A concise and practical synthesis of antigenic globotriose, α-d-Gal-(1→4)-β-d-Gal-(1→4)-β-d-Glc

Article abstract of DOI:10.1016/j.carres.2006.03.029

A concise and practical synthesis of the antigenic globotriose, α-d-Gal-(1→4)-β-d-Gal-(1→4)-β-d-Glc (13), was achieved by coupling of a monosaccharide donor, 3-O-allyl-2-O-benzoyl-4,6-O-benzylidene-α-d-galactopyranosyl trichloroacetimidate (4) with a disa

Full text of DOI:10.1016/j.carres.2006.03.029

Carbohydrate Research 341 (2006) 1174–1180
Note
A concise and practical synthesis of antigenic globotriose,
a-D-Gal-(1!4)-b-D-Gal-(1!4)-b-D-Glc
Langqiu Chen,a,* Xing-E. Zhao,a Duan Lai,a Zhiwei Songa and Fanzuo Kongb
aInstitute of Chemistry, Xiangtan University, Hunan Province 411105, PR China
bResearch Center for Eco-Environmental Sciences, Academia Sinica, PO Box 2871, Beijing 100085, PR China
Received 26 January 2006; received in revised form 19 March 2006; accepted 22 March 2006
Available online 21 April 2006
Abstract—A concise and practical synthesis of the antigenic globotriose, a-D-Gal-(1!4)-b-D-Gal-(1!4)-b-D-Glc (13), was achieved
by coupling of a monosaccharide donor, 3-O-allyl-2-O-benzoyl-4,6-O-benzylidene-a-D-galactopyranosyl trichloroacetimidate (4)
with a disaccharide acceptor, p-methoxyphenyl 2,3,6-tri-O-benzoyl-b-D-galactopyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-glucopyr-
anoside (8), followed by deprotection. In spite of the existence of a C-2-ester substituent capable of neighboring-group participation
in the donor, the coupling gave exclusively the a-linkage in satisfactory yield. The acceptor 8 was readily obtained from selective 3-
O-benzoylation of the galactosyl ring of p-methoxyphenyl 2,6-di-O-benzoyl-b-D-galactopyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-
glucopyranoside (7), which was prepared from p-methoxyphenyl b-D-lactoside (5) via isopropylidenation, benzoylation, and deiso-
propylidenation. Donor 4 was obtained from p-methoxylphenyl 3-O-allyl-2,4,6-tri-O-benzoyl-b-D-galactopyranoside (1) via selec-
tive 4,6-di-O-debenzoylation, oxidative removal of 1-O-MP, benzylidenation, and trichloroacetimidate formation.
ꢀ 2006 Elsevier Ltd. All rights reserved.
Keywords: Globotriose; Oligosaccharide; Neighboring-group participation
Although great effort has been expended in glyco-
chemistry over the last several decades, one focus of
extensive investigation in glycochemistry still remains:
the development of a rational methodology to highly
stereo- and regioselectively synthesize biologically rele-
vant oligosaccharides and their complexes that are being
discovered at a markedly increased rate.1 In principle,
the stereoselectivity of glycoside synthesis relies on many
factors such as the anomeric effect,1a neighboring-group
participation,2 and remote participation.3 Generally, it
is rather difficult to obtain pure 1,2-cis-linked glycosylic
linkages with the donors having the gluco- and galacto
configurations.
rides play important roles in biological processes. For
example, the glycosyl phosphatidylinositol (GPI) anchor
of Trypanosoma brucei is involved in the signal transduc-
tion of insulin, IL-2, and nerve growth factor (NGF).5
Many of the globoseries glycolipids containing the
globotriose fragment, a-D-Gal-(1!4)-b-D-Gal-(1!4)-
b-D-Glc, have been isolated and characterized.6 Globo-
triosides are the major glycosphingolipids present in
the membrane of human erythrocytes from all individu-
als,6c and as antigens these are recognized by antibodies
of the P blood-group system and by various bacterial
proteins.7 For example, globotrioside present in the
membrane of urinary tract epithelial cells acts as a recep-
tor for pathogenic strains of Escherichia coli responsible
for pyelonephritis.6c Furthermore, there are tumor-asso-
ciated antigens on human teratocarcinoma cells and
other tumor cells.8 Similarly, glycosphingolipid antigen
from the breast cancer cell line MCF-7 might be clini-
cally useful in promoting active immunity in the case
of sufficient synthesis.1b These oligosaccharides are also
apparently related to Fabry’s disease, which is due to a
In our ongoing interest in synthetic strategies, some
oligosaccharides containing 1,2-cis a-linked galactopyr-
anosyl linkages have attracted our attention.4 It is been
well known that a-linked galactopyranosyl oligosaccha-
*
Corresponding author. Tel.: +86 732 2370239; e-mail addresses:
chengood2003@263.net; chengood2003@hotmail.com
0008-6215/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2006.03.029

L. Chen et al. / Carbohydrate Research 341 (2006) 1174–1180
1175
deficiency of a-galactosidase activity.9 Globotriosyl cer-
amide is located on the surface of the kidney glomerular
endothelial cell and is known as the host receptor for
verotoxins. The glycosphingolipid is extremely selective,
and its potent affinity is mainly attributable to its globo-
triose component. Artificially created materials, includ-
ing its dendrimers, might be applicable as potential
glycomaterials for medicinal uses.10
