Two novel synthetic methods for 1,4-anhydro-α-xylopyranose derivatives

Article abstract of DOI:10.1016/S0008-6215(98)00135-9

Two novel methods for the syntheses of 1,4-anhydro-3-O-benzyl-2-O-pivaloyl-(1) and 2-O-acetyl-1,4-anhydro-3-O-benzyl-α-D-xylopyranose (2), starting materials for synthesizing stereoregular β-(1-15)-xylofuranan by ring-opening polymerization are reported. Both synthetic routes start from D-xylopyranose, involve nine reaction steps, and give approximately 30-35% overall yields. The key reaction in the novel synthetic routes is the intramolecular nucleophilic attack of C-1 oxyanion on the C-5 position of 3-O-benzyl-5-O-(p-toluenesulfonyl)-α-D-xylofuranose (10), resulting in 1,5-acetal bond formation in high yield. The present synthetic routes enable us to prepare 1,4-anhydro-α-D-xylopyranose derivatives having different substituents at the 2-O- and the 3-O-positions.

Full text of DOI:10.1016/S0008-6215(98)00135-9

Carbohydrate Research 309 (1998) 281±286
Two novel synthetic methods for 1,4-anhydro-ꢀ-
d-xylopyranose derivatives
Michiko Hori, Fumiaki Nakatsubo *
Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto
606-8502, Japan
Received 16 March 1998; accepted 18 May 1998
Abstract
Two novel methods for the syntheses of 1,4-anhydro-3-O-benzyl-2-O-pivaloyl- (1) and 2-O-
acetyl-1,4-anhydro-3-O-benzyl-ꢀ-d-xylopyranose (2), starting materials for synthesizing stereo-
regular ꢁ-(1!5)-xylofuranan by ring-opening polymerization are reported. Both synthetic routes
start from d-xylopyranose, involve nine reaction steps, and give approximately 30±35% overall
yields. The key reaction in the novel synthetic routes is the intramolecular nucleophilic attack of
C-1 oxyanion on the C-5 position of 3-O-benzyl-5-O-(p-toluenesulfonyl)-ꢀ-d-xylofuranose (10),
resulting in 1,5-acetal bond formation in high yield. The present synthetic routes enable us to
prepare 1,4-anhydro-ꢀ-d-xylopyranose derivatives having di€erent substituents at the 2-O- and
the 3-O-positions. # 1998 Elsevier Science Ltd. All rights reserved
Keywords: Ring-opening polymerization; Intramolecular nucleophilic attack; 1,5-Acetal bond formation;
1,4-Anhydro-ꢀ-d-xylopyranose derivatives; Stereoregular ꢁ-(1!5)-xylofuranan
1. Introduction
important role in stereoregularity of the resulting
polymer [2±11]. On the basis of this work, we
expect that there is a good possibility of synthesizing
stereoregular ꢁ-(1!5)-xylofuranan by the ring-
opening polymerization of 1,4-anhydro-3-O-ben-
zyl-2-O-pivaloyl- (1) and 2-O-acetyl-1,4-anhydro-
3-O-benzyl-ꢀ-d-xylopyranose (2).
Uryu et al. [1] synthesized 1,4-anhydro-2,3-di-O-
benzyl-ꢀ-d-xylopyranose from 1,4-anhydro-ꢀ-d-
xylopyranose; the latter was prepared by vacuum
pyrolysis of d-xylose according to the method of
Koll et al. [12]. This synthetic route is not suitable
for the syntheses of compounds 1 and 2 because it
is dicult to introduce two di€erent substituents
speci®cally in the 2-O- and 3-O-positions of 1,4-
anhydro-ꢀ-d-xylopyranose. Furthermore, vacuum
Uryu et al. reported the ring-opening poly-
merization of 1,4-anhydro-2,3-di-O-benzyl-ꢀ-d-xylo-
pyranose [1]. Stereoregular ꢀ-(1!5)-xylofuranan
.
was obtained only when BF3 Et2O was used as
catalyst, and a polymer consisting of a mixture of
ꢀ-(1!5)- and ꢁ-(1!5)-xylofuranose linkages was
obtained when other Lewis acids were used. Stereo-
regular ꢁ-(1!5)-xylofuranan was never obtained
by their method.
