Synthesis of a mannotetraose - The repeating unit of the cell-wall mannans of Microsporum gypseum and related species of Trychophyton

Article abstract of DOI:10.1081/CAR-100104864

A tetrasaccharide, α-D-mannopyranosyl-(1→2)-α-D-mannopyranosyl-(1→6)-α- D-mannopyranosyl-(1→6)-D-mannopyranose (1), the repeating unit of the cell-wall mannans of Microsporum gypseum and related species of Trychophyton, was synthesized using 6-O-acetyl-2,

Full text of DOI:10.1081/CAR-100104864

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SYNTHESIS OF A MANNOTETRAOSE—THE REPEATING
UNIT OF THE CELL-WALL MANNANS OF MICROSPORUM
GYPSEUM AND RELATED SPECIES OF TRYCHOPHYTON
Linsen Heng a , Jun Ning a & Fanzuo Kong a
a Research Center for Eco-Environmental Science, Academia Sinica , P.O. Box 2871,
Beijing, 100085, China
Published online: 16 Aug 2006.
To cite this article: Linsen Heng , Jun Ning & Fanzuo Kong (2001) SYNTHESIS OF A MANNOTETRAOSE—THE REPEATING
UNIT OF THE CELL-WALL MANNANS OF MICROSPORUM GYPSEUM AND RELATED SPECIES OF TRYCHOPHYTON , Journal of
Carbohydrate Chemistry, 20:3-4, 285-296, DOI: 10.1081/CAR-100104864
To link to this article: http://dx.doi.org/10.1081/CAR-100104864
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J. CARBOHYDRATE CHEMISTRY, 20(3&4), 285–296 (2001)
SYNTHESIS OF A MANNOTETRAOSE—THE
REPEATING UNIT OF THE CELL-WALL
MANNANS OF MICROSPORUM GYPSEUM AND
RELATED SPECIES OF TRYCHOPHYTON
Linsen Heng, Jun Ning, and Fanzuo Kong
Research Center for Eco-Environmental Science, Academia Sinica.
P.O. Box 2871, Beijing 100085, China
ABSTRACT
A tetrasaccharide, ꢀ-D-mannopyranosyl-(1→2)-ꢀ-D-mannopyranosyl-(1→6)-
ꢀ-D-mannopyranosyl-(1→6)-D-mannopyranose (1), the repeating unit of the
cell-wall mannans of Microsporum gypseum and related species of Trychophy-
ton, was synthesized using 6-O-acetyl-2,3,4-tri-O-benzoyl-ꢀ-D-mannopyra-
nosyl trichloroacetimidate (5) and 2-O-acetyl-3,4,6-tri-O-benzoyl-ꢀ-D-
mannopyranosyl trichloroacetimidate (13) as the glycosyl donors in “the
inverse Schmidt” procedure.
INTRODUCTION
Dermatophytes are a group of fungi which parasitise man and animals, and
cause superficial cutaneous infections involving primarily the keratinised tissues of
the epidermis, nails, and pilosebaceous follicles. The cell wall of dermatophytes is
made up of chitin, a water-insoluble ꢁ-(1→3)-glucan, and water-soluble polysac-
charides which are antigenically relevant. In many ascoycetous yeasts,1 the anti-
genically relevant outer polysaccharides have a skeleton composed of ꢀ-(1→6)-
linked mannopyranosyl residues, to most of which are attached one branching
moiety, each composed of chains of various lengths containing mainly ꢀ-, ꢁ(or
both)-(1→2) and/or ꢂ(1→3) links (the so-called comb-like structure, as for in-
stance, in Candida maltosa and C. Tropicalis2). A more complex structure (a tree-
like structure) has been reported for C. Albicans,3,4 which shows an analogous back-
bone of ꢀ-(1→6)-linked mannopyranosyl residues with (1→2) and/or (1→3) side
285
Copyright © 2001 by Marcel Dekker, Inc.
www.dekker.com

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HENG, NING, AND KONG
chains, some of which are branched. A third type of sequence has been proposed for
the C. Krusei mannan,5 which contains a main chain of mannopyranose with (1→2)
and (1→6) linkages in a 3:1 ratio but is lightly branched, either at the 2- or 6-posi-
tions.
In 1995, Jiménez-Barbero et al.6 investigated the structures of cell-wall man-
nans isolated from Microsporum gypseum and related species of Trychophyton and
found that all of them consist of an ꢀ-D-mannopyranosyl-(1→2)-ꢀ-D-mannopyra-
nosyl-(1→6)-ꢀ-D-mannopyranosyl-(1→6)-D-mannopyranose repeating tetrasac-
charide. Syntheses of the fragments of polysaccharides are important for elucida-
tion of biological functions of polysaccharides. In this paper, as a part of our
continuous synthetic approach directed toward epitopes of fungal cell-wall man-
nans, we report the synthesis of a tetrasaccharide 1, the repeating unit of mannans
isolated from Microsporum gypseum and related species of Trychophyton.
RESULTS AND DISCUSSION
Tritylation of mannose (2) followed by benzoylation in a one-pot manner gave
the 1,2,3,4-tetra-O-benzoyl-6-O-trityl-D-mannopyranose, selective acetolysis of
which using CH2Cl2-AcOH-Ac2O-H2SO4 in a ratio of 1:1:0.6:0.175 afforded the
corresponding 1,6-diacetate 3 in 71.3% yield (for three steps). The diacetate 3 was
selectively deacetylated at the anomeric position with benzylamine in THF in high
yield to give the corresponding 6-O-acetyl-2,3,4-tri-O-benzoyl-D-mannopyranose
(4). Subsequent reaction of 4 with CCl3CN/DBU in dichloromethane afforded the
glycosyl donor 5. A similar procedure gave another glycosyl donor 7 (Scheme 1).
Scheme 1. Reagents and conditions: (a) i.trityl chloride (1.2 equiv), pyridine, 50°C, 32 h; ii. Ph-
COCl (4.8 equiv), ꢃ40°C, 24 h; iii.CH2Cl2/HOAc/Ac2O/H2SO4 ꢄ 1/1/0.6/0.175 (v/v), rt, 20 h,
71.3% (for three steps); (b) benzylamine (3.2 equiv), THF, rt, 24 h, 86.2%.(c) CCl3CN (2.3–3.2
equiv), DBU (0.18–0.23 equiv), rt, 5 h, 88.1%–85.6%.

