Synthesis of two isomeric pentasaccharides, the possible repeating unit of the beta-glucan from the micro fungus Epicoccum nigrum Ehrenb. ex Schlecht.

Article abstract of DOI:10.1016/S0008-6215(02)00317-8

Two isomeric pentasaccharides, beta-D-Glcp-(1-->3)-[beta-D-Glcp-(1-->6)]-beta-D-Glcp-(1-->3)-[beta-D-Glcp-(1-->6)]-beta-D-Glcp (I) and beta-D-Glcp-(1-->6)-beta-D-Glcp-(1-->3)-[beta-D-Glcp-(1-->3)-beta-D-Glcp-(1-->6)]-beta-D-Glcp (II), the possible repeati

Full text of DOI:10.1016/S0008-6215(02)00317-8

Carbohydrate Research 337 (2002) 2383–2391
www.elsevier.com/locate/carres
Synthesis of two isomeric pentasaccharides, the possible repeating
unit of the b-glucan from the micro fungus Epicoccum nigrum
Ehrenb. ex Schlecht
Ying Zeng, Wenhui Zhang, Jun Ning,* Fanzuo Kong*
Research Center for Eco-En6ironmental Sciences, Academia Sinica, PO Box 2871, Beijing 100085, China
Received 28 June 2002; accepted 28 August 2002
Abstract
Two isomeric pentasaccharides, b-
D
-Glcp-(1“3)-[b-
D
-Glcp-(1“6)]-b-
D
-Glcp-(1“3)-[b-
D
-Glcp-(1“6)]-b-
D
-Glcp (I) and b-D-
Glcp-(1“6)-b- -Glcp-(1“3)-[b- -Glcp-(1“3)-b-
D
D
D
-Glcp-(1“6)]-b-
D
-Glcp (II), the possible repeating unit of the b-glucan from
the micro fungus Epicoccum nigrum Ehrenb. ex Schlecht, were synthesized as their 4-methoxyphenyl glycosides in a regio- and
stereoselective manner. The pentasaccharide I was obtained from 3-O-selective glycosylation of 4-methoxyphenyl 4,6-O-benzyli-
dene-b-
osyl-(1“6)]-2,4-di-O-acetyl-a-
6-O-selective glucosylation with 2,3,4,6-tetra-O-benzoyl-b-
The pentasaccharide II was obtained from 3-O-selective coupling of 12 with 2,3,4,6-tetra-O-benzoyl-b-
2,4-di-O-acetyl-3-O-allyl-a- -glucopyranosyl trichloroacetimidate (10) followed by acetylation, debenzylidenation, and 6-O-selec-
tive glycosylation with 2,3,4,6-tetra-O-benzoyl-b- -glucopyranosyl-(1“3)-2,4,6-tri-O-acetyl-a- -glucopyranosyl trichloro-
D
-glucopyranoside (12) with 2,3,4,6-tetra-O-benzoyl-b-
-glucopyranosyl trichloroacetimidate (6) followed by acetylation, debenzylidenation, and
-glucopyranosyl trichloroacetimidate (1), and then by deprotection.
-glucopyranosyl-(1“6)-
D
-glucopyranosyl-(1“3)-[2,3,4,6-tetra-O-benzoyl-b-
D-glucopyran-
D
D
D
D
D
D
acetimidate (11), and finally by deprotection. © 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Glucose oligosaccharides; Trichloroacetimidates; Regio- and stereoselective synthesis
1. Introduction
needed to prepare a series of b-(1“3)-linked glucan with
different b-(1“6)-side chains. The structures I and II
are interested in terms of their side chain position and
length. We present herein an unambiguous synthesis of
the two isomeric pentasaccharides.
b-(1“3)-Linked glucans occur in a variety of biolog-
ically important natural products with antitumor activi-
ties, such as schizophyllan, scleroglucan and lentinan.1
A highly side-chain/branched (1“3;1“6)-b-glucan,
epiglucan, was obtained from the micro fungus Epicoc-
cum nigrum Ehrenb. ex Schlecht. Structural analysis2 of
the epiglucan revealed that it has a b-(1“3)-linked
backbone with b-(1“6)-linked branches at frequencies
greater than the homologous scleroglucan and schizo-
phyllan. Two pentasaccharide structures I and II were
supposed to be the possible repeating unit of the epiglu-
can. As a part of our ongoing research on the struc-
ture–antitumor function relationship for glucan, we
2. Results and discussion
* Corresponding authors. Tel.: 86-10-62936613; fax: 86-10-
62923563
E-mail address: fzkong@mail.rcees.ac.cn (F. Kong).
For the synthesis of the target pentasaccharides,
some di- and trisaccharide intermediates were prepared
0008-6215/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(02)00317-8

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Y. Zeng et al. / Carbohydrate Research 337 (2002) 2383–2391
first. Coupling of 2,3,4,6-tetra-O-benzoyl-a-
ranosyl trichloroacetimidate3 (1) with 1,2:5,6-di-O-iso-
propylidene-a- -glucofuranose (2) afforded the
D
-glucopy-
prepared by hydrolysis of 3 in 80% HOAc under reflux,
acetylation, selective 1-O-deacetylation, and
trichloroacetimidation.
D
disaccharide 3 (Scheme 1). Selective removal of the
5,6-O-isopropylidene group gave crystalline 4, and sub-
sequent selective 6-O-glycosylation4 of 4 with 1 gave
the trisaccharide 5. Removal of the 1,2-O-isopropyli-
dene groups of furanose 5 was accompanied by ring
expansion. Subsequent acetylation with acetic anhy-
dride in pyridine, selective 1-O-deacetylation with am-
monia in 3:1 THF–MeOH, and trichloroacetimidation
in dichloromethane with trichloroacetonitrile in the
presence of potassium carbonate gave the 3,6-branched
trisaccharide donor 6. The b-(1“6)-linked disaccharide
10 was obtained as follows: Allylation of 2 at O-3,
selective removal of the 5,6-O-isopropylidene group,
followed by selective 6-O-glucosylation with 1 gave 9.
Subsequent hydrolysis, acetylation, selective 1-O-
deacetylation, and trichloroacetimidation furnished 10.
Another b-(1“3)-linked disaccharide donor 11 was
With the described di- and trisaccharide fragments in
hand, the synthesis of the target pentasaccharides was
readily achieved. In our previous work regarding the
synthesis of glucoheptaose repeating unit of lentinan,5
we reported that with 4,6-benzylidenated glucose
derivative as either the donor or the acceptor, coupling
reactions predominantly gave b-linked products. Thus,
coupling of 12 with the trisaccharide donor 6, followed
by acetylation, selectively afforded b-(1“3)-linked tet-
1
rasaccharide 13 (Scheme 2). The H NMR spectrum of
13 showed 4 H-1 at l 4.96, 4.86, 4.72, and 4.41 ppm,
respectively, with J1,2 8.0 Hz, indicating only b-linkage.
