Synthesis of a hexasaccharide fragment of the O-deacetylated GXM of C. neoformans serotype B

Article abstract of DOI:10.1016/j.carres.2004.04.010

β-D-Xylp-(1→4)-α-D-Manp-(1→3)-[β-D-Xylp- (1→2)]-α-D-Manp-(1→3)-[β-D-Xylp-(1→2)]-α-D-Manp, the fragment of the exopolysaccharide from Cryptococcus neoformans serovar B, was synthesized as its methyl glycoside. Thus, acetylation of allyl 3-O-benzoyl-4,6-O-benzylidene-α-D-mannopyranoside (1) followed by debenzylidenation and selective 6-O-benzoylation afforded allyl 2-O-acetyl-3,6-di-O-benzoyl-α-D-mannopyranoside (4). Glycosylation of 4 with 2,3,4-tri-O-benzoyl-D-xylopyranosyl trichloroacetimidate (5) furnished the β-(1→4)-linked disaccharide 6. Deallylation followed by trichloroacetimidate formation gave the disaccharide donor 8, and subsequent coupling with allyl 2,3,4-tri-O-benzoyl-β-D-xylopyranosyl-(1→2)-4,6- di-O-benzoyl-α-D-mannopyranoside (9), produced the tetrasaccharide 10. Reiteration of deallylation and trichloroacetimidate formation from 10 yielded the tetrasaccharide donor 12. The downstream disaccharide acceptor 18 was obtained by condensation of 5 with methyl 3-O-acetyl-4,6-O-benzylidene-α- D-mannopyranoside, followed by debenzylidenation, benzoylation, and selective 3-O-deacetylation. Coupling of 18 with 12 afforded the hexasaccharide 19, and subsequent deprotection gave the hexasaccharide glycoside 20. Selective 2″-O-deacetylation of 19 gave the hexasaccharide acceptor 21. Condensation of 21 with glucopyranosyluronate imidate 22 did not produce the expected heptasaccharide glycoside; instead, a transacetylation product 19 was obtained. Meanwhile, there was no reaction between 21 and the bromide donor 23.

Full text of DOI:10.1016/j.carres.2004.04.010

Carbohydrate
RESEARCH
Carbohydrate Research 339 (2004) 1779–1786
Synthesis of a hexasaccharide fragment of the O-deacetylated GXM
of C. neoformans serotype B
Wei Zhao and Fanzuo Kong*
Research Center for Eco-Environmental Sciences, Academia Sinica, PO Box 2871, Beijing 100085, China
Received 6 April 2004; accepted 15 April 2004
Available online 10 June 2004
Abstract—b-
of the exopolysaccharide from Cryptococcus neoformans serovar B, was synthesized as its methyl glycoside. Thus, acetylation of allyl
3-O-benzoyl-4,6-O-benzylidene-a- -mannopyranoside (1) followed by debenzylidenation and selective 6-O-benzoylation afforded
allyl 2-O-acetyl-3,6-di-O-benzoyl-a- -mannopyranoside (4). Glycosylation of 4 with 2,3,4-tri-O-benzoyl- -xylopyranosyl trichlo-
roacetimidate (5) furnished the b-(1 fi 4)-linked disaccharide 6. Deallylation followed by trichloroacetimidate formation gave the
disaccharide donor 8, and subsequent coupling with allyl 2,3,4-tri-O-benzoyl-b- -xylopyranosyl-(1 fi 2)-4,6-di-O-benzoyl-a-
D
-Xylp-(1 fi 4)-a-
D
-Manp-(1 fi 3)-[b-
D
-Xylp-(1 fi 2)]-a-
D
-Manp-(1 fi 3)-[b-
D
-Xylp-(1 fi 2)]-a-
D-Manp, the fragment
D
D
D
D
D-
mannopyranoside (9), produced the tetrasaccharide 10. Reiteration of deallylation and trichloroacetimidate formation from 10
yielded the tetrasaccharide donor 12. The downstream disaccharide acceptor 18 was obtained by condensation of 5 with methyl 3-O-
acetyl-4,6-O-benzylidene-a-D-mannopyranoside, followed by debenzylidenation, benzoylation, and selective 3-O-deacetylation.
Coupling of 18 with 12 afforded the hexasaccharide 19, and subsequent deprotection gave the hexasaccharide glycoside 20. Selective
200-O-deacetylation of 19 gave the hexasaccharide acceptor 21. Condensation of 21 with glucopyranosyluronate imidate 22 did not
produce the expected heptasaccharide glycoside; instead, a transacetylation product 19 was obtained. Meanwhile, there was no
reaction between 21 and the bromide donor 23.
Ó 2004 Elsevier Ltd. All rights reserved.
Keywords: Mannose; Xylose; Glucuronic acid
1. Introduction
pentasaccharide6––the repeating unit of the polysac-
charide in C. neoformans serovar D––have appeared. In
our previous work,7 the successful syntheses of the
hexasaccharide repeating unit of O-deacetylated GXM
of C. neoformans serotype A and its frame-shifted
hexasaccharide glycoside were reported. We now report
a convergent synthesis of the hexasaccharide fragment
of O-deacetylated GXM of C. neoformans serotype B,
and a trial for the synthesis of the repeating unit of the
serotype B.
Glucuronoxylomannan (GXM) as the major capsule
component is produced from Cryptococcus neoformans,
a primary cause of opportunistic infections associated
with AIDS.1;2 Of the four major serotypes3 A–D for
GXM, D has the simplest pentaose structure while C has
the most complex octasaccharide structure. All the four
serotypes are composed of a linear a-(1 ! 3)-linked
mannosyl backbone with b-glucopyranosyluronic acid,
b-xylopyranosyl, and 6-O-acetyl substituents4 (Fig. 1).
The synthesis of trisaccharide and tetrasaccharide
fragments5 corresponding to structures in capsular
polysaccharides of C. neoformans and the synthesis of a
2. Results and discussion
As outlined in Scheme 1, acetylation of allyl 3-O-ben-
zoyl-4,6-O-isopropylidene-a-D
-mannopyranoside,8 (1)
followed by debenzylidenation (80%) and selective 6-O-
benzoylation (90%), gave the glycosyl acceptor 4.
*Corresponding author. Tel.: +86-10-62936613; fax: +86-10-629235-
63; e-mail: fzkong@mail.rcees.ac.cn
0008-6215/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2004.04.010

1780
W. Zhao, F. Kong / Carbohydrate Research 339 (2004) 1779–1786
Figure 1. Model structures of deacetylated GXM of C. neoformans serotypes A–D.
Condensation of 4 with 2,3,4-tri-O-benzoyl-
D
-xylopyr-
glucopyranosyluronate bromide (23) did not occur at
all. Thus, the synthesis of the repeating unit of C. neo-
formans serotype B should be tried in other different
ways.
In summary, a convergent synthesis of the hexasac-
charide fragment of C. neoformans serotype B was
achieved, but the strategy presented here could not be
used for the synthesis of the repeating unit of GXM of
C. neoformans serotype B.
anosyl trichloroacetimidate9 (5) afforded b-(1 fi 4)-
linked disaccharide 6 (90%), and subsequent deallylation
(85%) with PdCl2 in methanol, and trichloroacetimidate
formation10 produced the upstream disaccharide donor
8 (90%). Coupling of 8 with allyl 2,3,4-tri-O-benzoyl-b-
D
-xylopyranosyl-(1 fi 2)-4,6-di-O-benzoyl-a-
D-manno-
pyranoside (9)7 afforded the tetrasaccharide 10 (75%),
subsequent deallylation (85%) and trichloroacetimidate
formation (90%) produced the tetrasaccharide donor 12.
