in acetone (100
1
H NMR (CDCl , 400 MHz): δ = 10.69 (s, 1 H), 5.20 (d, J = 6.3 Hz, 1 H)
3
mL) and MeOH (100 mL) was carefully added conc. H SO (10 mL) at
2
4
5.09 (s, 1 H), 4.69 (s, 1 H), 4.59 (d, J = 6.0 Hz, 1 H), 3.45 (s, 3 H), 1.50(s,
r.t. The resulting solution was stirred for 48 h. After the completion of
reaction by TLC monitoring, the solution was neutralized by the addi-
3
H), 1.34 (s, 3 H).
tion of solid NaHCO . The solid was filtered, then the mixture was
concentrated, and extracted with EtOAc. The organic layer was dried
3
2,3,5-Tri-O-(tert-butyldimethylsilyl)-L-ribonic Acid γ-Lactone (7)
(
MgSO ), filtered, and the solvent was evaporated. The crude product
To a stirred solution of 3 (5.0 g, 22.9 mmol) in distilled H O was added
Amberlyst 15 (H ) (5.0 g). The reaction mixture was maintained at 70
4
2
+
was purified by silica gel flash column chromatography to give the
°C for 5 h. After the completion of reaction by TLC monitoring, the
mixture was cooled to 0 °C and NaBH (3.47 g, 91.7 mmol) was slowly
4
O
HO
O
O
O
HO
O
O
added. When TLC revealed completion of the reaction, the reaction
HOOC
HO
OH
HO
+
O
was quenched by the addition of Amberlyst 15 (H ) to pH 7. The mix-
O
(i)
HO
HO
(ii)
OH (iii)
ture was filtered and the resin was washed with H O and MeOH.
2
HO
MeOH in the reaction mixture was evaporated in order to remove
boron residues as trimethyl borate, and this procedure was repeated
OH
O
OH
HO
+
three times. i-PrOH (50 mL) and Amberlyst 15 (H ) (5.0 g) were added
3
4
5
6
to the remaining solution, and the mixture was refluxed for 12 h. The
crude mixture was filtered through a short pad of silica gel and con-
centrated in vacuo. The residue was dissolved in anhydrous DMF (50
mL), and then imidazole (6.24 g, 91.7 mmol) and TBDMSCl (13.81 g,
91.7 mmol) were added, and the reaction mixture was heated to 50 °C
for 12 h. After the completion of reaction, the mixture was poured
O
TBDMSO
O
(
iv)
TBDMSO
TBDMSO
into H O and stirred for 30 min. The product was filtered and dis-
2
7
solved in CH Cl , and the solution was dried (MgSO ) and evaporated
2
2
4
Scheme 2 Sequential lactonization. Reagents and conditions: (i) Am-
berlyst 15 (H ), H O, 70 °C, 5 h; (ii) NaBH , 0 °C, 1 h; (iii) Amberlyst 15
H ), i-PrOH, reflux, 12 h; (iv) TBDMSCl, imidazole, DMF, 50 °C, 12 h,
7%.
to give a crude yellow liquid. The crude product was purified by silica
gel flash column chromatography to give compound 7 as a white sol-
+
2
4
+
(
6
id; yield: 7.53 g (67%); mp 113.5–114.5 °C; R = 0.5 (hexane/EtOAc =
f
20.5
22
2
0:1, v/v): [α]
–27.17 (c 0.99, CHCl ); for D-isomer: [α]D +28.2 (c
D
8
3
2
0.99, CHCl3).
IR (neat): 2929, 2885, 2857, 1791, 1472 cm–1
.
1
H NMR (CDCl , 400 MHz): δ = 4.58 (d, J = 5.0 Hz, 1 H), 4.25–4.30 (m, 2
3
H), 3.87 (dd, J = 12.0, 3.0 Hz, 1 H), 3.78 (dd, J = 12.0, 3.0 Hz, 1 H), 0.95
(s, 9 H), 0.90 (s, 9 H), 0.89 (s, 9 H), 0.10 (s, 3 H), 0.11 (s, 3 H), 0.14 (s, 3
H), 0.19 (s, 3 H), 0.08 (s, 3 H), 0.07 (s, 3 H).
13
C NMR (CDCl , 100 MHz): δ = 175.20, 85.63, 71.96, 70.54, 62.39,
3
2
–
5.84, 25.82, 25.68, 18.44, 18.30, 18.17, –4.57, –4.63, –4.84, –5.05,
5.53, –5.66.
+
Figure 2 X-ray crystallographic ORTEP plot of compound 3 and 7 with
0% ellipsoidal probability
HRMS (ESI/TOF-Q): m/z [M + H] calcd for C23H50O Si + H: 491.3044;
found: 491.3048.
5
3
5
©
Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–D

D
Synthesis
J. Ban et al.
Paper
2,3,5-Tri-O-(tert-butyldimethylsilyl)-L-ribose (8)
(6) Watson, J. Curr. Opin. Invest. Drugs 2002, 3, 680.
(
7) Reitsma, J. M.; Terhune, S. S. Antiviral Res. 2013, 100, 321.
The γ-lactone 7 (5.0 g, 10.18 mmol) was dissolved in CH Cl and
2
2
(
8) (a) Gunther, W. R.; Duong, Q.; Roman-Leshkov, Y. J. Mol. Catal.