Sequential irradiation of the 4 H-1 found the related
signals of 4 H-2 at l 5.45, 5.41, 5.27, and 4.84 ppm,
respectively, and collapsed the H-2 signals from a
triplet to a doublet. This confirmed the 3-O-selective
glucosylation, since 2-O-selective glucosylation would
Scheme 1. Reagents and conditions: (a) TMSOTf, CH2Cl2, N2, −20 °C to rt, 4 h; (b) 90% HOAc, 40 °C, 20 h; (c) 80% HOAc,
reflux, 4 h; (d) Ac2O–pyridine (dry), rt, 10 h; (e) THF–CH3OH, 1.5N NH3, rt, 1–2 h; (f) CCl3CN, DBU, CH2Cl2 (dry), 10 h;
(g) AllBr, DMF, NaH, 0 °C to rt, 4 h.

Y. Zeng et al. / Carbohydrate Research 337 (2002) 2383–2391
2385
Scheme 2. Reagents and conditions: (a) TMSOTf, CH2Cl2, N2, −20 °C to rt, 4 h; (b) Ac2O–pyridine (dry), rt, 10 h; (c) CH3OH,
CH3COCl (0.3%, v/v), rt, 2 h; (d) NH3, CH3OH; (e) PdCl2, CH3OH, 4 h.
give H-2a at l B4.2 ppm. Debenzylidenation of 13
gave the tetrasaccharide 14, whose characterization was
carried out through its acetylated derivative 15. Selec-
tive 6-O-glucosylation of the tetrasaccharide acceptor
14 with the donor 1 furnished the pentasaccharide 16,
and finally, deacylation of 16 in ammonia-saturated

2386
Y. Zeng et al. / Carbohydrate Research 337 (2002) 2383–2391
methanol gave the 4-methoxyphenyl pentaoside 17.
The 13C NMR of 17 showed 5 anomeric carbons at l
105.23, 105.23, 105.04, 105.04, and 103.36 ppm, indi-
cating all of the linkages in 17 are b. Another pen-
tasaccharide 23, corresponding to structure II was
synthesized in a similar way. Thus, the b-(1“6)-linked
disaccharide donor 10 was selectively coupled with the
acceptor 12, and subsequent acetylation gave the
trisaccharide 18. The regioselective glycosylation was
temperature. Then the mixture was neutralized with
Et3N. Concentration of the reaction mixture, followed
by purification on a silica gel column with 4:1
petroleum ether–EtOAc as the eluent, gave the
product 3 (2.91 g, 87%) as a syrup: [h]D +25.0° (c
1.0, CHCl3); 1H NMR (400 MHz, CDCl3): l 8.02–
7.34 (m, 20 H, 4 BzH), 5.92 (dd, 1 H, J3%,4%=J4%,5%=9.8
Hz, H-4%), 5.85 (d, 1 H, J1,2 3.0 Hz, H-1), 5.69 (dd, 1
H, J3%,4%=J2%,3%=9.8 Hz, H-3%), 5.55 (dd, 1 H, J1%,2% 8.0
Hz, J2%,3% 9.6 Hz, H-2%), 4.95 (d, 1 H, J1%,2% 8.0 Hz,
1
also confirmed by H NMR spectroscopy. Sequential
a
b
a
irradiation of the 3 H-1 at l 5.01, 4.78, and 4.45 ppm
identified the related signals of 3 H-2 at l 5.66, 5.35,
and 4.80 ppm, respectively. Debenzylidenation of 18,
followed by selective glycosylation with the disaccha-
ride donor 11, and then acetylation, afforded the pen-
tasaccharide 21 in satisfactory yield. Removal of the
allyl group with PdCl2 in methanol6 gave 22, and
deacylation of 22 in ammonia-saturated methanol fur-
nished the target pentaoside 23. Again, the 13C NMR
spectrum of 23 showed 5 anomeric carbons at l
105.39, 105.35, 105.20, 104.75, and 103.32 ppm, indi-
cating only b-linkages in 23.
H-1%), 4.68 (dd, 1 H, J6% ,6% 12.4 Hz, J5%,6% 3.2 Hz,
H-6%a), 4.51 (d, 1 H, J1,2 3.0 Hz, H-2), 4.48 (dd, 1 H,
J6% ,6% 12.4 Hz, J5%,6% 3.2 Hz, H-6%b), 4.12–3.86 (m, 7
H), 1.45, 1.37, 1.31, 1.28 (4 s, 4 CH3). Anal. Calcd for
C46H46O15: C, 65.87; H, 5.49. Found: C, 65.61; H,
5.53.
a
b
b
2,3,4,6-Tetra-O-benzoyl-i-
[2,3,4,6-tetra-O-benzoyl-i-
1,2-O-isopropylidene-h- -glucofuranose (5).—To a so-
D
-glucopyranosyl-(1“3)-
D
-glucopyranosyl-(1“6)]-
D
lution of 90% HOAc (20 mL) was added 3 (1.00 g,
1.20 mmol), and the mixture was stirred at 40 °C
overnight, then concentrated to dryness. The residue
was passed through a short silica gel column (1:1
petroleum ether–EtOAc) to give 4 (880 mg, 93%) as
crystals (mp 144–146 °C). Compound 5 was prepared
by coupling of 1 (750 mg, 1.0 mmol) with 4 (800 mg,
1.0 mmol) under the same conditions as described for
the synthesis of 3 by coupling of 1 with 2. Concentra-
tion of the reaction mixture followed by purification
on a silica gel column with 3:1 petroleum ether–
EtOAc as the eluent gave the product 5 (980 mg, 71%)
The bioassay of 17 and 23 is in progress and the
results will be reported in due course.
3. Experimental
General methods.—Optical rotations were deter-
mined at 25 °C with a Perkin–Elmer model 241-Mc
1
1
automatic polarimeter. H NMR, 13C NMR and H–
13C COSY spectra were recorded with Bruker ARX
400 spectrometers (400 MHz for 1H, 100 MHz for
13C) at 25 °C for solutions in CDCl3 or D2O as indi-
cated. Mass spectra were recorded with a VG PLAT-
FORM mass spectrometer using the ESI mode.
Thin-layer chromatography (TLC) was performed on
silica gel HF254 with detection by charring with 30%
(v/v) H2SO4 in MeOH or in some cases by a UV
lamp. Column chromatography was conducted by elu-
tion of a column (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.
Solutions were concentrated at B60 °C under reduced
pressure.
