A highly efficient total synthetic route to α-series gangliosides: GM1α, GD1α, and GT1α

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A HIGHLY EFFICIENT TOTAL SYNTHETIC ROUTE TO α-
SERIES GANGLIOSIDES: GM1α, GD1α, AND GT1α
Hiromi Ito a , Hideharu Ishida b & Makoto Kiso c
a Department of Bio-Organic Chemistry, Padualaan 8, PO Box 80.075, 3508 TB Utrecht ,
Utrecht University, Bijvoet , c/o Prof. Johannis P. Kammerling, the Netherlands
b Department of Applied Bioorganic Chemistry , Gifu University , Gifu, 501-1193, Japan
c Department of Applied Bioorganic Chemistry , Gifu University , Gifu, 501-1193, Japan
Published online: 16 Aug 2006.
To cite this article: Hiromi Ito , Hideharu Ishida & Makoto Kiso (2001) A HIGHLY EFFICIENT TOTAL SYNTHETIC ROUTE TO
α-SERIES GANGLIOSIDES: GM1α, GD1α, AND GT1α , Journal of Carbohydrate Chemistry, 20:2, 207-225, DOI: 10.1081/
CAR-100103959
To link to this article: http://dx.doi.org/10.1081/CAR-100103959
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J. CARBOHYDRATE CHEMISTRY, 20(2), 207–225 (2001)
A HIGHLY EFFICIENT TOTAL SYNTHETIC
ROUTE TO ꢀ-SERIES GANGLIOSIDES:
GM1ꢀ, GD1ꢀ, AND GT1ꢀ1,2
Hiromi Ito,* Hideharu Ishida,† and Makoto Kiso†
Department of Applied Bioorganic Chemistry, Gifu University
Gifu 501-1193, Japan
Dedicated to Professor Joachim Thieru on the occassion of his 60th birthday.
ABSTRACT
A highly efficient total synthetic route to ꢀ-series gangliosides GM1ꢀ, GD1
ꢀ and GT1ꢀ is described. The suitably protected gangliotriose (GgOse3)
derivatives, i.e., 2-(trimethylsilyl)ethyl (2-acetamido-2-deoxy-3-O-p-
methoxybenzyl-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-benzyl-ꢁ-D-galac-
topyranosyl)-(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside (8) and the
corresponding III3-levulinoyl derivative (9), were regioselectively glycosy-
lated with the phenyl 2-thioglycoside of N-acetylneuraminic acid (Neu5Ac)
promoted by N-iodosuccinimide (NIS)-trimethylsilyl trifluoromethanesul-
fonate (TMSOTf) or trifluoromethanesulfonic acid (TfOH) in acetonitrile, to
give the desired ꢀ-Neu5Ac-(2→6)-gangliotriose (III6Neu5AcGgOse3) deriva-
tives as the major products (11 and 12). The p-methoxybenzyl (MPM) group
in 11 or the levulinoyl group in 12 was selectively removed, and the resulting
2-(trimethylsilyl)ethyl (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-
dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-(2→6)-(2-ac-
etamido-2-deoxy-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-benzyl-ꢁ-D-
*Current address: c/o Prof. Johannis P. Kammerling, Utrecht University, Bijvoet, Department of Bio-
Organic Chemistry, Padualaan 8, PO Box 80.075, 3508 TB Utrecht, the Netherlands.
† Corresponding authors.
207
Copyright © 2001 by Marcel Dekker, Inc.
www.dekker.com

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ITO, ISHIDA, AND KISO
galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside (13), a key
glycosyl acceptor, was systematically glycosylated with the galactose donor
(14), ꢀ-Neu5Ac-(2→3)-galactose donor (15) and ꢀ-Neu5Ac-(2→8)-ꢀ-
Neu5Ac-(2→3)-galactose donor (20) to give the protected GM1ꢀ (16, 70%),
GD1ꢀ (17, 80%) and GT1ꢀ (21, 87%) oligosaccharides, respectively, which
can be converted to the target gangliosides by the introduction of ceramide and
then complete deprotection.
INTRODUCTION
Gangliosides are a group of sialylated glycosphingolipids widely present in
mammalian tissues and are involved in various biological phenomena such as cell-
cell recognition, cell growth, differentiation, transformation, and neural functions.
A new family (ꢀ-series) of gangliosides, which have in common one sialic
acid residue ꢀ(2→6)-linked to the N-acetylgalactosamine (GalNAc) moiety of the
gangliotetraose core structure, have been characterized as cholinergic neuron-spe-
cific gangliosides.3–11 Among them, GQ1bꢀ12 has been found13–16 to be an ex-
tremely high affinity ligand of myelin-associated glycoprotein (MAG), which is a
transmembrane cell surface glycoprotein of myelin-forming oligodendrocytes and
a member of sialic acid-binding immunoglobulin superfamily lectins (siglecs), pre-
viously termed sialoadhesins or I-type lectins.17–20 The binding activities of
GT1aꢀ21,22 and GD1ꢀ23 to MAG were also much higher than those of parent
GD1ꢀ and GM1b, suggesting a special importance of the Neu5Ac residue
ꢀ(2→6)-linked to GalNAc for siglec-binding. Very recently, a brain-specific
GD1ꢀ synthase (ST6GalNAc V) has been cloned.24 We describe herein a highly
efficient total synthetic route to three ꢀ-series gangliosides GM1ꢀ, GD1ꢀ and
GT1ꢀ by use of a facile, regio- and ꢀ-stereoselective method for the sialyl glyco-
side synthesis.25–29
RESULTS AND DISCUSSION
In our previous synthesis of ganglioside GM1ꢀ30 and GD1ꢀ,31 the gan-
gliotetraose (GgOse4) and ꢀ-Neu5Ac-(2→3)-gangliotetraose (IV3Neu5Ac
GgOse4; GM1b oligosaccharide) core structures were first constructed, and then
the regio- and ꢀ-stereoselective sialylation on O-6 of the N-acetylgalactosamine
(GalNAc) residue was conducted, raising a critical problem in the separation of the
resulting diastereoisomers. For the systematic synthesis of the ꢀ-series ganglio-
sides GM1ꢀ, GD1ꢀ and GT1ꢀ, we have now selected the suitably protected ꢀ-
Neu5Ac-(2→6)-gangliotriose (III6Neu5Ac GgOse3) derivative 13 as a common
key glycosyl acceptor.
Coupling of 3, which was prepared by regioselective p-methoxybenzylation
of phenyl 2-deoxy-2-phthalimido-1-thio-ꢁ-D-galactopyranoside (1) and the fol-
lowing 4,6-di-O-acetylation, with 2-(trimethylsilyl)ethyl (2,3,6-tri-O-benzyl-ꢁ-D-
galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside32,33 (4) was

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209
carried out in the presence of NIS and TfOH in dichloromethane at ꢂ30°C to give
5 in 90% yield (Scheme 1). The N-phthaloyl and O-acetyl groups in 5 were simul-
taneously cleaved by treatment with hydrazine monohydrate in ethanol, and the
resulting free amino group was selectively acetylated to afford one trisaccharide
acceptor 8 in high yield. 3-O-Levinoylation of 630 and cleavage of the 4,6-O-ben-
zylidene group gave another trisaccharide acceptor 9.
Iodonium-ion promoted,34,35 regio- and ꢀ-stereocontrolled glycosylation of 8
and 9 with a Neu5Ac donor 1036 was performed25–29 at ꢂ30°C in a solution of ace-
tonitrile to give the desired tetrasaccharides 11 (65%) and 12 (75%) containing the
sialyl ꢀ(2→6)GalNAc structure (Scheme 2). The total sialylation yields were 80%
Scheme 1. MPM ꢃ p-methoxybenzyl, NPhth ꢃ phthalimido, NIS ꢃ N-iodosuccinimide, TfOH ꢃ
trifluoromethanesulfonic acid, SE ꢃ 2-(timethylsilyl)ethyl, Lev ꢃ levulinyl.