phenyl 3-O-allyl-2-O-benzoyl-b-D-galactopyranoside (2)
in acceptable yield (69%). Subsequent removal of C-1-
O-MP by oxidative cleavage of 2 with ammonium
cerium(IV) nitrate (CAN) and benzylidenation yielded 3
(46% for two steps). Subsequent trichloroacetimidation
afforded the donor 4 in satisfactory yield (86%). The
disaccharide acceptor, 2,3,6-tri-O-benzoyl-b-D-galacto-
pyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-glucopyranoside
(8) was also readily prepared. Thus, p-methoxyphenyl
b-D-galactopyranosyl-(1!4)-b-D-glucopyranoside (5)19
was chosen as the starting material. Isopropylidenation
of 5 with dimethoxypropane and benzoylation with
benzoyl chloride in pyridine gave p-methoxyphenyl
2,6-di-O-benzoyl-3,4-O-isopropylidene-b-D-galactopyr-
anosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-galactopyranoside
(6) (67% for two steps). O-Deisopropylidenation of 6
with 80% HOAc–H2O at reflux was carried out smoothly
giving p-methoxyphenyl 2,6-di-O-benzoyl-b-D-galacto-
pyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-glucopyran-
oside (7) in high yield (95%). Subsequent selective
benzoylation of 7 with benzoyl chloride in pyridine
Globotriose, a-D-Gal-(1!4)-b-D-Gal-(1!4)-b-D-Glc,
and its derivatives and analogs have been previously
synthesized.6a,b,11 In the crucial a-D-galactosylation
step, applicable donors are mainly D-galactosyl donors
with an ether-type, non-participating group at the their
C-2 position, such as a perbenzylated galactosyl
halide,10,12 a sulfoxide,11d a tetramethylphosphoroami-
date,6a a dibenzyl phosphite,13 a trichloroacetimidate,1c
a thioglycoside,14 2,4,6-tri-O-benzyl-3-O-p-methoxyphen-
yl-b-D-galactopyranosyl fluoride,15 and 3-O-allyl-2,4,6-
tri-O-benzyl-D-galactopyranosyl chloride.6b However,
it was difficult to get high stereoselectivity for these
methods such as the coupling with galactosyl chloride
as the donor.6b On the other hand, Yang et al.16 found
an unexpected a-stereochemical 1,2-cis outcome for a
galactosyl heptasaccharide with a galactosyl tetrasac-
charide donor with acetyl group in its C-2 position.
Meanwhile, Boons and co-workers17 proposed through-
bond remote neighboring-group participation arising
from the C-4 position of the galactosyl donor, as well
as solvent effects, based on their a-anomeric selective
studies of the coupling of various donors such as ethyl
4-O-acyl-2,3,6-tri-O-benzyl-1-thio-D-galactoside and
acceptors like 1,2:3,4-di-O-isopropylidene-a-D-galacto-
pyranoside. Earlier, we4a found an intriguing strategy
for synthesis of a-linked galactopyranosides by using
the thio donors with a C-2 ester capable of neighbor-
ing-group participation. These results prompted us to
put more effort into researching the issue. As a part of
our ongoing synthetic studies concerning structure–
bioactivity relationships of the immunological specificity
of the globoseries of glycolipids,6b we describe herein a
very facile synthesis of the target compound, globotri-
ose, a-D-Gal-(1!4)-b-D-Gal-(1!4)-b-D-Glc.
1
afforded 8 in 87% yield. The H NMR spectrum of 8
showed the salient H0-4 upfield (d 4.15 ppm) with a
small coupling constant (J4,5 0.3 Hz), indicating selective
3-O-benzoylation. The coupling of donor 4 and acceptor
1
8 gave trisaccharide 9 in 89% yield, and its H and 13C
NMR spectra showed that the new glycosidic bond is
a-linked (d 5.33 ppm with J1,2 3.2 Hz for H-1, and d
100.0 ppm with JC1–H1 170.0 Hz for C-1). Debenzylide-
nation of 9 in 80% HOAc–H2O at 80 ꢁC give 10 (91%),
followed by acetylation of 10 with Ac2O in pyridine,
yielded p-methoxyphenyl 4,6-di-O-acetyl-3-O-allyl-2-
O-benzoyl-a-D-galactopyranosyl-(1!4)-2,3,6-tri-O-ben-
zoyl-b-D-galactopyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-
D-glucopyranoside (11) (93%). Subsequent deallylation
of 11 with PdCl2 in MeOH gave 12 (74%), and finally
deacylation of 12 with saturated ammonia–methanol
furnished the unprotected globotriose glycoside, p-meth-
oxyphenyl a-D-galactopyranosyl-(1!4)-b-D-galactopyr-
1
anosyl-(1!4)-b-D-glucopyranoside (13) (86%). The H
NMR spectrum of 13 was in agreement with the struc-
ture assigned. There are some salient characteristic
signals such as a doublet at d 4.42 ppm with J1,2
7.6 Hz for H-1 of b-Gal residue, a doublet at d
4.84 ppm with J1,2 3.6 Hz for the H-1 of the a-Gal resi-
due, a doublet at d 4.89 ppm with J1,2 7.6 Hz for the H-1
of the b-Glc residue. (See Supplementary data for
details.)
As outlined in Scheme 1, 3-O-allyl-2-O-benzoyl-4,6-O-
benzylidene-a-D-galactopyranosyl trichloroacetimidate
(4) was chosen as the donor since our previous study4a
indicated that either the sole 3-O-allylation or the sole
4,6-O-benzylidenation of benzoylated galactopyranosyl
donors gave a- and b-mixed products, while the galacto-
pyranosyl donors with both 3-O-allyl and 4,6-O-benzyl-
idene groups afforded very high a-stereoselectivity in
spite of the existence of the C-2 ester group. The ratio-
nale for the high a-selectivity in this case is still not clear.