The downstream disaccharide acceptor 18 was simi-
larly prepared. Thus, selective 3-O-acetylation of methyl
3. Experimental
4,6-O-benzylidene-a-
thyl 3-O-acetyl-4,6-O-benzylidene-a-
D
-mannopyranoside (13) gave me-
-mannopyrano-
D
3.1. General methods
side (14) in satisfactory yield (80%). Coupling of 14 with
5 (80%) followed by debenzylidenation (80%), benzoy-
lation (85%), and selective removal of the 3-O-acetyl
group (85%) by methanolysis11 with a mixture of Me-
COCl (2.0 mL) in CH2Cl2 (10 mL) and MeOH (40 mL)
produced the disaccharide acceptor 18.
Condensation of 18 with 12 successfully yielded the
hexasaccharide glycoside 19 (60%), and its deprotection
in ammonia-saturated-methanol gave the free hexasac-
charide fragment of C. neoformans serotype B.
A trial for the synthesis the heptasaccharide repeating
unit of the serotype B was carried out. Thus, selective 200-
O-deacetylation of 19 with a mixture of MeCOCl
(3.5 mL) in CH2Cl2 (10 mL) and MeOH (40 mL) for
3 days afforded the hexasaccharide acceptor 21 in a fair
yield (60%). This indicated that there was a serious steric
hindrance at C-200 position as the concentration of
MeCOCl used was relatively higher, the reaction time
was longer, but the yield was lower compared to selec-
tive deacetylation of 17.
Melting points were determined with a ‘Mel-Temp’
apparatus. Optical rotations were determined with a
Perkin–Elmer model 241-MC automatic polarimeter for
solutions in a 1-dm jacketed cell. 1H NMR and 13C
NMR spectra were recorded with Varian XL-400 and
Varian XL-200 spectrometers, for solutions in CDCl3 or
in D2O as indicated. Chemical shifts are expressed in
ppm downfield from the Me4Si resonance. Mass spectra
were recorded with a VG PLATFORM mass spec-
trometer using the ESI mode. Thin-layer chromatogra-
phy (TLC) was performed on silica gel HF with
detection by charring with 30% (v/v) sulfuric acid in
MeOH or by UV detection. Column chromatography
was conducted by elution of a column (8 · 100 mm,
16 · 240 mm, 18 · 300 mm, 35 · 400 mm) of silica gel
(100–200 mesh) with EtOAc–petroleum ether (bp 60–
90 ꢀC) as the eluent. Analytical LC was performed with
a Gilson HPLC consisting of a pump (model 306),
stainless-steel column packed with silica gel (Spherisorb
SiO2, 10 · 300 mm or 4.6 · 250 mm), differential refrac-
tometer (132-RI detector), UV–vis detector (model 118).
EtOAc–petroleum ether (bp 60–90 ꢀC) was used as the
eluent at a flow rate of 1–4 mL/min. Solutions were
concentrated at a temperature <60 ꢀC under diminished
pressure.
Reaction of 21 with methyl 2,3,4-tri-O-acetyl-a-D-
glucopyranosyluronate trichloroacetimidate (22) under
the coupling conditions did not give the expected hep-
tasaccharide glycoside. Instead, acetyl transferring
occurred giving 19 as the product. Meanwhile, reac-
tion between 21 and methyl 2,3,4-tri-O-acetyl-a-D-

W. Zhao, F. Kong / Carbohydrate Research 339 (2004) 1779–1786
1781
O
OBz
OR
BzO
Ph
BzO
BzO
RO
O
BzO
O
O
O
BzO
OAc
O
RO
HO
BzO
OAc
O
BzO
b
5 R = C(NH)CCl3
O
BzO
BzO
d
OAll
OAll
OR
6 R = All
e
f
R = H
3
1
2
R = H
Ac
c
a
R = H
7
8
4
R=Bz
R =
R = C(NH)CCl3
BzO
BzO
BzO
BzO
O
O
BzO
BzO
BzO
O
O
OAc
O
BzO
BzO
BzO
BzO
BzO
O
d
O
BzO
O
BzO
O
+
8
BzO
OR
O
HO
OAll
9
10 R = All
R = H
e
f
11
12 R = C(NH)CCl3
O
OBz
BzO
BzO
OR
BzO
BzO
BzO
BzO
Ph
O
BzO
O
OH
O
O
O
BzO
5 R = C(NH)CCl3
BzO
O
O
BzO
O
RO
BzO
O
RO
O
Ph
g
b
O
O
AcO
O
BzO
BzO
HO
O
RO
OMe
13 R = H
d
AcO
OMe
OMe
a
OMe
R = Ac
14
16 R = H
15
18
c
Bz
R =
17
HO
HO
BzO
BzO
O
O
O
O
O
BzO
BzO
HO
HO
HO
HO
HO
BzO
O
O
AcO
BzO
BzO
HO
O
HO
O
BzO
18
HO
HO
O
BzO
BzO
O
O BzO
O
HO
12
O
BzO
BzO
O
O
HO
HO
h
O
d
O
HO
O
BzO
HO
O
BzO
O
O
OMe
19
OMe
20
COOMe
O
BzO
BzO
AcO
AcO
O
BzO
BzO
O
O
BzO
BzO
AcO
22
O
OC(NH)CCl3
HO
O
g
BzO
19
BzO
O
BzO
BzO
O BzO
O
19
d
BzO
BzO
O
O
BzO
O
BzO
COOMe
O
AcO
AcO
21
OMe
AcO
Br
23
no reaction
i
Scheme 1. Reagents and conditions: (a) Ac2O, Pyridine (CH2Cl2); (b) 90% HOAc–H2O; (c) BzCl–Pyridine; (d) TMSOTf, CH2Cl2, )10 ꢀC to rt; (e)
PdCl2, CH2Cl2–MeOH, rt, 4 h; (f) CCl3CN, K2CO3, CH2Cl2, 10 h; (g) 4% (7%) CH3COCl in CH2Cl2–MeOH, 0 ꢀC–rt; (h) satd NH3–MeOH, rt, 72 h;
(i) silver triflate, CH2Cl2, 2,4-lutidine.
1
3.2. Allyl 2-O-acetyl-3-O-benzoyl-4,6-O-benzylidene-a-
D
-
CHCl3); H NMR (400 MHz, CDCl3): d 7.99–7.29 (m,
10 H, 2PhH), 5.88 (m, 1H, CH2@CHCH2O), 5.72 (dd,
1H, J2;3 3.6 Hz, J3;4 10.3 Hz, H-3), 5.63 (s, 1H, PhCHO2),
5.50 (dd, 1H, J1;2 1.3 Hz, H-2), 5.30 (m, 1H,
CH2@CHCH2O), 5.20 (m, 1H, CH2@CHCH2O), 4.88
(d, 1H, J1;2 1.3 Hz, H-1), 4.23 (dd, 1H, J 4.8, 10.6 Hz, H-
6a), 4.18 (m, 1H, CH2@CHCH2O), 4.08 (dd, 1H, J 10.0,
10.6 Hz, H-6b), 4.02 (m, 1H, CH2@CHCH2O), 3.98
(ddd, 1H, J 4.8, 10.0, 10.6 Hz, H-5), 3.83 (dd, 1H,
mannopyranoside (2)
Compound 1 (4.14 g, 10 mmol) was dissolved in pyridine
(30 mL), and Ac2O (3.00 mL, 25 mmol) was added. The
mixture was stirred at rt for 12 h, then was concentrated
to give a residue. Purification of the residue by silica gel
column chromatography (3:1 petroleum ether–EtOAc)
gave 2 (4.96 g, 90.0%) as a syrup: ½aŠD+42.0 (c 1.0,

1782
W. Zhao, F. Kong / Carbohydrate Research 339 (2004) 1779–1786
J3;4 ¼ J4;5 10.0 Hz, H-4), 2.14 (s, 3H, CH3CO). Anal.