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SYNTHESIS OF A MANNOTETRAOSE
287
Scheme 2. Reagents and conditions: (a) PhCOCl (3.3 equiv), pyridine, ꢃ40°C, 24 h, 94.8%; (b)
F3CCOOH (90%), rt, 4 h, 89.0%; (c) (Ac)2O, pyridine, rt, 5 h, 100%; (d) benzylamine (4.0 equiv),
THF, rt, 24 h, 88.4%.(e) CCl3CN (3.3 equiv), DBU (0.3 equiv), rt, 5 h, 86.3%.
Benzoylation of 1,2-O-ethylidene-ꢁ-D-mannopyranose7 (8) followed by hy-
drolysis with 90% CF3COOH afforded the 3,4,6-tri-O-benzoyl-D-mannopyranose
(10), subsequent acetylation with acetic anhydride in pyridine furnished the diac-
etate 11. Selective removal of the 1-O-acetyl group with benzylamine in THF
(→12), and then treatment with CCl3CN/DBU in dichloromethane afforded the
glycosyl donor 13. (Scheme 2).
As shown in Scheme 3, allyl 6-O-acetyl-2,3,4-tri-O-benzoyl-ꢀ-D-mannopy-
ranoside (14) was prepared by the Helferich reaction using 3 as the glycosyl donor
and allyl alcohol as the acceptor.8 Selective removal of the acetyl group of 14 in
Scheme 3. Reagents and conditions: (a) Allyl alcohol (2 equiv.), TMSOTf (0.26 equiv), CH2Cl2, rt,
3 h, 88%. (b) methanol/0.5% HCl, rt, 12–14 h, 93%–96%. (c) 5 (1.4 equiv), CH2Cl2, TMSOTf (0.08
equiv), rt, 3 h, 86.5%. (d) 13 (1.4 equiv), CH2Cl2, TMSOTf (0.16 equiv), rt, 3 h, 85.7%. (e) 7 (5
equiv), CH2Cl2, TMSOTf (0.3 equiv), rt, 3 h, 80.4%. (f) i. PdCl2, CH3OH, rt, 4 h; ii. CH3OH satd with
dry NH3, rt, 72 h, 70.2% (two steps).

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HENG, NING, AND KONG
methanol solution containing 0.5% HCl gave the glycosyl acceptor 15 in a high
yield. The disaccharide 16 was prepared using the “inverse Schmidt” strategy.9
Thus the glycosyl acceptor 15 and the catalyst TMSOTf were mixed first in dry
CH2Cl2, and after stirring for 15 min, the glycosyl donor 5 in dry dichloromethane
was added dropwise within 30 min in order to give 16 in a high yield. Selective re-
moval of the acetyl group of 16 gave the glycosyl acceptor 17, “inverse Schmidt”
coupling of which with 2-O-acetyl-3,4,6-tri-O-benzoyl-ꢀ-D-mannopyranosyl
1
trichloroacetimidate (13) afforded the trisaccharide 18 in 85.7% yield. The H
NMR spectrum of 18 showed one acetyl signal (ꢅ 2.14), one allyl signal, both sig-
nals characteristic of the structure of the trisaccharide 18. Selective removal of the
2-O-acetyl group of the trisaccharide 18 gave the glycosyl accepter 19. The fully
protected tetrasaccharide 20 was smoothly obtained using the “inverse Schmidt”
method, again by coupling with 2,3,4,6-tetra-O-benzoyl-ꢀ-D-mannopyranosyl
trichloroacetimidate (7). Deprotection of 20 using PdCl2 in CH3OH,10 followed by
treatment with NH3 in CH3OH, gave the title mannotetraose 1. The bioassay of 1
is in process.
EXPERIMENTAL
General Methods. Optical rotations were determined at 25°C with a
Perkin-Elmer Model 241-Mc automatic polarimeter. Melting points were deter-
1
mined with a “Mel-Temp” apparatus. H NMR and 13C NMR spectra were
recorded with Bruker ARX 400 spectrometers for solutions in CDCl3. Chemical
shifts are given in parts per million (ppm) downfield from internal Me4Si. Mass
spectra were recorded with a JMS-D300S mass spectrometer using a direct sample
introduction technique. Thin-layer chromatography (TLC) was performed on Sil-
ica Gel HF254 with detection by charring with 30% (v/v) H2SO4 in MeOH or in
some cases by UV detection. Column chromatography was conducted by elution
of a column (16 ꢆ 240, 18 ꢆ 300, 35 ꢆ 400 mm) of silica gel (100–200 mesh) with
EtOAc - petroleum ether (60–90°C) as the eluent. Solutions were concentrated at
ꢃ 60°C under diminished pressure.
1,6-Di-O-acetyl-2,3,4-tri-O-benzoyl-ꢀ-D-mannopyranose (3). A solu-
tion of mannose 2 (15 g, 83.3 mmol) and trityl chloride (28 g, 100.5 mmol) in pyri-
dine (100 mL) was stirred at 50°C for 32 h, at the end of which time TLC (4:1
EtOAc-methanol) indicated that the reaction was complete. The reaction mixture
was cooled to 0°C, and then benzoyl chloride (46.5 mL, 400.9 mmol) was added
dropwise for 30 min to keep the reaction temperature under 40°C. After 24 h, wa-
ter (300 mL) was added to the reaction mixture, and stirring was continued for 30
min. The aq solution was extracted with CH2Cl2 (3 ꢆ 100 mL), the extract was
washed with HCl (1 N) and saturated aqueous sodium bicarbonate, dried (Na2SO4)
and concentrated to dryness. The residue without separation was dissolved in
CH2Cl2 (50 mL), Ac2O (50 mL) and AcOH (30 mL), the solution cooled to 10°C
in an ice bath, and H2SO4 (8.8 mL) added dropwise over 20 min. After the addition