1
as a syrup: [h]D +42.3° (c 1.0, CHCl3); H NMR (400
MHz, CDCl3): l 8.02–7.34 (m, 40 H, 8 BzH), 5.91
(dd, 1 H, J3 ,4c=J4 ,5c=9.6 Hz, H-4c), 5.87 (d, 1 H,
c
c
J1 ,2 3.0 Hz, H-1a), 5.83 (dd, 1 H, J4 ,5b=J3 ,4b=9.6
a
a
b
b
Hz, H-4b), 5.63 (m, 2 H, H-3b, H-3c), 5.48 (dd, 1 H,
J1 ,2 8.0 Hz, J2 ,3 9.6 Hz, H-2c), 5.43 (dd, 1 H, J1 ,2
c
c
c
c
b b
8.0 Hz, J2 ,3 9.6 Hz, H-2b), 5.03 (d, 1 H, J1 ,2 8.0 Hz,
b
b
c c
H-1c), 4.94 (d, 1 H, J1 ,2 8.0 Hz, H-1b), 4.68 (m, 2 H),
b
b
4.45 (d, 1 H, J1 ,2 3.0 Hz, H-2a), 4.48–3.86 (m, 9 H),
1.37, 1.28 (2 s, 2 CH3). Anal. Calcd for C77H68O24: C,
67.15; H, 4.94. Found: C, 67.38; H, 4.98.
a
a
2,3,4,6-Tetra-O-benzoyl-i-
[2,3,4,6-tetra-O-benzoyl-i-
2,4-di-O-acetyl-h- -glucopyranosyl trichloroacetimidate
D
-glucopyranosyl-(1“3)-
D
-glucopyranosyl-(1“6)]-
D
(6).—A solution of 5 (950 mg, 0.69 mmol) in 80%
HOAc (50 mL) was heated under reflux for 4 h, then
concentrated to dryness. The residue was dissolved in
pyridine (10 mL), and then Ac2O (2 mL) was added.
After stirring the mixture at rt for 12 h, TLC (2:1
petroleum ether–EtOAc) indicated that the reaction
was complete. To the reaction mixture was added wa-
ter (10 mL), and the mixture was stirred for 0.5 h,
then washed with dil HCl, and extracted with CH2Cl2.
The organic phase was dried over anhyd Na2SO4, then
2,3,4,6-Tetra-O-benzoyl-i-
D
-glucopyranosyl-(1“3)-
-glucofuranose (3).—
-glucopyranosyl trichloro-
acetimidate 1 (3.0 g, 4.0 mmol) and 1,2:5,6-di-O-iso-
propylidene-a- -glucofuranose 2 (1.04 g, 4.0 mmol)
1,2:5,6-di-O-isopropylidene-h-
D
2,3,4,6-Tetra-O-benzoyl-b-
D
D
were dried together under high vacuum for 2 h, then
dissolved in anhyd CH2Cl2 (20 mL). TMSOTf (30 mL)
was added dropwise at −20 °C with N2 protection.
The reaction mixture was stirred for 3 h, during which
time the temperature was gradually raised to ambient

Y. Zeng et al. / Carbohydrate Research 337 (2002) 2383–2391
2387
a
b
a
concentrated to dryness. The resultant crude product
was dissolved in a 1 M solution of NH3 in 3:1 THF–
MeOH (20 mL), and the mixture was stirred at rt until
TLC (2:1 petroleum ether–EtOAc) indicated that the
reaction was complete. The solution was concentrated
and the residue was purified by column chromatogra-
phy with 2:1 petroleum ether–EtOAc as the eluent to
(dd, 1 H, J6% ,6% 12.4 Hz, J5%,6% 3.2 Hz, H-6%a), 4.50 (d,
a
b
1 H, J1,2 3.0 Hz, H-2), 4.48 (dd, 1 H, J6% ,6% 12.4 Hz,
J6% ,6% 3.2 Hz, H-6%b), 4.12–3.86 (m, 7 H), 1.39, 1.28 (2
s, 2 CH3). Anal. Calcd for C46H46O15: C, 65.87; H,
5.49. Found: C, 65.71; H, 5.43.
a
b
2,3,4,6-Tetra-O-benzoyl-i-
2,4-di-O-acetyl-3-O-allyl-h- -glucopyranosyl trichloro-
D
-glucopyranosyl-(1“6)-
D
give 2,3,4,6-tetra-O-benzoyl-b-
3)-[2,3,4,6-tetra-O-benzoyl-b- -glucopyranosyl-(1“6)]-
2,4-di-O-acetyl-a,b- -glucopyranose (560 mg, 57% for
D-glucopyranosyl-(1“
acetimidate (10).—A solution of 9 (1.20 g, 1.43 mmol)
in 80% HOAc (50 mL) was heated under reflux for 4
h, then concentrated to dryness. The residue was dis-
solved in pyridine (10 mL), and then Ac2O (1 mL) was
added. After stirring the mixture at rt for 12 h, TLC
(2:1 petroleum ether–EtOAc) indicated that the reac-
tion was complete. The reaction mixture was diluted
with water, and extracted with CH2Cl, washed with
1N HCl, water, and satd aq NaHCO3. The organic
phase was dried over anhyd Na2SO4, then concen-
trated to dryness. The resultant crude product was
dissolved in a 1 M solution of NH3 in MeOH (20
mL), and the mixture was stirred at rt until TLC (2:1
petroleum ether–EtOAc) indicated that the reaction
was complete. The solution was concentrated, and the
residue was purified by column chromatography with
2:1 petroleum ether–EtOAc as the eluent to give 2,3,4,6-
D
D
three steps) as a syrup. A mixture of the hemiacetal
(560 mg, 0.40 mmol), CCl3CN (1.0 mL, 5 mmol), and
1,8-diazabicyclo[5.4.0]undecene (DBU, 0.10 mL) in dry
CH2Cl2 (20 mL) was stirred for 3 h and then concen-
trated. The residue was purified by flash chromatogra-
phy (2:1 petroleum ether–EtOAc) to give 6 (510 mg,
82%) as a syrup: [h]D +79.2° (c 1.0, CHCl3); 1H
NMR (400 MHz, CDCl3): l 8.20 (s, 1 H, NH), 7.91–
a
a
7.27 (m, 40 H, 8 BzH), 6.21 (d, 1 H, J1 ,2 3.6 Hz,
H-1a), 5.92 (dd, 1 H, J3 ,4c=J4 ,5c=9.6 Hz, H-4c), 5.85
c
c
(dd, 1 H, J4 ,5b=J3 ,4b=9.6 Hz, H-4b), 5.64 (dd, 1 H,
b
b
J3 ,4c=J2 ,3c=9.6 Hz, H-3c), 5.62 (dd, 1 H, J3 ,4
=
c
c
b b
J2 ,3b=9.6 Hz, H-3b), 5.49 (dd, 1 H, J1 ,2 8.0 Hz,
b
c c
J2 ,3 9.6 Hz, H-2c), 5.43 (dd, 1 H, J1 ,2 8.0 Hz, J2 ,3
c
c
b
b
b b
9.6 Hz, H-2b), 4.98 (d, 1 H, J1 ,2 8.0 Hz, H-1c), 4.96
c
c
tetra-O-benzoyl-b-
D
-glucopyranosyl -(1“6) - 2,4 - di -O -
(d, 1 H, J1 ,2 8.0 Hz, H-1b), 4.86 (dd, 1 H, J3 ,4
=
a
a
a a
acetyl-a,b- -glucopyranose as a syrup (830 mg, 64%
D
J5 ,4a=9.6 Hz, H-4a), 4.65–4.40 (m, 4 H), 4.22–3.67
(m, 7 H), 1.94, 1.79 (2 s, 2 CH3CO). Anal. Calcd for
C80H68Cl3NO26: C, 61.36; H, 4.35. Found: C, 61.05;
H, 4.32.