Calcd for C25H26O8: C, 66.08; H, 5.73. Found: C, 65.94;
H, 5.77.
3 h, during which time the temperature was gradually
warmed to ambient temperature. Then the mixture was
neutralized with Et3N and concentrated to dryness.
Purification of the residue by silica gel column chro-
3.3. Allyl 2-O-acetyl-3-O-benzoyl-a-
(3)
D
-mannopyranoside
matography (3:1 petroleum ether–EtOAc) gave 6
(4.80 g, 90%) as a foamy solid: ½aŠ ꢀ25:5 (c 1.0,
D
1
CHCl3); H NMR (400 MHz, CDCl3): d 8.10–7.17 (m,
A mixture of 2 (4.1 g, 9.1 mmol) and 90% HOAc–H2O
(80 mL) was stirred for 2 h at 70 ꢀC, then concentrated to
dryness. Purification of the residue by silica gel column
chromatography (1:1 petroleum ether–EtOAc) gave 3
25H, 5PhH), 5.89 (m, 1H, CH2@CHCH2O), 5.76 (dd,
1H, J2;3 3.4 Hz, J3;4 9.6 Hz, H-3 of Manp), 5.66 (dd, 1H,
J2;3 ¼ J3;4 ¼ 7.1 Hz, H-3 of Xylp), 5.37 (dd, 1H, J1;2
1.7 Hz, H-2 of Manp), 5.32 (dd, 1H, J1;2 5.2 Hz, H-2
of Xylp), 5.30–5.10 (m, 3H, H-4 of Manp,
CH2@CHCH2O), 4.97 (d, 1H, J1;2 5.2 Hz, H-1 of Xylp),
4.87 (d, 1H, J1;2 1.7 Hz, H-1 of Manp), 4.63 (dd, 1H, J5;6a
1.8, J6a;6b 12.2 Hz, H-6a of Manp), 4.48 (dd, 1H, J5;6b 4.2,
J6a;6b 12.2 Hz, H-6b of Manp), 4.35 (dd, 1H,
J3;4 ¼ J4;5 ¼ 9.6 Hz, H-4 of Manp), 4.10 (dd, 1H, J4;5a
3.0 Hz, J5a;5b 11.8 Hz, H-5a of Xylp), 4.17–3.26 (m, 4H),
2.07 (s, 3H, H3CO). Anal. Calcd for C51H46O16: C,
66.96; H, 5.03. Found: C, 67.07; H, 5.22.
1
(2.66 g, 80%) as a syrup: ½aŠD+42.0 (c 1.0, CHCl3); H
NMR (400 MHz, CDCl3): d 7.98–7.41 (m, 5H, PhH),
5.89 (m, 1H, CH2@CHCH2O), 5.47 (dd, 1H, J2;3 3.5 Hz,
J3;4 9.9 Hz, H-3), 5.37 (dd, 1H, J1;2 1.6 Hz, H-2), 5.30 (m,
1H, CH2@CHCH2O), 5.20 (m, 1H, CH2@CHCH2O),
4.88 (d, 1H, H-1), 4.20 (m, 1H, CH2@CHCH2O), 4.15
(dd, 1H, J3;4 ¼ J4;5 ¼ 9.9 Hz, H-4), 4.12 (m, 1H,
CH2@CHCH2O), 3.93–3.91 (m, 2H, H-6a, H-6b), 3.81
(m, 1H, H-5), 2.10 (s, 3H, H3CO). Anal. Calcd for
C18H22O8: C, 59.02; H, 6.01. Found: C, 59.32; H, 5.98.
3.6. 2,3,4-Tri-O-benzoyl-b-
acetyl-3,6-di-O-benzoyl-D-mannopyranose (7)
D
-xylopyranosyl-(1 ! 4)-2-O-
3.4. Allyl 2-O-acetyl-3,6-di-O-benzoyl-a-
anoside (4)
D
-mannopyr-
To a solution of 6 (4.21 g, 4.6 mmol) in anhyd CH2Cl2
(10 mL) and anhyd MeOH (40 mL), PdCl2 (450 mg,
2.55 mmol) was added with N2 protection. After stirring
the reaction mixture for 4 h at rt, TLC (2:1 petroleum
ether–EtOAc) indicated that the reaction was complete.
Then the mixture was filtered, and the solution was
concentrated to dryness. Purification of the residue by
column chromatography (2:1 petroleum ether–EtOAc)
gave 7 (3.62 g, 85%) as a syrup, and the a-anomer was
Compound 3 (2.52 g, 7.0 mmol) was dissolved in anhyd
CH2Cl2 (30 mL) containing pyridine (4.1 mL, 50 mmol),
then under N2 protection and stirring, a solution of
benzoyl chloride (0.5 mL, 7.0 mmol) in anhyd CH2Cl2
(6 mL) was added dropwise within 30 min at 0 ꢀC. The
reaction temperature slowly raised to rt. After stirring
the mixture for 8 h, TLC (3:1 petroleum ether–EtOAc)
indicated that the reaction was complete. The reaction
mixture was concentrated to give a residue. Purification
of the residue by silica gel column chromatography (3:1
petroleum ether–EtOAc) gave 4 (2.95 g, 90%) as a syr-
up: ½aŠD+46.1 (c 1.0, CHCl3); 1H NMR (400 MHz,
CDCl3): d 8.10–7.39 (m, 10H, 2PhH), 5.90 (m, 1H,
CH2@CHCH2O), 5.54 (dd, 1H, J2;3 3.4 Hz, J3;4 9.6 Hz,
H-3), 5.38 (dd, 1H, J1;2 1.6 Hz, H-2), 5.30 (m, 1H,
CH2@CHCH2O), 5.20 (m, 1H, CH2@CHCH2O), 4.92
(d, 1H, H-1), 4.73–4.64 (m, 2H, H-6a, H-6b), 4.16 (m,
1H, CH2@CHCH2O), 4.12 (dd, 1H, J3;4 ¼ J4;5 ¼ 9.6 Hz,
H-4), 4.12 (m, 1H, CH2@CHCH2O), 4.08 (m, 1H, H-5),
2.10 (s, 3H, H3CO). Anal. Calcd for C25H26O9: C, 63.83;
H, 5.53. Found: C, 63.99; H, 5.51.
isolated and characterized: ½aŠ ꢀ45:6 (c 1.0, CHCl3); 1H
D
NMR (400 MHz, CDCl3): d 8.10–7.17 (m, 25H, 5 PhH),
5.80 (dd, 1H, J2;3 3.3 Hz, J3;4 9.6 Hz, H-3 of Manp), 5.66
(dd, 1H, J2;3 ¼ J3;4 ¼ 7.1 Hz, H-3 of Xylp), 5.38 (dd, 1H,
J1;2 ¼ 1.6 Hz, H-2 of Manp), 5.33 (dd, 1H, J1;2 5.2 Hz, H-
2 of Xylp), 5.23 (d, 1H, J1;2 1.6 Hz, H-1 of Manp), 5.08
(m, 1H, H-4 of Xylp), 5.00 (d, 1H, J1;2 5.2 Hz, H-1 of
Xylp), 4.66 (dd, 1H, J5;6a 1.6 Hz, J6a;6b 12.2 Hz, H-6a of
Manp), 4.46 (dd, 1H, J5;6b 3.4 Hz, H-6b of Manp), 4.38
(dd, 1H, J3;4 ¼ J4;5 ¼ 9.6 Hz, H-4 of Manp), 4.24 (m, 1H,
H-5 of Manp), 4.03 (dd, 1H, J4;5a 4.0 Hz, J5a;5b 12.3 Hz,
H-5a of Xylp), 3.30 (dd, 1H, J4;5b 6.6 Hz, J5a;5b 12.3 Hz,
H-5b of Xylp), 2.03 (s, 3H, CH3CO). Anal. Calcd
for C48H42O16: C, 65.90; H, 4.80. Found: C, 66.01; H,
4.71.