For the synthesis of 4, selective 4- and 6-O-debenzoyl-
ation of 3-O-allyl-2,4,6-tri-O-benzoyl-b-D-galactopyran-
oside 118 with MeONa in MeOH at room temperature
was carried out within a short time, giving p-methoxyl-
In summary, we present herein a facile synthesis
of globotriose, a-D-Gal-(1!4)-b-D-Gal-(1!4)-b-D-Glc,
with a galactosyl donor containing a C-2 ester capable
of neighboring-group participation. Furthermore, the
intermediates 10, 11, and 12 are useful synthons that
can be used to further elongate sugar chains to obtain
higher oligosaccharides with similar structures such as
lipopolysaccharides.

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L. Chen et al. / Carbohydrate Research 341 (2006) 1174–1180
Ph
OBz OBz
O
OH OH
O
Ph
O
O
O
c
a
b
O
O
AllO
OMP
AllO
OMP
OBz
O
AllO
AllO
OBz
1
2
OBz
OBz
4
3
OH
OC(NH)CCl
3
Me
Me
O
OBz
O
OH OH
O
OBz
OH
e
d
O
O
O
O
HO
O
OMP
OBz
OMP
BzO
HO
OBz
OH
OH
6
5
OH OBz
O
OH OBz
O
OBz
OBz
g
f
O
HO
O
O
BzO
O
OMP
4
BzO
OMP
BzO
OBz
OBz
OBz
OBz
7
8
Ph
OH
OH
AllO
O
O
O
O
i
h
AllO
OBz
OBz
O
OBz
O
O
OBz
O
OBz
O
OBz
BzO
O
O
BzO
O
OMP
BzO
OMP
OBz
BzO
10
OBz
OBz
9
OBz
OAc
OAc
OAc
OAc
O
O
HO
AllO
j
OBz
OBz
O
O
OBz
O
OBz
O
OBz
OBz
O
BzO
O
O
BzO
O
OMP
OMP
OBz
BzO
BzO
12
OBz
11
OBz
OBz
k
OH
OH
HO
O
OH
O
OH
O
OH
O
HO
O
OMP
HO
OH
OH
13
Scheme 1. Reagents and conditions: (a) MeONa–MeOH, rt; (b) CAN, CH3CN–H2O, rt; PhCHO, HC(OEt)3, p-TsOH, rt; (c) CCl3CN, K2CO3, rt;
(d) Me2C(OMe)2, p-TsOH, rt; PhCOCl, Pyr. rt; (e) 80% HOAc–H2O, heat; (f) PhCOCl, Pyr. 0 ꢁC; (g) TMSOTf, ꢀ25 ꢁC; (h) 80% HOAc–H2O, heat;
(i) Ac2O, Pyr., rt; (j) PdCl2, MeOH, 40 ꢁC; (k) NH3–MeOH, rt.
1. Experimental
1.1. General methods
spray-ionization (ESI) mode. The progress of all reac-
tions was followed by thin-layer chromatography
(TLC) that was performed on silica gel HF with detec-
tion by charring with 30% (v/v) sulfuric acid in MeOH
or by UV detection. Purification of the crude product
by chromatography was conducted by elution of a
column (8 · 100 mm, 16 · 240 mm, 18 · 300 mm,
35 · 400 mm) of silica gel (100–200 mesh) with EtOAc–
petroleum ether as the eluent. HPLC was performed
with a Gilson instrument consisting of a pump (model
306), stainless steel column packed with silica gel (Spher-
isorb SiO2, 10 · 300 mm or 4.6 · 250 mm), differential
refractometer (132-RI detector) and a UV/vis detector
Melting points were determined with a ‘Mel-Temp’
apparatus. Optical rotations were determined with a
Perkin–Elmer model 241-MC automatic polarimeter
1
for solutions in a 1-dm, jacketed cell. H NMR and
13C NMR spectra were recorded on Bruker AV 400
spectrometer at 400 and 100.6 MHz, respectively. All
chemical shifts are quoted on the d-scale in parts per
million (ppm). Mass spectra were recorded with a VG
PLATFORM mass spectrometer using the electro-

L. Chen et al. / Carbohydrate Research 341 (2006) 1174–1180
1177
(model 118). EtOAc–petroleum ether (bp 60–90 ꢁC)
was used as the eluent at a flow rate of 1–4 mL/min.
Solutions were concentrated at a temperature of 60 ꢁC
under diminished pressure.
CH2@CHCH2O), 4.25 (1H, dd, J5,6 1.2 Hz, H-60), 4.35
(1H, dd, J4,5 1.5 Hz, H-4), 5.14–5.31 (2H, m,
CH2@CHCH2O), 5.50 (1H, d, H-2), 5.57 (1H, s,
PhCH@), 5.69 (1H, d, J1,2 3.5 Hz, H-1), 5.80–5.94
(2H, m, CH2@CHCH2O), 7.33–7.35 (3H, m, Ar–H),
7.41–7.45 (3H, m, Ar–H), 7.54–7.57 (2H, m, Ar–H),
8.06–8.08 (2H, m, Ar–H). Anal. Calcd for C23H24O7:
C, 66.97; H, 5.88; Found: C, 66.72; H, 5.85.