We have chemically synthesized cellulose and
found that substituents on the monomer played an
* Corresponding author. Fax: +81 (75) 753-6300; e-mail:
michiko@kais.kyoto-u.ac.jp
0008-6215/98/$Ðsee front matter # 1998 Elsevier Science Ltd. All rights reserved
PII S0008-6215(98)00135-9

282
M. Hori, F. Nakatsubo/Carbohydrate Research 309 (1998) 281±286
pyrolysis of d-xylose gave 1,4-anhydro-ꢀ-d-xylo-
pyranose in only 5% yield, even though only one
reaction step was involved.
In this paper, we describe two new synthetic
methods for compounds 1 and 2. As expected,
these two monomers were found to induce stereo-
selective ꢁ-glycosidic bond formation by the
neighboring-group participation of the 2-O-acyl
group to give ꢁ-(1!5)-xylofuranan as will be
reported in a separate paper [13].
2. Results and discussion
General considerations.ÐThe two methods syn-
thesize compounds 1 and 2 from d-xylopyranose in
nine steps. Both methods involve a common starting
intermediate, 1,2-O-isopropylidene-ꢀ-d-xylofuranose
(3), which is synthesized from d-xylose in two steps
according to the method of Levene and Raymond
[17]. The two methods also share a common ®nal
four steps starting from 3-O-benzyl-1,2-O-iso-
propylidene-ꢀ-d-xylofuranose (8). Thus, the two
methods di€er from each other only by the three-
step synthesis of compound 8 from compound 3 as
shown in Scheme 1. We shall ®rst describe the two
di€erent methods, A and B, for the synthesis of
compound 8 from compound 3. This is to be fol-
lowed by description of the common ®nal four
steps from compound 8 to compounds 1 and 2.
Synthesis of compound 8 from compound 3.Ð
Method A (reaction steps: a±c in Scheme 1). 1,2-
O-Isopropylidene-ꢀ-d-xylofuranose (3) was treated
with triphenylmethyl chloride and triethylamine in
dry 1,4-dioxane to a€ord 1,2-O-isopropylidene-5-
O-triphenylmethyl-ꢀ-d-xylofuranose (4) in 78%
yield (reaction step a in Scheme 1). However, pur-
i®cation of compound 4 was dicult because tri-
phenylmethyl alcohol, which is a byproduct, has
almost the same Rf value as that of compound 4 on
the TLC plate developed with a number of organic
solvents and solvent mixtures, for example with
1:2 EtOAc±n-hexane. Compound 4 was converted
to 3-O-benzyl-1,2-O-isopropylidene-5-O-triphenyl-
methyl-ꢀ-d-xylofuranose (6) by benzylation (reac-
tion step b in Scheme 1). Detriphenylmethylation
of compound 6 was performed with formic acid in
diethyl ether to give 3-O-benzyl-1,2-O-iso-
propylidene-ꢀ-d-xylofuranose (8) in 77% yield
(reaction step c in Scheme 1), but a side reaction
also occurred because the isopropylidene group
was not stable under the acidic conditions.
Scheme 1. Reagents and conditions: (a) TrCl, Et3N, anhydrous
dioxane, 100 ꢀC, 3 h, 78%; (b, e) BnBr, NaH, Bu4NI, THF,
r.t., overnight, 98%; (c) formic acid, diethyl ether, r.t., 30 min,
77%; (d) t-BuPh2SiCl, imidazole, DMF, r.t., overnight, 99%;
(f) Bu4NF, THF, r.t., overnight, 79%; (g) TsCl, pyridine,
60 ꢀC, overnight, 99%; (h) trifuruoroacetic acid, H2O, r.t., 3 h,
80%; (i) Me4NOH, DMF, 60 ꢀC, 3 h, 93%; (j) PivCl, pyridine,
80 ꢀC, overnight, 78%; (k) Ac2O, pyridine, r.t., overnight,
86%.
Method B (Reaction steps: d±f in Scheme 1).
The tert-butyldiphenylsilyl group, which can be
selectively removed with tetrabutylammonium
¯uoride, was introduced onto the 5-OH of compound
3 to give 5 - O-tert-butyldiphenylsilyl-1,2-O-iso-
propylidene-ꢀ-d-xylofuranose (5) in 99% yield
(reaction step d in Scheme 1). Compound 5 was
converted to 3-O-benzyl-5-O-tert-butyldiphenyl-
silyl-1,2-O-isopropylidene-ꢀ-d-xylofuranose (7) by
benzylation (reaction step e in Scheme 1), and
subsequent de-tert-butyldiphenylsilylation of com-
pound 7 gave compound 8 in 79% yield without
any side reactions (reaction step f in Scheme 1).