3.5. Allyl 2,3,4-tri-O-benzoyl-b-
D
-xylopyranosyl-(1 ! 4)-
2-O-acetyl-3,6-di-O-benzoyl-a-
D
-mannopyranoside (6)
3.7. 2,3,4-Tri-O-benzoyl-b-
D
-xylopyranosyl-(1 ! 4)-2-O-
Compound 4 (2.64 g, 5.60 mmol) and 2,3,4-tri-O-ben-
zoyl-a- -xylopyranosyl trichloroacetimidate 5 (3.62 g,
acetyl-3,6-di-O-benzoyl-a-D-mannopyranosyl trichloro-
D
acetimidate (8)
6.0 mmol) were dried together under high vacuum for
2 h, then dissolved in anhyd CH2Cl2 (50 mL). TMSOTf
(10 lL, 0.09 mmol) was added dropwise at )10 ꢀC with
nitrogen protection. The reaction mixture was stirred for
Compound 7 (3.20 g, 3.7 mmol) was dissolved in CH2Cl2
(40 mL), and CCl3CN (0.5 mL, 5 mmol) and K2CO3
(1.5 g) were added. The reaction mixture was stirred for

W. Zhao, F. Kong / Carbohydrate Research 339 (2004) 1779–1786
1783
10 h, at the end of which time TLC (2:1 petroleum ether–
EtOAc) indicated that the reaction was complete. Then
the mixture was filtered, and the solution was concen-
trated to dryness. Purification of the residue on a silica
gel column with 3:1 petroleum ether–EtOAc furnished
the disaccharide donor 8 (3.50 g, 90%) as a foamy solid:
61.44, 60.25 (C-2 to C-6), 20.3 (COCH3). Anal. Calcd
for C99H84O30: C, 67.36; H, 4.86. Found: C, 67.49; H,
5.03.
3.9. 2,3,4-Tri-O-benzoyl-b-
acetyl-3,6-di-O-benzoyl-a-
[2,3,4-tri-O-benzoyl-b-
-xylopyranosyl-(1 ! 2)]-4,6-di-
O-benzoyl-a- -mannopyranose (11)
D
-xylopyranosyl-(1 ! 4)-2-O-
D
-mannopyranosyl-(1 ! 3)-
1
½aŠ ꢀ18:1 (c 0.8, CHCl3); H NMR (400 MHz, CDCl3)
D
D
d 8.73 (s, 1H, CNHCCl3), 8.08–7.16 (m, 25H, 5PhH),
6.28 (s, 1H, J1;2 2.0 Hz, H-1 of Manp), 5.80 (dd, 1H, J2;3
3.4 Hz, J3;4 9.6 Hz, H-3 of Manp), 5.65 (dd, 1H,
J2;3 ¼ J3;4 ¼ 6.6 Hz, H-3 of Xylp), 5.60 (dd, 1H, H-2 of
Manp), 5.31 (dd, 1H, J1;2 4.7 Hz, H-2 of Xylp), 5.09 (m,
1H, H-4 of Xylp), 5.03 (d, 1H, J1;2 4.7 Hz, H-1 of Xylp),
4.72 (dd, 1H, J5;6a 1.9 Hz, J6a;6b 12.4 Hz, H-6a of Manp),
4.53 (dd, 1H, J5;6b 3.8 Hz, H-6b of Manp), 4.49 (dd, 1H,
J3;4 ¼ J4;5 ¼ 9.6 Hz, H-4 of Manp), 4.22 (m, 1H, H-5 of
Manp), 4.10 (dd, 1H, J4;5a 4.5 Hz, J5a;5b 12.4 Hz, H-5a
of Xylp), 3.33 (dd, 1H, J4;5b 6.0 Hz, J5a;5b 12.4 Hz, H-5b
of Xylp), 2.10 (s, 3H, CH3CO). Anal. Calcd for
C50H42Cl3NO16: C, 58.88; H, 4.12. Found: C, 58.62; H,
4.21.
D
To a solution of 10 (3.20 g, 1.86 mmol) in anhyd CH2Cl2
(10 mL) and anhyd MeOH (40 mL), PdCl2 (220 mg,
1.22 mmol) was added with nitrogen protection. After
stirring the reaction mixture for 4 h at rt, TLC (1:1
petroleum ether–EtOAc) indicated that the reaction was
complete. Then the mixture was filtered, and the solu-
tion was concentrated to dryness. Purification of the
residue by column chromatography (2:1 petroleum
ether–EtOAc) gave 11 (2.66 g, 85%) as a foamy solid:
½aŠ ꢀ 39:4 (c 1.0, CHCl3); 1H NMR (CDCl3, 400 MHz):
D
d 8.16–7.04 (m, 50H, 10PhH), 5.86 (dd, 1H, J2;3
3.3 Hz, J3;4 8.7 Hz, H-3 of Manp), 5.77 (dd, 1H,
J2;3 ¼ J3;4 ¼ 5.1 Hz, H-3 of Xylp), 5.69 (dd, 1H, J2;3
¼
J3;4 ¼ 7.1 Hz, H-3 of Xylp), 5.67 (dd, 1H, J3;4 ¼ J4;5
¼
3.8. Allyl 2,3,4-tri-O-benzoyl-b-
2-O-acetyl-3,6-di-O-benzoyl-a-
(1 ! 3)-[2,3,4-tri-O-benzoyl-b-
4,6-di-O-benzoyl-a-
D
-xylopyranosyl-(1 ! 4)-
10.1 Hz, H-4 of Manp), 5.42 (dd, 1H, J1;2 5.3 Hz, H-2 of
Xylp), 5.30–5.24 (m, 3H), 5.18 (m, 1H, H-4 of Xylp),
5.14 (dd, 1H, H-2 of Manp), 5.07 (d, 1H, J1;2 1.9 Hz, H-1
of Manp), 4.98 (d, 1H, J1;2 4.8 Hz, H-1 of Xylp), 4.94 (d,
1H, J1;2 5.3 Hz, H-1 of Xylp), 4.87–3.25 (m, 13H), 1.89
(s, 3H, COCH3); 13C NMR (100 MHz, CDCl3): 168.6
(COCH3), 166.1, 165.7, 165.5, 165.2, 165.1, 165.0, 164.9,
164.9, 164.8, 164.6, (10C, 10 COPh), 101.1, 99.3, 98.1,
92.0 (4C, C-1I–IV), 75.18, 74.57, 70.63, 70.30, 70.13,
69.97, 69.64, 69.57, 69.27, 69.16, 68.81, 68.45, 68.30,
63.89, 63.02, 61.57, 60.19 (C-2 to C-6), 20.3 (COCH3).