ORDER
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SYNTHESIS OF A MANNOTETRAOSE
289
was complete, the ice bath was removed and the reaction was continued for 20 h at
ambient temperature. The reaction solution was poured into ice water (400 mL),
stirring was continued for an additional 15 min, and the aqueous solution was ex-
tracted with chloroform (3 ꢆ 100 mL). The combined chloroform extracts were
carefully washed with 10% aq NaHCO3 (3 ꢆ 60 mL), dried over Na2SO4, and con-
centrated to a syrup which was subjected to column chromatography with 4:1
petroleum ether-EtOAc as the eluent. Compound 3 was obtained as a syrup (34.2
g, 71.3%); [ꢀ]D ꢇ 9.5° (c 1.0, CHCI3); 1H NMR (400 MHz, CDCI3): ꢅ 8.11–7.28
(m, 15 H, 3 PhH), 6.36 (d, 1 H, J1,2 ꢄ 2.0 Hz, H-1), 6.01 (t, 1 H, J3,4 ꢄ J4,5 ꢄ 10.2
Hz, H-4), 5.88 (dd, 1 H, J2,3 ꢄ 3.2 Hz, J3,4 ꢄ 10.2 Hz, H-3), 5.70 (dd, 1 H,
J1,2 ꢄ 2.0 Hz, J2,3 ꢄ 3.2 Hz, H-2), 4.34 (m, 2 H, H-5, 6a), 4.27 (dd, 1 H,
J
6a,6b ꢄ 13.4 Hz, J5,6b ꢄ 4.2 Hz, H-6b), 2.28, 2.08 (2 s, 6 H, 2COCH3); 13C NMR
(100 MHz, CDCl3): 170.0, 167.7 (2 C, 2 COCH3), 165.1, 165.0, 164.6 (3 C, 3
COPh), 133.3–127.8 (Ph), 90.2 (C-1), 70.2, 69.3, 68.8, 65.9 (4 C, C-2, 3, 4, 5), 62.0
(C-6), 20.4, 20.1 (2 C, 2 COCH3).
Anal. Calcd for C31H28O11: C, 64.58; H, 4.89. Found: C, 64.67; H, 4.94.
6-O-Acetyl-2,3,4-tri-O-benzoyl-ꢀ-D-mannopyranose (4). A solution of
compound 3 (5 g, 8.67 mmol) and benzylamine (3 mL, 27.4 mmol) in anhydrous
THF (30 mL) was stirred at room temperature for 24 h, at the end of which time
TLC (3:1 petroleum ether-EtOAc) indicated that the reaction was complete. The
solution was concentrated. Purification by flash column chromatography on silica
gel (3:1 petroleum ether-EtOAc) gave compound 4 as a syrup (4.0 g, 86.2%); [ꢀ]D
1
ꢇ 16.8° (c 1.0, CHCI3); H NMR (400 MHz, CDCI3): ꢅ 8.11–7.27 (m, 15 H, 3
PhH), 5.98 (m, 2 H, H-3, 4), 5.71 (dd, 1 H, J1,2 ꢄ 1.6Hz, J2,3 ꢄ 2.4 Hz, H-2), 5.53
(d, 1 H, J1,2 ꢄ 1.6 Hz, H-), 4.55 (m, 1 H, H-5), 4.33 (m, 2 H, H-6a, 6b), 2.09( s, 3
H,COCH3); 13C NMR (100 MHz, CDCl3) ; 170.6 (COCH3), 166.1, 165.2, 165.2 (3
C, 3 COPh), 133.1–127.9 (Ph), 91.7 (C-1), 70.6, 69.4, 68.0, 66.5 (4 C, C-2, 3, 4, 5),
62.4 (C-6), 20.3 (COCH3).
Anal. Calcd for C29H26O10: C, 65.17; H, 4.90. Found: C, 65.42; H, 4.94.
6-O-Acetyl-2,3,4-tri-O-benzoyl-ꢀ-D-mannopyranosyl trichloroacetimi-
date (5). A mixture of 4 (4.0 g, 7.48 mmol), trichloroacetonitrile (2.1 mL, 20.9
mmol), and 1,8-diazabicyclo[5.4.0]undecene (DBU) (0.25 mL, 1.67 mmol) in dry
dichloromethane (25mL) was stirred under nitrogen for 5 h and then concentrated
in vacuo. The residue was purified by flash chromatography (4:1 petroleum ether-
EtOAc) to give 5 (4.47 g, 88.1%) as crystals; mp 88–91°C; [ꢀ]D ꢇ 20.3° (c 1.0,
1
CHCI3); H NMR (400 MHz, CDCI3): ꢅ 8.87 (s, 1 H, OC(NH)CCI3), 8.12–7.27
(m, 15 H, 3 PhH), 6.55 (d, 1 H, J1,2 ꢄ 2.0 Hz, H-1), 6.06 (t, 1 H, J3,4 ꢄ J4,5 ꢄ 10.0
Hz, H-4), 5.93 (dd, 1 H, J2,3 ꢄ 3.2 Hz, J3,4 ꢄ 10.0 Hz, H-3), 5.90 (dd, 1 H,
J
1,2 ꢄ 2.0 Hz, J2,3 ꢄ 3.2 Hz, H-2), 4.49 (m, 1 H, H-5), 4.34 (m, 2 H, H-6a, 6b), 2.07
(s, 3 H, COCH3); 13C NMR (100 MHz, CDCl3): 170.0 (COCH3), 165.0, 164.6,
159.4 (4 C, 3 COPh, C(NH)CCl3 ), 133.3–127.9 (Ph), 94.1 (C-1), 90.1 (CCl3),
70.8, 69.2, 68.3, 65.7 (4 C, C-2, 3, 4, 5), 61.9 (C-6), 20.1 (COCH3).
Anal. Calcd for C31H26NO10CI3: C, 54.84; H, 3.86. Found: C, 54.72; H, 3.90.