1.2. p-Methoxylphenyl 3-O-allyl-2-O-benzoyl-b-D-galac-
topyranoside (2)
To a solution of 118 (19.3 g, 30.2 mmol) in CH2Cl2
(20 mL)–MeOH (200 mL) was added 4.0 M NaOMe–
MeOH solution dropwise to pH 10. After stirring the
mixture at rt within 0.5 h, TLC (1:1 EtOAc–MeOH)
indicated no remaining starting material and the forma-
tion of a major product. The reaction mixture was neu-
tralized with acidic ion-exchange resin, the resin was
removed by filtration, and the filtrate was concentrated.
Purification of the residue by column chromatography
(1:1 petroleum ether–EtOAc) gave 2 as a foamy solid
(8.97 g, 69%): [a]D +15.6 (c 1.1, CHCl3); 1H NMR
(400 MHz, CDCl3): d 2.99 (2H, br, OH), 3.71 (3H, s,
CH3O), 3.71–3.76 (2H, m, H-3, H-5), 3.93 (1H, dd,
J5,6 4.8 Hz, J6,6 11.9 Hz, H-6), 4.02–4.21 (4H, m, H-4,
H-60, CH2@CHCH2O), 5.01 (1H, d, J1,2 8.2 Hz, H-1),
5.10–5.23 (2H, m, CH2@CHCH2O), 5.68 (1H, dd, J2,3
9.5 Hz, H-2), 5.68–5.81 (2H, m, CH2@CHCH2O),
6.72–6.75 (2H, m, CH3OC6H4–), 6.89–6.91 (2H, m,
CH3OC6H4–), 7.43–7.47 (2H, m, Ar–H), 7.58 (1H, m,
Ar–H), 8.05–8.07 (2H, m, Ar–H). Anal. Calcd for
C23H26O8: C, 64.17; H, 6.10; Found: C, 63.89; H, 6.07.
1.4. 3-O-Allyl-2-O-benzoyl-4,6-O-benzylidene-a-D-galac-
topyranosyl trichloroacetimidate (4)
Compound 3 (1.40 g, 3.39 mmol) was dissolved in
CH2Cl2 (20 mL), and CCl3CN (1.5 mL) and anhyd
K2CO3 (1.4 g) were added. The reaction mixture was
stirred overnight at room temperature, at the end of
which time TLC (2:1 petroleum ether–EtOAc) indicated
that the reaction was complete. The reaction mixture
was then filtered. Concentration of the filtrate, followed
by purification of the crude product on a silica-gel col-
umn with 2.5:1 petroleum ether–EtOAc as the eluant,
gave donor 4 as foamy solid (1.62 g, 86%): [a]D +93.0
1
(c 1.1, CHCl3); H NMR (400 MHz, CDCl3): d 4.00
(1H, m, H-5), 4.12 (1H, dd, J5,6 1.6 Hz, J6,6 12.8 Hz,
H-6), 4.22–4.25 (2H, m, CH2@CHCH2O), 4.28 (1H,
dd, J2,3 10.4 Hz, J3.4 3.2 Hz, H-3), 4.37 (1H, dd, J5,6
1.5 Hz, H-60), 4.49 (1H, dd, J4,5 0.9 Hz, H-4), 5.16–
5.32 (2H, m, CH2@CHCH2O), 5.63 (1H, s, PhCH@),
5.81 (1H, dd, H-2), 5.84–5.94 (2H, m, CH2@CHCH2O),
6.80 (1H, dd, J1,2 3.4 Hz, H-1), 7.37–7.45 (5H, m, Ar–
H), 7.57–7.59 (3H, m, Ar–H), 8.03–8.05 (2H, m, Ar–
H), 8.53 (1H, s, NH). Anal. Calcd for C25H24O7NCl3:
C, 53.92; H, 4.35; Found: C, 54.14; H, 4.37.
1.3. 3-O-Allyl-2-O-benzoyl-4,6-O-benzylidene-a-D-galac-
topyranose (3)
To a solution of 2 (4.42 g, 10.3 mmol) in 8:1 CH3CN–
H2O (90 mL) was added CAN ((NH4)2Ce(NO3)6)
(25.3 g, 46.1 mmol), and the mixture was stirred for
30 min at room temperature, at the end of which time
TLC (EtOAc) indicated that the reaction was complete.
The mixture was extracted with EtOAc and washed with
satd aq NaHCO3. The organic layer was concentrated
under reduced pressure and purified by column chroma-
tography (EtOAc) to afford a syrup that was used
directly for the next step.
1.5. p-Methoxyphenyl 2,6-di-O-benzoyl-3,4-O-isopropyl-
idene-b-D-galactopyranosyl-(1!4)-2,3,6-tri-O-benzoyl-
b-D-glucopyranoside (6)
To a solution of 519 (4.28 g, 9.54 mmol) in dry DMF
(50 mL) were added p-TsOHÆH2O (0.2 g) and 2,2-
dimethoxypropane (3.6 mL, 29.3 mmol). After stirring
the mixture for 4 h at 40 ꢁC, TLC (5:1 EtOAc–MeOH)
indicated that the reaction was complete. The reaction
mixture was neutralized with Et3N (0.5 mL), and the
mixture was concentrated. Purification of the crude
product by column chromatography (5:1 EtOAc–
MeOH) gave a syrup. To the solution of the syrup in
pyridine (15 mL) was added PhCOCl (5.0 mL,
43.1 mmol) dropwise, and the mixture was stirred over-
night at rt. TLC (2:1 petroleum ether–EtOAc) indicated
that the reaction was complete. The mixture was diluted
with CH2Cl2 (100 mL), washed with 1 N HCl, water,
and satd aq NaHCO3. The organic layer was combined,
dried, and concentrated. Purification of the crude prod-
uct by column chromatography (2.5:1 petroleum ether–
EtOAc) gave 6 as a foamy solid (6.45 g, 67%): [a]D +46.9
The syrup was dissolved in DMF (50 mL), and
PhCHO (2.4 mL, 24.0 mmol), (EtO)3CH (3.18 mL,
19.1 mmol), and p-TsOHÆH2O (0.03 g) were added.