Anal. Calcd for C94H80O30 : C, 66.82; H, 4.74. Found: C,
66.93; H, 4.64.
D
-mannopyranosyl-
-xylopyranosyl-(1 ! 2)]-
D
D
-mannopyranoside (10)
Compound
8 (2.64 g, 2.60 mmol) and 9 (2.27 g,
2.60 mmol) were dried together under high vacuum
for 2 h, then dissolved in anhyd CH2Cl2 (50 mL).
TMSOTf (15 lL, 0.12 mmol) was added dropwise at
)10 ꢀC with nitrogen protection. The reaction mixture
was stirred for 3 h, during which time it was allowed to
warm to ambient temperature. The mixture was then
neutralized with Et3N and concentrated to dryness.
Purification of the residue by silica gel column chro-
matography (2:1 petroleum ether–EtOAc) gave 10
3.10. 2,3,4-Tri-O-benzoyl-b-
O-acetyl-3,6-di-O-benzoyl-a-
[2,3,4-tri-O-benzoyl-b-
-xylopyranosyl-(1 ! 2)]-4,6-di-
O-benzoyl-a- -mannopyranosyl trichloroacetimidate (12)
D
-xylopyranosyl-(1 ! 4)-2-
(3.36 g, 75%) as a foamy solid: ½aŠ ꢀ36:3 (c 1.0,
D
-mannopyranosyl-(1 ! 3)-
D
1
CHCl3); H NMR (CDCl3, 400 MHz): d 8.15–7.02 (m,
D
50H, 10PhH), 5.85 (dd, 1H, J2;3 3.3 Hz, J3;4 8.9 Hz, H-3
of Manp), 5.75 (dd, 1H, J2;3 ¼ J3;4 ¼ 5.9 Hz, H-3 of
Xylp), 5.70 (m, 1H, CH2@CHCH2O), 5.65 (dd, 1H,
J2;3 ¼ J3;4 ¼ 7.2 Hz, H-3 of Xylp), 5.61 (dd, 1H,
J3;4 ¼ J4;5 ¼ 10.0 Hz, H-4 of Manp), 5.40 (dd, 1H, J1;2
5.2 Hz, H-2 of Xylp), 5.30 (dd, 1H, J1;2 5.1 Hz, H-2 of
Xylp), 5.20 (m, 1H, H-4 of Xylp), 5.18 (m, 1H, H-4
of Xylp), 5.15–5.05 (m, 4H), 4.96 (d, 1H, J1;2 5.1 Hz, H-1
of Xylp), 4.95 (d, 1H, J1;2 5.2 Hz, H-1 of Xylp), 4.87 (s,
1H, H-1 of Manp), 4.81–3.25 (m, 15H), 1.94 (s, 3H,
COCH3); 13C NMR (100 MHz, CDCl3): 168.6 (C
OCH3), 165.9, 165.7, 165.4, 165.4, 165.3, 165.1, 164.9,
164.9, 164.8, 164.6, (10C, 10 COPh), 118.1
(OCH2CH@C2), 101.0, 99.4, 98.4, 96.3 (4C, C-1I–IV),
75.62, 75.13, 70.55, 70.12, 70.10, 69.96, 69.60, 69.31,
69.27, 69.05, 68.85, 68.58, 68.40, 68.30, 63.83, 62.93,
D
Compound 11 (2.6 g, 1.54 mmol) was dissolved in
CH2Cl2 (30 mL), and CCl3CN (0.5 mL, 5 mmol) and
K2CO3 (1.0 g) were added. The reaction mixture was
stirred for 10 h, at the end of which time TLC (2:1
petroleum ether–EtOAc) indicated that the reaction was
complete. Then the mixture was filtered, and the solu-
tion was concentrated to dryness. Purification of the
residue on a silica gel column with 3:1 petroleum ether–
EtOAc as the eluent furnished the tetrasaccharide donor
12 (2.54 g, 90.6%) as a foamy solid: ½aŠ ꢀ46:9 (c 0.5,
D
1
CHCl3); H NMR (CDCl3, 400 MHz): d 8.71 (s, 1H,
CNHCCl3), 8.15–7.02 (m, 50H, 10PhH), 6.38 (d, 1H, J1;2
1.4 Hz, H-1 of Manp), 5.88 (dd, 1H, J2;3 3.2 Hz, J3;4
8.9 Hz, H-3 of Manp), 5.85 (dd, 1H, J2;3 ¼ J3;4 ¼ 5.0 Hz,

1784
W. Zhao, F. Kong / Carbohydrate Research 339 (2004) 1779–1786
H-3 of Xylp), 5.76 (dd, 1H, J3;4 ¼ J4;5 ¼ 10.1 Hz, H-4 of
Manp), 5.66 (dd, 1H, J2;3 ¼ J3;4 ¼ 7.1 Hz, H-3 of Xylp),
5.43–5.40 (m, 2H), 5.30 (m, 1H, H-4 of Xylp), 5.21–5.14
(m, 2H), 5.14 (d, 1H, J1;2 5.0 Hz, H-1 of Xylp), 5.11 (s,
1H, H-1 of Manp), 4.97 (d, 1H, J1;2 5.2 Hz, H-1 of Xylp),
4.87–3.30 (m, 13H), 2.03 (s, 3H, COCH3); 13C NMR
(100 MHz, CDCl3): 168.6 (COCH3), 165.9, 165.6, 165.4,
165.3, 165.2, 165.1, 165.0, 164.9, 164.8, 164.6, (10C,
10COPh), 101.1, 99.5, 98.5, 94.8 (4C, C-1I–IV), 90.5
(–CCl3), 75.16, 74.99, 74.77, 71.65, 70.70, 70.31, 69.88,
69.60, 69.33, 69.15, 69.00, 68.43, 68.40, 63.30, 62.59,
61.60, 60.64, 60.31 (C-2 to C-6), 20.2 (COCH3). Anal.
Calcd for C96H80Cl3NO30: C, 62.85; H, 4.36. Found: C,
63.08; H, 4.54.
(dd, 1H, J2;3 ¼ J3;4 ¼ 5.6 Hz, H-3 of Xylp), 5.40 (dd, 1H,
J1;2 4.6 Hz, J2;3 5.6 Hz, H-2 of Xylp), 5.31 (dd, 1H, J2;3
3.4 Hz, J3;4 10.5 Hz, H-3 of Manp), 5.29 (m, 1H, H-4 of
Xylp), 5.23 (s, 1H, PhCHO2), 4.93 (d, 1H, J1;2 4.6 Hz, H-
1 of Xylp), 4.67 (d, 1H, J1;2 1.2 Hz, H-1 of Manp), 4.60
(dd, 1H, J5;6a 3.3 Hz, J6a;6b 12.4 Hz, H-6a of Manp), 4.28
(dd, 1H, J1;2 1.2 Hz, J2;3 3.4 Hz, H-2 of Manp), 4.08 (dd,
1H, J4;5a 4.6 Hz, J5a;5b 10.1 Hz, H-5a of Xylp), 3.98 (dd,
1 H, J4;5b ¼ J5a;5b 10.1 Hz, H-5b of Xylp), 3.82–3.76 (m,
2H, H-5 of Manp, H-6b of Manp), 3.48 (dd, 1H,
J3;4 ¼ J4;5 ¼ 10.1 Hz, H-4 of Manp), 3.32 (s, 3H, CH3O),
2.14 (s, 3H, CH3CO). Anal. Calcd for C42H40O14: C,
65.63; H, 5.21. Found: C, 65.30; H, 5.38.