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HENG, NING, AND KONG
2,3,4,6-Tetra-O-benzoyl-ꢀ-D-mannopyranosyl trichloroacetimidate (7).
A mixture of 2,3,4,6-tetra-O-benzoyl-ꢀ-D-mannopyranose (6)11 (3.5 g, 5.87
mmol), trichloroacetonitrile (1.9 mL, 18.9 mmol), and 1,8-diazabicyclo[5.4.0]un-
decene (DBU) (0.20 mL, 1.34 mmol) in dry dichloromethane (30 mL) was stirred
under nitrogen for 5 h and then concentrated in vacuo. The residue was purified by
flash chromatography (4:1 petroleum ether-EtOAc) to give 7 (3.72 g, 85.6%) as
1
crystals; mp 132–134°C; [ꢀ]D ꢇ48.3° (c 1.0, CHCI3); H NMR (400 MHz,
CDCI3): ꢅ 8.86 (s, 1 H, OC(NH)CCI3), 8.10–7.26 (m, 20 H, 4 PhH), 6.57 (d, 1 H,
J
1,2 ꢄ 1.3 Hz, H-1), 6.23 (t, 1 H, J3,4 ꢄ J4,5 ꢄ 10.0 Hz, H-4), 5.99–5.94 (, 2 H, H-
2, 3), 4.72 (dd, 1 H, J5,6a ꢄ 2.4 Hz, J6b,6a ꢄ12.3 Hz, H-6b), 4.62 (m, 1 H, H-5), 4.50
(dd, 1 H, J5,6b ꢄ 4.0 Hz, J6b,6a ꢄ 12.3 Hz, H-6b); 13C NMR (100 MHz, CDCl3),
165.5, 165.0, 164.9, 164.6 (4 C, 4 COPh), 159.0 (C(NH)CCl3), 133.2–127.9 (Ph),
94.2 (C-1), 71.1, 69.4, 68.4, 65.6 (4 C, C-2, 3, 4, 5), 61.95 (C-6).
Anal. Calcd for C36H28NO10CI3: C, 58.35; H, 3.81. Found: C, 58.44; H, 3.76.
3,4,6-Tri-O-benzoyl-1,2-O-(S-ethylidene)-ꢁ-D-mannopyranose (9). 1,2-
O-(S-ethylidene)-ꢁ-D-mannopyranose (8)7 (6.4 g, 31.1 mmol) in pyridine (30 ml)
was cooled to 0°C, and then benzoyl chloride (11.9 mL, 102.5mmol) was added
dropwise for 30 min to keep the reaction temperature under 40°C. After 24 h, wa-
ter (300 mL) was added to the reaction mixture, and stirring was continued for 30
min. The aq solution was extracted with CH2Cl2 (3 ꢆ 100 mL), the extract was
washed with HCl (1 N) and then saturated sodium bicarbonate, dried (Na2SO4) and
concentrated to dryness. The residue was purified by flash chromatography (4:1
petroleum ether-EtOAc) to give 9 (15.3 g, 94.8%) as crystals; mp 123–125°C; [ꢀ]D
1
ꢇ 25.9° (c 1.0, CHCI3); H NMR (400MHz, CDCI3): ꢅ 8.04–7.25 (m, 15 H, 3
PhH), 6.01 (t, 1 H, J3,4 ꢄ J5,4 ꢄ 10.2 Hz, H-4), 5.80 (dd, 1 H, J3,2 ꢄ 3.6 Hz, J4,3
ꢄ10.2 Hz, H-3), 5.51 (dd, 1 H, J1,2 ꢄ 2.0 Hz, J3,2 ꢄ 3.6 Hz, H-2), 5.45 (q, 1 H, J
ꢄ 5.0 Hz, CH3CH), 5.36 (d, 1 H, J2,1 ꢄ 2.0 Hz, H-1), 4.70 (m, 1 H, H-5), 4.50–4.44
(m, 2 H, H-6, 6ꢈ), 1.57 (d, 3 H, J ꢄ 5.0 Hz, CH3CH); 13C NMR (100 MHz, CDCl3),
165.7, 165.5, 164.8 (3 C, 3 COPh), 133.0–127.8 (Ph), 104.4 (CHCH3), 96.3 (C-1),
77.06, 71.4, 71.0, 66.3 (4 C, C-2, 3, 4, 5), 62.9 (C-6), 21.1 (CHCH3).
Anal. Calcd for C29H26O9: C, 67.18; H, 5.05. Found: C, 67.33; H, 5.00.
3,4,6-Tri-O-benzoyl-D-mannopyranose (10). A solution of compound 9
(7.2 g, 13.9 mmol) in 90% F3CCOOH (30 mL) was stirred at room temperature for
4 h, at the end of which time TLC (1:1 petroleum ether-EtOAc) indicated that the
reaction was complete. The reaction mixture was diluted with toluene (50 mL) and
then concentrated to dryness. Purification by flash column chromatography on sil-
ica gel (3:1 petroleum ether-EtOAc) gave compound 10 as a crystalline mixture of
ꢀ and ꢁ forms in a ratio of 2:1 (6.1 g, 89.0%); mp 99–101°C; [ꢀ]D ꢇ 40.8° (c 1.0,
CHCI3); 1H NMR (400 MHz, CDCI3): ꢅ 8.04–7.27 (m, 15 H, 3 PhH), 6.00 (t, 0.66
H, J3,4 ꢄ J5,4 ꢄ 9.8 Hz, H-4 of ꢀ anomer), 5.92 (t, 0.34 H, J3,4 ꢄ J5,4 ꢄ 9.9 Hz, H-
4 of ꢁ anomer), 5.76 (dd, 0.66 H, J3,2 ꢄ 3.2 Hz, J4,3 ꢄ 9.8 Hz, H-2 of ꢀ anomer),
5.44 (dd, 0.34 H, J3,2 ꢄ 3.1 Hz, J4,3 ꢄ9.7 Hz, H-2 of ꢁ anomer), 5.43 (d, 0.66 H,
J
2,1 ꢄ 1.0 Hz, H-1 of ꢀ anomer), 5.1 (d, 0.34 H, J2,1 ꢄ 1.1 Hz, H-1 of ꢁ anomer),