Synthesis of compounds 1 and 2 from compound
8.ÐCompound 8 was treated with p-toluenesulfo-
nyl chloride in pyridine to a€ord 3-O-benzyl-1,2-O-
isopropylidene-5-O-(p-toluenesulfonyl)-ꢀ-d-xylo-
furanose (9). Compound 9 was then treated with
9:1 tri¯uoroacetic acid±H2O to give 3-O-benzyl-5-
O-(p-toluenesulfonyl)-ꢀ-d-xylofuranose (10). An
overall yield of 80% was obtained in these two
steps starting from compound 8. Compound 10
was treated with tetramethylammonium hydroxide

M. Hori, F. Nakatsubo/Carbohydrate Research 309 (1998) 281±286
283
method B may be preferred over method A. Com-
pounds 1 and 2 were obtained from d-xylose by
our synthetic route (especially method B) in 32.1
and 35.5% overall yield, respectively. The present
synthetic methods are extremely useful for the two
secondary hydroxyl groups, as the C-2 and C-3
positions in 1,4-anhydro-ꢀ-d-xylopyranose may be
substituted with di€erent substituents.
4. Experimental
General methods.Ð1H and 13C NMR spectra
were recorded with a Bruker AC 300 FT-NMR
(300 MHz) spectrometer, in chloroform-d with tet-
ramethylsilane (Me4Si) as an internal standard.
Chemical shifts (ꢂ) and coupling constants (J) are
given in ꢂ-values (ppm) and Hz, respectively. Some
chemical shift assignments were assigned using a
decoupling method; others were assigned by com-
paring with literature data and with model com-
Fig. 1. 1H NMR spectrum (300 MHz, CDCl3) of 1,4-anhydro-
3-O-benzyl-2-O-pivaloyl-ꢀ-d-xylopyranose (1).
ꢀ
in DMF at 60 C for 3 h to a€ord 1,4-anhydro-3-
O-benzyl-ꢀ-d-xylofuranose (11) in a 93% yield.
Pivaloylation or acetylation of compound 11 gave
compound 1 or compound 2, respectively.
ꢀ
pounds. Optical rotations were measured at 25 C
Compounds 1 and 2 are synthesized in seven
reaction steps from compound 3 by either method
A or method B. Comparing the two methods,
method B is preferred over method A for higher
overall yield, simpler puri®cation steps, and less
complicated reactions. The key step of these novel
synthetic routes is the formation of a 1,5-acetal
bond resulting from elimination of the p-toluene-
sulfonyl group at 5-O-position by the backside
attack of the C-1 oxyanion of compound 10 (reac-
tion step i in Scheme 1) [15].
The 1H NMR spectrum of compound 1 is shown
in Fig. 1. The anomeric proton appears at ꢂ
5.4 ppm, which is in agreement with its having a
dihedral angle of ꢁ90ꢀ with H-2. The endo proton
H-5 appears as a broad doublet (J 6.64 Hz) at ꢂ
4.18 ppm as a result of having a dihedral angle of
ꢁ90ꢀ with H-4 [15]. The observed long-range cou-
plings of the anomeric proton with H-4 and of H-3
with the exo proton H-5 also support the strained
1,4-anhydro structure. The spectrum of compound
2 was almost the same as that of compound 1.
using a JASCO Dip-1000 digital polarimeter. A
standard workup procedure was employed in each
synthesis step. The procedure included diluting the
mixture with ethyl acetate, washing with aqueous
NaHCO3 and brine, drying the organic extract
over Na2SO4, and evaporating the solvents in
vacuo.
1,2-O-Isopropylidene-5-O-triphenylmethyl-a-d-
xylofuranose (4).ÐTo a solution of 1,2-O-iso-
propylidene-ꢀ-d-xylofuranose (3) (3 g, 15.8 mmol)
in dioxane dried over 4A MS (100 mL) triphe-
nylmethyl chloride (6.9 mg, 17.4 mmol) and tri-
ethylamine (22 mL, 0.2 mmol) were added, and
ꢀ
then the reaction mixture was heated to 100 C.
After 3 h, the reaction mixture was worked up by
the standard procedure to a€ord an orange syrup.