3.13. Methyl 2,3,4-tri-O-benzoyl-b-
D-xylopyranosyl-
3.11. Methyl 3-O-acetyl-4,6-O-benzylidene-a-
pyranoside (14)
D
-manno-
(1 ! 2)-3-O-acetyl-a- -mannopyranoside (16)
D
A mixture of 15 (3.85 g, 5.0 mmol) and 90% HOAc–H2O
(60 mL) was stirred for 2 h at 70 ꢀC. The solution was
concentrated to dryness. Purification of the residue by
silica gel column chromatography (1:1 petroleum ether–
EtOAc) gave 16 (2.71 g, 80%) as a foamy solid:
Compound 13 (2.90 g, 10 mmol) was dissolved in anhyd
CH2Cl2 (30 mL) containing pyridine (8.1 mL,
100 mmol), a solution of Ac2O (1.20 mL, 10 mmol) in
anhyd CH2Cl2 (10 mL) was added dropwise within
30 min at 0 ꢀC. The reaction temperature was slowly
raised to rt. After stirring the mixture for 12 h, TLC (3:1
petroleum ether–EtOAc) indicated that the reaction was
complete. The reaction mixture was concentrated to give
a residue, and purification of the residue by column
chromatography on a silica gel column (3:1 petroleum
ether–EtOAc) gave compound 14 (2.62 g, 80.6%) as a
½aŠ ꢀ31:4 (c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3):
D
d 7.94–7.31 (m, 15H, 3 PhH), 5.73 (dd, 1H, J2;3 ¼ J3;4
¼
7.6 Hz, H-3 of Xylp), 5.38 (dd, 1H, J1;2 5.6 Hz, J2;3
7.6 Hz, H-2 of Xylp), 5.28 (m, 1H, H-4 of Xylp), 4.96
(dd, 1H, J2;3 3.2 Hz, J3;4 10.0 Hz, H-3 of Manp), 4.72 (d,
1H, J1;2 5.6 Hz, H-1 of Xylp), 4.47 (d, 1H, J1;2 1.6 Hz, H-
1 of Manp), 4.42 (dd, 1H, J4;5a 4.4 Hz, J5a;5b 12.0 Hz, H-
5a of Xylp), 4.10 (dd, 1H, J1;2 1.6 Hz, J2;3 3.2 Hz, H-2 of
Manp), 4.01 (dd, 1H, J3;4 ¼ J4;5 ¼ 10.0 Hz, H-4 of Manp),
3.62–3.44 (m, 4H, H-5b of Xylp, H-6a of Manp, H-6b of
Manp, H-5 of Manp), 3.16 (s, 3H, CH3O), 2.10 (s,
3H, CH3CO). Anal. Calcd for C35H36O14: C, 61.76; H,
5.29. Found: C, 61.94; H, 5.38.
1
syrup: ½aŠD+62.8 (c 1.0, CHCl3); H NMR (400 MHz,
CDCl3): d 7.46–7.26 (m, 5H, PhH), 5.55 (s, 1H,
PhCHO2), 5.32 (dd, 1H, J2;3 3.3 Hz, J3;4 10.1 Hz, H-3),
4.75 (d, 1H, J1;2 1.5 Hz, H-1), 4.30 (dd, 1H, J 4.2 Hz,
10.1 Hz, H-6a), 4.15 (dd, 1H, J1;2 1.5 Hz, J2;3 3.3 Hz, H-
2), 4.09 (dd, 1H, J 10.1 Hz, 10.1 Hz, H-6b), 3.93 (m, 1H,
H-5), 3.84 (dd, 1H, J3;4 ¼ J4;5 ¼ 10.1 Hz, H-4), 3.40 (s,
3H, OCH3), 2.13 (s, 3H, CH3CO). Anal. Calcd for
C16H20O7: C, 59.26; H, 6.17. Found: C, 59.42; H, 6.21.
3.14. Methyl 2,3,4-tri-O-benzoyl-b-
D
-xylopyranosyl-
-mannopyrano-
(1 ! 2)-3-O-acetyl-4,6-di-O-benzoyl-a-
D
side (17)
3.12. Methyl 2,3,4-tri-O-benzoyl-b-
D
-xylopyranosyl-
-mannopyrano-
(1 ! 2)-3-O-acetyl-4,6-O-benzylidene-a-
D
Compound 16 (2.5 g, 3.67 mmol) was dissolved in pyri-
dine (30 mL), and benzoyl chloride (2.47 mL, 20 mmol)
was added. The mixture was stirred at rt for 12 h, then
quenched with MeOH (3 mL). The reaction mixture was
concentrated to give a residue. Purification of the resi-
due by silica gel column chromatography (3:1 petroleum
ether–EtOAc) gave 17 (2.78 g, 85%) as a foamy solid:
side (15)
Compound 14 (2.11 g, 6.50 mmol) and 2,3,4-tri-O-ben-
zoyl- -xylopyranosyl trichloroacetimidate (5) (4.00 g,
D
6.60 mmol) were dried together under high vacuum for
2 h, then dissolved in anhyd CH2Cl2 (50 mL). TMSOTf
(15 lL, 0.10 mmol) was added dropwise at ꢀ10 ꢀC with
N2 protection. The reaction mixture was stirred for 3 h,
during which time it was allowed to warm to ambient
temperature. The mixture was then neutralized with
Et3N and concentrated to dryness. Purification of the
residue by silica gel column chromatography (3:1
petroleum ether–EtOAc) gave 15 (4.05 g, 80%) as a
½aŠ ꢀ27:5 (c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3):
D
d 8.16–7.30 (m, 25H, 5PhH), 5.70 (dd, 1H, J2;3
J3;4 ¼ 5.1 Hz, H-3 of Xylp), 5.67 (dd, 1H, J3;4 ¼ J4;5
¼
¼
10.0 Hz, H-4 of Manp), 5.48 (dd, 1H, J2;3 3.3 Hz, J3;4
10.0 Hz, H-3 of Manp), 5.37 (dd, 1H, J1;2 5.0 Hz, J2;3
5.1 Hz, H-2 of Xylp), 5.27 (m, 1H, H-4 of Xylp), 4.99 (d,
1H, J1;2 5.0 Hz, H-1 of Xylp), 4.81 (d, 1H, J1;2 1.4 Hz,
H-1 of Manp), 4.64 (dd, 1H, J4;5a 3.0, J5a;5b 12.4 Hz, H-5a
of Xylp), 4.34 (dd, 1H, J5;6a 3.0 Hz, J6a;6b 11.8 Hz, H-6a
foamy solid: ½aŠ ꢀ38:9 (c 1.0, CHCl3); 1H NMR
D
(400 MHz, CDCl3): d 8.15–7.33 (m, 20H, 4PhH), 5.70

W. Zhao, F. Kong / Carbohydrate Research 339 (2004) 1779–1786
1785
of Manp), 4.24 (dd, 1H, H-2 of Manp), 4.18 (m, 1H,
H-5 of Manp), 4.03 (dd, 1H, J5;6b 6.5 Hz, J6a;6b 11.8 Hz,
H-6b of Manp), 3.80 (dd, 1H, J4;5b 4.5 Hz, J5a;5b 12.4 Hz,
H-5b of Xylp), 3.39 (s, 3H, CH3O), 1.98 (s, 3H,
CH3CO). Anal. Calcd for C49H44O16: C, 66.22; H, 4.95.
Found: C, 66.09; H, 5.01.
