Synthesis of (R)-2,3-epoxypropyl(1→3)-β-D-pentaglucoside

Article abstract of DOI:10.1016/j.carres.2005.01.015

The title pentasaccharide was synthesized via a 2 + 3 strategy. The disaccharide donor, 3-O-acetyl-2-O-benzoyl-4,6-O-benzylidene-β-d- glucopyranosyl-(1→3)-2-O-benzoyl-4,6-O-benzylidene-α-d- glucopyranosyl trichloroacetimidate (8), was obtained by selectiv

Full text of DOI:10.1016/j.carres.2005.01.015

Carbohydrate
RESEARCH
Carbohydrate Research 340 (2005) 603–608
Synthesis of (R)-2,3-epoxypropyl(1!3)-b-D-pentaglucoside
Gang-Liang Huang,a,* Xin-Ya Meib and Man-Xi Liua
aSchool of Life Science and Technology, Huazhong University of Science and Technology (East Campus),
1037 Luoyu Road, Wuhan 430074, China
bSchool of Chemistry, Central China Normal University, 100 Luoyu Lu, Wuhan 430079, China
Received 14 December 2004; received in revised form 18 January 2005; accepted 18 January 2005
Available online 2 February 2005
Abstract—The title pentasaccharide was synthesized via a 2 + 3 strategy. The disaccharide donor, 3-O-acetyl-2-O-benzoyl-4,6-O-
benzylidene-b-D-glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-a-D-glucopyranosyl trichloroacetimidate (8), was obtained
by selective coupling of allyl 2-O-benzoyl-4,6-O-benzylidene-a-D-glucopyranoside with 3-O-acetyl-2-O-benzoyl-4,6-O-benzylidene-
a-D-glucopyranosyl trichloroacetimidate (4), followed by deallylation, and trichloroacetimidation. Meanwhile, the trisaccharide
acceptor, allyl 2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyranosyl-
(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyranoside (12), was prepared by coupling of allyl 2-O-benzoyl-4,6-O-benzyl-
idene-b-D-glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyranoside with 4, followed by deacetylation. Condensa-
tion of 8 with 12, followed by epoxidation, and deprotection, gave the target pentaoside.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: (R)-2,3-Epoxypropyl; (1!3)-b-D-Pentaglucoside; Synthesis
1. Introduction
oligomers, high molecular weight branched b-
(1!3),b-(1!6)-glucans from fungal cell walls, and
the branched b-(1!6),b-(1!3)-heptaglucan showed
that the elicitor effects observed in tobacco with b-glu-
cans are specific of the linear b-(1!3) linkage, with
laminaripentaose being the smallest elicitor-active
structure.1 Therefore, one could anticipate that re-
search and development of linear b-(1!3) oligogluco-
sides could become an alternative strategy in tobacco
protection.
However, the elicitor-active oligosaccharides can be
hydrolyzed by endo- or exo-hydrolases from higher
plants, and give elicitor-inactive oligosaccharide frag-
ments.2 Therefore, improving the stability of the elici-
tor-active oligosaccharides is the key to develop the
oligosaccharide elicitors.
Signal molecules from the pathogen or from the host
that are able to trigger defense responses are known
as elicitors. Many of the elicitors of defense reactions
in plants are oligosaccharides. It happens that lamina-
ran, 3-O-b-D-glucopyranosyl-D-glucose, is a structural
analogue of the linear b-(1!3)-glucan oligosaccharides
naturally involved in the cell–cell recognition mecha-
nisms in plant–pathogen interactions, either exogenous
(resulting from the degradation of fungal cell walls) or
endogenous (callose fragments) to the host. Yet, as
such, laminaran and laminaran oligomers are potent
defense elicitors, both in other dicots (tomato and
bean) and in monocots (wheat and rice), and these
b-(1!3)-glucans thus might become interesting, alterna-
tive tools for disease control in agronomic crops.
Structure–activity studies with laminaran, laminaran
The use of epoxyalkyl glycosides as active-site-direc-
ted inhibitors has been invaluable in delineating the
mechanism of action for a variety of hydrolases, for
example, b-D-glucan endo- and exo-hydrolases.3,4 The
epoxyalkyl glycoside moiety targets the inhibitor to the
substrate-binding site and if the length of the alkyl chain
*
Corresponding author. Tel.: +86 2787554296; fax: +86 2787464570;
e-mail: hgl226@126.com
0008-6215/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2005.01.015

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G.-L. Huang et al. / Carbohydrate Research 340 (2005) 603–608
is correct, the epoxide group is brought into the vicinity
of the catalytic amino acids. Protonation of the epoxide
oxygen opens the epoxide ring and results in the forma-
tion of a stable ester linkage between the inhibitor and
the catalytic nucleophile. It has been well demonstrated5
that the chain length of the aglycone in the mechanism-
based epoxide-bearing inhibitors has a significant effect
on their activity.