a
for three steps). A mixture of the product, CCl3CN
(2.0 mL, 10 mmol), and DBU (0.20 mL, 1.50 mmol)
in dry CH2Cl2 (20 mL) was stirred for 3 h and then
concentrated. The residue was purified by flash chro-
matography (3:1 petroleum ether–EtOAc) to give 10
(840 mg, 87%) as a syrup: [h]D +45.4° (c 1.0, CHCl3);
1H NMR (400 MHz, CDCl3): l 8.63 (s, 1 H, NH),
8.06–7.29 (m, 20 H, 4 BzH), 6.31 (d, 1 H, J1,2 3.2 Hz,
H-1), 5.94 (dd, 1 H, J3%,4%=J4%,5%=9.6 Hz, H-4%), 5.85
(m, 1 H, ꢀCHꢁ), 5.70 (dd, 1 H, J3%,4%=J2%,3%=9.8 Hz,
H-3%), 5.54 (dd, 1 H, J1%,2% 8.0 Hz, J2%,3% 9.6 Hz, H-2%),
5.29–5.18 (m, 2 H, CH2ꢁ), 5.04 (d, 1 H, J1%,2% 8.0 Hz,
H-1%), 4.88 (dd, 1 H, J3,4=J5,4=9.8 Hz, H-4), 4.86
2,3,4,6-Tetra-O-benzoyl-i-
3-O-allyl-1,2-O-isopropylidene-h-
D
-glucopyranosyl-(1“6)-
-glucofuranose (9).
D
—To a solution of 2 (13 g, 50 mmol) in dry DMF (50
mL), AllBr (4.4 mL, 1.01 equiv) and NaH (4.0 g, 49%)
were added under cooling with an ice bath. The mix-
ture was stirred for 2 h at rt, then diluted with CH2Cl2
and washed 3–4 times with H2O. The organic phase
was dried over anhyd Na2SO4, then concentrated to
dryness. The resultant crude product was dissolved in
90% HOAc (100 mL), and the mixture was stirred
overnight at 40 °C and then concentrated. The residue
was purified by flash chromatography (2:1 petroleum
ether–EtOAc) to give 8 (9.5 g, 73% for two steps) as a
syrup. The donor 1 (1.5 g, 2 mmol) and acceptor 8
(520 mg, 2 mmol) were coupled under the same condi-
tions as described for the synthesis of 3 by coupling of
1 with 2. Concentration of the reaction mixture fol-
lowed by purification on a silica gel column with 3:1
petroleum ether–EtOAc as the eluent gave the product
9 (1.25 g, 76%) as a syrup: [h]D +35.1° (c 1.0,
CHCl3); 1H NMR (400 MHz, CDCl3): l 8.05–7.34
(m, 20 H, 4 BzH), 5.94 (dd, 1 H, J3%,4%=J4%,5%=9.8 Hz,
H-4%), 5.88 (m, 1 H, ꢀCHꢁ), 5.84 (d, 1 H, J1,2 3.0 Hz,
H-1), 5.71 (dd, 1 H, J3%,4%=J2%,3%=9.8 Hz, H-3%), 5.54
(dd, 1 H, J1%,2% 8.0 Hz, J2%,3% 9.6 Hz, H-2%), 5.28–5.14
(m, 2 H, CH2ꢁ), 4.94 (d, 1 H, J1%,2% 8.0 Hz, H-1%), 4.67
(dd, 1 H, J6% ,6% 10.4 Hz, J5%,6% 3.0 Hz, H-6%a), 4.67 (dd,
a
b
a
1 H, J6% ,6% 10.4 Hz, J5%,6% 3.2 Hz, H-6%b), 4.50 (dd, 1
H, J1,2 3.0 Hz, J2,3 9.6 Hz, H-2), 4.24–3.86 (m, 7 H),
a
b
b
2.04, 1.81 (2 s,
C49H46Cl3NO17: C, 57.28; H, 4.48. Found: C, 57.41;
H, 4.41.
2,3,4,6-Tetra-O-benzoyl-i-
2,4,6-tri-O-acetyl-h- -glucopyranosyl trichloroacetimi-
date (11).—A solution of 3 (900 mg, 1.07 mmol) in
80% HOAc (20 mL) was heated under reflux for 4 h,
then concentrated to dryness. The residue was dis-
solved in pyridine (10 mL), and then Ac2O (1 mL) was
added. After stirring the mixture at rt for 12 h, TLC
(2:1 petroleum ether–EtOAc) indicated that the reac-
tion was complete. The reaction mixture was diluted
with water (10 mL), then extracted with CH2Cl2 and
2
CH3CO). Anal. Calcd for
D
-glucopyranosyl-(1“3)-
D

2388
Y. Zeng et al. / Carbohydrate Research 337 (2002) 2383–2391
H-1b), 4.18–3.82 (m, 8 H), 3.81 (s, 3 H, CH3O), 3.67–
3.63 (m, 2 H), 2.03, 1.94, 1.79 (3 s, 3 CH3CO). Anal.
Calcd for C100H90O33: C, 66.01; H, 4.95. Found: C,
66.07; H, 4.91.
washed with dil HCl. The organic phase was combined,
dried, and concentrated. The resultant crude product
was dissolved in a 1 M solution of NH3 in MeOH (20
mL), and the mixture was stirred at rt until TLC (2:1
petroleum ether–EtOAc) indicated that the reaction
was complete. The solution was concentrated, and the
residue was purified on a silica gel column with 2:1
petroleum ether–EtOAc to give 2,3,4,6-tetra-O-benzoyl-
4-Methoxyphenyl 2,3,4,6-tetra-O-benzoyl-i-
pyranosyl-(1“3)-[2,3,4,6-tetra-O-benzoyl-i-
pyranosyl-(1“6)]-2,4-di-O-acetyl-i- -glucopyranosyl-
(1“3)-2,4,6-tri-O-acetyl-i- -glucopyranoside (15).—
D-gluco-
D
-gluco-
D
D
To a solution of 13 (900 mg, 0.50 mmol) in MeOH (50
mL) was added AcCl (0.3 mL). The solution was
stoppered in a flask and stirred at rt for 1 h, at the end
of which time TLC (1:1 petroleum ether–EtOAc)
showed that the starting material had disappeared. The
solution was neutralized with Et3N, then concentrated
to dryness. The residue was purified by flash chro-
matography (2:1 petroleum ether–EtOAc) to give 14
(750 mg, 83%) as a syrup. Compound 14 (50 mg, 0.29
mmol) was dissolved in pyridine (2 mL) and Ac2O (0.1
mL) was added. After stirring the mixture at rt for 12 h,
TLC (1:1 petroleum ether–EtOAc) showed that the
reaction was complete. The residue was purified by
flash chromatography (2:1 petroleum ether–EtOAc) to
give 15 (45 mg, 90%) as a syrup: [h]D +39.1° (c 0.5,
b -
D
-glucopyranosyl - (1“3) - 2,4 - di -O - acetyl - a,b - D-
glucopyranose as a syrup (675 mg, 71% for three steps).