Compound 4 was puri®ed on a silica gel column
(Wakogel C-200) eluted with 1:9 ethyl acetate±n-
hexane and 1:1 ethyl acetate±n-hexane to give a
yellow syrup (5.3 g, 78.0% yield): [ꢀ]2d5 +6.32ꢀ (c 2,
1
CHCl3); H NMR (CDCl3): ꢂ 5.97 (d, 1 H, J1,2
3.72 Hz, H-1), 4.49 (d, 1 H, J2,3 0 Hz, H-2), 4.24±
4.28 (H-3, H-4), 3.55 (dd, 1 H, J4,5a 5.11 Hz, H-5a),
3.46 (dd, 1 H, Jgem 10.3 Hz, J4,5b 3.89 Hz, H-5b),
7.22±7.45 (Ar), 1.48, 1.30 (s, 3 H, respectively,
CH3); 13C NMR (CDCl3): ꢂ 105.0 (C-1), 87.5, 85.1,
78.5, 76.3, 61.8 [C-2, C-3, C-4, C-5, C(C6H5)3],
26.8, 26.2 (CH3), 111.5 [(CH3)2C(O-)2], 143.2,
128.5, 128.1, 127.3 (Ar). Anal. Calcd for C27H28O5:
C, 74.98; H, 6.52. Found: C, 74.78; H, 6.53.
3. Conclusions
We have developed two novel synthetic methods
for 1,4-anhydro-3-O-benzyl-2-O-pivaloyl- (1) and
2-O-acetyl-1,4-anhydro-3-O-benzyl-ꢀ-d-xylopyranose
(2). For large-scale preparations, we found that

284
M. Hori, F. Nakatsubo/Carbohydrate Research 309 (1998) 281±286
5-O-tert-Butyldiphenylsilyl-1,2-O-isopropylidene-
used for the benzylation of compound 4 as descri-
bed in the above section for the preparation of
compound 6. Compound 7 was then puri®ed on a
silica gel column (Wakogel C-200) eluted with 1:9
ethyl acetate±n-hexane to give a colorless syrup
(7.91 g, 97.6% yield): [ꢀ]2d5 21.9ꢀ (c 1, CHCl3); 1H
NMR (CDCl3): ꢂ 5.89 (d, 1 H, J1,2 3.78 Hz, H-1),
4.60 (d, 1 H, J2,3 0 Hz, H-2), 4.06 (d, 1 H, J3,4
3.16 Hz, H-3), 4.32 (m, 1 H, J4,5a 7.76 Hz, H-4),
3.99 (dd, 1 H, Jgem 9.99 Hz, H-5a), 3.91 (dd, 1 H,
J4,5b 5.36 Hz, H-5b), 4.67, 4.57 (d, 1 H, respec-
tively, J 11.8 Hz, CH2C6H5), 7.26±7.40, 7.63±7.66
(Ar), 1.49, 1.31 (s, 3 H, respectively, CH3), 1.07,
1.06, 1.04 [s, 3 H, respectively, C(CH3)3]; 13C NMR
(CDCl3): ꢂ 105.1 (C-1), 82.6, 81.6, 80.6, 72.3, 60.8
(C-2, C-3, C-4, C-5, CH2C6H5,), 26.9, 26.6, 26.4
a-d-xylofuranose (5).ÐTo a solution of 1,2-O-iso-
propylidene-ꢀ-d-xylofuranose (3) (3 g, 15.8 mmol)
in DMF (20 mL), tert-butyldiphenylsilyl chloride
(5.47 mL, 19.0 mmol) and imidazole (2.58 g,
37.9 mmol) were added, and the mixture was kept
at room temperature. After 1 day, the reaction
mixture was worked up by the standard procedure.