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ITO, ISHIDA, AND KISO
and 100% including the ꢁ isomer 15% and 25%, respectively. Selective removal
of the MPM or Lev group afforded the key glycosyl acceptor 13, which was
systematically glycosylated with methyl 2,4,6-tri-O-benzoyl-3-O-benzyl-1-thio-
ꢁ-D-galactopyranoside37 (14), methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-
dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-(2→3)-2,4,
6-tri-O-benzoyl-1-thio-ꢁ-D-galactopyranoside38 (15) and methyl 5-acetamido-8-
O-(5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-ꢀ
D-galacto-
2-nonulopyranosylono-1ꢄ,9-lactone)-4,7-di-O-acetyl-3,5-dideoxy-D-glycero-ꢀ
-D-galacto-2-nonulopyranosylonate]-(2→3)-2,4,6-tri-O-benzoyl-D-glucopyra-
nosyl trichloroacetimidate (20).
Regio- and stereoselective glycosylations at O-3 of the GalNAc residue in 13
were carried out (Scheme 3) by employing 14 and 15 as the glycosyl donors and
DMTST25,39,40 as the glycosyl promoter in dichloromethane to yield the desired
1630 (70%) and 1731 (80%), respectively, which had been transformed into gan-
gliosides GM1ꢀ30 and GD1ꢀ.31 On the other hand, the glycosylation of 13 with 20

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ꢀ-SERIES GANGLIOSIDES
211
was performed at 0°C in the presence of TMSOTf and MS4A (AW-300) in
dichloromethane to give the heptasaccharide derivative 21 (87%) as a precursor of
ganglioside GT1ꢀ (Scheme 4).
Hydrogenolytic removal of the benzyl groups in 17 over Pd(OH)2 in 10 : 1
ethanol-acetic acid, followed by complete acetylation of the resulting free hydrox-
yls with Ac2O-pyridine, afforded the fully acylated oligosaccharide 22 in 85%
yield. Selective removal of the 2-(trimethylsilyl)ethyl (SE) group32,41 was
achieved by treatment of 22 with trifluoroacetic acid in dichloromethane to give

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ITO, ISHIDA, AND KISO
the 1-hydroxy compound 23 (93%), which upon further treatment42 with
trichloroacetonitrile in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)
in dichloromethane, gave the trichloroacetimidate 24 in high yield.
Coupling of 24 with (2S,3R,4E)-2-azido-3-O-(tert-butyldiphenylsilyl)-4-oc-
tadecene-1,3-diol22 (25) was carried out in the presence of TMSOTf and MS-4Å
(AW300) in dichloromethane to give 26 in 64% yield. Selective reduction of the
azido group in 26 with triphenylphosphine in 5 : 1 benzene-water gave the amine,
which on condensation with stearic acid using 1-(3-dimethylaminopropyl)-3-
ethylcarbodiimide hydrochloride (WSC) in dichloromethane, afforded the fully
protected ganglioside GD1ꢀ (27) in 53% yield. Finally, removal of the tert-
butyldiphenylsilyl group in 27 with 1.0 M tetrabutylammonium fluoride in ace-
tonitrile, O-deacetylation with sodium methoxide in methanol, and subsequent
saponification of the methyl ester group gave ganglioside GD1ꢀ (28) as an amor-
phous mass in a quantitative yield, after chromatography on a column of

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213
Sephadex LH-20 with 5 : 5 : 1 chloroform-methanol-water (Scheme 5). The
physicochemical properties and spectral data were identical with those reported31
previously.
In conclusion, a highly efficient total synthetic route to ꢀ-series ganglio-
sides GM1ꢀ, GD1ꢀ and GT1ꢀ was developed by using the key glycosyl accep-
tor 13 and the suitably protected glycosyl donors 14, 15 and 20. Ganglioside
GD1ꢀ has been found to be a high affinity ligand of myelin-associated glyco-
protein (MAG).23,43

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ITO, ISHIDA, AND KISO
EXPERIMENTAL
General Procedures. Optical rotations were determined with a Union PM-
201 polarimeter at 25°C, and IR spectra were recorded with a Jasco IRA-100 spec-
trophotometer. 1H NMR spectra were recorded on Varian Unity Inova (400 MHz)
spectrometer with TMS as the internal standard. All reactions were monitored by
TLC (Merck silica gel aluminium plate 60F-254) and preparative chromatography
was performed on silica gel (Fuji Silysia Co. 300 mesh) with the solvent systems
specified. Concentrations were conducted in vacuo.
Phenyl 2-Deoxy-2-phthalimido-1-thio-ꢁ-D-galactopyranoside (1). To a
solution of 1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-D-galactopyranose (6.1
g, 12.7 mmol) in CH2Cl2 (50 mL) were added thiophenol (1.44 mL, 13.9 mmol)
and BF3•OEt2 (3.94 mL, 31.8 mmol) and the mixture was stirred for 24 h at room
temperature. The solution was extracted with chloroform, and the extract was suc-
cessively washed with M Na2CO3 and water, dried (Na2SO4) and concentrated.
Column chromatography (1 : 3 ethyl acetate-hexane) of the residue on silica gel
gave phenyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-1-thio-ꢁ-D-galactopyra-
noside (6.5 g, 97%) as an amorphous mass. To a solution of phenyl 3,4,6-tri-O-
acetyl-2-deoxy-2-phthalimido-1-thio-ꢁ-D-galactopyranoside (6.5 g, 12.3 mmol) in
methanol (50 mL) was added a catalytic amount of sodium methoxide, and the
mixture was stirred for 5 h at room temperature, then neutralized with Amberlite
IR-120 (Hꢅ) resin. The resin was filtered off and washed with methanol, and the
combined filtrate and washings were concentrated. Column chromatography (15:1
chloroform -methanol) of the residue on silica gel gave 1 (4.8 g, 98%) as an amor-
phous mass; [ꢀ]D ꢅ33.6° (c 0.2, CHCl3); 1H NMR (CDCl3) ꢆ 3.72 (m, 1H, H-5),
3.94 (m, 2H, H-6 and H-6ꢄ), 4.17 (d, 1H, J3,4 ꢃ 3.0 Hz, H-4), 4.40 (dd, 1H, J2,3
ꢃ 10.3 Hz, J3,4 ꢃ 3.0 Hz, H-3), 4.47 (t, 1H, J1,2 ꢃ J2,3 ꢃ 10.3 Hz, H-2), 5.61 (d,
1H, J1,2 ꢃ 10.3 Hz, H-1), and 7.22–7.85 (m, 9H, 2Ph).
Anal. Calcd for C20H19NO6S (401.4): C, 59.84; H, 4.77; N, 3.49. Found: C,
59.72; H, 4.51; N, 3.40.
Phenyl 2-Deoxy-3-O-p-methoxybenzyl-2-phthalimido-1-thio-ꢁ-D-galac-
topyranoside (2). To a solution of 1 (4.0 g, 10 mmol) in MeOH (50 mL) was
added dibutyltin oxide (5.0 g, 20 mmol), and the mixture was boiled under reflux
for 5 h, and concentrated to dryness. The residue was treated with 4-methoxy-
benzyl chloride (3.37 mL, 25 mmol) and tetrabutylammonium bromide (1.6 g,
5.0 mmol) in benzene (40 mL) under reflux for 1 h. The mixture was concen-
trated and the residual syrup was washed with hexane to remove the excess
reagents. Column chromatography (1 : 1 ethyl acetate-hexane) of the residue on
1
silica gel gave amorphous 2 (3.12 g, 58%) : [ꢀ]D ꢅ131.2° (c 0.5, CHCl3); H
NMR (CDCl3) ꢆ 3.62 (s, 3H, MeO), 3.68 (m, 1H, H-5), 3.82 (dd, 1H, Jgem ꢃ 11.7
Hz, J5,6 ꢃ 4.4 Hz, H-6), 4.00 (dd, 1H, Jgem ꢃ 11.7 Hz, J5,6 ꢃ 6.6 Hz, H-6ꢄ), 4.13
(d, 1H, J3,4 ꢃ 3.3 Hz, H-4), 4.23 (dd, 1H, J2,3 ꢃ 10.6 Hz, J3,4 ꢃ 3.3 Hz, H-3),
4.49 (dd, 1H, J1,2 ꢃ J2,3 ꢃ 10.6 Hz, H-2), 5.50 (d, 1H, J1,2 ꢃ 10.6 Hz, H-1), and
6.40–7.85 (m, 13H, 3Ph).