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SYNTHESIS OF A MANNOTETRAOSE
291
4.67–4.37 (m, 4 H, H-2, 5, 6, 6ꢈ); 13C NMR (100 MHz, CDCl3): 166.1, 165.5,
165.3 (3 C, 3 COPh), 133.3–127.9 (Ph), 94.0, (C-1), 72.2, 69.2, 68.0, 66.5 (4 C, C-
2, 3, 4, 5), 63.2 (C- 6).
Anal. Calcd for C27H24O9: C, 65.85; H, 4.91. Found: C, 66.02; H, 4.95.
1,2-Di-O-acetyl-3,4,6-tri-O-benzoyl-ꢀ-D-mannopyranose (11). Acetyla-
tion of 10 (3 g, 6.1 mmol) with acetic anhydride (8 mL) in pyridine (10 mL) at
room temperature for 4 h gave compound 11 in a quantitative yield as crystals; mp
1
115–117°C; [ꢀ]D ꢇ 35.9° (c 1.0, CHCI3); H NMR (400MHz, CDCI3): ꢅ
8.05–7.27 (m, 15 H, 3 PhH), 6.24 (d, 1 H, J2,1 ꢄ 2.0 Hz, H-1), 6.01 (t, 1 H,
J
3,4 ꢄ J5,4 ꢄ 10 Hz, H-4), 5.80 (dd, 1 H, J3,2 ꢄ 3.6 Hz, J4,3 ꢄ 10.2 Hz, H-3), 5.51
(dd, 1 H, J1,2 ꢄ 2.0 Hz, J3,2 ꢄ 3.6 Hz, H-2), 4.63 (m, 1 H, H-5), 4.49–4.43 (m, 2 H,
H-6,6ꢈ), 2.26, 2.18 (2 s, 6 H, 2 COCH3); 13C NMR (75 MHz, CDCl3): 169.5, 168.2
(2C, 2 COCH3), 166.0, 165.6, 165.3 (3C, 3 COPh), 133.6–128.3 (Ph), 90.6 (C-1),
70.8, 69.5, 68.7, 66.4 (4 C, C-2, 3, 4, 5), 62.8 (C-6), 21.0, 20.7 (2 C, 2 COCH3).
Anal. Calcd for C31H28O11: C, 64.58; H, 4.89. Found: C, 64.70; H, 4.93.
2-O-Acetyl-3,4,6-tri-O-benzoyl-ꢀ-D-mannopyranose (12). A solution of
compound 11 (8 g, 13.8 mmol) and benzylamine (6 mL, 54.9 mmol) in anhydrous
THF (50 mL) was stirred at room temperature for 24 h, at the end of which time
TLC (3:1 petroleum ether-EtOAc) indicated that the reaction was complete. The
solution was concentrated. Purification by flash column chromatography on silica
gel (3:1 petroleum ether-EtOAc) gave compound 12 as crystals (6.56g, 88.4%); mp
89–91°C; [ꢀ]D ꢇ 39.8° (c 1.0, CHCI3); 1H NMR (400 MHz, CDCI3): ꢅ 8.07–7.34
(m, 15 H, 3 PhH), 5.96 (t, 1 H, J3,4 ꢄ J5,4 ꢄ 10 Hz, H-4), 5.87 (dd, 1 H, J3,2 ꢄ 3.2
Hz, J4,3 ꢄ 10.0 Hz, H-3), 5.50 (dd, 1 H, J1,2 ꢄ 2.0 Hz, J3,2 ꢄ 3.2 Hz, H-2), 5.37 (d,
1 H, J2,1 ꢄ 2.0 Hz, H-1), 4.66 (dd, 1 H, J6ꢈ,6 ꢄ 12.0 Hz, J5,6 ꢄ 2.8 Hz, H-6), 4.60
(m, 1 H, H-5), 4.44 (dd, 1 H, J6,6ꢈ ꢄ 12.0 Hz, J5,6ꢈ ꢄ 4.4 Hz, H-6), 2.18 (s, 3H,
COCH3); 13C NMR (100 MHz, CDCl3), 169.6 (COCH3), 165.9, 165.1 (3 C, 3
COPh), 132.9–127.9 (Ph), 91.7 (C-1), 70.0, 69.1, 68.4, 66.6 (4 C, C-2, 3, 4, 5), 62.7
(C-6), 20.3 (COCH3).
Anal. Calcd for C29H26O10: C, 65.17; H, 4.90. Found: C, 65.02; H, 4.85.
2-O-Acetyl-3,4,6-tri-O-benzoyl-ꢀ-D-mannopyranosyl trichloroacetimi-
date (13). A mixture of 12 (4.9 g, 9.17 mmol), trichloroacetonitrile (3.0 mL, 30.0
mmol), and 1,8-diazabicyclo[5.4.0]undecene (DBU) (0.40 mL, 2.7 mmol) in dry
dichloromethane (40 mL) was stirred under nitrogen for 5 h and then concentrated
in vacuo. The residue was purified by flash chromatography (4:1 petroleum ether-
EtOAc) to give 13 (5.37 g, 86.3%) as crystals; mp 87–90°C; [ꢀ]D ꢇ 36.7° (c 1.0,
CHCI3); 1H NMR (400 MHz, CDCI3): ꢅ 8.82 (s, 1 H, OC(NH)CCI3), 8.04–7.36 (m,
15 H, 3 PhH), 6.42 (d, 1 H, J1,2 ꢄ 2.0 Hz, H-1), 6.03 (t, 1 H, J3,4 ꢄ J4,5 ꢄ 10.0 Hz,
H-4), 5.85 (dd, 1 H, J2,3 ꢄ 3.4 Hz, J3,4 ꢄ 10.0 Hz, H-3), 5.71 (dd, 1 H,
J
1,2 ꢄ 2.0 Hz, J2,3 ꢄ 3.4 Hz, H-2), 4.64 (dd, 1 H, J6,6ꢈ ꢄ 12.8 Hz, J5,6 ꢄ 7.0 Hz, H-
6), 4.56 (m, 1 H, H-5),4.46 (dd, 1 H, J6ꢈ,6 ꢄ 12.8 Hz, J5,6ꢈ ꢄ 2.8 Hz, H-6ꢈ), 2.17 (s,
3H, COCH3); 13C NMR (100 MHz, CDCl3), 169.5 (COCH3), 165.9, 165.1, 165.0,