5.10 (s, 1H, H-1 of Manp), 5.10 (d, 1H, J1;2 5.0 Hz, H-1
of Xylp), 5.04 (d, 1H, J1;2 4.9 Hz, H-1 of Xylp), 5.00 (m,
1H, H-4 of Xylp), 4.84 (s, 1H, H-1 of Manp), 4.80 (d,
1H, J1;2 4.8 Hz, H-1 of Xylp), 4.55 (s, 1H, H-1 of Manp),
4.75–3.10 (m, 21H), 3.21 (s, 3H, OCH3), 1.81 (1s, 3H,
COCH3); 13C NMR (100 MHz, CDCl3): 168.9
(COCH3), 166.0, 166.0, 165.6, 165.5, 165.4, 165.3, 165.3,
165.2, 165.1, 165.1, 165.1, 164.9, 164.6, 164.6, 164.5
(15C, 15COPh), 100.9, 100.1, 99.7, 99.6, 99.5, 98.8 (6C,
C-1I–IV), 78.88, 77.57, 77.26, 76.85, 75.17, 74.46, 70.55,
70.21, 70.18, 70.10, 69.93, 69.77, 69.62, 69.30, 69.23,
69.11, 68.97, 68.40, 68.32, 64.36, 64.00, 62.13, 61.40,
60.95, 60.40 (C-2 to C-6), 54.9 (OCH3), 20.3 (COCH3).
Anal. Calcd for C141H120O44: C, 67.25; H, 4.77. Found:
C, 67.48; H, 4.66.
3.15. Methyl 2,3,4-tri-O-benzoyl-b-
D-xylopyranosyl-
(1 ! 2)-4,6-di-O-benzoyl-a- -mannopyranoside (18)
D
To a solution of 17 (2.71 g, 3.1 mmol) in anhyd CH2Cl2
(10 mL) was added anhyd MeOH (40 mL), then AcCl
(2.0 mL) was added to the reaction mixture at 0 ꢀC. The
solution was stoppered in a flask and stirred at rt
overnight, TLC (2:1 petroleum ether–EtOAc) showed
that the starting material disappeared. The solution was
neutralized with Et3N, then concentrated to dryness.
Purification of the residue by silica gel column chro-
matography (2:1 petroleum ether–EtOAc) gave 18
3.17. Methyl b-
D
-xylopyranosyl-(1 ! 4)-a-
D
-mannopyr-
-manno-
-xylopyranosyl-(1 ! 2)]-a- -manno-
anosyl-(1 ! 3)-[b-
D
-xylopyranosyl-(1 ! 2)]-a-
D
pyranosyl-(1! 3)-[b-
D
D
(2.20 g, 85%) as a foamy solid: ½aŠ ꢀ 10:5 (c 1.0,
pyranoside (20)
D
1
CHCl3); H NMR (400 MHz, CDCl3): d 8.04–7.30 (m,
25H, 5PhH), 5.77 (dd, 1H, J2;3 ¼ J3;4 ¼ 6.8 Hz, H-3 of
Xylp), 5.46 (dd, 1H, J3;4 ¼ J4;5 ¼ 9.8 Hz, H-4 of Manp),
5.41 (dd, 1H, J1;2 5.0 Hz, J2;3 6.7 Hz, H-2 of Xylp), 5.30
(m, 1H, H-4 of Xylp), 5.01 (d, 1H, J1;2 5.0 Hz, H-1 of
Xylp), 4.72 (d, 1H, J1;2 1.0 Hz, H-1 of Manp), 4.62 (dd,
1H, J4;5a 4.0 Hz, J5a;5b 12.3 Hz, H-5a of Xylp), 4.49 (dd,
1H, J5;6a 2.6, J6a;6b 11.9 Hz, H-6a of Manp), 4.24 (dd, 1H,
J5;6b 5.8, J6a;6b 11.9 Hz, H-6b of Manp), 4.16–4.09 (m,
3H, H-3 of Manp, H-5 of Manp, H-2 of Manp), 3.87
(dd, 1H, J4;5b 6.5 Hz, J5a;5b 12.3 Hz, H-5b of Xylp), 1.60
(br s, 1H, OH). Anal. Calcd for C47H42O15: C, 66.67; H,
5.20. Found: C, 66.89; H, 5.11.
Hexasaccharide 19 (100 mg, 0.04 mmol) was dissolved in
a satd methanolic ammonia (10 mL). After stirring at rt
for 72 h, the reaction mixture was concentrated and
purified on a Bio-Gel P2 column (eluent: water),
affording the target hexasaccharide 20 (30 mg, 80%) as a
1
foamy solid: ½aŠD+70.1 (c 0.5, H2O); H NMR (D2O,
400 MHz): d 5.09 (s, 1H, H-1 of Manp), 5.00 (s, 1H, H-1
of Manp), 4.75 (s, 1H, H-1 of Manp), 4.32 (d, 1H, J1;2
7.8 Hz, H-1 of Xylp), 4.30 (d, 1H, J1;2 7.9 Hz, H-1 of
Xylp), 4.28 (d, 1H, J1;2 7.8 Hz, H-1 of Xylp), 4.16–3.20
(m, 36H); 13C NMR (100 MHz, D2O): 103.6, 103.5,
103.4, 102.2, 100.5, 99.0 (6C, C-1I–IV), 78.85, 78.00,
77.11, 76.28, 76.05, 75.84, 75.56, 73.40, 73.29, 72.69,
72.64, 71.98, 69.72, 69.50, 69.30, 69.26, 69.18, 69.11,
66.41, 66.09, 65.16, 64.99, 60.74, 60.23 (C-2 to C-6), 54.9
(OCH3). Anal. Calcd for C34H58O28: C, 44.64; H, 6.35.
Found: C, 44.53; H, 6.42.
3.16. Methyl 2,3,4-tri-O-benzoyl-b-
(1 ! 4)-2-O-acetyl-3,6-di-O-benzoyl-a-
yl-(1 ! 3)-[2,3,4-tri-O-benzoyl-b- -xylopyranosyl-
(1 ! 2)]-4,6-di-O-benzoyl-a- -mannopyranosyl-(1 ! 3)-
[2,3,4-tri-O-benzoyl-b-
-xylopyranosyl-(1 ! 2)]-4,6-di-
O-benzoyl-a- -mannopyranoside (19)
D
-xylopyranosyl-
D
-mannopyranos-
D
D
D
D
3.18. Methyl 2,3,4-tri-O-benzoyl-b-
(1 ! 4)-3,6-di-O-benzoyl-a- -mannopyranosyl-(1 ! 3)-
[2,3,4-tri-O-benzoyl-b-
-xylopyranosyl-(1 ! 2)]-4,6-di-
O-benzoyl-a-
-mannopyranosyl-(1 ! 3)-[2,3,4-tri-O-ben-
zoyl-b-
-xylopyranosyl-(1 ! 2)]-4,6-di-O-benzoyl-a-
mannopyranoside (21)
D-xylopyranosyl-
D
To a cooled solution (0 ꢀC) of 12 (1.83 g, 1.0 mmol) and
18 (580 mg, 0.7 mmol) in anhyd CH2Cl2 (10 mL) was
added TMSOTf (8 lL, 0.05 mmol). The mixture was
stirred at this temperature for 2 h, and then quenched
with Et3N (one drop). The solution was concentrated to
give a residue. Purification of the residue by silica gel
column chromatography (1:1.5 petroleum ether–EtOAc)
D
D
D
D-
To a solution of 19 (470 mg, 0.17 mmol) in anhyd
CH2Cl2 (10 mL) was added anhyd MeOH (40 mL), then
AcCl (3.5 mL) was added to the reaction mixture at 0 ꢀC.