With the aim of improving the stability of elicitor-ac-
tive laminaripentaose, herein we present a very facile
and convergent synthesis of (R)-2,3-epoxypropyl b-
(1!3)-D-pentaglucoside, with benzylidene glucose
derivatives as the key intermediates. It is an analogue
of laminaripentaose, where the (R)-2,3-epoxypropyl
group has been introduced at the reducing end of the oli-
gosaccharides. The present results are in continuation of
our previous synthetic studies on phytoalexin-elicitor
oligosaccharides.6–9
2. Results and discussion
2.1. Synthesis of (R)-2,3-epoxypropyl(1!3)-b-D-
pentaglucoside
Retrosynthetic analysis revealed that the best way to
synthesize the target compound 15 was first to prepare
the b-(1!3)-linked disaccharide and trisaccharide frag-
ments, then connect them at C-3 of the glucose residue
of the trisaccharide backbone. Previous studies10 indi-
cated that in (1!3)-glucosylation, the glycosyl bond
originally present in either donor or acceptor controlled
the stereoselectivity of the forthcoming bond, that is, the
newly formed glycosidic linkage has the opposite ano-
meric configuration of that of either the donor or accep-
tor. In addition, some reports11,12 revealed that with 4,6-
O-benzylidene glucose derivatives as either donor or
acceptor, b-linked oligosaccharides are readily obtained.
Ph
O
Ph
Ph
O
Ph
O
O
O
O
O
O
O
c
O
a
O
b
95%
O
HO
AcO
AcO
HO
80%
BzO
80%
BzO
BzO
HO
OC(NH)CCl3
OAll
OAll
OAll
1
2
3
4
Ph
Ph
O
O
a
O
O
O
OAll
O
OAll
75%
HO
HO
BzO
HO
5
6
Ph
Ph
O
O
Ph
Ph
O
O
O
O
O
O
O
O
c
O
O
O
O
d
53%
BzO
2+4
6+ 4
BzO
81%
AcO
AcO
BzO
BzO
OC(NH)CCl3
OAll
7
8
Ph
Ph
O
O
Ph
Ph
O
O
O
O
O
O
OAll
O
OAll
e
80%
d
53%
O
O
O
O
O
BzO
BzO
HO
AcO
BzO
BzO
9
10
Ph
O
Ph
O
Ph
O
O
Ph
O
O
OAll
O
O
Ph
O
O
OAll
O
O
Ph
O
O
O
O
O
O
BzO
e
O
d
49%
O
BzO
O
O
BzO
4+10
8+12
HO
83%
BzO
AcO
BzO
BzO
11
12
Ph
O
O
O
Ph
O
O
OAll
Ph
Ph
O
O
O
O
O
Ph
O
O
O
BzO
O
O
O
O
d
82%
O
BzO
O
BzO
BzO
AcO
BzO
O
Ph
13
H
H
O
Ph
O
O
O
O
O
Ph
Ph
O
O
O
H
O
O
Ph
O
O
O
BzO
O
O
O
O
f
O
BzO
O
BzO
O
BzO
AcO
H
H
75%
HO
HO
O
BzO
14
HO
O
O
HO
HO
HO
O
H
HO
O
HO
HO
HO
O
O
HO
HO
g
O
O
HO
O
HO
HO
89%
HO
15
Scheme 1. Reagents and conditions: (a) PhCOCl, CH2Cl2, 0 ꢁC; (b) Ac2O, pyridine, rt; (c) PdCl2, CH3OH, 40 ꢁC/CCl3CN, CH2Cl2, K2CO3, rt; (d)
TMSOTf, CH2Cl2, 0 ꢁC; (e) HBF4, THF, rt, 4 h; (f) m-CPBA, CH2Cl2, rt; (g) 90% AcOH–water, reflux, 3 h, MeONa–MeOH, rt.