The reaction mixture was stirred at room temperature
overnight, after which time TLC showed the reaction
was complete. Et3N (0.3 mL) was added, the reaction
mixture was concentrated, and the residue was purified
by column chromatography (2:1 petroleum–EtOAc) to
give 3 as a foamy solid (1.96 g, 46%): [a]D +105.9 (c
1
1.1, CHCl3); H NMR (400 MHz, CDCl3): d 2.84 (1H,
s, OH), 3.96 (1H, m, H-5), 4.06–4.08 (1H, dd, J2,3
10.8 Hz, J3.4 1.8 Hz, H-3), 4.16–4.19 (1H, dd, J5,6
3.3 Hz, J6,6 10.4 Hz, H-6), 4.19–4.21 (2H, m,

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L. Chen et al. / Carbohydrate Research 341 (2006) 1174–1180
1
(c 1.1, CHCl3); H NMR (400 MHz, CDCl3): d 1.26
(3H, s, (CH3)2C), 1.54 (3H, s, (CH3)2C), 3.69 (3H, s,
CH3O), 3.67–3.72 (1H, m), 3.84 (1H, m, H-5), 3.96
(1H, s, H-50), 4.10 (1H, dd, J3,4 2.0 Hz, J4,5 5.6 Hz, H-
40), 4.21–4.28 (3H, m, H-4, H-30, H-60), 4.48 (1H, dd,
J5,6 5.6 Hz, J6,6 12.0 Hz, H-6), 4.62 (1H, d, J1,2 7.9 Hz,
H-10), 4.64 (1H, dd, J5,6 2.4 Hz, H-6), 5.09 (1H, d, J1,2
7.9 Hz, H-1), 5.17 (1H, dd, J2,3 7.4 Hz, H-20), 5.66
(1H, dd, H-2), 5.78 (1H, dd, J2,3 = J3,4 9.2 Hz, H-3),
6.63 (2H, d, J 8.8 Hz, CH3OC6H4–), 6.85 (2H, d, J
8.8 Hz, CH3OC6H4–), 7.31–7.37 (8H, m, Ar–H), 7.51–
7.61 (7H, m, Ar–H), 7.93–8.10 (10H, m, Ar–H). Anal.
Calcd for C57H52O17: C, 67.84; H, 5.20; Found: C,
68.13; H, 5.23.
s and br, OH), 3.64–3.73 (2H, m), 3.68 (3H, s, CH3O),
3.99 (1H, m, H-5), 4.10 (1H, dd, J5,6 5.9 Hz, J6,6
12.7 Hz, H-60), 4.15 (1H, dd, J3,4 3.2 Hz, J4,5 0.3 Hz,
H-40), 4.45 (1H, dd, J4,5 9.2 Hz, H-4), 4.49 (1H, dd,
J5,6 5.6 Hz, J6,6 11.9 Hz, H-6), 4.61 (1H, dd, J5,6
0.8 Hz, H-6), 4.80 (1H, d, J1,2 7.9 Hz, H-10), 5.12 (1H,
d, J1,2 7.9 Hz, H-1), 5.17 (1H, dd, J2,3 10.3, J3,4
3.2 Hz, H-30), 5.67 (1H, dd, H-2), 5.75 (1H, dd, H-20),
5.82 (1H, dd, J2,3 = J3,4 9.2 Hz, H-3), 6.62 (2H, d, J
8.9 Hz, CH3OC6H4–), 6.86 (2H, d,
J
8.9 Hz,
CH3OC6H4–), 7.25–7.48 (18H, m, Ar–H), 7.91–8.01
(12H, m, Ar–H). Anal. Calcd for C61H52O18: C, 68.27;
H, 4.89; Found: C, 68.57; H, 4.87.