Compound 5 was puri®ed on a silica gel column
(Wakogel C-200) eluted with 1:9 ethyl acetate±n-
hexane to give a colorless syrup (6.7 g, 99.3%
yield): [ꢀ]2d5
1.93ꢀ (c 1, CHCl3); 1H NMR
(CDCl3): ꢂ 6.00 (d, 1 H, J1,2 3.67 Hz, H-1), 4.54 (d,
1 H, J2,3 0 Hz, H-2), 4.02 (d, 1 H, J3,4 3.14 Hz, H-
3), 4.37 (t, 1 H, J4,5a 0 Hz, H-4), 4.10±4.14 (over-
lapped, 2 H, H-5a, H-5b), 7.40±7.44, 7.66±7.73
(Ar), 1.47, 1.33 (s, 3 H, respectively, CH3), 1.05 [s,
9 H, C(CH3)3]; 13C NMR (CDCl3): ꢂ 105.0 (C-1),
85.5, 78.4, 76.9, 62.8 (C-2, C-3, C-4, C-5), 26.8,
26.7 (CH3), 19.1 [(CH3)2C(O-)2], 127.9, 130.1,
135.5, 135.7 (Ar). Anal. Calcd for C24H32O5Si: C,
67.26; H, 7.53; O, 18.66. Found: C, 67.07; H, 7.53.
3-O-Benzyl-1,2-O-isopropylidene-5-O-triphenyl-
methyl-a-d-xylofuranose (6).ÐCompound 4 (5.3 g,
12.3 mmol) was dissolved in THF (60 mL) and
sodium hydride (1 g, 24.5 mmol, 60% in mineral
oil), tetrabutylammonium iodide (453 mg) and
benzyl bromide (2.19 mL, 18.4 mmol) were added.
The mixture was stirred at room temperature.
After 15 h, methanol was added to the reaction
mixture to decompose excess benzyl bromide. The
reaction mixture was worked up by the standard
procedure to give a yellow oil. Compound 6 was
puri®ed on a silica gel column (Wakogel C-200)
eluted with 1:4 ethyl acetate±n-hexane to give a
yellow syrup (6.25 g, 97.6% yield): [ꢀ]2d5 30.8ꢀ (c
[CH3,
C(CH3)3],
19.2
[C(CH3)3],
111.7
[(CH3)2C(O )2], 127.5-137.7 (Ar). Anal. Calcd for
C31H38O5Si: C, 71.78; H, 7.38; O, 15.42. Found: C,
71.80; H, 7.38.
3-O-Benzyl-1,2-O-isopropylidene-a-d-xylofuranose
(8).Ð(From compound 6.) To a solution of com-
pound 6 (4 g, 7.67 mmol) in diethyl ether (15 mL),
formic acid (19.2 mL) was added. The reaction
mixture was stirred for 15 min at room tempera-
ture. The reaction mixture was worked up by the
standard procedure to give a yellow oil. Com-
pound 8 was puri®ed on a silica gel column
(Wakogel C-200) eluted with 1:4 ethyl acetate±n-
hexane and 1:1 ethyl acetate±n-hexane to give a
yellow syrup (1.7 g, 77.3% yield) after evaporation.
(From compound 7.) To a solution of compound
7
(4 g, 7.72 mmol) in THF (5 mL), tetra-
buthylammonium ¯uoride (16.3 mL, 15.4 mmol)
was added. The reaction mixture was stirred at
room temperature overnight. The reaction mixture
was diluted with ethyl acetate, washed with N HCl
and brine, dried over Na2SO4, and evaporated in
vacuo to give a yellow oil. Compound 8 was pur-
i®ed on a silica gel column (Wakogel C-200) eluted
with 1:9 ethyl acetate±n-hexane, 1:4 ethyl acetate±
n-hexane and 1:1 ethyl acetate±n-hexane to give a
yellow syrup (1.71 g, 79.2% yield): [ꢀ]2d5 63.6ꢀ (c
1
2, CHCl3); H NMR (CDCl3): ꢂ 5.89 (d, 1 H, J1,2
3.81 Hz, H-1), 4.56 (d, 1 H, J2,3 0 Hz, H-2), 3.96 (d,
1 H, J3,4 3.12 Hz, H-3), 4.38 (m, 1 H, J4,5a 5.76 Hz,
H-4), 3.54 (dd, 1 H, Jgem 9.35 Hz, H-5a), 3.31 (dd,
1 H, J4,5b 6.81 Hz, H-5b), 4.57, 4.42 (d, 1 H,
respectively, J 12.0 Hz, CH2C6H5) 7.23±7.43 (Ar),
1.52, 1.31 (s, 3 H, respectively, CH3); 13C NMR
(CDCl3): ꢂ 105.0 (C-1), 86.9, 82.4, 81.6, 79.4, 72.0,
64.3 [C-2, C-3, C-4, C-5, CH2C6H5, C(C6H5)3],
26.8, 26.2 (CH3), 111.5 [(CH3)2C(O-)2], 143.8,
137.4, 127.0±128.7 (Ar). Anal. Calcd for C34H34O5:
C, 78.14; H, 6.56. Found: C, 78.31; H, 6.53.