G.-L. Huang et al. / Carbohydrate Research 340 (2005) 603–608
605
Thus, in the present research, benzylidene glucose deriv-
atives were applied as key intermediates. As outlined in
Scheme 1, allyl 4,6-O-benzylidene-a-D-glucopyranoside
(1) and allyl 4,6-O-benzylidene-b-D-glucopyranoside
(5), obtained from 4,6-O-benzylidenation of allyl a-D-
glucopyranoside and allyl b-D-glucopyranoside, respec-
tively,13 were monobenzoylated to afford allyl 2-O-benz-
oyl-4,6-O-benzylidene-a-D-glucopyranoside (2, 80%)
and allyl 2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyr-
anoside (6, 75%), respectively.14 Conventional acetyl-
ation of 2 furnished allyl 3-O-acetyl-2-O-benzoyl-4,6-
O-benzylidene-a-D-glucopyranoside (3) in high yield
(95%). Deallylation of 3 with PdCl2 in methanol,15 fol-
lowed by trichloroacetimidation16 with Cl3CCN, gave
3-O-acetyl-2-O-benzoyl-4,6-O-benzylidene-a-D-gluco-
pyranosyl trichloroacetimidate (4, 80%). Then 4 was
coupled with the acceptor 2 or 6 in the presence of
TMSOTf to afford a unique disaccharide 7 or 9 in
53% yield. Deallylation of 7, followed by trichloroace-
timidation, again gave 3-O-acetyl-2-O-benzoyl-4,6-O-
benzylidene-b-D-glucopyranosyl-(1!3)-2-O-benzoyl-
4,6-O-benzylidene-a-D-glucopyranosyl trichloroacetimi-
date (8, 81%). Deacetylation of 9 with HBF4 gave the
disaccharide acceptor allyl 2-O-benzoyl-4,6-O-benzyl-
idene-b-D-glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-benz-
ylidene-b-D-glucopyranoside (10) in satisfactory yield
(80%). Then 4 was again coupled with acceptor 10 in
the presence of TMSOTf to give allyl 3-O-acetyl-2-O-
benzoyl-4,6-O-benzylidene-b-D-glucopyranosyl-(1!3)-2-
O-benzoyl-4,6-O-benzylidene-b-D-glucopyranosyl-(1!3)-
2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyranoside (11,
49%). Compound 11 was deacetylated with HBF4 to
give allyl 2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyr-
anosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-gluco-
pyranosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-
glucopyranoside (12, 83%). Then coupling of 8 with the
trisaccharide acceptor 12 gave allyl 3-O-acetyl-2-O-benz-
oyl-4,6-O-benzylidene-b-D-glucopyranosyl-(1!3)-2-O-
benzoyl-4,6-O-benzylidene-b-D-glucopyranosyl-(1!3)-
2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyranosyl-
(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyrano-
syl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyr-
anoside (13) as the sole product in 82% yield. The
reaction of 13 with m-chloroperoxybenzoic acid (m-
CPBA) in dichloromethane at room temperature gave
the corresponding 2,3-epoxypropyl 3-O-acetyl-2-O-benz-
oyl-4,6-O-benzylidene-b-D-glucopyranosyl-(1!3)-2-O-
benzoyl-4,6-O-benzylidene-b-D-glucopyranosyl-(1!3)-
2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyranosyl-
(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyrano-
syl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyr-
anoside (14, 75%). Finally, sequential deprotection of 14
with 90% AcOH–water followed by sodium methoxide
in methanol gave the target 2,3-epoxypropyl b-D-gluco-
pyranosyl-(1!3)-b-D-glucopyranosyl-(1!3)-b-D-gluco-
pyranosyl-(1!3)-b-D-glucopyranosyl-(1!3)-b-D-gluco-
pyranoside (15, yield: 89%). The bioassay of 15 is in
progress. Epoxidation of 13 generates a new chiral cen-
tre at C-2 in the aglycone. The major isomer was iso-
lated and purified by column chromatography on silica
1
gel, and the H NMR spectrum indicated that C-2 of
the aglycone was R configurated. According to Ref.
17, we concluded that the anomeric proton of this major
compound 15 (C-2 R, d 3.09) resonates at higher field
(or has a lower d) as compared to the minor diastereo-
isomer (C-2 S, d 3.24).
As seen from the above-mentioned synthetic route,
the method was simple and practical, and it should be
possible to apply the process to large-scale synthesis of
15.
3. Experimental
3.1. General methods
Optical rotations were determined at 25 ꢁC with a Per-
kin–Elmer Model 241-Mc automatic polarimeter. 1H
and 13C NMR spectra were recorded with Bruker
ARX 400 spectrometers (400 MHz for 1H, 75 MHz
for 13C) at 25 ꢁC for solns in CDCl3 or D2O as indi-
cated. Mass spectra were recorded with a VG PLAT-
FORM mass spectrometer using the ESI mode.
Kieselgel 60F254 (E. Merck) was used for TLC. Dichlo-
romethane and 1,2-dichloroethane were distilled from
P2O5.