A mixture of the hemiacetal, CCl3CN (1.5 mL, 7.5
mmol), and DBU (0.15 mL, 1.20 mmol) in dry CH2Cl2
(20 mL) was stirred for 3 h and then concentrated. The
residue was purified by flash chromatography (2:1
petroleum ether–EtOAc) to give 11 (600 mg) as a
syrup: [h]D +21.3° (c 1.0, CHCl3); 1H NMR (400
MHz, CDCl3): l 8.61 (s, 1 H, NH), 8.06–7.27 (m, 20
H, 4 BzH), 6.44 (d, 1 H, J1,2 3.2 Hz, H-1), 5.95 (dd, 1
H, J3%,4%=J4%,5%=9.6 Hz, H-4%), 5.74 (dd, 1 H, J3%,4%
J2%,3%=9.8 Hz, H-3%), 5.46 (dd, 1 H, J1%,2%=J2%,3%=8.8
Hz, H-2%), 5.19 (dd, 1 H, J3,4=J4,5=9.8 Hz, H-4), 5.03
=
a
b
(d, 1 H, J1%,2% 8.0 Hz, H-1%), 4.86 (dd, 1 H, J6% ,6% 10.4
Hz, J5%,6% 3.0 Hz, H-6%a), 4.69 (dd, 1 H, J6% ,6% 10.4 Hz,
a
a b
b
1
J5%,6% 3.2 Hz, H-6%b), 4.48 (dd, 1 H, J1,2 3.0 Hz, J2,3 9.6
CHCl3); H NMR (400 MHz, CDCl3): l 7.98–7.35 (m,
Hz, H-2), 4.24–4.07 (m, 5 H), 2.08, 1.99, 1.81 (3 s, 3
CH3CO). Anal. Calcd for C48H44Cl3NO18: C, 56.00; H,
4.08. Found: C, 55.83; H, 4.03.
40 H, 8 PhH), 6.95–6.80 (dd, 4 H, ꢀC6H4ꢀ), 5.86 (dd, 1
H, J3 ,4d=J4 ,5d=9.6 Hz, H-4d), 5.84 (dd, 1 H, J4 ,5
=
d
d
c c
J3 ,4c=9.6 Hz, H-4c), 5.69 (dd, 1 H, J3 ,4d=J2 ,3d=9.6
c
d
d
Hz, H-3d), 5.67 (dd, 1 H, J3 ,4c=J2 ,3c=9.6 Hz, H-3c),
c
c
4-Methoxyphenyl 2,3,4,6-tetra-O-benzoyl-i-
pyranosyl-(1“3)-[2,3,4,6-tetra-O-benzoyl-i-
pyranosyl-(1“6)]-2,4-di-O-acetyl-i- -glucopyranosyl-
(1“3)-2-O-acetyl-4,6-O-benzylidene-i- -glucopyran-
D-gluco-
5.49 (dd, 1 H, J1 ,2 8.0 Hz, J2 ,3 9.6 Hz, H-2d), 5.39
d
d
d d
D
-gluco-
(dd, 1 H, J1 ,2 8.0 Hz, J2 ,3 9.6 Hz, H-2c), 5.14 (d, 1 H,
c
c
c c
D
J1 ,2 8.0 Hz, H-1d), 5.12 (dd, 1 H, J1 ,2 8.0 Hz, J2 ,3
d
d
a
a
a a
D
9.6 Hz, H-2a), 4.94 (dd, 1 H, J4 ,5b=J3 ,4b=9.6 Hz,
b
b
oside (13).—Compound 13 was prepared by coupling
of 6 (800 mg, 0.51 mmol) with 125 (190 mg, 0.51 mmol)
under the same conditions as described for the synthesis
of 3 by coupling of 1 with 2. Concentration of the
reaction mixture, followed by purification on a silica gel
column with 3:1 petroleum ether–EtOAc as the eluent,
gave a tetrasaccharide (607 mg, 67%). The tetra-
saccharide was quantitatively acetylated in pyridine (10
mL) with Ac2O (2 mL), then concentrated to dryness.
The residue was purified by flash chromatography (2:1
petroleum ether–EtOAc) to give 13 (592 mg, 95%) as a
syrup: [h]D +45.1° (c 2.0, CHCl3); 1H NMR (400
MHz, CDCl3): l 8.01–7.32 (m, 45 H, 9 PhH), 6.95–
H-4b), 4.86 (d, 1 H, J1 ,2 8.0 Hz, H-1c), 4.82 (d, 1 H,
c
c
J1 ,2 8.0 Hz, H-1a), 4.70 (m, 2 H, H-4a, H-2b), 4.68–
a
a
4.48 (m, 4 H, 2 H-6a, 2 H-6d), 4.33 (d, 1 H, J1 ,2 8.4
Hz, H-1b), 4.22–4.3.81 (m, 7 H), 3.81 (s, 3 H, CH3O),
3.67–3.63 (m, 3 H), 2.03, 1.94, 1.79 (5 CH3CO). Anal.
Calcd for C97H90O35: C, 64.17; H, 4.96. Found: C,
63.91; H, 4.92.
b
b
4-Methoxyphenyl 2,3,4,6-tetra-O-benzoyl-i-
pyranosyl-(1“3)-[2,3,4,6-tetra-O-benzoyl-i-
D
-gluco-
D
-gluco-
pyranosyl-(1“6)]-2,4-di-O-acetyl-i-
(1“3)-[2,3,4,6-tetra-O-benzoyl-i-
(1“6)]-2,4-di-O-acetyl-i-
D
-glucopyranosyl-
D
-glucopyranosyl-
D
-glucopyranoside
(16).—
d
d d
6.82 (dd, 4 H, ꢀC6H4ꢀ), 5.88 (dd, 1 H, J3 ,4d=J4 ,5
=
The acceptor 14 (220 mg, 0.13 mmol) and donor 1 (100
mg, 0.13 mmol) were dried together under high vacuum
for 2 h, then dissolved in anhyd CH2Cl2 (20 mL).