1
1, CHCl3); H NMR (CDCl3): ꢂ 5.98 (d, 1 H, J1,2
3.83 Hz, H-1), 4.63 (d, 1 H, J2,3 0 Hz, H-2), 4.00 (d,
1 H, J3,4 3.49 Hz, H-3), 4.27 (m, 1 H, H-4), 3.84±
3.96 (overlapped, 2 H, H-5a, H-5b), 4.74, 4.49 (d, 1
H, respectively, J 12.1 Hz, CH2C6H5) 7.30±7.35
(Ar), 1.48, 1.32 (s, 3 H, respectively, CH3); 13C
NMR (CDCl3): ꢂ 105.0 (C-1), 82.5, 82.4, 80.2, 71.8,
60.8 (C-2, C-3, C-4, C-5, CH2C6H5), 26.7, 26.1
(CH3), 137.1, 137.3, 132.2, 128.5, 128.0, 127.6 (Ar).
3-O-Benzyl-5-O-tert-butyldiphenylsilyl-1,2-O-iso-
propylidene-a-d-xylofuranose (7).ÐThe procedure
used for benzylation of compound 5 (6.7 g,
15.7 mmol) to compound 7 was identical to that

M. Hori, F. Nakatsubo/Carbohydrate Research 309 (1998) 281±286
285
Anal. Calcd for C15H20O5: C, 64.27; H, 7.19.
Found: C, 64.40; H, 6.97.
DMF (5 mL), Me4NOH (10.6 mL, 9.64 mmol) was
ꢀ
added. The reaction mixture was stirred at 60 C.
3-O-Benzyl-1,2-O-isopropylidene-5-O-(p-toluene-
sulfonyl)-a-d-xylofuranose (9).ÐTo a solution of
compound 8 (1.7 g, 6.07 mmol) in pyridine (20 mL),
p-toluenesulfonyl chloride (1.27 g, 6.68 mmol) was
After 3 h, the reaction mixture was neutralized by
AcOH and evaporated in vacuo. Compound 11 was
puri®ed on a silica gel column (Wakogel C-200)
eluted with 1:1 ethyl acetate±n-hexane to give a
7.64ꢀ (c
ꢀ
25
added. The reaction mixture was stirred at 60 C
yellow syrup (839 mg, 92.8% yield): [ꢀ]d
1
overnight. The reaction mixture was worked up by
the standard procedure to give a yellow oil. Com-
pound 9 was puri®ed on a silica gel column
(Wakogel C-200) eluted with CHCl3 to give a yel-
low syrup (2.62 g, 99.4% yield): [ꢀ]2d5 22.3ꢀ (c 1,
1, CHCl3); H NMR (CDCl3): ꢂ 5.34 (d, 1 H, J1,4
0.94 Hz, H-1), 3.81 (s, 1 H, J2,3 0 Hz, H-2), 3.76 (m,
1 H, J3,4 4.83 Hz, H-3), 4.72 (dd, 1 H, J4,5b 3.23 Hz,
H-4), 4.09 (d, 1 H, J4,5a 0 Hz, H-5a), 3.41 (m, 1 H,
Jgem 6.60 Hz, H-5b), 4.67, 4.56 (d, 1 H, respec-
tively, J 11.7 Hz, CH2C6H5) 7.35±7.37 (Ar); 13C
NMR (CDCl3): ꢂ 104.3 (C-1), 85.9, 78.0, 76.0, 72.9,
62.5 (C-2, C-3, C-4, C-5, CH2C6H5), 137.3, 127.0±
128.5 (Ar). Anal. Calcd for C12H14O4: C, 64.85; H,
6.35. Found: C, 64.62; H, 6.36.
1
CHCl3); H NMR (CDCl3): ꢂ 5.86 (d, 1 H, J1,2
3.72 Hz, H-1), 4.56 (d, 1 H, J2,3 0 Hz, H-2), 3.96 (d,
1 H, J3,4 3.18 Hz, H-3), 4.35 (m, 1 H, J4,5b 5.96 Hz,
H-4), 4.29 (dd, 1 H, J4,5a 6.02 Hz, H-5a), 4.18 (dd,
1 H, Jgem 9.80 Hz, H-5b), 4.61, 4.46 (d, 1 H,
respectively, J 11.8 Hz, CH2C6H5) 7.79, 7.76, 7.26±
7.32 (Ar), 2.42 (s, 3 H, p-CH3C6H4SO2), 1.44, 1.29
(s, 3 H, respectively, CH3); 13C NMR (CDCl3): ꢂ
105.2 (C-1), 82.1, 81.2, 77.6, 72.1, 67.0 (C-2, C-3,
C-4, C-5, CH2C6H5), 26.8, 26.3 (CH3), 21.6
(CH3C6H4SO2), 137.0, 144.9, 127.7±132.7 (Ar).