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215
Anal. Calcd for C28H27NO7S (521.6): C, 64.48; H, 5.22; N, 2.69. Found: C,
64.38; H, 5.21; N, 2.58.
Phenyl 4,6-Di-O-acetyl-2-deoxy-3-O-p-methoxybenzyl-2-phthalimido-1-
thio-ꢁ-D-galactopyranoside (3). To a stirred solution of 2 (3.12 g, 5.98 mmol)
in pyridine (10 mL) was added acetic anhydride (1.5 mL) at 0°C. The mixture
was stirred for 8 h at room temperature, and methanol (5 mL) was added. The so-
lution was concentrated to a syrup which was extracted with chloroform. The ex-
tract was successively washed with 2 M HCl, water, M Na2CO3 and water, dried
(Na2SO4) and concentrated. Column chromatography (2:3 ethyl acetate-hexane)
of the residue on silica gel gave 3 (3.60 g, 99%) as an amorphous mass: [ꢀ]D
ꢅ111.7° (c 0.5, CHCl3); 1H NMR (CDCl3) ꢆ 2.04 and 2.16 (2s, 6H, 2AcO), 3.63
(s, 3H, MeO), 3.98 (m, 1H, H-5), 4.19 (m, 2H, H-6, H-6ꢄ), 4.27 (dd, 1H, J2,3
ꢃ
10.6 Hz, J3,4 ꢃ 3.3 Hz, H-3), 4.44 (dd, 1H, J1,2 ꢃ J2,3 ꢃ 10.6 Hz, H-2), 5.51 (d,
1H, J1,2 ꢃ 10.6 Hz, H-1), 5.55 (d, 1H, J3,4 ꢃ 3.3 Hz, H-4), and 6.36–7.83 (m,
13H, 3Ph).
Anal. Calcd for C32H31NO9S (605.7): C, 63.46; H, 5.16; N, 2.31. Found: C,
63.38; H, 4.87; N, 2.17.
2-(Trimethylsilyl)ethyl (4,6-Di-O-acetyl-2-deoxy-3-O-p-methoxybenzyl-
2-phthalimido-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-benzyl-ꢁ-D-galac-
topyranosyl)-(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside (5). To
a
solution of 2-(trimethylsilyl)ethyl (2,3,6-tri-O-benzyl-ꢁ-D-galactopyranosyl)-
(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside (4; 4.45 g, 4.66 mmol) and 3 (3.39
g, 5.60 mmol) in dichloromethane (30 mL) were added molecular sieves 4Å (5 g)
and the mixture was stirred for 3 h at room temperature, then cooled to ꢂ30°C. To
the stirred mixture were added NIS (1.84 g, 8.40 mmol) and TfOH (34 ꢇL, 0.39
mmol), and the stirring was continued for 30 min at ꢂ30°C. The precipitates were
filtered off and washed with chloroform. The filtrate and washings were combined,
and the solution was successively washed with M Na2CO3 and M Na2S2O3, dried
(Na2SO4) and concentrated. Column chromatography (1:3 ethyl acetate-hexane) of
the residue on silica gel gave 5 (6.20 g, 90%) as an amorphous mass: [ꢀ]D ꢅ25.8°
(c 0.5, CHCl3); 1H NMR (CDCl3) ꢆ 1.00 (m, 2H, Me3SiCH2CH2), 2.03, 2.19 (2s,
6H, 2AcO), 3.29 (dd, 1H, J1,2 ꢃ 8.1 Hz, J2,3 ꢃ 9.2 Hz, H-2a), 3.52 (t, 1H, J2,3
ꢃ J3,4 ꢃ 9.2 Hz, H-3a), 3.60 (s, 3H, MeO), 3.62 (m, 1H, H-4b), 3.74 (t, 1H, J3,4 ꢃ
J
4,5 ꢃ 9.2 Hz, H-4a), 4.18 (d, 1H, J1,2 ꢃ 7.6 Hz, H-1b), 4.35 (d, 1H, J1,2 ꢃ 7.8 Hz,
H-1a), 5.18 (d, 1H, J1,2 ꢃ 8.4 Hz, H-1c), 5.60 (d, 1H, J3,4 ꢃ 3.7 Hz, H-4c), and
6.40–7.84 (m, 34H, 7Ph).
Anal. Calcd for C85H95NO20Si (1478.8): C, 69.04; H, 6.48; N, 0.95. Found:
C, 68.75; H, 6.35; N, 0.76.
2-(Trimethylsilyl)ethyl (2-Acetamido-4,6-O-benzylidene-2-deoxy-3-O-
levulinyl-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-benzyl-ꢁ-D-galactopyra-
nosyl)-(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside (7). To a solution of
2-(trimethylsilyl)ethyl (2-acetamido-4,6-O-benzylidene-2-deoxy-ꢁ-D-galactopy-

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ITO, ISHIDA, AND KISO
ranosyl)-(1→4)-(2,3,6-tri-O-benzyl-ꢁ-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-
benzyl-ꢁ-D-glucopyranoside (6; 540 mg, 0.42 mmol) in pyridine (10 mL) was
added levulinic anhydride (181 mg, 0.84 mmol). The mixture was stirred for 2 h at
room temperature, and methanol (5 mL) was added. The solution was concentrated
then extracted with chloroform. The extracted was successively washed with 2M
HCl, water, M Na2CO3 and water, dried (Na2SO4) and concentrated. Column chro-
matography (1:3 ethyl acetate-hexane) of the residue on silica gel gave 7 (476 mg,
82%) as an amorphous mass: [ꢀ]D ꢅ34.3° (c 2.1, CHCl3); 1H NMR (CDCl3) ꢆ 1.00
(m, 2H, Me3SiCH2CH2), 1.80 (s, 3H, AcN), 2.18 (1s, 3H, CH3COCH2CH2),
2.43–2.76 (m, 4H, CH3COCH2CH2), 5.59 (s, 1H, PhCH), and 7.22–7.58 (m, 35H,
7Ph).
Anal. Calcd for C79H93NO18Si (1372.7): C, 69.12; H, 6.83; N, 1.02. Found:
C, 68.84; H, 6.64; N, 1.00.
2-(Trimethylsilyl)ethyl (2-Acetamido-2-deoxy-3-O-p-methoxybenzyl-ꢁ-
D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-benzyl-ꢁ-D-galactopyranosyl)-
(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside (8). A solution of 5 (6.05 g,
4.09 mmol) in ethanol (100 mL) and hydrazine monohydrate (4.36 mL) was heated
for 30 h under reflux. After cooling, insoluble materials were filtered off and
washed with ethanol. The filtrate and washings were combined and concentrated
to dryness. The residue was treated with acetic anhydride (7.6 mL) and methanol
(100 mL) for 8 h at room temperature, and the solution was concentrated. Column
chromatography (40:1 dichloromethane-methanol) of the residue on silica gel gave
1
8 (4.85 g, 85%) as an amorphous mass; [ꢀ]D ꢅ56.1° (c 1.2, CHCl3); H NMR
(CDCl3) ꢆ 1.00 (m, 2H, Me3SiCH2CH2), 1.60 (s, 3H, AcN), 3.26 (dd, 1H, J2,3
ꢃ 9.5 Hz, J3,4 ꢃ 2.6 Hz, H-3b), 3.37 (dd, 1H, J1,2 ꢃ 7.3 Hz, J2,3 ꢃ 8.5 Hz, H-2a),
3.47 (dd, 1H, J1,2 ꢃ 8.4 Hz, J2,3 ꢃ 9.5 Hz, H-2b), 3.52 (t, 1H, J2,3 ꢃ J3,4 ꢃ8.5 Hz,
H-3a), 3.80 (s, 3H, MeO), 3.92 (m, 1H, H-4b), 4.32 (d, 1H, J1,2 ꢃ 8.5 Hz, H-1b),
4.35 (d, 1H, J1,2 ꢃ 7.3 Hz, H-1a), 5.28 (d, 1H, J1,2 ꢃ 7.7 Hz, H-1c), and 6.83–7.42
(m, 34H, 7Ph).
Anal. Calcd for C75H91NO17Si (1306.6): C, 68.94; H, 7.02; N, 1.07. Found:
C, 68.86; H, 6.79; N, 0.96.
2-(Trimethylsilyl)ethyl (2-Acetamido-2-deoxy-3-O-levulinyl-ꢁ-D-galac-
topyranosyl)-(1→4)-(2,3,6-tri-O-benzyl-ꢁ-D-galactopyranosyl)-(1→ 4)-2,3,6-
tri-O-benzyl-ꢁ-D-glucopyranoside (9). A solution of 7 (417 mg, 0.30 mmol) in
aqueous 80% acetic acid (5 mL) was heated, with stirring, for 24 h at 50°C, then
concentrated. Column chromatography (2:1 ethyl acetate-hexane) of the residue on
silica gel gave 9 (390 mg, quantitative) as an amorphous mass: [ꢀ]D ꢅ15.4° (c 3.1,
CHCl3); 1H NMR (CDCl3) ꢆ 1.03 (m, 2H, Me3SiCH2CH2), 1.60 (s, 3H, AcN), 2.14
(1s, 3H, CH3COCH2CH2), 2.43–2.76 (m, 4H, CH3COCH2CH2), 5.57 (d, 1H, J1,2
ꢃ 7.7 Hz, H-1c), and 7.22–7.42 (m, 30H, 6Ph).
Anal. Calcd for C72H89NO18Si (1286.4): C, 67.32; H, 6.98; N, 1.09. Found:
C, 67.17; H, 6.78; N, 0.95.