TMSOTf (15 mL) was added dropwise at −20 °C with
N2 protection. The reaction mixture was stirred for 3 h,
during which time the reaction mixture was gradually
raised to ambient temperature. Then the mixture was
neutralized with Et3N. Concentration of the reaction
mixture followed by purification on a silica gel column
with 1:1 petroleum ether–EtOAc as the eluent gave the
product. To the solution of the product in pyridine (20
9.6 Hz, H-4d), 5.86 (dd, 1 H, J4 ,5c=J3 ,4c=9.6 Hz,
c
c
H-4c), 5.66 (dd, 1 H, J3 ,4d=J4 ,5d=9.6 Hz, H-3d), 5.65
d
d
(dd, 1 H, J3 ,4c=J2 ,3c=9.6 Hz, H-3c), 5.51 (s, 1 H,
c
c
d
d
d d
PhCH), 5.45 (dd, 1 H, J1 ,2 8.0 Hz, J2 ,3 9.6 Hz,
H-2d), 5.41 (dd, 1 H, J1 ,2 8.0 Hz, J2 ,3 9.6 Hz, H-2c),
c
c
c c
5.27 (dd, 1 H, J1 ,2 8.0 Hz, J2 ,3 9.6 Hz, H-2a), 4.96 (d,
a
a
a a
1 H, J1 ,2 8.0 Hz, H-1d), 4.86 (d, 1 H, J1 ,2 8.0 Hz,
d
d
a a
H-1a), 4.84 (dd, 1 H, J1 ,2b=J2 ,3b=9.2 Hz, H-2b), 4.79
b
b
(m, 2 H), 4.72 (d, 1 H, J1 ,2 8.0 Hz, H-1c), 4.68–4.48
c
c
(m, 4 H, 2 H-6a, 2 H-6d), 4.41 (d, 1 H, J1 ,2 8.0 Hz,
b
b

Y. Zeng et al. / Carbohydrate Research 337 (2002) 2383–2391
2389
mL), Ac2O (1 mL, 10 mmol) was added dropwise, and
4-Methoxyphenyl 2,3,4,6-tetra-O-benzoyl-i-
pyranosyl-(1“6)-2,4-di-O-acetyl-3-O-allyl-i-
pyranosyl-(1“3)-2-O-acetyl-4,6-O-benzylidene-i-
D
-gluco-
the mixture was stirred overnight at rt. TLC (1.5:1
petroleum ether–EtOAc) indicated that the reaction
was complete. The mixture was diluted with CH2Cl2,
washed with 1N HCl, water, and then with satd aq
NaHCO3. The organic layers were combined, dried,
and concentrated. Purification by column chromatog-
raphy (2:1 petroleum ether–EtOAc) gave 16 (220 mg,
74% for two steps) as a syrup: [h]D +43.1° (c 1.0,
CHCl3); 1H NMR (400 MHz, CDCl3): l 8.08–7.32
(m, 60 H, 12 BzH), 6.81 (dd, 4 H, ꢀC6H4ꢀ), 5.85 (dd,
1 H, J 9.6 Hz), 5.84 (dd, 1 H, J 9.6 Hz), 5.76 (dd, 1
H, J 9.6 Hz), 5.66–5.62 (m, 3 H), 5.49 (dd, 1 H, J 9.2
Hz), 5.47 (dd, 1 H, J 9.6 Hz), 5.37 (dd, 1 H, J 9.6
Hz), 4.96 (d, 1 H, J 8.0 Hz, bH-1), 4.91 (dd, 1 H, J
9.6 Hz), 4.89 (d, 1 H, J 8.0 Hz, bH-1), 4.82 (dd, 1 H,
J 8.0 Hz, bH-1), 4.63–4.55 (m, 6 H), 4.52–4.47 (m, 4
H), 4.43 (d, 1 H, J 8.0 Hz, bH-1), 4.16–4.09 (m, 2 H),
3.97–3.94 (m, 1 H), 3.88–3.80 (m, 3 H), 3.76 (s, 3 H,
CH3O), 3.67–3.62 (m, 2 H), 3.57–3.51 (m, 2 H),
3.49–3.42 (m, 1 H), 2.04, 1.86, 1.86, 1.66 (4 CH3CO);
13C NMR (100 MHz, CDCl3): l 169.53, 169.10,
168.76, 168.20 (4 CH3CO), 166.02, 165.97, 165.93,
165.76, 165.64, 165.57, 165.17, 165.15, 165.09, 165.04,
164.98, 164.75 (12 C6H5CO), 155.84, 151.27, 133.61,
133.44, 133.40, 133.34, 133.31, 133.21, 133.18, 133.15,
133.08, 132.85, 118.07, 116.41, 101.14, 100.35, 100.35,
99.83, 99.47 (5 C-1), 73.85. 73.54, 73.01, 72.77, 72.77,
72.57, 72.35, 72.38, 72.15, 71.86, 71.86, 71.76, 71.45,
69.44, 69.40, 69.33, 68.85, 68.26, 67.67, 62.67, 55.53,
20.96, 20.82, 20.75, 20.40. Anal. Calcd for
D
-gluco-
D-
glucopyranoside (18).—Compound 18 was prepared by
coupling of 10 (800 mg, 0.78 mmol) with 12 (210 mg,
0.78 mmol) under the same conditions as described for
the synthesis of 3 by coupling of 1 with 2. Concentra-
tion of the reaction mixture, followed by purification
on a silica gel column with 3:1 petroleum ether–
EtOAc as the eluent, gave the product. Acetylation in
pyridine (10 mL) with Ac2O (1 mL), and concentra-
tion, then purification of the residue by flash chro-
matography (2:1 petroleum ether–EtOAc) gave 18
(950 mg, 67% for two steps) as a syrup: [h]D +17.0°
1
(c 0.5, CHCl3); H NMR (400 MHz, CDCl3): l 7.90–
7.32 (m, 25 H, 5 PhH), 6.95–6.82 (dd, 4 H, ꢀC6H4ꢀ),
5.88 (dd, 1 H, J4¦,5¦=J3¦,4¦=9.6 Hz, H-4¦), 5.70–5.68
(m, 2 H, ꢀCHꢁ, H-3¦), 5.66 (dd, 1 H, J2¦,3¦=J1¦,2¦
9.6 Hz, H-2¦), 5.46 (s, 1 H, pHCH), 5.35 (dd, 1 H,
2,3=J1,2=9.6 Hz, H-2), 5.16–5.07 (m, 2 H, ꢁCH2),
=
J
5.01 (d, 1 H, J1¦,2¦ 8.0 Hz, H-1¦), 4.87 (dd, 1 H, J3%,4%
8.0 Hz, J4%,5% 9.6 Hz, H-4%), 4.80 (dd, 1 H, J1,2 8.0 Hz,
J2,3 9.6 Hz, H-2%), 4.78 (d, 1 H, J
8.0 Hz, H-1), 4.62
1,2
(m, 1 H, H-6¦a), 4.54 (m, 1 H, H-6¦b), 4.45 (d, 1 H,
J1%,2% 8.0 Hz, H-1%), 4.24–4.16 (m, 2 H), 3.97–3.82 (m,
4 H), 3.81 (s, 3 H, CH3O), 3.73–3.56 (m, 3 H), 3.49–
3.44 (m, 3 H), 1.96, 1.80, 1.75 (3 s, 3 CH3CO). Anal.