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HENG, NING, AND KONG
164.9(4 C, 3 COPh, C(NH)CCl3), 133.2–127.9 (Ph), 95.7 (C-1), 91.7 (C(NH)CCl3),
69.9, 69.1, 68.4, 66.6 (4 C, C-2, 3, 4, 5), 62.7 (C-6), 20.3 (COCH3).
Anal. Calcd for C31H26NO10CI3: C, 54.84; H, 3.86. Found: C, 54.69; H, 3.98.
Allyl 6-O-Acetyl-2,3,4-tri-O-benzoyl-ꢀ-D-mannopyranoside (14). A so-
lution of 3 (2.5 g, 4.3 mmol) and allyl alcohol (0.6 mL, 8.8 mmol) in dry
dichloromethane (40 mL) was stirred with dried molecular sieves (4 A, 1 g) under
nitrogen for 15 min, and then TMSOTf (0.2 mL, 1.1 mmol) was added dropwise.
After 1 h the reaction mixture was diluted with dichloromethane (50 mL) and
washed with a satd sodium hydrogen carbonate solution (15 mL). The organic
layer was dried with Na2SO4 and concentrated in vacuo. Purification of the residue
by flash chromatography (3:1 petroleum ether-EtOAc) gave 14 as a syrup (2.19 g,
88%); [ꢀ]D ꢇ 15.9° (c 1.0, CHCI3); 1H NMR (400MHz, CDCI3): ꢅ 8.11–7.26 (m,
15 H, 3 PhH), 6.12–5.91 (m, 3 H, H-3, 4,CH2CHꢄCH2), 5.68 (dd, J1,2 ꢄ 2.0 Hz,
J
3,2 ꢄ 2.8 Hz, H-2), 5.40 (dd, 1 H, 2J ꢄ 1.6Hz, 3Jtrans ꢄ 17.2 Hz, CH2CHꢄCH2 ),
5.30 (dd, 1 H, 2J ꢄ 1.6 Hz, 3Jcis ꢄ10.4 Hz, CH2CHꢄCH2), 5.14 (d, J1,2 ꢄ 2.0 Hz,
H-1), 4.47–4.27 (m, 4 H, H-6, 6ꢈ, CH2CHꢄCH2), 4.17 (m, 1 H, H-5), 2.10 (s, 3
H,COCH3); 13C NMR (100 MHz, CDCl3), 170.1 (COCH3), 165.7, 165.6, 165.5 (3
C,3 COPh), 133.7–128.4 (Ph, CH2CHꢄCH2), 118.7 (CH2CHꢄCH2), 96.7 (C-1),
70.5, 70.0, 69.0, 68.7, 66.9 (5 C, C-2, 3, 4, 5, CH2CHꢄCH2), 62.8 (C-6), 20.8
(COCH3).
Anal. Calcd for C32H30O10: C, 66.89; H, 5.26. Found: C, 66.93; H, 5.31.
Allyl 2,3,4-Tri-O-benzoyl-ꢀ-D-mannopyranoside (15). A solution of 14
(1.6 g, 2.8 mmol) in methanol solution (80 mL) containing 0.5 % HCl was stirred
at room temperature for 12 h, at the end of which time TLC (2:1 petroleum ether-
EtOAc) indicated that the starting material had disappeared. The mixture was care-
fully neutralized with triethylamine, and then concentrated to dryness. The residue
was partitioned between water and CH2Cl2, then the organic layer dried over
Na2SO4, and concentrated to a syrup. Purification of the residue by flash chro-
matography (2:1 petroleum ether-EtOAc) gave 15 as a syrup (1.42 g, 96%); [ꢀ]D
1
ꢇ 14.2° (c 1.0, CHCI3); H NMR (400MHz, CDCI3): ꢅ 8.12–7.24 (m, 15 H,3
PhH), 6.03–5.98 (m, 2 H, H-3, CH2CHꢄCH2), 5.85 (t, 1 H, J3,4 ꢄ J4,5 ꢄ 10.0 Hz,
H-4), 5.69 (dd, J1,2 ꢄ 1.6Hz, J2,3 ꢄ 3.2Hz, H-2), 5.40 (dd, 1 H, 2J ꢄ 1.6 Hz, 3Jtrans
2
3
ꢄ 17.2 Hz, CH2CHꢄCH2), 5.29 (dd, 1 H, J ꢄ 1.6Hz, Jcis ꢄ 10.4 Hz,
CH2CHꢄCH2), 5.16 (d, J1,2 ꢄ 1.6 Hz, H-1), 4.34–4.16 (m, 2 H, CH2CHꢄCH2 ),
4.11 (m, 1 H, H-5), 3.83–3.79 (m, 2 H, H-6,6ꢈ); 13C NMR (100 MHz, CDCl3).
166.6, 165.6, 165.5 (3 C, 3 COPh), 133.7–128.3 (Ph, CH2CHꢄCH2), 118.5 (Ph,
CH2CHꢄCH2), 96.8 (C-1), 71.0, 70.7, 69.6, 68.8, 67.3 (5 C, C-2, 3, 4, 5,
CH2CHꢄCH2), 61.3 (C-6).
Anal. Calcd for C30H28O9: C, 67.66; H, 5.30. Found: C, 67.83; H, 5.37. .
Allyl 6-O-Acetyl-2,3,4-tri-O-benzoyl-ꢀ-D-mannopyranosyl-(1→6)-2,3,4-
tri-O-benzoyl-ꢀ-D-mannopyranoside (16). A solution of 15 (0.37 g, 0.69 mmol)
and TMSOTf (10 ꢉL, 0.055mmol) in dry dichloromethane (6 mL) was stirred with