A: Chem. 2013, 379, 294. (b) Jeon, Y. J.; Song, S. M.; Lee, C. S.;
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cooled till –70 °C. A solution of DIBAL-H in CH Cl (1.0 M, 10.18 mL,
2
2
10.18 mmol) was slowly added via a syringe over 30 min. The mixture
was stirred for 1 h. After completion of the reaction by TLC monitor-
ing, the reaction was quenched with H O and extracted with CH Cl .
2
2
2
The organic layer was dried (MgSO ), filtered, evaporated, and the res-
4
idue was purified by column chromatography to give the product 8 as
27, 547.
a white solid; yield: 3.85 g (77%); mp 39.5–40.5 °C; R = 0.4 (hex-
f
20.1
(9) Moyroud, E.; Strazewski, P. Tetrahedron 1999, 55, 1277.
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ane/EtOAc = 20:1, v/v); [α]D
–31.62 (c 1.00, CHCl3).
(
IR (neat): 3503, 2858, 2739, 1472, 1390 cm–1
.
1
H NMR (CDCl , 400 MHz): δ = 5.04 (dd, J = 7.6, 4.0 Hz, 1 H), 4.24 (d, J =
3
1
2
0
1.2 Hz, 1 H), 4.14–4.12 (m, 1 H), 4.09–4.05 (m, 2 H), 3.67 (dd, J = 11.2,
.8 Hz, 1 H), 3.55 (dd, J = 11.2, 4.8 Hz, 1 H), 0.93 (s, 9 H), 0.90 (s, 9 H),
.89 (s, 9 H), 0.12 (s, 3 H), 0.11 (s, 3 H), 0.11 (s, 3 H), 0.10 (s, 3 H), 0.58
(
(
d) Jung, M. E.; Xu, Y. Patent PCT Int. Appl. WO9839347, 1998.
e) Jung, M. E.; Xu, Y. Tetrahedron Lett. 1997, 38, 4199.
(s, 3 H), 0.54 (s, 3 H).
13
C NMR (CDCl , 100 MHz): δ = 97.95, 85.67, 74.39, 72.67, 63.73,
(11) Seo, M. J.; An, J.; Shim, J. H.; Kim, G. Tetrahedron Lett. 2003, 44,
3051.
(12) Qi, S.; Zhang, W.; Feng, Y. Tianranqi Huagong 2007, 32, 69.
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3
2
–
6.13, 26.11, 25.97, 18.59, 18.50, 18.24, –4.45, –4.51, –4.58, –4.78,
5.17, –5.31.
+
HRMS (ESI/TOF-Q): m/z [M + H] calcd for C23H52O Si + H: 493.3201;
5
3
(
(
found: 493.3199.
(
(
(
b) Wulff, G.; Hansen, A. Carbohydr. Res. 1987, 164, 123.
c) Matteson, D. S.; Peterson, M. L. J. Org. Chem. 1987, 52, 5116.
d) Wulff, G.; Hansen, A. Angew. Chem., Int. Ed. Engl. 1986, 25,
L-Ribose (9)29
To a solution of compound 8 (2.70 g, 5.48 mmol) in MeOH (20 mL)
was added anhydrous CsF (3.33 g, 21.9 mmol). The reaction mixture
was stirred at r.t. for 24 h. After completion of the reaction by TLC
monitoring, the solvent was evaporated, and the residue was purified
by preloaded silica gel chromatography. The product was dried under
full vacuum overnight to give L-ribose (9) as a white gummy solid;
5
60. (e) Yamaguchi, M.; Mukaiyama, T. Chem. Lett. 1981, 1005.
16) Takahashi, H.; Iwai, Y.; Hitomi, Y.; Ikegami, S. Org. Lett. 2002, 4,
401.
(
(
2
17) Amorati, R.; Pedulli, G. F.; Pratt, D. A.; Valgimigli, L. Chem.
Commun. 2010, 46, 5139.
20
yield: 0.61 g (74%); R = 0.2 (CHCl /MeOH = 5:1, v/v); [α]
+20.00 (c
f
25
3
D
(18) (a) Huang, L.; Teumelsan, N.; Huang, X. Chem. Eur. J. 2006, 12,
5246. (b) Bosch, M. P.; Campos, F.; Niubó, I.; Rosell, G.; Díaz, J. L.;
Brea, J.; Loza, M. I.; Guerrero, A. J. Med. Chem. 2004, 47, 4041.
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Fliegert, R.; Yorgan, T.; Bauche, A.; Harneit, A.; Guse, A. H.;
Potter, B. V. L. J. Med. Chem. 2013, 56, 10079. (b) Prabhakar, P.;
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dron: Asymmetry 2010, 21, 216.
2
9
0
.1, H O) {Lit. [α]D +18.3 (c 1.8, H O)}.
2
2
1
The H NMR spectrum of L-ribose is superimposable with that of the
corresponding D-isomer (starting material).
Acknowledgment
(
(
(
20) Zhao, M.; Li, J.; Mano, E.; Song, Z.; Tschaen, D. M.; Grabowski, E.
J. Ban acknowledges the financial support from Korean Ministry of
Education through BK21-Plus Project for Hanyang University Gradu-
ate Program.
J. J.; Reider, P. J. J. Org. Chem. 1999, 64, 2564.
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Chem. 2003, 68, 4999.
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Supporting Information
(23) Lerner, L. M. Carbohydr. Res. 1988, 184, 250.
(
24) CCDC 1446880 and CCDC 1446881 contain the supplementary
crystallographic data for this paper. The data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/get structures.
Supporting information for this article is available online at
https://doi.org/10.1055/s-0036-1588857.
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25) Punirun, T.; Soorukram, D.; Kuhakarn, C.; Reutrakul, V.;
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Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–D