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217
2-(Trimethylsilyl)ethyl (Methyl 5-Acetamido-4,7,8,9-tetra-O-acetyl-3,5-
dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-(2→6)-(2-ac-
etamido-2-deoxy-3-O-p-methoxybenzyl-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-
tri-O-benzyl-ꢁ-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyra
noside (11). To a solution of 8 (500 mg, 0.38 mmol) and methyl (phenyl 5-ac-
etamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero-D-galacto-2-nonu-
lopyranosid)onate (10; 458 mg, 0.76 mmol) in acetonitrile (7 mL) were added
molecular sieves 3Å (3 g), and the mixture was stirred for 6 h at room temperature,
then cooled to ꢂ30°C. To the stirred mixture were added NIS(353 mg, 1.52 mmol)
and TMSOTf (15 ꢇL, 0.076 mmol), and the stirring was continued for 40 h at
ꢂ30°C. The precipitates were filtered off and washed with chloroform. The filtrate
and washings were combined, and the solution was successively washed with M
Na2CO3 and M Na2S2O3, dried (Na2SO4) and concentrated. Column chromatogra-
phy (50:1 chloroform-methanol) of the residue on silica gel gave 11 (445 mg, 65%)
1
accompanied by the ꢁ-isomer (103 mg, 15%) as an amorphous mass: H NMR
(CDCl3) ꢆ 1.00 (m, 2H, Me3SiCH2CH2), 1.63, 1.86, 1.93, 2.01, 2.05, and 2.10 (6s,
18H, 2AcN and 4AcO), 2.59 (dd, 1H, Jgem ꢃ 12.8 Hz, J3eq,4 ꢃ 4.8 Hz, H-3eq of
Neu5Ac), 3.77 and 3.80 (2s, 6H, 2MeO), and 6.83–7.40 (m, 34H, 7Ph).
Anal. Calcd for C95H118N2O29Si (1780.1): C, 64.10; H, 6.68; N, 1.57. Found:
C, 63.98; H, 6.51; N, 1.53.
2-(Trimethylsilyl)ethyl (Methyl 5-Acetamido-4,7,8,9-tetra-O-acetyl-3,
5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-(2→6)-(2-ac-
etamido-2-deoxy-3-O-levulinyl-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-
benzyl-ꢁ-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside
(12). Glycosylation of 9 (1.58 g, 1.22 mmol) with 10 (1.44 g, 2.44 mmol) in ace-
tonitrile (13 mL) in the presence of NIS (1.11 g, 4.88 mmol), TfOH (22 ꢇg, 0.24
mmol), and MS 3Å (1.7 g) for 36 h at ꢂ30°C, then work up as described for 11,
gave 12 (1.62 mg, 75%) accompanied by the ꢁ-isomer (0.51 mg, 25%) as an amor-
1
phous mass: [ꢀ]D ꢅ20.3° (c 2.4, CHCl3); H NMR (CDCl3) ꢆ 1.02 (m, 2H,
Me3SiCH2CH2), 1.87–2.14 (7s, 21H, 2AcN, 4AcO, and CH3COCH2CH2), 2.53
(dd, 1H, Jgem ꢃ 13.0 Hz, J3eq,4 ꢃ 5.2 Hz, H-3deq), 3.76 (s, 3H, MeO), 5.39 (m, 1H,
H-4d), and 7.32–7.65 (m, 30H, 6Ph).
Anal. Calcd for C92H116N2O30Si (1758.0): C, 62.86; H, 6.65; N, 1.59. Found:
C, 62.63; H, 6.60; N, 1.44.
2-(Trimethylsilyl)ethyl (Methyl 5-Acetamido-4,7,8,9-tetra-O-acetyl-3,5-
dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-(2→6)-(2-ac-
etamido-2-deoxy-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-benzyl-ꢁ-D-
galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside (13). To a
solution of 11 (400 mg, 0.225 mmol) in 9 : 1 ethyl acetate - H2O (4 mL) was added
ammonium cerium(IV) nitrate (250 mg, 0.45 mmol), and the mixture was stirred
for 3 h at room temperature. Ethyl acetate was added and mixture was successively
washed with water, M Na2CO3 and water, dried (Na2SO4) and concentrated. Col-

ORDER
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218
ITO, ISHIDA, AND KISO
umn chromatography (40:1 chloroform-methanol) of the residue on silica gel af-
forded 13 (360 mg, 95%) as an amorphous mass: [ꢀ]D ꢅ8.9° (c 2.0, CHCl3); 1H
NMR (CDCl3) ꢆ 1.01 (m, 2H, Me3SiCH2CH2), 1.51, 1.86, 1.96, 2.03, 2.12, and
2.13 (6s, 18H, 2AcN and 4AcO), 2.60 (dd, 1H, Jgem ꢃ 12.6 Hz, J3,4 ꢃ 4.7 Hz, H-
3eq of Neu5Ac), 3.77 (s, 3H, MeO), and 7.23–7.42 (m, 30H, 6Ph).
Anal. Calcd for C87H110N2O28Si (1659.9): C, 62.95; H, 6.68; N, 1.69. Found:
C, 62.81; H, 6.53; N, 1.65.
2-(Trimethylsilyl)ethyl (2,4,6-Tri-O-benzoyl-3-O-benzyl-ꢁ-D-galactopy-
ranosyl)-(1→3)-[(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy
-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-(2→6)]-(2-acetamido-2-de-
oxy-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-benzyl-ꢁ-D-galactopyranosyl)-
(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside (16). To a solution of 13 (300
mg, 0.18 mmol) and methyl 2,4,6-tri-O-benzoyl-3-O-benzyl-1-thio-ꢁ-D-galac-
topyranoside (14; 133 mg, 0.21 mmol) in CH2Cl2 (10 mL) were added molecular
sieves 4Å (1.2 g) and the mixture was stirred for 5 h at room temperature and
cooled to ꢂ10°C. DMTST (196 mg, 0.43 mmol) was added, and the stirring was
continued for 24 h. After reaction was over, the precipitates were filtered off and
washed with chloroform. The filtrate and washings were combined, and the solu-
tion was successively washed with M Na2CO3 and water, dried (Na2SO4) and con-
centrated. Column chromatography (50:1 chloroform-methanol) of the residue on
silica gel gave 16 (273 mg, 68%) as an amorphous mass: [ꢀ]D ꢅ26.8° (c 1.4,
CHCl3); 1H NMR (CDCl3): ꢆ 1.02 (m, 2H, Me3SiCH2CH2), 1.80–2.20 (6s, 18H,
4AcO and 2AcN), 2.50 (m, 1H, H-3e-eq), 3.74 (s, 3H, MeO), 4.80 (m, 1H, H-4e),
5.30 (m, 1H, H-8e), 5.34 (d, 1H, J7,8 ꢃ 10.1 Hz, H-7e), 5.50 (dd, 1H, J1,2 ꢃ 9.9 Hz,
J
2,3 ꢃ 8.8 Hz, H-2d), 5.91 (d, 1H, J3,4 ꢃ 3.3 Hz, H-4d), and 7.03–8.31 (m, 50H,
10Ph)
Anal. Calcd for C121H138N2O36Si (2224.5): C, 65.33; H, 6.25; N, 1.26.
Found: C, 65.18; H, 6.02; N, 1.14.
2-(Trimethylsilyl)ethyl (Methyl 5-Acetamido-4,7,8,9-tetra-O-acetyl-3,
5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-(2→ 3)-(2,4,6-tri-
O-benzoyl-ꢁ-D-galactopyranosyl)-(1→3)-[(methyl 5-acetamido-4,7,8,9-tetra-
O-acetyl-3,5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-
(2→6)]-(2-acetamido-2-deoxy-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-benz
yl-ꢁ-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside (17).
To a solution of 13 (1.5 g, 0.90 mmol) and methyl (methyl 5-acetamido-4,7,8,9-
tetra-O-acetyl-3,5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-
(2→3)-2,4,6-tri-O-benzoyl-1-thio-ꢁ-D-galactopyranoside (15; 1.8 g, 1.80 mmol)
in CH2Cl2 (20 mL) were added molecular sieves 4Å (2.2 g) and the mixture was
stirred for 6 h at room temperature and cooled to 0°C. DMTST (1.94 g, 4.50 mmol)
was added, and the stirring was continued for 24 h. After reaction was over, the
precipitates were filtered off and washed with chloroform. The filtrate and wash-
ings were combined, and the solution was successively washed with M Na2CO3 and
water, dried (Na2SO4) and concentrated. Column chromatography (40:1 chloro-