Calcd for C69H68O24: C, 64.69; H, 5.31. Found: C,
64.71; H, 5.28.
4-Methoxyphenyl 2,3,4,6-tetra-O-benzoyl-i-
pyranosyl-(1“6)-2,4-di-O-acetyl-3-O-allyl-i-
pyranosyl-(1“3)-2,4,6-tri-O-acetyl-i-
D
-gluco-
D
-gluco-
C129H114O43: C, 65.87; H, 4.85. Found: C, 65.88; H,
D
-glucopyran-
4.82. Anal. Calcd for C129H114O43: C, 65.87; H, 4.85.
Found: C, 65.79; H, 4.87.
oside (20).—Compound 19 (220 mg, 84%) was pre-
pared by debenzylidenation of 18 (280 mg, 0.22 mmol)
under the same conditions as described for the prepa-
ration of 14 with AcCl in MeOH. For the convenience
of identification, 19 (50 mg) was acetylated with Ac2O
in pyridine to give 20 (45 mg, 92%) as a syrup: [h]D
4-Methoxyphenyl i-
glucopyranosyl - (1“6)] - i -
[i- -glucopyranosyl-(1“6)]-i-
D
-glucopyranosyl-(1“3)-[i-
- glucopyranosyl - (1“3)-
-glucopyranoside (17).
D-
D
D
D
—Compound 16 (200 mg, 0.085 mmol) was added to
an NH3-satd MeOH solution (40 mL). After a week at
rt, the reaction mixture was concentrated, and the
residue was purified by chromatography on Sephadex
LH-20 (column 2.0×30 cm, flow 5 mL/min, about
300 mL MeOH) to afford the product 17 (75 mg,
95%) as a white amorphous powder: [h]D +24.2° (c
1
+27.6° (c 1.0, CHCl3); H NMR (400 MHz, CDCl3):
l 8.06–7.29 (m, 20 H, 4 BzH), 6.92–6.83 (dd, 4 H,
ꢀC6H4ꢀ), 5.92 (dd, 1 H, J3¦,4¦=J4¦,5¦=9.6 Hz, H-4¦),
5.80 (m, 1 H, ꢀCHꢁ), 5.70 (t, 1 H, J3¦,4¦=J2¦,3¦=9.8
Hz, H-3¦), 5.50 (dd, 1 H, J1¦,2¦ 8.0 Hz, J2¦,3¦ 9.6 Hz,
H-2¦), 5.27–5.16 (m, 2 H, CH2ꢁ), 5.08 (d, 1 H, J1¦,2¦
8.0 Hz, H-1¦), 5.01 (dd, 1 H, J3,4=J4,5=9.8 Hz, H-4),
4.88 (dd, 1 H, J1,2=J2,3=9.8 Hz, H-2), 4.83 (d, 1 H,
J1,2 8.0 Hz, H-1), 4.81 (m, 2 H, H-4%, H-2%), 4.72 (dd, 1
1
5.0, HOCH3); H NMR (400 MHz, D2O): l 6.80 (dd,
4 H, ꢀC6H4ꢀ), 4.93 (d, 1 H, J 7.6 Hz, H-1),), 4.74 (d,
1 H, J 7.6 Hz, H-1), 4.63 (d, 1 H, J 8.0 Hz, H-1), 4.41
(d, 1 H, J 7.6 Hz, H-1), 4.35 (d, 1 H, J 7.6 Hz, H-1),
4.09 (m, 2 H), 3.82–3.22 (m, 31 H); 13C NMR (100
MHz, D2O): l 157.33, 153.21, 120.92, 117.63, 105.23,
105.23, 105.04, 105.04, 103.36 (5 C-1), 87.45, 86.92 (2
C-3), 78.48, 78.32, 78.22, 78.17, 77.45, 77.02, 75.98,
75.85, 75.66, 75.50, 74.85, 72.16, 71.23, 70.76, 70.69,
70.55, 63.31, 63.31, 63.31, 58.42. Anal. Calcd for
C37H58O27: C, 47.53; H, 6.21. Found: C, 47.68; H,
6.12.
H, J6% ,6% 10.4 Hz, J5%,6% 3.0 Hz, H-6%a), 4.64 (dd, 1 H,
a
b
J6% ,6% 10.4 Hz, J5%,6% 3.2 Hz, H-6%b), 4.47 (d, 1 H, J1,2
8.0 Hz, H-1%), 4.14–3.88 (m, 5 H), 3.82 (s, 3 H,
CH3O), 3.78–3.42 (m, 6 H), 2.09, 2.07, 2.04, 1.92, 1.81
(5 s, 5 CH3CO). Anal. Calcd for C66H68O26: C, 62.07;
H, 5.33. Found: C, 62.32; H, 5.37.
a
b
4-Methoxyphenyl 2,3,4,6-tetra-O-benzoyl-i-
pyranosyl-(1“6)-2,4-di-O-acetyl-3-O-allyl-i-
D
-gluco-
D
-gluco-

2390
Y. Zeng et al. / Carbohydrate Research 337 (2002) 2383–2391
8.0 Hz, bH-1), 4.26–4.05 (m, 3 H), 4.01–3.87 (m, 3 H),
3.85–3.71 (m, 2 H), 3.67 (m, 1 H), 3.60–3.54 (m, 2 H),
3.49–3.44 (m, 2 H), 3.42 (m, 1 H), 2.10, 2.05, 2.04, 1.96,
1.94, 1.80, 1.60 (7 s, 7 CH3CO); 13C NMR (100 MHz,
CDCl3): l 171.65, 170.36, 169.49, 169.49, 169.20,
168.67, 168.05 (7 CH3CO), 165.99, 165.99, 165.93,
165.66, 165.34, 165.14, 165.14, 164.83 (8 C6H5CO),
155.21, 151.32, 133.61, 133.44, 133.40, 133.34, 133.31,
133.21, 133.18, 133.15, 133.08, 132.85, 117.74, 114.67,
101.04, 100.60, 100.49, 100.22, 99.60 (5 C-1), 78.56,
78.39, 73.99, 73.49, 73.21, 72.85, 72.63, 72.36, 72.12,
71.90, 71.52, 71.23, 69.52, 69.34, 68.52, 67.10, 67.68,
67.43, 20.96, 20.75, 20.68, 20.54, 20.52, 20.46, 20.37.