1.8. p-Methoxyphenyl 3-O-allyl-4,6-O-benzylidene-2-O-
benzoyl-a-D-galactopyranosyl-(1!4)-2,3,6-tri-O-benzoyl-
b-D-galactopyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-
glucopyranoside (9)
1.6. p-Methoxyphenyl 2,6-di-O-benzoyl-b-D-galactopyr-
anosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-glucopyranoside (7)
Compound 6 (4.84 g, 4.80 mmol) was dissolved in 80%
HOAc (100 mL), and the mixture was refluxed for 2 h,
at the end of which time TLC (1:1 petroleum ether–
EtOAc) indicated that the reaction was complete. The
mixture was concentrated under reduced pressure, and
the residue was passed through a silica-gel column with
1.5:1 petroleum ether–EtOAc as the eluent to give 7 as
foamy solid (4.41 g, 95%): [a]D +51.3 (c 1.1, CHCl3);
1H NMR (400 MHz, CDCl3): d 3.29 (2H, br, OH),
3.54–3.60 (2H, m), 3.69 (3H, s, CH3O), 3.73–3.76 (1H,
m, H-5), 3.89–3.93 (2H, m), 4.02 (1H, dd, J5,6 8.9 Hz,
J6,6 14.0 Hz, H-60), 4.14 (1H, dd, J4,5 8.8 Hz, H-4),
4.52 (1H, dd, J5,6 5.7 Hz, J6,6 11.9 Hz, H-6), 4.59 (1H,
dd, J5,6 1.9 Hz, H-6), 4.62 (1H, d, J1,2 8.0 Hz, H-10),
5.04 (1H, d, J1,2 7.5 Hz, H-1), 5.41 (1H, dd, J2,3
8.8 Hz, H-20), 5.64 (1H, dd, H-2), 5.69 (1H, dd,
Donor 4 (0.25 g, 0.45 mmol) and acceptor 8 (0.38 g,
0.35 mmol) were dried together under high vacuum for
2 h, then dissolved in anhyd CH2Cl2 (10 mL). TMSOTf
(6.8 lL, 0.035 mmol) was added at ꢀ25 ꢁC with N2 pro-
tection. The reaction mixture was stirred for 2 h, at the
end of which time TLC indicated that the reaction was
complete. The mixture was then neutralized with Et3N
and concentrated under reduced pressure to dryness.
Purification of the crude product by column chromato-
graphy (2.5:1 petroleum ether–EtOAc) gave 9 as a foamy
solid (0.46 g, 89%): [a]D +61.7 (c 1.1, CHCl3); 1H NMR
(400 MHz, CDCl3): d 3.55 (1H, m), 3.68 (3H, s, CH3O),
3.63–3.72 (2H, m), 3.96–4.12 (4H, m), 4.18–4.31 (5H,
m), 4.44 (2H, m), 4.73 (1H, dd, J5,6 2.1 Hz, J6,6
11.8 Hz, H-6), 4.96 (1H, d, J1,2 7.7 Hz, H-10), 5.08
(1H, dd, J3,4 2.6 Hz, H-30), 5.10 (1H, d, J1,2 7.7 Hz, H-
1), 5.13–5.32 (2H, m, CH2@CHCH2O), 5.33 (1H, d,
J1,2 3.2 Hz, H-100), 5.46 (1H, s, PhCH@), 5.55 (1H, dd,
J1,2 3.2 Hz, J2,3 10.5 Hz, H-200), 5.59 (1H, dd, J1,2
7.7 Hz, J2,3 9.0 Hz, H-20), 5.72 (1H, dd, J1,2 7.7 Hz,
J2,3 10.8 Hz, H-2), 5.87 (1H, dd, J2,3 = J3,4 7.8 Hz, H-
3), 5.80–5.93 (1H, m, CH2@CHCH2O), 6.61 (2H, d, J
J2,3 = J3,4 9.6 Hz, H-3), 6.63 (2H, d,
J 8.8 Hz,
CH3OC6H4–), 6.85 (2H, d, J 8.8 Hz, CH3OC6H4–),
7.29–7.44 (15H, m, Ar–H), 7.91–8.05 (10H, m, Ar–H).
Anal. Calcd for C54H48O17: C, 66.93; H, 5.00; Found:
C, 66.63; H, 4.98.
1.7. p-Methoxyphenyl 2,3,6-tri-O-benzoyl-b-D-galacto-
pyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-glucopyran-
oside (8)
9.0 Hz, CH3OC6H4–), 6.84 (2H, d,
J
9.0 Hz,
CH3OC6H4–), 7.19–7.46 (24H, m, Ar–H), 7.71–8.00
(16H, m, Ar–H); 13C NMR (CDCl3): d 55.4 (CH3O),
60.3, 62.6, 63.7, 69.0, 69.7, 71.0, 71.0, 72.1, 72.4, 72.8,
72.9, 73.0, 73.2, 73.7, 74.5, 75.9, 100.0 (JC1–H1
170.0 Hz, C-100, a), 100.3 (JPhC-H 162.4 Hz, PhCH@),
100.8 (JC1–H1 160.7 Hz, C-10, b), 100.8 (JC1–H1
160.7 Hz, C-1, b), 114.3 (CH3OC6H4–), 116.9
(CH2@CHCH2O), 118.9 (CH3OC6H4–), 128.0, 128.3,
128.3, 128.4, 128.4, 128.5, 128.5, 129.5, 129.5, 129.6,
129.6, 129.7, 129.7, 133.0, 133.0, 133.1, 133.2, 133.2,
133.3, 133.6, 134.7, 137.7, 150.8 (CH3OC6H4–), 155.6
(CH3OC6H4–), 165.0, 165.1, 165.1, 165.4, 165.6, 165.9,
166.0 (7 PhCO). Anal. Calcd for C84H74O24: C, 68.74;
H, 5.09; Found: C, 68.97; H, 5.11.