3.2. Allyl 2-O-benzoyl-4,6-O-benzylidene-a-D-glucopyr-
anoside (2) and allyl 2-O-benzoyl-4,6-O-benzylidene-b-D-
glucopyranoside (6)
To a soln of 1 or 5 (3.80 g, 20.0 mmol) in pyridine
(10 mL) was added benzoyl chloride (2.32 mL,
20.0 mmol) at 0 ꢁC. The reaction mixture was stirred
overnight at rt. TLC (EtOAc) indicated that the reac-
tion was complete. Water (50 mL) was added, and the
mixture was extracted with CH2Cl2 (3 · 50 mL). The ex-
tract was washed with M HCl and satd aq NaHCO3,
dried (Na2SO4) and concentrated. Purification by flash
chromatography (EtOAc) gave a colourless syrup 2
(4.70 g, 80%) or 6 (4.41 g, 75%); 2: [a]D ꢀ1.0 (c 1.1,
CHCl3); 1H NMR (CDCl3, 400 MHz): d 8.16–7.26
(10H, m, Ar–H), 5.90 (1H, m, –CH@), 5.58 (1H, s,
PhCH), 5.26 (2H, m, @CH2), 5.15–3.71 (8H, m, H-2,
3, 4, 5, 6, CH2–CH@CH2), 4.75 (1H, d, J 7.1 Hz, bH-
1), 2.62 (1H, s, OH-3); 13C NMR (CDCl3, 75 MHz): d
166.51 (C@O), 137.17–126.38 (Ar–C, –CH@), 117.58
(@CH2), 101.97 (PhCH), 96.08 (a-C-1), 81.52 (C-3),
75.58 (C-2), 74.13 (C-4), 68.80 (C-6), 62.46 (C-5);
ESIMS m/z (%) 435 [M+Na]+. Anal. Calcd for
C23H24O7: C, 66.99; H, 5.83. Found: C, 67.38; H,
1
5.71; 6: [a]D +75.3 (c 1.1, CHCl3); H NMR (CDCl3,

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G.-L. Huang et al. / Carbohydrate Research 340 (2005) 603–608
400 MHz): d 8.16–7.26 (10H, m, Ar–H), 5.87 (1H, m,
–CH@), 5.58 (1H, s, PhCH), 5.27 (2H, m, @CH2),
5.18 (1H, d, J 4.2 Hz, aH-1), 5.15–3.71 (8H, m, H-2,
3, 4, 5, 6, CH2–CH@CH2), 2.60 (1H, s, OH-3); 13C
NMR (CDCl3, 75 MHz): d 166.51 (C@O), 137.17–
126.38 (Ar–C, –CH@), 117.65 (@CH2), 101.97 (PhCH),
94.36 (bC-1), 81.50 (C-3), 75.58 (C-2), 74.08 (C-4), 68.80
(C-6), 62.45 (C-5); ESIMS: m/z (%) 435 [M+Na]+. Anal.
Calcd for C23H24O7: C, 66.99; H, 5.83. Found: C, 67.38;
H, 5.71.
3.5. Allyl 3-O-acetyl-2-O-benzoyl-4,6-O-benzylidene-b-D-
glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-a-
D-glucopyranoside (7) and allyl 3-O-acetyl-2-O-benzoyl-
4,6-O-benzylidene-b-D-glucopyranosyl-(1!3)-2-O-benz-
oyl-4,6-O-benzylidene-b-D-glucopyranoside (9)
Compounds 2 or 6 (150 mg, 0.20 mmol) and 4 (60 mg,
0.21 mmol) were dried together under high vacuum
for 2 h, then dissolved in anhyd CH2Cl2 (5 mL).