The mixture was stirred at rt for 3 days, TLC (1:1
petroleum ether–EtOAc) showed that the starting
material disappeared. The solution was neutralized with
Et3N, then concentrated to dryness. Purification of the
residue by silica gel column chromatography (1:1.9
petroleum ether–EtOAc) gave 21 (244 mg, 60%) as a
gave 19 (1.02 g, 60%) as a foamy solid: ½aŠ ꢀ26:9 (c 0.5,
D
1
CHCl3); H NMR (CDCl3, 400 MHz): d 8.09–7.23 (m,
75H, 15PhH), 5.82 (dd, 1H, J2;3 3.2 Hz, J3;4 10.0 Hz, H-3
of Manp), 5.70 (dd, 1H, J2;3 ¼ J3;4 ¼ 5.8 Hz, H-3 of
Xylp), 5.66 (dd, 1H, J2;3 ¼ J4;5 ¼ 7.0 Hz, H-3 of Xylp),
5.54 (dd, 1H, J3;4 ¼ J4;5 ¼ 10.0 Hz, H-4 of Manp), 5.50
(dd, 1H, J2;3 ¼ J3;4 ¼ 10.0 Hz, H-4 of Manp), 5.47 (m,
1H, H-4 of Xylp), 5.47–5.36 (m, 3H), 5.21–5.15 (m, 2H),
foamy solid: ½aŠ ꢀ37:5 (c 1.0, CHCl3); 1H NMR
D

1786
W. Zhao, F. Kong / Carbohydrate Research 339 (2004) 1779–1786
(400 MHz, CDCl3): d 8.13–7.25 (m, 75H, 15 PhH), 5.70
(dd, 1H, J3;4 ¼ J4;5 ¼ 5.6 Hz, H-3 of Xylp), 5.68 (dd,
1H, J2;3 3.3 Hz, J3;4 10.1 Hz, H-3 of Manp), 5.62 (dd,
1H, J2;3 ¼ J3;4 ¼ 7.2 Hz, H-3 of Xylp), 5.52 (dd, 1H,
J3;4 ¼ J4;5 ¼ 10.2 Hz, H-4 of Manp), 5.49 (dd, 1H,
J3;4 ¼ J4;5 ¼ 10.1 Hz, H-4 of Manp), 5.40–5.36 (m, 4H),
5.19–5.15 (m, 2H), 5.10 (s, 1H, H-1 of Manp), 5.03 (d,
1H, J1;2 4.8 Hz, H-1 of Xylp), 5.00 (m, 1H, H-4 of Xylp),
4.84 (d, 1H, J1;2 4.9 Hz, H-1 of Xylp), 4.82 (s, 1H, H-1 of
Manp), 4.51 (d, 1H, J1;2 4.9 Hz, H-1 of Xylp), 4.41 (s,
1H, H-1 of Manp), 4.75–3.10 (m, 22H), 3.20 (s, 3H,
OCH3); 13C NMR (100 MHz, CDCl3): 165.9, 165.9,
165.5, 165.5, 165.4, 165.3, 165.2, 165.1, 165.0, 165.0,
165.0, 164.8, 164.8, 164.4, 164.4 (15C, 15COPh), 102.0,
100.9, 100.9, 99.7, 99.7, 98.7 (6C, C-1I–IV), 78.73, 77.59,
77.20, 76.27, 74.87, 77.17, 72.20, 70.70, 70.47, 70.29,
70.10, 69.88, 69.81, 69.50, 69.35, 69.13, 69.08, 68.97,
68.90, 68.83, 68.21, 64.21, 63.80, 62.14, 61.40, 60.97,
60.83, 60.22 (C-2 to C-6), 54.7 (OCH3). Anal. Calcd
for C139H118O43: C, 67.42; H, 4.77. Found: C, 67.20; H,
4.88.
(14 mg, 0.06 mmol). The mixture was stirred at this
temperature for 6 h, and no reaction occurred.
Acknowledgements
This work was supported by The Chinese Academy of
Sciences (KZCX3-J-08) and by The National Natural
Science Foundation of China (Projects 30070185 and
39970864).
References
1. Cherniak, R. Top. Med. Mycol. 1988, 2, 40–54.
2. Bhattacharjee, A. K.; Bennett, J. E.; Glaudemans, C. P. J.
Rev. Infect. Dis. 1982, 6, 619–624.
3. Wilson, D. E.; Bennett, J. E.; Bailey, J. W. Proc. Soc. Exp.
Biol. Med. 1968, 127, 820–827.
4. (a) Bhattacharjee, A. K.; Kwon-Chung, K. J.; Glaude-
mans, C. P. J. Carbohydr. Res. 1979, 73, 183–192; (b)
Bhattacharjee, A. K.; Kwon-Chung, K. J.; Glaudemans,
C. P. J. Carbohydr. Res. 1981, 95, 237–245; (c) Bhatta-
charjee, A. K.; Kwon-Chung, K. J.; Glaudemans, C. P. J.
Carbohydr. Res. 1980, 82, 103–111; (d) Bhattacharjee, A.
K.; Kwon-Chung, K. J.; Glaudemans, C. P. J. Mol.
Immunol. 1979, 16, 531–540.
3.19. Acetyl-transfer reaction and a trial with bromide 23
as the donor
5. (a) Garegg, P. J.; Olsson, L.; Oscarson, S. J. Carbohydr.
Chem. 1993, 12, 195–203; (b) Garegg, P. J.; Olsson, L.;
Oscarson, S. Bioorg. Med. Chem. 1996, 4, 1867–1878.
6. Zegelaar-Jaarsveld, K.; Smits, S. A. W.; van der Marel, G.
A.; van Boom, J. H. Bioorg. Med. Chem. 1996, 4, 1819–
1823.
7. (a) Zhang, J.; Kong, F. Tetrahedron Lett. 2003, 1839–
1850; (b) Zhang, J.; Kong, F. Bioorg. Med. Chem. 2003,
11, 4027–4037; (c) Zhang, J.; Kong, F. Carbohydr. Res.
2003, 338, 1719–1725.
8. Zhang, J.; Kong, F. Tetrahedron: Asymmetry 2002, 13,
243–252.
9. Chen, L.; Kong, F. Carbohydr. Res. 2002, 337, 2335–2341.
10. Schmidt, R. R.; Kinzy, W. Adv. Carbohydr. Chem.
Biochem. 1994, 50, 21–125.
To a cooled solution (0 ꢀC) of 21 (120 mg, 0.05 mmol)
and 22 (50 mg, 0.10 mmol) in anhyd CH2Cl2 (5 mL)
was added TMSOTf (2 lL, 0.01 mmol). The mixture was
stirred at this temperature for 2 h, and then
quenched with Et3N (one drop). The solution was con-
centrated to give a residue. Purification of the residue
by silica gel column chromatography (1:1.5 petroleum
ether–EtOAc) gave a product (40 mg) as a foamy
solid, and its H NMR data were identical with that of
19.
To a cooled solution (0 ꢀC) of 21 (120 mg, 0.05 mmol)
and 23 (23 mg, 0.06 mmol) in anhyd CH2Cl2 (5 mL) and
2,4-lutidine (6 lL, 0.05 mmol), was added silver triflate
1
11. Byramova, N. E.; Ovchinnikov, M. V.; Backinowsky, L.
V.; Kochetkov, N. K. Carbohydr. Res. 1983, 124, c8–c10.