To the solution of 7 (1.97 g, 2.0 mmol) in pyridine
(5 mL) at 0 ꢁC was added dropwise PhCOCl (0.24 mL,
2.1 mmol), and the mixture was stirred overnight. TLC
(1:1 petroleum ether–EtOAc) indicated that the reaction
was complete. The mixture was diluted with CH2Cl2
(100 mL), washed with 1 N HCl, water, and satd aq
NaHCO3. The organic layer was combined, dried, and
concentrated. Purification of the crude product by col-
umn chromatography (2:1 petroleum ether–EtOAc)
gave 8 as a foamy solid (1.87 g, 87%): [a]D +54.5 (c
1
1.1, CHCl3); H NMR (400 MHz, CDCl3): d 2.20 (1H,

L. Chen et al. / Carbohydrate Research 341 (2006) 1174–1180
1179
1.9. p-Methoxyphenyl 3-O-allyl-2-O-benzoyl-a-D-galac-
topyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-galactopyr-
anosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-glucopyranoside
(10)
9.1 Hz, CH3OC6H4–), 7.30–7.40 (21H, m, Ar–H),
7.85–7.94 (14H, m, Ar–H); 13C NMR (CDCl3): d 20.1,
20.1 (2 CH3CO), 55.6 (CH3O), 61.4, 61.4, 62.7 (3 C-6),
67.5, 67.9, 69.9, 71.2, 71.2, 71.5, 71.5, 71.7, 72.3,
72.9, 73.0, 73.0, 73.3, 73.5, 75.8, 98.8 (a), 100.5 (b),
101.1 (b) (3 C-1), 114.5 (CH3OC6H4–), 117.3
(CH2@CHCH2O), 119.0 (CH3OC6H4–), 128.5, 128.6,
128.8, 129.2, 129.3, 129.5, 129.6, 129.8, 130.0, 133.2,
133.3, 133.4, 133.7, 134.2, 150.2, 155.6, 165.1, 165.2,
165.3, 165.6, 165.7, 166.2, 166.3 (7 PhCO), 170.3,
170.6 (2 CH3CO). Anal. Calcd for C81H74O26: C,
66.47; H, 5.11; Found: C, 66.17; H, 5.13.
Compound 9 (0.68 g, 0.46 mmol) was dissolved in 80%
HOAc (16 mL), and the mixture was heated at 80 ꢁC
for 2 h, at the end of which time TLC (1:1 petroleum
ether–EtOAc) indicated that the reaction was complete.
The mixture was concentrated under reduced pressure,
and the residue was passed through a silica-gel column
with 1.5:1 petroleum ether–EtOAc as the eluent to give
10 as foamy solid (0.58 g, 91%): [a]D +30.6 (c 1.1,
1
CHCl3); H NMR (400 MHz, CDCl3): d 2.73 (1H, s,
1.11. p-Methoxyphenyl 4,6-di-O-acetyl-2-O-benzoyl-a-D-
galactopyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-galacto-
pyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-glucopyran-
oside (12)
br, OH), 2.85 (1H, s, br, OH), 3.67 (3H, s, CH3O),
3.66–3.68 (1H, m), 3.83–3.89 (3H, m), 3.94–4.07 (2H,
m), 4.08–4.32 (6H, m), 4.35 (1H, m), 4.46 (1H, dd, H-
6), 4.67 (1H, dd, H-6), 4.92 (1H, d, J1,2 7.9 Hz, H-10),
5.08 (1H, d, J1,2 7.9 Hz, H-1), 5.12–5.27 (2H, m,
CH2@CHCH2O), 5.21 (1H, dd, J1,2 2.3 Hz, H-200), 5.27
(1H, d, J1,2 2.3 Hz, H-100), 5.32 (1H, dd, J2,3 10.3 Hz,
J3,4 3.2 Hz, H-30), 5.60 (1H, dd, H-20), 5.69 (1H, dd,
H-2), 5.80–5.90 (1H, m, CH2@CHCH2O), 5.84 (1H,
dd, J2,3 = J3,4 9.2 Hz, H-3), 6.60 (2H, d, J 8.8 Hz,
CH3OC6H4–), 6.83 (2H, d, J 8.8 Hz, CH3OC6H4–),
7.21–7.41 (21H, m, Ar–H), 7.71–8.02 (14H, m, Ar–H).
Anal. Calcd for C77H70O24: C, 67.04; H, 5.13; Found:
C, 66.75; H, 5.14.
To a solution of 11 (0.3 g, 0.20 mmol) in anhyd CH3OH
(10 mL) was added PdCl2 (0.035 g), and the mixture was
stirred for 4 h at 40 ꢁC, at the end of which time TLC
(1:1 petroleum ether–EtOAc) indicated that the reaction
was complete. The mixture was filtered, the filtrate was
concentrated, and the residue was chromatographed
on a silica-gel column with 1.5:1 petroleum ether–
EtOAc as the eluant to gave 12 as a foamy solid
(0.21 g, 74%): [a]D +42.0 (c 1.1, CHCl3); 1H NMR
(400 MHz, CDCl3): d 2.00 (3H, s, CH3CO), 2.13 (3H,
s, CH3CO), 3.68 (3H, s, CH3O), 3.68–3.72 (1H, m),
3.96–4.06 (3H, m), 4.09–4.17 (4H, m), 4.26–4.31 (1H,
dd, J5,6 = J6,6 9.4 Hz, H-60), 4.43 (1H, dd, J5,6 5.9 Hz,