TMSOTf (8 lL) was added dropwise at 0 ꢁC with N2
protection. The reaction mixture was stirred for 3 h,
during which time the temperature was gradually raised
to ambient temperature. Then the mixture was neutral-
ized with Et3N. After concentration of the reaction mix-
ture, the residue was purified by flash chromatography
(3:1 petroleum ether–EtOAc) to give 7 (95 mg, 53%)
or 9 (95 mg, 53%) as a syrup; 7: [a]D ꢀ1.5 (c 1.0,
CHCl3); 1H NMR (CDCl3, 400 MHz): d 7.51–7.34
(20H, m, Bz–H, Ph–H), 5.91–5.82 (1H, m, –CH@),
5.57 (1H, s, PhCH), 5.34 (1H, s, PhCH), 5.33–5.21
(2H, m, @CH2), 5.21 (1H, dd, J3,4 = J2,3 9.6 Hz, H-3I),
5.01 (1H, dd, J1,2 7.8, J2,3 9.6 Hz, H-2I), 4.88 (1H, d,
J1,2 7.8 Hz, H-1II), 4.86 (1H, dd, J1,2 4.0, J2,3 9.6 Hz,
H-2), 4.67 (1H, d, J1,2 6.9 Hz, bH-1), 4.32–4.16 (4H,
m), 4.02–3.89 (2H, m), 3.79–3.63 (4H, m), 3.49–3.42
(1H, m), 2.16 (3H, s, CH3CO); ESIMS: m/z 831
[M+Na]+. Anal. Calcd for C45H44O14: C, 66.83; H,
5.45. Found: C, 66.74; H, 5.53; 9: [a]D +69.0 (c 1.0,
CHCl3); 1H NMR (CDCl3, 400 MHz): d 7.51–7.34
(20H, m, Bz–H, Ph–H), 5.95–5.83 (1H, m, –CH@),
5.57 (1H, s, PhCH), 5.34 (1H, s, PhCH), 5.33–5.22
(2H, m, @CH2), 5.21 (1H, dd, J3,4 = J2,3 9.6 Hz, H-3I),
5.05 (1H, d, J1,2 4.0 Hz, aH-1), 5.00 (1H, dd, J1,2 7.8,
J2,3 9.6 Hz, H-2I), 4.86 (1H, d, J1,2 7.8 Hz, H-1II), 4.84
(1H, dd, J1,2 4.0, J2,3 9.6 Hz, H-2), 4.32–4.16 (4H, m),
4.02–3.90 (2H, m), 3.79–3.65 (4H, m), 3.49–3.40 (1H,
m), 2.16 (3H, s, CH3CO); ESIMS: m/z 831 [M+Na]+.
Anal. Calcd for C45H44O14: C, 66.83; H, 5.45. Found:
C, 66.74; H, 5.53.
3.3. Allyl 3-O-acetyl-2-O-benzoyl-4,6-O-benzylidene-a-D-
glucopyranoside (3)
To a soln of 2 (0.30 g, 1.0 mmol) in pyridine (5 mL) was
added Ac2O (0.25 mL, 2.65 mmol). The reaction mix-
ture was stirred overnight at rt. TLC (3:1 petroleum
ether–EtOAc) indicated that the reaction was complete.
Water (20 mL) was added, and the mixture was ex-
tracted with CH2Cl2 (3 · 20 mL). The extract was
washed with M HCl and satd aq NaHCO3, dried
(Na2SO4) and concentrated. Purification by flash chro-
matography (3:1 petroleum ether–EtOAc) gave
3
(0.38 g, 95%) as a foamy solid: [a]D ꢀ0.7 (c 1.1, CHCl3);
1H NMR (CDCl3, 400 MHz): d 8.16–7.26 (10H, m, Ar–
H), 5.90 (1H, m, –CH@), 5.58 (1H, s, PhCH), 5.26 (2H,
m, @CH2), 5.18 (1H, d, J 6.9 Hz, bH-1), 5.15–3.71 (8H,
m, H-2, 3, 4, 5, 6, CH2–CH@CH2), 2.03 (3H, s,
CH3COO); ESIMS m/z (%) 477 [M+Na]+. Anal. Calcd
for C25H26O8: C, 66.08; H, 5.73. Found: C, 66.03; H,
5.5.89.
3.4. 3-O-Acetyl-2-O-benzoyl-4,6-O-benzylidene-a-D-
glucopyranosyl trichloroacetimidate (4)
To a soln of 3 (5.51 g, 11.6 mmol) in anhyd MeOH
(100 mL) was added PdCl2 (0.5 g), and the mixture
was stirred at 40 ꢁC for 4 h, at the end of which time
TLC (3:1 petroleum ether–EtOAc) indicated that the
reaction was complete. The mixture was filtered, and
the filtrate was concentrated to dryness. To the residual
solid were added CCl3CN (4.2 mL, 20 mmol), anhyd
K2CO3 (5.10 g) and dry CH2Cl2 (80 mL). The mixture
was stirred overnight and was then filtered, and the fil-
trate was concentrated under diminished pressure. The
residue was purified by flash chromatography (3:1 petro-
leum ether–EtOAc) to give 4 as a foamy solid (5.33 g,
80% for two steps): [a]D ꢀ1.3 (c 1.1, CHCl3); 1H
NMR (CDCl3, 400 MHz): d 8.59 (1H, s, CNHCCl3),
8.09–7.40 (10H, m, Bz–H, Ph–H), 6.66 (1H, d, J1,2
7.0 Hz, bH-1), 5.66 (1H, s, PhCH), 5.57 (dd, 1H,
J1,2 = J2,3 7.8 Hz, H-2), 5.39 (dd, 1H, J1,2 3.6, J2,3
9.6 Hz, H-2), 4.46–3.81 (5H, m, H-3, H-4, H-5, 2H-6),
2.03 (3H, s, CH3COO); ESIMS: m/z 582 [M+Na]+.