Anal. Calcd for C107H104O42: C, 62.33; H, 5.05. Found:
C, 62.15; H, 4.99.
pyranosyl-(1“3)-[2,3,4,6-tetra-O-benzoyl-i-
pyranosyl-(1“3)-2,4,6-tri-O-acetyl-i- -glucopyran-
osyl-(1“6)]-2,4-di-O-acetyl-i- -glucopyranoside (21).
D-gluco-
D
D
—Compound 19 (180 mg, 0.15 mmol) and donor 11
(150 mg, 0.15 mmol) were dried together under high
vacuum for 4 h, then dissolved in anhyd CH2Cl2 (20
mL). TMSOTf (60 mL) was added dropwise at −20 °C
with N2 protection. The reaction mixture was stirred
for 3 h, during which time the reaction mixture was
gradually raised to ambient temperature. Then the mix-
ture was neutralized with Et3N. Concentration of the
reaction mixture, followed by purification on a silica gel
column with 1:1 petroleum ether–EtOAc as the eluent,
gave the product. To a solution of the product in
pyridine (10 mL), Ac2O (0.1 mL, 1 mmol) was added
dropwise, and the mixture was stirred overnight at rt.
TLC (1.5:1 petroleum ether–EtOAc) indicated that the
reaction was complete. The mixture was diluted with
CH2Cl2, washed with 1N HCl, water, and satd aq
NaHCO3. The organic layers were combined, dried,
and concentrated. Purification by column chromatogra-
phy (1:1 petroleum ether–EtOAc) gave 21 (220 mg,
69% for two steps) as a foamy solid: [h]D +32.5° (c
4-Methoxyphenyl
glucopyranosyl-(1“3)-[i-
-glucopyranosyl-(1“6)]-i-
i-
D
-glucopyranosyl-(1“6)-i-
-glucopyranosyl-(1“3)-i-
-glucopyranoside (23).—
D-
D
D
D
Compound 22 (180 mg, 1.07 mmol) was added to a
satd solution of NH3 in MeOH (40 mL). After a week
at rt, the reaction mixture was concentrated, and the
residue was purified by chromatography on a Sephadex
LH-20 (column 2.0×30 cm, flow 5 mL/min, about 300
mL MeOH) to afford the pentasaccharidic 23 (76 mg,
93%) as a white amorphous powder: [h]D +47.5° (c
1
1.0, CHCl3); H NMR (400 MHz, CDCl3): l 7.90–7.32
(m, 40 H, 8 BzH), 6.95–6.82 (dd, 4 H, ꢀC6H4ꢀ), 5.92
(dd, 1 H, J 9.6 Hz), 5.89 (dd, 1 H, J 9.6 Hz), 5.72–5.60
(m, 3 H), 5.50 (dd, 1 H, J 9.6 Hz), 5.47 (dd, 1 H, J 9.6
Hz), 5.15–4.90 (m, 7 H), 4.73 (d, 1 H, J 8.0 Hz, bH-1),
4.71 (d, 1 H, J 8.0 Hz, bH-1), 4.68–4.59 (m, 3 H),
4.56–4.43 (m, 3 H), 4.42 (d, 1 H, J 8.0 Hz, bH-1), 4.34
(d, 1 H, J 8.0 Hz, bH-1), 4.26–4.05 (m, 6 H), 4.01–3.87
(m, 3 H), 3.85–3.71 (m, 4 H), 3.67 (m, 1 H), 3.60–3.54
(m, 2 H), 3.49–3.44 (m, 2 H), 3.42 (m, 1 H), 2.10, 2.05,
2.04, 1.96, 1.94, 1.80, 1.60 (7 s, 7 CH3CO). Anal. Calcd
for C110H108O42: C, 62.86; H, 5.14. Found: C, 63.01; H,
5.10.
1
3.3, CH3OH); H NMR (400 MHz, HOCH3): l 6.92–
6.83 (dd, 4 H, ꢀC6H4ꢀ), 4.97 (d, 1 H, J 8.0 Hz, H-1),
4.65 (d, 1 H, J 7.8 Hz, H-1), 4.60 (d, 1 H, J 7.6 Hz,
H-1), 4.41 (d, 1 H, J 7.6 Hz, H-1), 4.40 (d, 1 H, J 8.0
Hz, H-1), 4.10 (m, 2 H), 3.83–3.22 (m, 31 H); 13C
NMR (100 MHz, D2O): l 157.19, 154.23, 121.01,
117.71, 105.39, 105.35, 105.20, 104.75, 103.32 (5 C-1),
87.54, 87.54 (2 C-3), 78.53, 78.37, 78.20, 78.15, 78.06,
77.98, 77.60, 77.39, 76.01, 75.88, 75.71, 75.23, 74.85,
72.21, 72.15, 72.09, 71.27, 70.76, 70.65, 63.34, 63.34,
63.25, 58.52. Anal. Calcd for C37H58O27: C, 47.53; H,
6.21. Found: C, 47.72; H, 6.16.
4-Methoxyphenyl 2,3,4,6-tetra-O-benzoyl-i-
pyranosyl-(1“6)-2,4-di-O-acetyl-i- -glucopyranosyl-
(1“3)-[2,3,4,6-tetra-O-benzoyl-i- -glucopyranosyl-(1
“3)-2,4,6-tri-O-acetyl-i- -glucopyranosyl-(1“6)]-
2,4-di-O-acetyl-i- -glucopyranoside (22).—To a solu-
D-gluco-
D
D
Acknowledgements
D
D
This work was supported by The Chinese Academy
of Sciences (KZCX3-J-08) and by The National Natu-
ral Science Foundation of China (Projects 39970864
and 30070815).
tion of 21 (220 mg) in MeOH (10 mL) was added PdCl2
(15 mg). After stirred for 3 h at rt, TLC (3:2 petroleum
ether–EtOAc) indicated that the reaction was complete.
The mixture was filtered, the solution was concentrated
to dryness, and the resultant residue was purified by
flash chromatography (2:1 petroleum ether–EtOAc) to
give 22 (180 mg, 84%) as a syrup: [h]D +46.1° (c 1.0,
References
1
CHCl3); H NMR (400 MHz, CDCl3): l 7.90–7.32 (m,
40 H, 8 BzH), 6.95–6.82 (dd, 4 H, ꢀC6H4ꢀ), 5.92 (dd 1
H, J 9.6 Hz), 5.89 (dd, 1 H, J 9.6 Hz), 5.72–5.60 (m, 3
H), 5.50 (dd, 1 H, J 9.6 Hz), 5.47 (dd, 1 H, J 9.6 Hz),
5.15–4.90 (m, 7 H), 4.73 (d, 1 H, J 8.0 Hz, bH-1), 4.71
(d, 1 H, J 8.0 Hz, bH-1), 4.68–4.59 (m, 3 H), 4.56–4.43
(m, 3 H), 4.42 (d, 1 H, J 8.0 Hz, bH-1), 4.34 (d, 1 H, J
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