ORDER
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ꢀ-SERIES GANGLIOSIDES
219
form-methanol) of the residue on silica gel gave 17 (2.01 g, 86%) as an amorphous
mass: [ꢀ]D ꢅ17.3° (c 1.7, CHCl3); 1H NMR (CDCl3) ꢆ 1.00 (m, 2H,
Me3SiCH2CH2), 2.42 (dd, 1H, J3,4 ꢃ 4.4 Hz, H-3e-eq), 2.56 (dd, 1H, J3,4 ꢃ 4.4 Hz,
H-3f-eq), 3.69 and 3.79 (2s, 6H, 2MeO), 5.33 (d, 1H, J3,4 ꢃ 3.2 Hz, H-4d), 5.44
(dd, 1H, J1,2 ꢃ J23 ꢃ 7.7 Hz, H-2d), and 7.18–8.17 (m, 45H, 9Ph).
Anal. Calcd for C134H159N3O48Si (2607.8): C, 61.72; H, 6.15; N, 1.61.
Found: C, 61.57; H, 6.02; N, 1.33.
[Methyl
5-Acetamido-8-O-(5-acetamido-4,7,8,9-tetra-O-acetyl-3,
5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylono-1ꢄ,9-lactone)-4,
7-di-O-acetyl-3,5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate]-
(2→3)-2,4,6-tri-O-benzoyl-D-glucopyranosyl Trichloroacetimidate (20). To
a solution of 1844 (380 mg, 0.27 mmol) in dichloromethane (1.9 mL) was added tri-
fluoroacetic acid (1.7 mL) at 0°C, and the mixture was stirred for 2 h at room tem-
perature and concentrated. Column chromatography (25:1 dichloromethane-
methanol) of the residue on silica gel gave 19 (320 mg, 91%) as an amorphous
mass. To a solution of 19 (320 mg, 0.24 mmol) in dichloromethane (5.5 mL) and
trichloroacetonitrile (1 mL, 7.20 mmol) was added 1,8-diazabicyclo[5.4.0]undec-
7-ene (DBU, 50 ꢇL, 0.30 mmol) at 0°C, and the mixture was stirred for 2 h at 0°C,
then concentrated. Column chromatography (20:1 dichloromethane-methanol) of
the residue on silica gel gave 20 (320 mg, 90%) as an amorphous mass: [ꢀ]D
ꢅ23.6° (c 1.1, CHCl3); 1HNMR (CDCl3): ꢆ 1.88–2.12 (8s, 24H, 2AcN and 6AcO),
2.59 (dd, 1H, J3ax,3eq ꢃ 13.5, J3eq,4 ꢃ 6.6 Hz, H-3beq), 3.36 (s, 3 H, MeO), 5.00 (d,
1H, J7,8 ꢃ 10.0 Hz, H-7b), 5.37 (d, 1H, J7,8 ꢃ 10.0 Hz, H-7c), 5.57 (m, 1H, H-4c),
5.69 (dd, 1H, J1,2 ꢃ 3.4, J2,3 ꢃ 7.0 Hz, H-2a), 5.94 (d, 1H, J3,4 ꢃ 3.1 Hz, H-4a),
6.84 (d, 1H, J1,2 ꢃ 3.4 Hz, H-1a), 7.30–8.11 (m, 15H, 3Ph) and 8.63 (s, 1H,
CꢃNH).
Anal. Calcd for C64H70Cl3N3O30 (1467.6): C, 52.38; H, 4.81; N, 2.86. Found:
C, 52.15; H, 4.54; N, 2.82.
2-(Trimethylsilyl)ethyl [Methyl 5-Acetamido-8-O-(5-acetamido-4,7,8,
9-tetra-O-acetyl-3,5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylono-1ꢄ,
9-lactone)-4,7-di-O-acetyl-3,5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyra-
nosylonate]-(2→3)-(2,4,6-tri-O-benzoyl-ꢁ-D-galactopyranosyl)-(1→3)-
[(methyl
5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-ꢀ
-D-galacto-2-nonulopyranosylonate)-(2→6)]-(2-acetamido-2-deoxy-ꢁ-D-
galactopyranosyl)-(1→4)-(2,3,6-tri-O-benzyl-ꢁ-D-galactopyranosyl)-(1→4)-
2,3,6-tri-O-benzyl-ꢁ-D-glucopyranoside (21). To a solution of 13 (321 mg,
0.19 mmol) and 20 (380 mg, 0.26 mmol) in dichloromethane (7 mL) were added
molecular sieves 4Å (AW-300; 5.6 g), and the mixture was stirred for 12 h at room
temperature, then cooled to 0°C. TMSOTf (13 ꢇL, 0.066 mmol) was added, and
the mixture was stirred for 24 h at 0°C, then filtered. The insoluble materials were
washed with chloroform, and the combined filtrate and washings were washed
with M NaHCO3 and water, dried (Na2SO4) and concentrated. Column chromatog-
raphy (40:1 chloroform-methanol) of the residue on silica gel gave 21 (500 mg,