Anal. Calcd for C24H22Cl3NO8: C, 51.57; H, 3.94.
Found: C, 51.49; H, 3.84.
3.6. 3-O-Acetyl-2-O-benzoyl-4,6-O-benzylidene-b-D-
glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-a-
D-glucopyranosyl trichloroacetimidate (8)
Compound 8 (4.73 g, 81% from two steps) was obtained
from 7 (95 mg) following the procedure above described
1
for the preparation of 4: [a]D ꢀ1.2 (c 1.0, CHCl3); H
NMR (CDCl3, 400 MHz): d 8.62 (1H, s, CNHCCl3),
7.59–7.38 (20H, m, Bz–H, Ph–H), 6.39 (1H, d, J1,2
7.3 Hz, bH-1), 5.61 (1H, s, PhCH), 5.43 (1H, dd, J1,2
7.9, J2,3 9.5 Hz, H-2I), 5.39 (1H, s, PhCH), 5.30 (1H,
dd, J3,4 = J2,3 9.5 Hz, H-3I), 5.13 (1H, d, J1,2 7.9 Hz,
H-1II), 5.04 (dd, J1,2 3.9, J2,3 9.5 Hz, H-2), 3.80–3.58
(4H, m), 2.12 (3H, s, CH3CO); ESIMS: m/z 936
[M+Na]+. Anal. Calcd for C44H40Cl3NO14: C, 57.86;
H, 4.38. Found: C, 57.70; H, 4.51.

G.-L. Huang et al. / Carbohydrate Research 340 (2005) 603–608
607
3.7. Allyl 2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyr-
anosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-gluco-
pyranoside (10)
J3,4 = J4,5 9.7 Hz, H-4I), 5.89–5.82 (1H, m, –CH@),
5.62 (1H, dd, J2,3 = J3,4 9.7 Hz, H-3I), 5.53 (1H, s,
PhCH), 5.39 (1H, dd, J1,2 7.9, J2,3 9.8 Hz, H-2I), 5.35
(1H, s, PhCH), 5.32–5.21 (2H, m, @CH2), 5.00–4.81
(5H, m, H-1II, H-2I, H-2II, H-4I, H-4II), 4.53 (2H, m,
2H-6II), 4.46 (1H, d, J1,2 8.1 Hz, H-1I), 4.24 (1H, dd,
J5,6e 6.5, J6e,6a 12.3 Hz, H-6eIII), 4.13–4.02 (5H, m, H-
5I, H-5II, H-6aII, H-6eI, H-6aI), 3.91 (1H, dd,
J2,3 = J3,4 9.4 Hz, H-3II), 3.67 (1H, ddd, J4,5 9.7, J5,6e
5.8, J5,6a 5.7 Hz, H-5III); ESIMS: m/z 1143 [M+Na]+.
Anal. Calcd for C63H60O19: C, 67.50; H, 5.36. Found:
C, 67.24; H, 5.17.
To a soln of 9 (3.04 g, 3.7 mmol) in THF (125 mL) was
added HBF4 (0.36 g), and the mixture was stirred at rt
for 4 h, at the end of which time TLC (3:1 petroleum
ether–EtOAc) indicated that the reaction was complete.
The mixture was concentrated. The residue was passed
through a silica-gel column with 3:1 petroleum ether–
EtOAc as the eluent to give 10 as a foamy solid
(2.18 g, 80%): [a]D +20.3 (c 1.0, CHCl3); 1H NMR
(CDCl3, 400 MHz): d 7.51–7.34 (20H, m, Bz–H, Ph–
H), 5.91–5.82 (1H, m, –CH@), 5.57 (1H, s, PhCH),
5.34 (1H, s, PhCH), 5.33–5.21 (2H, m, @CH2), 5.21
(1H, dd, J3,4 = J2,3 9.6 Hz, H-3I), 5.05 (1H, d, J1,2
4.0 Hz, aH-1), 5.01 (1H, dd, J1,2 7.8, J2,3 9.6 Hz, H-
2I), 4.88 (1H, d, J1,2 7.8 Hz, H-1II), 4.86 (dd, J1,2 4.0,
J2,3 9.6 Hz, H-2), 4.32–4.16 (4H, m), 4.02–3.89 (2H,
m), 3.79–3.63 (4H, m), 3.49–3.42 (1H, m); ESIMS: m/z
789 [M+Na]+. Anal. Calcd for C43H42O13: C, 67.36;
H, 5.48. Found: C, 67.64; H, 5.35.