Anal. Calcd for C23H28O7S: C, 61.59; H, 6.29; S,
7.15. Found: C, 61.84; H, 6.19; S, 7.09.
3-O-Benzyl-5-O-(p-toluenesulfonyl)-d -xylo-
furanose (10).ÐCompound 9 (2.62 g, 6.04 mmol)
was dissolved in 9:1 tri¯uoroacetic acid±H2O
(20 mL). The mixture was stirred at room tem-
perature for 1.5 h. The ꢀreaction mixture was eva-
porated in vacuo at 40 C to remove the solvents.
The resulting oil was diluted with ethyl acetate,
washed with satd aq NaHCO3 and brine, dried
over anhydrous sodium sulfate, and concentrated
to dryness. Compound 10 was puri®ed on a silica
gel column (Wakogel C-200) eluted with 1:1 ethyl
1,4-Anhydro-3-O-benzyl-2-O-pivaloyl-a-d-xylo-
pyranose (1).ÐTo a solution of compound 11
(500 mg, 2.25 mmol) in pyridine (5 mL) was added
pivaloyl chloride (693.5 ꢃL, 5.63 mmol), and the
ꢀ
mixture was heated to 80 C and kept overnight.
Then 0.1 mL MeOH was added, and the mixture
was worked up by the standard procedure. Com-
pound 1 was puri®ed on a silica gel column
(Wakogel C-200) eluted with 1:4 ethyl acetate±n-
hexane to give a colorless oil (535.5 mg, 77.7%
yield): [ꢀ]2d5
36.3ꢀ (c 1, CHCl3); 1H NMR
(CDCl3): ꢂ 5.40 (d, 1 H, J1,4 0.86 Hz, H-1), 4.70 (d,
1 H, J2.3 1.57 Hz, H-2), 3.85 (m, 1 H, J3,4 4.93 Hz,
H-3), 4.54 (m, 1 H, J4,5endo 0 Hz, H-4), 4.18 (d, 1 H,
Jgem 6.64 Hz, H-5endo), 3.44 (m, 1 H, J4,5exo
2.38 Hz, H-5exo), 1.20 (s, 9 H, C=OC(CH3)3),
4.71, 4.50 (d, 1 H, J 11.9 Hz, respectively,
CH2C6H5), 7.31±7.33 (Ar); 13C NMR (CDCl3): ꢂ
102.2 (C-1), 82.2, 78.5, 75.8, 72.6, 62.8 (C-2, C-3,
C-4, C-5, CH2C6H5), 26.9 [C(CH3)3], 38.4
[C(CH3)3], 137.1, 128.4, 127.9, 127.8 (Ar), 177.3
(C=O). Anal. Calcd for C17H22O5: C, 66.65; H,
7.24. Found: C, 66.36; H, 7.26.
acetate±n-hexane to give a yellow syrup (1.9 g,
ꢀ
80.0% yield): [ꢀ]2d5 +10.2 (c 1, CHCl3); H NMR
1
(CDCl3): ꢂ 5.54 (d, 1 H, J1,2 2.42 Hz, H-1ꢀ), 5.17 (s,
1 H, J1,2 0 Hz, H-1b), 4.04±4.61 (H-2, H-3, H-4, H-
5a, H-5ꢁ), 4.59, 4.39 (d, 1 H, respectively, J
11.8 Hz, CH2C6H5) 7.72, 7.69, 7.20±7.27 (Ar), 2.37
(s, 3 H, p-CH3C6H4SO2); 13C NMR (CDCl3): ꢂ
96.9 (C-1ꢁ), 82.7, 76.4, 75.1, 72.1, 69.2 (C-2ꢁ, C-
3ꢁ, C-4ꢁ, C-5ꢁ, CH2C6H5ꢁ), 103.3 (C-1ꢀ), 82.0,
78.6, 72.8, 68.9, 60.5 (C-2ꢀ, C-3ꢀ, C-4ꢀ, C-5ꢀ,
CH2C6H5ꢀ), 21.6 (CH3C6H4SO2), 132.4, 136.7,
145.1, 124.4±132.2 (Ar). Anal. Calcd for
C20H24O7S: C, 58.81; H, 5.92; S, 7.85. Found: C,
58.72; H, 6.18.