ORDER
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220
ITO, ISHIDA, AND KISO
1
87%) as an amorphous mass:[ꢀ]D ꢅ10.8° (c 1.8, CHCl3); H NMR (CDCl3): ꢆ
1.00 (m, 2H, Me3SiCH2CH2), 1.82–2.18 (14s, 42H, 10AcO and 4AcN), 2.37–2.60
(m, 3H, H-3e-eq, H-3f-eq, and H-3g-eq), 3.47 and 3.80 (2s, 6H, 2MeO), and
7.21–8.13 (m, 45H, 9Ph).
Anal. Calcd for C149H178N4O57Si (2965.1): C, 60.36; H, 6.05; N, 1.89.
Found: C, 60.24; H, 5.84; N, 1.88.
2-(Trimethylsilyl)ethyl (Methyl 5-Acetamido-4,7,8,9-tetra-O-acetyl-3,
5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-(2→3)-(2,4,
6-tri-O-benzoyl-ꢁ-D-galactopyranosyl)-(1→3)-[(methyl 5-acetamido-4,7,8,
9-tetra-O-acetyl-3,5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-
(2→6)]-(2-acetamido-4-O-acetyl-2-deoxy-ꢁ-D-galactopyranosyl)
-(1→4)-(2,3,6-tri-O-acetyl-ꢁ-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-acetyl-ꢁ-
D-glucopyranoside (22). Compound 17 (1.2 g, 0.46 mmol) in ethanol (30 mL)
and acetic acid (3 mL) was hydrogenolyzed in the presence of 20% Pd(OH)2 (1.2
g) for 96 h at 40°C, and the reaction mixture was filtered. The filtrate was concen-
trated to a residue which was acetylated with acetic anhydride (5 mL) and pyridine
(10 mL) for 20 h at 40°C. The mixture was concentrated, and a solution of the
residue in chloroform was successively washed with 2 M HCl and M Na2CO3, dried
(Na2SO4) and concentrated. Column chromatography (30:1 chloroform-methanol)
of the residue on silica gel gave 22 (935 mg, 85%) as an amorphous mass: [ꢀ]D
1
ꢅ6.0° (c 0.4, CHCl3); H NMR (CDCl3) ꢆ 1.00 (m, 2H, Me3SiCH2CH2),
1.53–2.18 (18s, 54H, 15AcO and 3AcN), 2.39 (dd, 1H, H-3e-eq), 2.53 (dd, 1H, H-
3f-eq), 2.74 (m, 1H, H-2c), 3.74 and 3.79 (2s, 6H, 2MeO), 5.44 (dd, 1H, J1.2 ꢃ J2.3
ꢃ 7.7 Hz, H-2d), 5.46 (d, 1H, J3,4 ꢃ 3.3 Hz, H-4c), 5.80 (d, 1H, NH-c), and
7.40–8.19 (m, 15H, 3Ph).
Anal. Calcd for C106H137N3O55Si (2361.31): C, 53.92; H, 5.85; N, 1.78.
Found: C, 53.85; H, 5.68; N, 1.60.
(Methyl 5-Acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-ꢀ
-D-galacto-2-nonulopyranosylonate)-(2→3)-(2,4,6-tri-O-benzoyl-ꢁ-D-
galactopyranosyl)-(1→3)-[(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,
5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-(2→6)]-(2-ac-
etamido-4-O-acetyl-2-deoxy-ꢁ-D-galactopyranosyl)-(1→4)-O-(2,3,6-tri-O-
acetyl-ꢁ-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-acetyl-D-glucopyranosyl
Trichloroacetimidate (24). To a solution of 22 (935 mg, 0.396 mmol) in
dichloromethane (7 mL) was added trifluoroacetic acid (3 mL) at 0°C, and the mix-
ture was stirred for 3 h at room temperature and concentrated. Column chro-
matography (20:1 chloroform-methanol) of the residue on silica gel gave 23 (838
mg, 93%) as an amorphous mass: IR (KBr) 3600-3100 (OH, NH), 1740 and 1220
(ester), 1670 and 1550 (amide), and 720 (Ph).
To a solution of 23 (300 mg, 0.12 mmol) in dichloromethane (2 mL) and
trichloroacetonitrile (590 ꢇL, 0.36 mmol) was added 1,8-diazabicyclo[5.4.0]un-
dec-7-ene (DBU; 22 ꢇL, 0.15 mmol) at 0°C, and the mixture was stirred for 1 h at
0°C, then concentrated. Column chromatography (20:1 chloroform-methanol) of

ORDER
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ꢀ-SERIES GANGLIOSIDES
221
the residue on silica gel gave 24 (317 mg, quantitative) as an amorphous mass: [ꢀ]D
1
ꢅ22.9° (c 0.3 CHCl3); H NMR (CDCl3) ꢆ 1.52–2.19 (18s, 54H, 15AcO and
3AcN), 2.40 (dd, 1H, H-3e-eq), 2.51 (dd, 1H, H-3f-eq), 2.98 (m, 1H, H-2c), 3.77
and 3.80 (2s, 6H, 2MeO), 5.44 (d, 1H, J3,4 ꢃ 3.3 Hz, H-4c), 6.11 (d, 1H, NH-c),
6.51 (d, 1H, J1,2 ꢃ 3.6 Hz, H-1a), 7.41–8.23 (m, 15H, 3Ph), and 8.73 (s, 1H,
CꢃNH).
Anal. Calcd for C103H125Cl3N4O55 (2405.47): C, 51.43; H, 5.24; N, 2.33.
Found: C, 51.25; H, 5.14; N, 2.06.
(Methyl 5-Acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-ꢀ-
D-galacto-2-nonulopyranosylonate)-(2→3)-(2,4,6-tri-O-benzoyl-ꢁ
-D-galactopyranosyl)-(1→3)-[(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,
5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-(2→6)]
-(2-acetamido-4-O-acetyl-2-deoxy-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-
acetyl-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-acetyl-ꢁ-D-glucopyranosyl)-
(1→1)-(2S,3R,4E)-2-azido-3-O-(tert-butyldiphenylsilyl)-4-octadecene-1,3-diol
(26). To a solution of 24 (90 mg, 0.037 mmol) and (2S,3R,4E)-2-azido-3-O-(tert-
butyldiphenylsilyl)-4-octadecene-1,3-diol1 (25, 94 mg, 0.068 mmol) in dichlo-
romethane (1.1 mL) were added molecular sieves 4Å (AW-300; 1.0 g), and the mix-
ture was stirred for 12 h at room temperature, then cooled to 0°C. TMSOTf (2 ꢇL,
0.010 mmol) was added, and the mixture was stirred for 36 h at 0°C, then filtered.
The insoluble materials were washed with chloroform, and the combined filtrate and
washings was washed with M NaHCO3 and water, dried (Na2SO4) and concentrated.
Column chromatography (25:1 chloroform-methanol) of the residue on silica gel
gave 26 (66 mg, 64%) as an amorphous mass: [ꢀ]D ꢅ0.47° (c 0.4 CHCl3); IR (KBr)
3300 (NH), 3100-2900 (CH), 2100 (azide), 1740 and 1220 (ester), 1670 and 1550
(amide), 710 and 700 cmꢂ1 (phenyl); 1H NMR (CDCl3) ꢆ 0.88 (t, 3H, JMe,CH2 ꢃ 6.6
Hz, MeCH2), 1.04 (s, 9H, Me3C), 1.26 (s, 22H, 11CH2), 1.53–2.03 (18s, 54H, 3AcN
and 15AcO), 2.44 (dd, 1H, Jgem ꢃ 12.8 Hz, J3eq,4 ꢃ 4.8 Hz, H-3eeq), 2.50 (dd, 1H,
J
gem ꢃ 12.8 Hz, J3eq,4 ꢃ 4.6 Hz, H-3feq), 2.95 (m, 1H, H-2c), 3.75 and 3.81 (2s, 6H,
2MeO), 6.19 (d, 1H, NH-c), and 7.24–8.16 (m, 25H, 5Ph).
Anal. Calcd for C135H176N6O56Si (2806.97): C, 57.75; H, 6.32; N, 2.99.
Found: C,57.58; H, 6.19; N, 2.75.
(Methyl 5-Acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-ꢀ
-D-galacto-2-nonulopyranosylonate)-(2→3)-(2,4,6-tri-O-benzoyl-ꢁ-D-
galactopyranosyl)-(1→3)-[(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,
5-dideoxy-D-glycero-ꢀ-D-galacto-2-nonulopyranosylonate)-(2→6)]-(2-ac-
etamido-4-O-acetyl-2-deoxy-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,
6-tri-O-acetyl-ꢁ-D-galactopyranosyl)-(1→4)-(2,3,6-tri-O-acetyl-ꢁ-D-glucopy-
ranosyl)-(1→1)-(2S,3R,4E)-3-O-(tert-butyldiphenylsilyl)-2-octadecanamido-
4-octadecene-1,3-diol (27). To a solution of 26 (200 mg, 0.071 mmol) in
benzene (6.5 mL) and water (0.26 mL) was added triphenylphosphine (34 mg, 0.13
mmol), and the mixture was stirred for 48 h at 30°C and concentrated. To a solu-
tion of the residue in dichloromethane (5 mL) were added octadecanoic acid (57