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293
dried molecular sieves (4 A, 0.4 g) under nitrogen for 15 min, and then 5 (0.66 g,
0.97 mmol) in dichloromethane (4 mL) was added dropwise for 20 min. After 3 h
the reaction mixture was diluted with dichloromethane (30 mL) and washed with
satd sodium hydrogen carbonate solution (5 mL). The organic layer was dried with
Na2SO4 and concentrated in vacuo. Purification of the residue by flash chromatog-
raphy (2:1 petroleum ether-EtOAc) gave 16 as a syrup (0.63 g, 86.5%); [ꢀ]D ꢇ 35.3°
1
(c 1.0, CHCI3); H NMR (400 MHz, CDCI3): ꢅ 8.08–7.27 (m, 30 H, 6 PhH),
6.07–5.91 (m, 5 H, H-3A, 3B, 4A, 4B, CH2CHꢄCH2), 5.77 (dd, 1 H, J1,2 ꢄ 1.5 Hz,
J
2,3 ꢄ 3.2 Hz, H-2A), 5.74 (dd, 1 H, J1,2 ꢄ 1.5 Hz, J2,3 ꢄ 3.2 Hz, H-2B), 5.50 (dd, 1
H, 2J ꢄ 1.6 Hz, 3Jtrans ꢄ 17.2 Hz, CH2CHꢄCH2 ), 5.35 (dd, 1 H, 2J ꢄ 1.6 Hz, 3Jcisꢄ
10.4 Hz,), 5.18 (d, 1 H, J1,2 ꢄ 1.5 Hz, H-1A), 5.13 (d, 1 H, J1,2 ꢄ 1.5 Hz, H-1B),
4.45–3.76 (m, 8 H, H-5A, 5B, 6A, 6b, 6Aꢈ, 6Bꢈ, CH2CHꢄCH2), 1.92 (s, 3 H, COCH3);
13C NMR (100 MHz, CDCl3), 169.5 (COCH3), 164.6, 164.5, 164.2, 164.1 (6 C, 6
COPh), 132.6–127.3 (Ph, CH2CHꢄCH2). 117.6 (CH2CHꢄCH2), 96.4, 95.7 (2 C,
C-1A, 1B), 69.5, 69.1, 68.8, 68.5, 67.9, 67.7, 65.9, 65.7, 61.5 (11 C, C-2A, 2B, 3A, 3B,
4A, 4B, 5A, 5B, 6A, 6B, CH2CHꢄCH2 ), 19.5 (COCH3).
Anal. Calcd for C59H52O18: C, 67.55; H, 5.00. Found: C, 67.34; H, 4.96.
Allyl 2,3,4-Tri-O-benzoyl-ꢀ-D-mannopyranosyl-(1→6)-2,3,4-tri-O-ben-
zoyl-ꢀ-D-mannopyranoside (17). A solution of 16 (0.55 g, 0.52 mmol) in
methanol solution (25 mL) containing 0.5 % HCl was stirred at room temperature
for 14 h, at the end of which time TLC (2:1 petroleum ether-EtOAc) indicated that
the starting material had disappeared. The mixture was carefully neutralized with
triethylamine, and then concentrated to dryness. The residue was partitioned be-
tween water and CH2Cl2, then the organic layer dried over Na2SO4, and concen-
trated to a syrup. Purification of the residue by flash chromatography (2:1
petroleum ether-EtOAc) gave 17 as a syrup (0.5 g, 95.6%); [ꢀ]D ꢇ 31.0° (c 1.5,
CHCI3); 1H NMR (400 MHz, CDCI3):ꢅ 8.17–7.26 (m, 30 H, 6 PhH), 6.06–5.80 (m,
5 H, H-3A, 3B, 4A, 4B, CH2CHꢄCH2), 5.76–5.73 (m, 2 H, H-2A, 2B), 5.34 (dd, 1
2
3
2
H, J ꢄ 1.6 Hz, Jtrans ꢄ 17.2 Hz, CH2CHꢄCH2 ), 5.50 (dd, 1 H, J ꢄ 1.6 Hz,
3Jcisꢄ 10.4 Hz,), 5.17 (d, 1 H, J1,2 ꢄ 1.6 Hz, H-1A), 5.14 (d, 1 H, J1,2 ꢄ 1.6 Hz, H-
1B), 4.44–3.55 (m, 8 H, H-5A, 5B, 6A, 6B, 6Aꢈ, 6Bꢈ, CH2CHꢄCH2); 13C NMR (100
MHz, CDCl3), 166.7, 165.7, 165.5, 165.4, 165.2 (6 C, 6 COPh), 133.7–128.3 (Ph,
CH2CHꢄCH2), 118.6 (CH2CHꢄCH2), 97.8, 96.7 (2 C, C-1A, 1B), 70.9, 70.6, 70.4,
70.2, 69.5, 68.9, 67.1, 67.0, 66.7, 61.0 (11 C, C-2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6A,
6B, CH2CHꢄCH2 ).
Anal. Calcd for C57H50O17: C, 67.99; H, 5.00. Found: C, 68.11; H, 5.02.
Allyl 2-O-Acetyl-3,4,6-tri-O-benzoyl-ꢀ-D-mannopyranosy-(1→6)-2,3,4-
tri-O-benzoyl-ꢀ-D-mannopyranosyl-(1→6)-2,3,4-tri-O-benzoyl-ꢀ-D-
mannopyranoside (18). A solution of 17 (0.25 g, 0.25 mmol) and trimethylsilyl
trifluoromethanesulfonate (8 ꢉL, 0.04 mmol) in dry dichloromethane (20 mL) was
stirred with dried molecular sieves (4 A, 1 g) under nitrogen for 15 min, and 13
(0.24 g, 0.35 mmol) in dry dichloromethane (10 mL) was added dropwise for 30
min. After 3 h the reaction mixture was diluted with dichloromethane (20 mL) and

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HENG, NING, AND KONG
washed with satd sodium hydrogen carbonate solution (8 mL). The organic layer
was dried with Na2SO4 and concentrated in vacuo. Purification of the residue by
column chromatography (2:1 petroleum ether-EtOAc) gave 18 as a syrup (0.32 g,
85.7%); [ꢀ]D ꢇ 28.7° (c 1.0, CHCI3); 1H NMR (400 MHz, CDCI3): ꢅ 8.10–7.25
(m, 45 H, 9 PhH), 6.21–5.88 (m, 7 H, H-3A, 3B, 3C, 4A, 4B, 4C, CH2CHꢄCH2), 5.84
(dd, 1 H, J1,2 ꢄ 1.6 Hz, J2,3 ꢄ 3.2 Hz, H-2A), 5.79 (dd, 1 H, J1,2 ꢄ 1.6 Hz,
J
2,3 ꢄ 3.2 Hz, H-2B), 5.44 (dd, 1 H, 2J ꢄ 1.6 Hz, 3Jtrans ꢄ 17.2 Hz, CH2CHꢄCH2
), 5.37 (dd, 1 H, J1,2 ꢄ 1.6 Hz, J2,3 ꢄ 3.2 Hz, H-2C), 5.26 (dd, 1 H, 2J ꢄ 1.6 Hz,
3Jcis ꢄ 10.4 Hz, CH2CHꢄCH2), 5.20 (d, 1 H, J1,2 ꢄ 1.6 Hz, H-1A), 5.16 (d, 1 H,
J
1,2 ꢄ 1.6 Hz, H-1B), 4.73 (d, 1 H, J1,2 ꢄ 1.6 Hz, H-1C), 4.43–4.37 (m, 11 H, H-5A,
5B, 5C, 6A, 6B, 6C, 6Aꢈ, 6Bꢈ, 6Cꢈ, CH2CHꢄCH2 ), 2.07 (s, 3 H, COCH3); 13C NMR
(100 MHz, CDCl3), 169.5 (COCH3), 166.0, 165.7, 165.5, 165.3, 165.2 (9 C, 9
COPh), 133.4–128.3 (Ph, CH2CHꢄCH2), 118.8 (CH2CHꢄCH2), 98.0, 97.2, 96.9
(3 C, C-1A, 1B, 1C), 20.7 (COCH3).
Anal. Calcd for C86H74O26: C, 67.80; H, 4.90. Found: C, 68.04; H, 4.96.
Allyl 3,4,6-Tri-O-benzoyl-ꢀ-D-mannopyranosyl-(1→6)-2,3,4-tri-O-ben-
zoyl-ꢀ-D-mannopyranosyl-(1→6)-2,3,4-tri-O-benzoyl-ꢀ-D-mannopyranoside
(19). A solution of 18 (0.37 g, 0.24 mmol) in methanol solution (25 mL) con-
taining 0.5 % HCl was stirred at room temperature for 14 h, at the end of which
time TLC (2:1 petroleum ether-EtOAc) indicated that the starting material had dis-
appeared. The mixture was carefully neutralized with triethylamine, and then con-
centrated to dryness. The residue was partitioned between water and CH2Cl2, then
the organic layer dried over Na2SO4, and concentrated to a syrup. Purification of
the residue by flash chromatography (2:1 petroleum ether-EtOAc) gave 19 as a
syrup (0.34 g, 93.5%); [ꢀ]D ꢇ 23.0° (c 1.5, CHCI3); 1H NMR (400 MHz, CDCI3):ꢅ
8.09–7.26 (m, 45 H, 9 PhH), 6.19–5.70 (m, 10 H, H-2A, 2B, 2C, 3A, 3B, 3C, 4A, 4B,
4C, CH2CHꢄCH2), 5.48 (dd, 1 H, 2J ꢄ 1.6 Hz, 3Jtrans ꢄ 17.2 Hz, CH2CHꢄCH2 ),
5.29 (dd, 1 H, 2J ꢄ 1.6 Hz, 3Jcis ꢄ 10.4 Hz, CH2CHꢄCH2), 5.20 (d, 1 H, J1,2 ꢄ 1.6
Hz, H-1A), 5.17 (d, 1 H, J1,2 ꢄ 1.6 Hz, H-1B), 4.75 (d, 1 H, J1,2 1.6 Hz, H-1C),
4.43–4.37 (m, 11 H, H-5A, 5B, 5C, 6A, 6B, 6C, 6Aꢈ, 6Bꢈ, 6Cꢈ, CH2CHꢄCH2 ); 13
C
NMR (100 MHz, CDCl3), 166.1, 165.8, 165.7, 165.6, 165.5, 165.4, 165.3, 165.2,
165.1 (9 C, 9 COPh), 133.6–27.7 (Ph, CH2CHꢄCH2), 118.5 (CH2CHꢄCH2),
97.7, 96.8, 96.4 (3 C, C-1A, 1B, 1C).
Anal. Calcd for C84H72O25: C, 68.10; H, 4.90. Found: C, 67.99; H, 4.94.
Allyl 2,3,4,6-Tetra-O-benzoyl-ꢀ-D-mannopyranosyl-(1→2)-3,4,6-tri-O-
benzoyl-ꢀ-D-mannopyranosyl-(1→6)-2,3,4-tri-O-benzoyl-ꢀ-D-mannopyra-
nosyl-(1→6)-2,3,4-tri-O-benzoyl-ꢀ-D-mannopyranoside (20). A solution of
19 (0.21 g, 0.14 mmol) and trimethylsilyl trifluoromethanesulfonate (8 ꢉL, 0.04
mmol) in dry dichloromethane (20 mL) was stirred with dried molecular sieves (4
A, 1 g) under nitrogen for 15 min, and then 7 (0.52 g, 0.70 mmol) in dry
dichloromethane (10 mL) was added dropwise for 30 min. After 3 h the reaction
mixture was diluted with dichloromethane (20 mL) and washed with satd sodium
hydrogen carbonate solution (8 mL). The organic layer was dried over Na2SO4 and