2-O-Acetyl-1,4-anhydro-3-O-benzyl-a-d-xylopyr-
anose (2).ÐTo a solution of compound 11
(300 mg, 1.35 mmol) in pyridine (2 mL), acetic
anhydride (2 mL) was added, and the mixture was
stirred at room temperature overnight. The reac-
tion mixture was evaporated in vacuo. Compound
2 was puri®ed on a silica gel column (Wakogel C-
200) eluted with 1:2 ethyl acetate±n-hexane to give
a yellow oil (306.5 mg, 86.0% yield): [ꢀ]2d5 43.9ꢀ (c
1
1, CHCl3); H NMR (CDCl3): ꢂ 5.44 (d, 1 H, J1,4
1,4-Anhydro-3-O-benzyl-a-d-xylopyranose (11).Ð
To a solution of compound 10 (1.9 g, 4.82 mmol) in
0.92 Hz, H-1), 4.69 (d, 1 H, J2.3 1.45 Hz, H-2), 3.90
(m, 1 H, J3,4 4.95 Hz, H-3), 4.73 (m, 1 H, J4,5endo

286
M. Hori, F. Nakatsubo/Carbohydrate Research 309 (1998) 281±286
0 Hz, H-4), 4.17 (d, 1 H, Jgem 6.65 Hz, H-5endo),
3.44 (m, 1 H, J4,5exo 2.30 Hz, H-5exo), 2.08 (s, 3 H,
Ac-CH3), 4.70, 4.52 (d, 1 H, J 11.8 Hz, respectively,
CH2C6H5), 7.31±7.33 (Ar); 13C NMR (CDCl3): ꢂ
102.3 (C-1), 82.5, 79.0, 76.0, 73.0, 63.0 (C-2, C-3,
C-4, C-5, CH2C6H5), 20.9 (CH3), 127.9-128.5 (Ar),
170.0 (C=O). Anal. Calcd for C14H16O5: C, 63.63;
H, 6.10. Found: C, 63.76; H, 6.19.
[3] T. Takano, T. Harada, F. Nakatsubo, and K. Mur-
akami, Cellul. Chem. Technol., 24 (1990) 333±
342.
[4] T. Takano, T. Harada, F. Nakatsubo, and K.
Murakami, Mokuzai Gakkaishi, 36 (1990) 212±217;
Chem. Abstr. 114 (1990) 134389u.
[5] T. Nishimura, T. Takano, F. Nakatsubo, and K.
Murakami, Mokuzai Gakkaishi, 39 (1993) 40±47;
Chem. Abstr. 119 (1993) 162634n.
[6] T. Nishimura, T. Takano, F. Nakatsubo, and K.
Murakami, Mokuzai Gakkaishi, 40 (1994) 44±49;
Chem. Abstr. 121 (1994) 282437p.
Acknowledgements
[7] T. Nishimura and F. Nakatsubo, Carbohydr. Res.,
294 (1996) 53±64.
[8] T. Nishimura and F. Nakatsubo, Tetrahedron
Lett., 37 (1996) 9215±9218.
[9] T. Nishimura and F. Nakatsubo, Cellulose, 4
(1997) 109±130.
[10] H. Kamitakahara, F. Nakatsubo, and F. Mur-
akami, Macromolecules, 27 (1994) 5937±5942.
[11] F. Nakatsubo, H. Kamitakahara, and M. Hori, J.
Am. Chem. Soc., 118 (1996) 1677±1681.
[12] P. Koll, S. Deyhim and K. Heyns, Chem. Ber., 106
(1973) 3565±3570.
The authors are indebted to Dr. Hou-min
Chang, Professor at North Carolina State Uni-
versity, for his critical reading of the manuscript.
This investigation was supported in part by a
Grant-in-Aid for Scienti®c Research from the
Ministry of Education, Science, Sports, and Cul-
ture of Japan (No. 09460076).
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