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ITO, ISHIDA, AND KISO
mg, 0.20 mmol) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochlo-
ride (38 mg, 0.20 mmol), and the mixture was stirred for 20 h at 30°C. The mixture
was diluted with chloroform and the solution was washed with water, dried
(Na2SO4) and concentrated. Column chromatography (25:1 chloroform-methanol)
of the residue on silica gel gave 27 (113 mg, 52%) as an amorphous mass: [ꢀ]D
ꢅ3.0° (c 1.3 CHCl3); 1H NMR (CDCl3) ꢆ 0.84 (t, 3H, Jvic ꢃ 6.6 Hz, MeCH2), 0.97
(s, 9H, Me3C), 1.22 (s, 50H, 25CH2), 1.74–2.10 (18s, 54H, 15AcO and 3AcN),
2.41 (dd, 1H, Jgem ꢃ 12.3 Hz, J3eq,4 ꢃ 4.1 Hz, H-3e-eq), 2.48 (dd, 1H, Jgem ꢃ 12.8
Hz, J3eq,4 ꢃ 3.5 Hz, H-3f-eq), 2.90 (m, 1H, H-2c), 3.72 and 3.78 (2s, 6H, 2MeO),
6.36 (d, 1H, NH-c), and 7.24–8.16 (m, 25H, 5Ph).
Anal. Calcd for C153H212N4O57Si (3047.44): C, 60.30; H, 7.01; N, 1.84.
Found: C,60.11; H, 6.83; N, 1.65.
Ganglioside GD1ꢀ (28). To a solution of 27 (113 mg, 0.037 mmol) in ace-
tonitrile (3 mL) was added 1.0 M tetrabutylammonium fluoride in tetrahydrofuran
(1 mL), and the mixture was stirred for 48 h at room temperature, then concen-
trated. To a solution of the residue in methanol (2 mL) was added a catalytic
amount of sodium methoxide, and the mixture was stirred for 48 h at room tem-
perature. Water (0.5 mL) was added and the solution was stirred for 24 h at room
temperature, then neutralized with Amberlite IR-120 (Hꢅ) resin. The resin was fil-
tered off and washed with 1:1 chloroform-methanol, and the combined filtrate and
washings were concentrated. Column chromatography (5:5:1 chloroform-
methanol-water) of the residue on Sephadex LH-20 gave 28 (63 mg, 92%) as an
1
amorphous mass: [ꢀ]D ꢅ3.4° (c 0.3, 5:5:1 CHCl3-MeOH-H2O); H NMR
((CD3)2SO-D2O) ꢆ 0.84 (t, 6H, 2MeCH2), 1.23 (s, 50H, 25CH2), 1.82, 1.87, 1.88
(3s, 9H, 3AcN), 1.93 (q, 2H, CHꢃCH2CH2), 2.01 (t, 2H, COCH2), 2.64 (dd, 1H,
J
3eq,4 ꢃ 4.4 Hz, H-3f-eq), 2.51 (dd, 1H, J3eq,4 ꢃ 4.4 Hz, H-3e-eq), 3.03 (t, 1H, H-
2a), 3.84 (br d, 1H, H-4b), 4.15 (d, 1H, J1,2 ꢃ 8.0 Hz, H-1a), 4.20 (d, 1H, J1,2 ꢃ 8.1
Hz, H-1b), 4.23 (d, 1H, J1,2 ꢃ 7.3 Hz, H-1d), 4.50 (d, 1H, J1,2 ꢃ 8.8 Hz, H-1c), 5.32
(m, 1H, H-4 of ceramide), and 5.51 (m, 1H, H-5 of ceramide);
Anal. Calcd for C84H148N4O39 (1838.10): C, 54.89; H, 8.12; N, 3.05. Found:
C, 54.63; H, 7.96; N, 3.01.
ACKNOWLEDGMENT
This work was supported in part by Grants-in-Aid (No. 12306007 and No.
12045228) for Scientific Research from the Ministry of Education, Science and
Culture of Japan, and Japan Society for Promotion of Science.
REFERENCES
1. Dedicated to Professor Joachim Thiem on the occasion of his 60th birthday.
2. Synthetic Studies on Sialoglycoconjugates, Part 118. For Part 117, see Otsubo, N.;
Ishida, H.; Kiso, M. Carbohydr. Res. 2001, 330(1), 1–5.

ORDER
REPRINTS
ꢀ-SERIES GANGLIOSIDES
223
3. Richardson, P. J.; Walker, J. H.; Jones, R. T.; Whittaker, V. P. Identification of a
cholinergic-specific antigen Chol-1 as a ganglioside. J. Neurochem. 1982, 38(6),
1605–1614.
4. Hirabayashi, Y.; Hyogo, A.; Nakao, T.; Tsuchida, K.; Suzuki, Y.; Matsumoto, M.;
Kon, K.; Ando, S. Isolation and characterization of extremely minor gangliosides,
GM1b and GD1ꢀ, in adult bovine brains as developmentally regulated antigens. J.
Biol. Chem. 1990, 265, 8144–8151.
5. Ando, S.; Hirabayashi, Y.; Kon, K.; Inagaki, F.; Tate, S.; Whittaker, V. P. A trisialo-
ganglioside containing a sialyl-ꢀ(2-6)-N-acetylgalactosamine residue is a choliner-
gic-specific antigen, Chol-1ꢀ. J. Biochem. 1992, 111, 287–290.
6. Hirabayashi, Y.; Nakao, T.; Irie, F.; Whittaker, V. P.; Kon, K.; Ando, S. Structural
characterization of a novel cholinergic neuron-specific ganglioside in bovine brain. J.
Biol. Chem. 1992, 267, 12973–12978.
7. Derrington, E. A.; Whittaker, V. P. The cholinergic marker Chol-1 is selectively lo-
calized in nerve terminals. NeuroReport 1993, 4, 317–319.
8. Borroni, E.; Derrington, E. A.; Whittaker, V. P. Distribution of the cholinergic-spe-
cific antigen Chol-1 in mouse spinal cord neurons developing in culture. Dev. Brain
Res. 1993, 71, 247–252.
9. Irie, F.; Hidari, K.; Tai, T.; Li, Y.-T.; Sayama, Y.; Hirabayashi, Y. Biosynthetic path-
way for a new series of gangliosides, GT1aꢀ and GQ1bꢀ. FEBS Lett. 1994, 351,
291–294.
10. Irie, F.; Hashikawa, T.; Tai, T.; Sayama, Y.; Hirabayashi, Y. Distribution of cholin-
ergic neuron-specific gangliosides (GT1aꢀ and GQ1bꢀ) in the rat central nervous
system. Brain Res. 1994, 665, 161–166.
11. Irie, F.; Kurono, S.; Li, Y.-T.; Seyama, Y.; Hirabayashi, Y. Isolation of three novel
cholinergic neuron-specific gangliosides from bovine brain and their in vitro synthe-
ses. Glycoconjugate J. 1996, 13, 177–186.
12. Hotta, K.; Ishida, H.; Kiso, M.; Hasegawa, A. First total synthesis of a cholinergic
neuron-specific ganglioside GQ1bꢀ. J. Carbohydr. Chem. 1995, 14, 491–506.
13. J.-S. Yang, L.; B. Zeller, C.; L. Shaper, N.; Kiso, M.; Hasegawa, A.; Shapiro, R. E.;
Schnaar, R. L. Gangliosides are neuronal ligands for myelin-associated glycoprotein.
Proc. Natl. Acad. Sci. USA 1996, 93, 814–818.
14. Collins, B. E.; Yang, L. J.-S.; Mukhopadhyay, G.; Filbin, M. T.; Kiso, M.; Hasegawa,
A.; Schnaar, R. L. Sialic acid specificity of myelin-associated glycoprotein binding.
J. Biol. Chem. 1997, 272, 1248–1255.
15. Collins, B. E.; Kiso, M.; Hasegawa, A.; Tropak, M. B.; Roder, J. C.; Crocker, P. R.;
Schnaar, R. L. Binding specificites of the sialoadhesin family of I-type lectins. J. Biol.
Chem. 1997, 272, 16889–16895.
16. Schnaar, R. L.; Collins, B.; Wright, L. P.; Kiso, M.; Tropak, M. B.; Roder, J. C.;
Crocker, P. R. Myelin-associated glycoprotein binding to gangliosides: Structural
specificity and functional implications. In Sphingolipids as Signaling Modulators in
the Nervous System; Ledeen, R. W.; Hakomori, S.; Yates, A. J.; Schneider, J. S.; Yu,
R. K. Eds.; the New York Academy of Sciences.; New York, 1998; Vol. 845, 92–105.
17. Kelm, S.; Pelz, A.; Schauer, R.; Filbin, M. T.; Tong, S.; Bellard, d. M.-E.; Schnaar,
R. L.; Mahoney, J. A.; Hartnell, A.; Bradfield, P.; Crocker, P. R. Sialoadhesin,
myelin-associated glycoprotein and CD22 define a new family of sialic acid-depen-
dent adhesion molecules of the immunoglobulin superfamily. Curr. Biol. 1994, 4,
965–972.
18. Powell, L. D.; Varki, A. I-type lectins. J. Biol. Chem. 1995, 270, 14243–14246.