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295
concentrated in vacuo. Purification of the residue by column chromatography (2:1
petroleum ether-EtOAc) gave 20 as a syrup (0.23 g, 80.4%); [ꢀ]D ꢇ 14.7° (c 1.0,
CHCI3); 1H NMR (400 MHz, CDCI3): ꢅ 8.04–7.18 (m, 65 H, 13 PhH), 6.21–5.80
(m, 13 H, H-2A, 2B, 2C, 2D, 3A, 3B, 3C, 3D, 4A, 4B, 4C, 4D, CH2CHꢄCH2), 5.45 (dd,
1 H, 2J ꢄ 1.6 Hz, 3Jtrans ꢄ 17.2 Hz, CH2CHꢄCH2 ), 5.28 (dd, 1 H, 2J ꢄ 1.6 Hz,
3Jcis ꢄ 10.4 Hz, CH2CHꢄCH2), 5.24 (d, 1 H, J1,2 ꢄ 1.6 Hz, H-1A), 5.22 (d, 1 H,
J
1,2 ꢄ 1.6 Hz, H-1B), 5.05 (d, 1 H, J1,2 ꢄ 1.6 Hz, H-1C), 4.87 (d, 1 H, J1,2 ꢄ 1.6 Hz,
H-1D), 4.43–4.37 (m, 14 H, H-5A, 5B, 5C, 5D, 6A, 6B, 6C, 6D, 6Aꢈ, 6Bꢈ, 6Cꢈ, 6Dꢈ,
CH2CHꢄCH2 ); 13C NMR (100 MHz, CDCl3), 166.2, 165.9, 165.7, 165.6, 165.5,
165.4, 165.2, 165.0, 164.8 (13 C, 13 COPh), 133.4–128.3 (Ph, CH2CHꢄCH2),
118.4 (CH2CHꢄCH2), 99.7, 98.1, 98.0, 97,6 (4 C, C-1A, 1B, 1C, 1D).
Anal. Calcd for C118H98O34: C, 68.80; H, 4.79. Found: C, 68.97; H, 4.74.
ꢀ-D-Mannopyranosyl-(1→2)-ꢀ-D-mannopyranosyl-(1→6)-ꢀ-D-
mannopyranosyl-(1→6)-D-mannopyranose (1). A mixture of compound 20
(0.1 g, 0.048 mmol) and PdCl2 (0.02 mg) in dry methanol (10 mL) was stirred vig-
orously for 4 h at room temperature, TLC (1:1 petroleum ether-EtOAc) indicated
that the reaction was complete, then filtered through Celite. The filtrate was con-
centrated to dryness. The resulting compound was dissolved in methanol (20 mL)
satd with dry NH3 and stirred at room temperature for 72 h, at the end of which time
TLC (1:1.5 Methanol-EtOAc) indicated that the reaction was complete. The solu-
tion was concentrated to dryness and was chromatographed (methanol) on a col-
umn of Sephadex LH-20 to afford 1 (0.023 g, 70.2%) as an amorphous mass; [ꢀ]D
ꢇ 3.1° (c 0.1, MeOH); 1H NMR (400 MHz, D2O): ꢅ 5.09, 5.01, 4.91, 4.89 (4 d, 4
H, J1,2 ꢄ 1.5 Hz, H-1A, 1B, 1C, 1D); 13C NMR (100 MHz, D2O), ꢅ 100.3, 100.1,
99.8, 98.6 (4 C, C-1A, 1B, 1C, 1D). ESMS Calcd for C24H42O21: 666.58 (M). Found:
665.4 (M-H).
ACKNOWLEDGMENTS
This work was supported by the Chinese Academy of Sciences (KJ952J1510
and KIP-RCEES9904) and the National Natural Science Foundation of China
(59973026 and 29905004). Mr. Linsen Heng is a visiting scholar from Da Xian
Normal College, Si Chuan, P. R. China.
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Received September 20, 2000
Accepted March 22, 2001

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