3.10. Allyl 3-O-acetyl-2-O-benzoyl-4,6-O-benzylidene-b-
D-glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-
b-D-glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-benzyl-
idene-b-D-glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-benz-
ylidene-b-D-glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-
benzylidene-b-D-glucopyranoside (13)
Compound 13 (79 mg, 82%) was obtained from 12
(2.05 g) following the procedure above described for
the preparation of 7 and 9: [a]D ꢀ1.8 (c 1.1, CHCl3);
1H NMR (CDCl3, 400 MHz): d 8.10–6.92 (50H, m,
Bz–H, PhH), 6.50 (1H, d, J 3.5 Hz, aH-1), 5.70 (1H,
m, –CH@), 5.65 (1H, dd, J2,3 = J3,4 7.0 Hz, H-3V),
5.26 (1H, dd, J1,2 5.3, J2,3 7.0 Hz, H-2V), 5.19–5.03
(2H, m, CH2@), 5.15–5.03 (4H, m), 5.00 (1H, m, H-
4IV), 4.95 (3H, m), 4.78 (1H, d, J1,2 4.8 Hz, H-1IV),
4.72–4.62 (5H, m), 4.52 (2H, m), 4.38–4.23 (3H, m),
4.15–4.06 (3H, m), 4.09–3.82 (2H, m, @CH–CH2–),
3.98–3.77 (5H, m), 3.63–3.57 (2H, m), 3.42 (1H, dd,
J3,4 5.3, J4,4 12.7 Hz, H-5I), 3.27 (1H, dd, J3,4 4.5, J4,4
12.6 Hz, H-5V), 3.21–3.10 (2H, m), 2.04 (3H, s,
CH3CO); ESIMS: m/z 1893 [M+Na]+. Anal. Calcd for
3.8. Allyl 3-O-acetyl-2-O-benzoyl-4,6-O-benzylidene-b-D-
glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-
D-glucopyranosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-
b-D-glucopyranoside (11)
Compound 11 (88 mg, 49%) was obtained from 10
(2.18 mg) following the procedure above described for
the preparation of 7 and 9: [a]D ꢀ2.6 (c 1.0, CHCl3);
1H NMR (CDCl3, 400 MHz): d 7.51–7.34 (30H, m,
Bz–H, Ph–H), 6.42 (1H, d, 3.7 Hz, aH-1), 5.90 (1H,
dd, J3,4 = J4,5 9.7 Hz, H-4I), 5.89–5.82 (1H, m, –CH@),
5.64 (1H, dd, J2,3 = J3,4 9.7 Hz, H-3I), 5.57 (1H, s,
PhCH), 5.38 (1H, dd, J1,2 7.9, J2,3 9.8 Hz, H-2I), 5.34
(1H, s, PhCH), 5.33–5.21 (2H, m, @CH2), 5.02–4.81
(5H, m, H-1II, H-2I, H-2II, H-4I, H-4II), 4.56 (2H, m,
2H-6II), 4.46 (1H, d, J1,2 8.1 Hz, H-1II), 4.25 (1H, dd,
J5,6e 6.5, J6e,6a 12.3 Hz, H-6eIII), 4.16–4.04 (5H, m, H-
C
105H98O32: C, 67.38; H, 5.24. Found: C, 67.50; H, 5.30.
3.11. (R)-2,3-Epoxypropyl 3-O-acetyl-2-O-benzoyl-4,6-
O-benzylidene-b-D-glucopyranosyl-(1!3)-2-O-benzoyl-
4,6-O-benzylidene-b-D-glucopyranosyl-(1!3)-2-O-benz-
oyl-4,6-O-benzylidene-b-D-glucopyranosyl-(1!3)-2-O-
benzoyl-4,6-O-benzylidene-b-D-glucopyranosyl-(1!3)-2-
O-benzoyl-4,6-O-benzylidene-b-D-glucopyranoside (14)
5I, H-5II, H-6aIII
,
H-6eI, H-6aI), 3.91 (1H, dd,
J2,3 = J3,4 9.4 Hz, H-3I), 3.68 (1H, ddd, J4,5 9.7, J5,6e
5.8, J5,6a 5.7 Hz, H-5III), 2.19 (3H, s, CH3CO); ESIMS:
m/z 1185 [M+Na]+. Anal. Calcd for C65H62O20: C,
67.13; H, 5.34. Found: C, 67.00; H, 5.30.