ORDER
REPRINTS
224
ITO, ISHIDA, AND KISO
19. Crocker, P. R.; Clark, E. A.; Filbin, M.; Gordon, S.; Jones, Y.; Kehrl, J. H.; Kelm, S.;
Douarin, L. N.; Powell, L.; Roder, J.; Schnaar, R. L.; Sgroi, D. C.; Stamenkovic, I.;
Schauer, R.; Schachner, M.; van den Berg, T. K.; van der Merwe, P. A.; Watt, S. M.;
Varki, A. Siglecs. A family of sialic-acid binding lectins. Glycobiology 1998, 8(2), v.
20. Angata, T.; Varki, A. Cloning, characterization, and phylogenetic analysis of siglec-
9, a new member of the CD33-related group of siglecs. Evidence for co-evolution
with sialic acid synthesis pathways. J. Biol. Chem. 2000, 275(29), 22127–22135.
21. Ito, H.; Ishida, H.; Kiso, M.; Hasegawa, A. First total synthesis of ganglioside GT1aꢀ.
Carbohydr. Res. 1997, 304, 187–190; Erratum: ibid. 1998, 306, 579–585.
22. Ito, H.; Ishida, H.; Waki, H.; Ando, S.; Kiso, M. Total synthesis of a cholinergic neu-
ron-specific ganglioside GT1aꢀ, a high affinity ligand for myelin-associated glyco-
protein (MAG). Glycoconjugate J. 1999, 16, 585–598.
23. Sawada, N.; Ishida, H.; Collins, B. E.; Schnaar, R. L.; Kiso, M. Ganglioside GD1ꢀ
analogues as high-affinity ligands for myelin-associated glycoprotein (MAG). Car-
bohydr. Res. 1999, 316, 1–5.
24. Okajima, T.; Fukumoto, S.; Ito, H.; Kiso, M.; Hirabayashi, Y.; Urano, T.; Furukawa,
K.; Furukawa, K. Molecular cloning of brain-specific GD1ꢀ synthase (ST6GalNAc
V) containing CAG/glutamine repeats. J. Biol. Chem. 1999, 274, 30557–30562.
25. Murase, T.; Ishida, H.; Kiso, M.; Hasegawa, A. A facile regio- and stereo-selective
synthesis of ꢀ-glycosides of N-acetylneuraminic acid. Carbohydr. Res. 1988, 184,
c1–c4.
26. Hasegawa, A.; Nagahama, T.; Ohki, H.; Kiso, M. A facile total synthesis of ganglio-
side GM2. J. Carbohydr. Chem. 1992, 11, 699–714.
27. Hasegawa A.; Kiso, M. Carbohydrates-synthetic Methods and Applications in
Medicinal Chemistry; Ogura, H.; Hasegawa, A.; Suami, T. Eds.; Kodansha/VCH:
Tokyo/Basel, 1992; 243–266.
28. Hasegawa, A.; Kiso, M. Synthesis of sialyl Lewis X ganglioside and analogs. In
Methods in Enzymology; Abelson, J. N.; Simon, M. I. Eds.; Academic Press.; San
Diego, 1994; Vol. 242, 158–172.
29. Hasegawa, A.; Kiso, M. Chemical synthesis of sialyl glycosides. In Preparative Car-
bohydrate Chemistry; Hanessian, S. Ed.; Marcel Dekker, Inc.; New York, 1997; Vol.
357–379.
30. Hotta, K.; Komba, S.; Ishida, H.; Kiso, M.; Hasegawa, A. Synthesis of ꢀ-series gan-
glioside GM1ꢀ. J. Carbohydr. Chem. 1994, 13, 665–677.
31. Prabhanjan, H.; Aoyama, K.; Kiso, M.; Hasegawa, A. Synthesis of disialoganglioside
GD1ꢀ and its positional isomer. Carbohydr. Res. 1992, 233, 87–99.
32. Jansson, K.; Ahlfors, S.; Frejd, T.; Kihlberg, J.; Magnusson, G.; Dahmen, J.; Noori,
G.; Stenvall, K. 2-(Trimethylsilyl)ethyl glycosides. Synthesis, anomeric deblocking,
and transformation into 1,2-trans 1-O-acyl sugars. J. Org. Chem. 1988, 53,
5629–5647.
33. Prabhanjan, H.; Kameyama, A.; Ishida, H.; Kiso, M.; Hasegawa, A. Regio- and
stereo-selective synthesis of ganglioside GM1b and some positional analogs. Carbo-
hydr. Res. 1991, 220, 127–143.
34. Veeneman, G. H.; van Leeuwen, S. H.; van Boom, J. H. Iodonium ion promoted re-
actions at the anomeric centre. II. An efficient thioglycoside mediated approach to-
ward the formation of 1,2-trans linked glycosides and glycosidic esters. Tetrahedron
Lett. 1990, 31, 1331–1334.
35. Konradsson, P.; Udodong, U. E.; Fraser-Reid, B. Iodonium promoted reactions of
disarmed thioglycosides. Tetrahedron Lett. 1990, 31, 4313–4316.

ORDER
REPRINTS
ꢀ-SERIES GANGLIOSIDES
225
36. Marra, A.; Sinaÿ, P. A novel stereoselective synthesis of N-acetyl-ꢀ-neuraminosyl-
galactose disaccharide derivatives, using anomeric S-glycosyl xanthates. Carbohydr.
Res. 1990, 195, 303–308.
37. Hasegawa, A.; Ishida, H. K.; Nagahama, T.; Kiso, M. Total synthesis of gangliosides
GM1 and GD1a. J. Carbohydr. Chem. 1993, 12, 703–718.
38. Kameyama, A.; Ishida, H.; Kiso, M.; Hasegawa, A. Stereoselective synthesis of sia-
lyl-lactotetraosylceramide and sialylneolactotetraosylceramide. Carbohydr. Res.
1990, 200, 269–285.
39. Fügedi, P.; Garegg, P. J. A novel promoter for the efficient construction of 1,2-trans
linkages in glycoside synthesis, using thioglycosides as glycosyl donors. Carbohydr.
Res. 1986, 149, c9–c12.
40. Kanie, O.; Kiso, M.; Hasegawa, A. Glycosylation using methylthioglycosides of N-
acetylneuraminic acid and dimethyl (methylthio) sulfonium triflate. J. Carbohydr.
Chem. 1988, 7, 501–506.
41. Magnusson, G. 2-(Trimethylsilyl)ethyl(TMSEt) glycosides; anomeric blocking, de-
blocking and activation in the synthesis of oligosaccharides. TIGG 1992, 4, 358–367.
42. Schmidt, R. R.; Grundler, G. Einfache synthese von ꢁ-D-glucopyranosyluronaten.
Synthesis 1981, 885–887.
43. Collins, B. E.; Ito, H.; Sawada, N.; Ishida, H.; Kiso, M.; Schnaar, R. L. Enhanced
binding of the neural siglecs, myelin-associated glycoprotein and schwann cell
myelin protein, to Chol-1 (ꢀ-series) gangliosides and novel sulfated Chol-1 analogs.
J. Biol. Chem. 1999, 274, 37637–37643.
44. Ishida, H. K.; Ohta, Y.; Tsukada, Y.; Kiso, M.; Hasegawa, A. A synthetic approach
to polysialogangliosides containing ꢀ-sialyl-(2-8)-sialic acid: total synthesis of gan-
glioside GD3. Carbohydr. Res. 1993, 246, 75–88.
Received October 10, 2000
Accepted December 28, 2000

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