J6,6 12.0 Hz, H-6), 4.49 (1H, dd, J5,6 = J6,6 6.9 Hz, H-
600), 4.68 (1H, dd, J5,6 1.7 Hz, J6,6 12.0 Hz, H-6), 4.88
(1H, d, J1,2 7.8 Hz, H-10), 5.09 (1H, d, J1,2 7.8 Hz, H-
1), 5.14 (1H, dd, J2,3 10.0 Hz, H-20), 5.20 (1H, d, J1,2
3.3 Hz, H-100), 5.18–5.21 (1H, dd, J2,3 10.6 Hz, J3,4
0.9 Hz, H-30), 5.47 (1H, dd, J3,4 3.3 Hz, J4,5 1.0 Hz, H-
400), 5.62–5.67 (2H, m, H-2, H-20), 5.83 (1H, dd,
1.10. p-Methoxyphenyl 4,6-di-O-acetyl-3-O-allyl-2-O-
benzoyl-a-D-galactopyranosyl-(1!4)-2,3,6-tri-O-ben-
zoyl-b-D-galactopyranosyl-(1!4)-2,3,6-tri-O-benzoyl-
b-D-glucopyranoside (11)
To a solution of 10 (0.35 g, 0.25 mmol) in pyridine
(1 mL) was added Ac2O (0.5 mL), and the mixture was
stirred overnight at rt. TLC (1:1 petroleum ether–
EtOAc) indicated that the reaction was complete. The
mixture was diluted with CH2Cl2 (20 mL), washed with
1 N HCl, water, and satd aq NaHCO3. The organic
layer was combined, dried, and concentrated. Purifica-
tion of the crude product by column chromatography
(2:1 petroleum ether–EtOAc) gave 11 as a foamy solid
(0.34 g, 93%): [a]D +36.0 (c 1.1, CHCl3); 1H NMR
(400 MHz, CDCl3): d 1.97 (3H, s, CH3CO), 2.08 (3H,
s, CH3CO), 3.67 (3H, s, CH3O), 3.66–3.68 (1H, m),
3.93–4.04 (6H, m), 4.17–4.21 (3H, m), 4.27 (1H, dd,
J5,6 = J6,6 9.3 Hz, H-60), 4.44 (1H, dd, J5,6 5.9 Hz, J6,6
12.0 Hz, H-6), 4.52 (1H, dd, J5,6 = J6,6 6.9 Hz, H-
600), 4.69 (1H, dd, J5,6 1.7 Hz, J6,6 9.3 Hz, H-6), 4.91
(1H, d, J1,2 7.9 Hz, H-10), 5.08 (1H, d, J1,2 7.8 Hz, H-
1), 5.10–5.28 (2H, m, CH2@CHCH2O), 5.18–5.28 (3H,
m, H-100, H-200, H-300), 5.57–5.61 (2H, m, H-20, H-400),
5.69–5.73 (1H, dd, H-2), 5.76–5.85 (1H, m,
CH2@CHCH2O), 5.83 (1H, dd, J2,3 = J3,4 9.0 Hz, H-
3), 6.59 (2H, d, J 9.1 Hz, CH3OC6H4–), 6.83 (2H, d, J
J2,3 = J3,4 9.2 Hz, H-3), 6.62 (2H, d,
J 9.1 Hz,
CH3OC6H4–), 6.85 (2H, d, J 9.1 Hz, CH3OC6H4–),
7.26–7.54 (21H, m, Ar–H), 7.87–8.12 (14H, m, Ar–H);
13C NMR (CDCl3):
d 20.5, 29.4 (2 CH3CO),
55.2 (CH3O), 61.0, 61.3, 62.3 (3 C-6), 65.9, 67.6, 69.6,
70.3, 71.6, 72.2, 72.4, 72.6, 72.9, 73.0, 75.4, 75.8, 98.1,
100.3, 100.5 (3 C-1), 114.1 (CH3OC6H4–), 118.6 (CH3O-
C6H4–), 128.1, 128.3, 128.4, 128.9, 129.2, 129.3, 129.5,
129.6, 129.7, 132.9, 133.0, 150.6, 155.4, 164.6, 164.8,
164.9, 165.0, 165.4, 165.7, 166.3 (7 PhCO), 170.3, 170.8
(2 CH3CO). Anal. Calcd for C78H70O26: C, 65.81; H,
4.97; Found: C, 66.10; H, 4.98.
1.12. p-Methoxyphenyl a-D-galactopyranosyl-(1!4)-b-D-
galactopyranosyl-(1!4)-b-D-glucopyranoside (13)
Compound 12 (0.12 g, 0.084 mmol) was dissolved in a
satd solution of NH3 in anhyd CH3OH (10 mL). After

1180
L. Chen et al. / Carbohydrate Research 341 (2006) 1174–1180
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a week at room temperature, the reaction mixture was
concentrated, and the residue was purified by chroma-
tography on Sephadex LH-20 (MeOH) to afford 13 as
a syrup (0.044 g, 86%): [a]D ꢀ5.7 (c 0.9, H2O); 1H
NMR (400 MHz, D2O): d 3.45–3.93 (17H, m), 3.68
(3H, s, CH3O), 4.23–4.26 (1H, m), 4.42 (1H, d, J1,2
7.6 Hz, H-10), 4.84 (1H, d, J1,2 3.6 Hz, H-100), 4.89
(1H, d, J1,2 7.6 Hz, H-1), 6.84 (2H, d, J 9.0 Hz,
–OC6H4OCH3), 7.00 (2H, d, J 9.0 Hz, –OC6H4OCH3);
13C NMR (D2O): d 58.4 (CH3O), 62.5, 63.0, 63.1,
71.2, 71.6, 71.8, 73.5, 73.5, 74.8, 75.4, 76.9, 77.5, 78.0,
80.0, 81.0, 102.9, 103.6, 105.9 (3 C-1), 117.6, 120.8,
153.5, 157.3. MALDI-TOF MS: calcd for C25H38O17:
m/z 610.21 [M]; found: m/z 633.21 [M+Na].
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Supplementary data associated with this article can be
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