To a soln of 13 (0.38 mmol) in CH2Cl2 (7 mL), m-
CPBA, (1.0 mmol) was added and the suspension was
stirred. When TLC showed that all starting compound
had been consumed (about 3 h), the reaction mixture
was washed successively with 5% aq NaOH and water,
dried (MgSO4), filtered and the filtrate evaporated to
dryness. The solids obtained were purified by recrystal-
lization from EtOH. The obtained materials were stored
3.9. Allyl 2-O-benzoyl-4,6-O-benzylidene-b-D-glucopyr-
anosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-gluco-
pyranosyl-(1!3)-2-O-benzoyl-4,6-O-benzylidene-b-D-
glucopyranoside (12)
Compound 12 (2.05 g, 83%) was obtained from 11
(88 mg) following the procedure above described for
1
in the dark at 4 ꢁC: [a]D ꢀ1.1 (c 1.1, CHCl3); H NMR
1
the preparation of 10: [a]D +16.4 (c 1.0, CHCl3); H
(CDCl3, 400 MHz): d 8.10–6.92 (50H, m, Bz–H, Ph–H),
5.65 (1H, dd, J2,3 = J3,4 7.0 Hz, H-3V), 6.50 (1H, d,
3.5 Hz, aH-1), 5.26 (1H, dd, J1,2 5.3, J2,3 7.0 Hz,
NMR (CDCl3, 400 MHz): d 8.00–7.26 (30H, m, Bz–H,
Ph–H), 6.40 (1H, d, 3.7 Hz, aH-1), 5.90 (1H, dd,

608
G.-L. Huang et al. / Carbohydrate Research 340 (2005) 603–608
H-2IV), 5.15–5.03 (4H, m), 5.00 (1H, m, H-4III), 4.95 (3H,
m), 4.78 (1H, d, J1,2 4.8 Hz, H-1II), 4.72–4.62 (5H, m),
4.52 (2H, m), 4.38–4.23 (3H, m), 4.15–4.06 (3H, m),
3.98–3.77 (5H, m), 3.63–3.57 (2H, m), 3.42 (1H, dd,
J3,4 5.3, J4,4 12.7 Hz, H-5I), 3.27 (1H, dd, J3,4 4.5, J4,4
12.6 Hz, H-5V), 3.21–3.10 (2H, m), 3.09 (1H, m,
–CH(O)CH2), 2.76–2.68 (2H, m, –CH(O)CH2), 2.04
(3H, s, CH3CO); ESIMS: m/z 1909 [M+Na]+. Anal.
Calcd for C105H98O33: C, 66.81; H, 5.20. Found: C,
66.90; H, 5.15.
(–CH(O)CH2), 44.2, 44.1 (–CH(O)CH2); ESIMS: m/z
907 [M+Na]+. Anal. Calcd for C33H56O27: C, 44.80;
H, 6.33. Found: C, 44.67; H, 6.40.
References
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D-glucopyranosyl-(1!3)-b-D-glucopyranosyl-(1!3)-b-D-
glucopyranosyl-(1!3)-b-D-glucopyranoside (15)
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1
pressure at 45 ꢁC: [a]D +86.3 (c 1.1, CHCl3); H NMR
(D2O, 400 MHz): d 5.24 (1H, d, J1,2 3.5 Hz, aH-10),
4.62–4.54 (5H, m, H-1V,IV,III,II), 3.92–3.85 (5H, m),
3.75–3.33 (19H, m), 3.25–3.19 (6H, m), 3.09 (1H, m,
–CH(O)CH2), 2.76–2.68 (2H, m, –CH(O)CH2); 13C
NMR (D2O, 75 MHz): d 103.8, 103.65 (C-1I, 1V),
103.4 (3C) (C-1II, 1III, 1IV), 85.4 (C-3I), 85.2 (C-3II),
85.0 (2C) (C-3III, 3IV), 6.8 (C-5V), 76.45, 76.4 (5C) (C-
3V, 5I, 5II, 5III, 5IV), 74.3 (C-2V), 74.1 (3C) (C-2II, 2III,
2IV), 73.6 (C-2I), 70.4 (C-4V), 69.0, 68.9 (4C) (C-4I, 4II,
4III, 4IV), 61.55 (5C) (C-6I, 6II, 6III, 6IV, 6V), 50.4