Concise synthesis of two pentasaccharides corresponding to the α-chain oligosaccharides of Neisseria gonorrhoeae and Neisseria meningitidis

Article abstract of DOI:10.1016/j.tet.2008.07.004

Two pentasaccharides containing a common tetrasaccharide (lacto-N-neotetraose) core, and d-galactosamine and N-acetyl neuraminic acid in the non-reducing ends, respectively, corresponding to the lipooligosaccharides of Neisseria gonorrhoeae and Neisseria

Full text of DOI:10.1016/j.tet.2008.07.004

Tetrahedron 64 (2008) 8685–8691
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Tetrahedron
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Concise synthesis of two pentasaccharides corresponding to the a-chain
oligosaccharides of Neisseria gonorrhoeae and Neisseria meningitidisq
*
Pintu Kumar Mandal, Anup Kumar Misra
Medicinal and Process Chemistry Division, Central Drug Research Institute, Chattar Manzil Palace, Lucknow 226001, Uttar Pradesh, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Two pentasaccharides containing a common tetrasaccharide (lacto-N-neotetraose) core, and D-galac-
Received 24 April 2008
Received in revised form 27 June 2008
Accepted 1 July 2008
tosamine and N-acetyl neuraminic acid in the non-reducing ends, respectively, corresponding to the
lipooligosaccharides of Neisseria gonorrhoeae and Neisseria meningitidis were synthesized in a very
concise manner from a common trisaccharide derivative using minimum number of steps. Thioglyco-
sides and glycosyl trichloroacetimidate have been used as glycosyl donors for glycosylations and yields
were excellent in every step.
Available online 3 July 2008
Keywords:
Lipopolysaccharides
Glycosylations
Ó 2008 Elsevier Ltd. All rights reserved.
Antigens
Neisseria gonorrhoeae
Neisseria meningitidis
1. Introduction
lacto-N-neotetraose moiety. The
a-chain of gonococcal LOS termi-
nated with a -galactosamine moiety whereas in the case N. men-
D
Neisseria gonorrhoeae and Neisseria meningitidis are two im-
portant human pathogens causing gonorrhea, meningitis, and
septicemia.1 Although, gonorrhea infection is more common in
comparison to meningococcal meningitis, meningitis and induced
septicemia are of much more serious concern because of the as-
sociated mortality.2 The pathogenicity of N. gonorrhoeae and N.
meningitidis originated from the antigenic lipooligosaccharides
(LOSs) present in the outer surface of their cell membranes.3 In
general, LOSs are a family of complex oligosaccharides3 found in the
cell-wall glycolipids of Gram-negative bacteria and possess
a number of antigenic haptens responsible for natural and acquired
immunity.3,4 The intensity of infections caused by these two species
is proportional to the levels of circulating gonococcal and menin-
gococcal LOSs in the endotoxins released from their cell surfaces.5
The LOS induces a proinflammatory response in the host, which
influence the colonization to cross the epithelial barrier to induce
the clinical outcome of gonorrhea and meningitis infections.6 Se-
rologically meningococcal LOS has been classified into 12 immu-
notypes of which 8 have been structurally characterized.7 Recent
structural and immunochemical analysis of gonococcal2,8 and me-
ningococcal9 LOSs established that both LOSs are multiantennary
ingitidis it is N-acetyl neuraminic acid (sialic acid).
Development of antibacterial vaccines is one of the thrust areas
of research in the medicinal chemistry. Due to the established an-
tigenic properties of LOSs, biologists have focused extensive efforts
toward the study of bacterial oligosaccharides as potential anti-
bacterial glycoconjugate vaccine candidates and a number of
reports appeared in the literature for the development of the gly-
coconjugate vaccine candidates against several pathogenic bacte-
ria.10 Although, LOSs can be isolated from the natural sources, their
limited availability cannot always meet the required quantity for
their extensive biological evaluation. Therefore, only option left for
the large-scale production of the oligosaccharides is to develop
efficient chemical synthetic strategies. In this report, we describe
concise synthesis of two pentasaccharides corresponding to the a-
chain of N. gonorrhoeae and N. meningitidis as their 4-methoxy-
phenyl glycosides (Fig. 1).
2. Results and discussion
Two target pentasaccharides as their 4-methoxyphenyl glyco-
sides (1 and 2) was synthesized using a combination of sequential
and contain a pentasaccharide a-chain having a common core of
glycosylations and block synthetic strategy.
A common tri-
saccharide derivative (13) was used as a glycosyl acceptor in both
cases minimizing protective group manipulations. Suitably func-
tionalized monosaccharide derivatives (Fig. 2) used in the synthesis
of target molecules were prepared from the commercially available
q
CDRI communication no. 7373.
* Corresponding author. Tel.: þ91 522 2612411–18x4336; fax: þ91 522 2623405.
E-mail address: akmisra69@rediffmail.com (A.K. Misra).
0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.07.004

8686
P.K. Mandal, A.K. Misra / Tetrahedron 64 (2008) 8685–8691
OH
In another experiment, iodonium ion promoted glycosylation
HO
O
OH
HO
HO
HO
O
OH
OH
OH
of thioglycoside 420 with disaccharide acceptor 321 using NIS–
TMSOTf furnished trisaccharide derivative 12, which was deace-
tylated to give trisaccharide glycosyl acceptor 13 in excellent yield.
Formation of compound 12 was confirmed from its spectral
analysis. Selective glycosylation of disaccharide donor 11 with
trisaccharide diol acceptor 13 in the presence of TMSOTf15 affor-
ded the pentasaccharide derivative 14 in 86% yield, which was
supported by its NMR spectra. Deprotection of protecting groups
involving hydrazinolysis,22 N-acetylation, saponification, and
hydrogenolysis23 furnished target pentasaccharide 1 as its 4-
methoxyphenyl glycoside in 78% overall yield. Presence of signals
O
O
O
O
D
O
O
E
B
C
O
A
HO
OMp
OH
HO
NHAc
OH
NHAc
OH
1
HO
OH
CO2Na
HO
OH
HO
OH
OH
HO
OH
E
O
O
AcHN
O
O
D
O
O
B
O
C
O
O
NHAc
HO
A
HO
OMp
HO
OH
OH
OH
2
Figure 1. Structure of the synthesized pentasaccharides corresponding to the a-chain
of Neisseria gonorrhoeae (1) and Neisseria meningitidis (2) as their 4-methoxyphenyl
at
d 5.08 (d, H-1D), 4.74 (d, H-1C), 4.66 (d, H-1E), 4.51 (2d, H-1A and
glycosides.
H-1B) in the 1H NMR and at
d 103.3 (C-1E), 102.9 (2C, C-1A and C-
1B), 102.7 (C-1C), 101.0 (C-1D) in the 13C NMR spectra confirmed
reducing sugars using the literature reported methodologies.
Compound 5 was prepared in 80% overall yield from 4-methoxy-
the formation of compound 1 (Scheme 2).
phenyl 2,3,4,6 tetra-O-acetyl-b-D
-galactopyranoside (9)11 following
a
sequence of reactions comprising deacetylation, iso-
3 + 4
propylidenation,12 benzoylation, and acid catalyzed removal of
isopropylidene ketal13 followed by selective acetylation via
orthoesterification using triethyl orthoacetate and p-TsOH14
(Scheme 1).
a
90%
OBn
OBn AcO
OBn
O
O
O
After having the access to a series of suitably protected mono-
saccharide derivatives, synthesis of target pentasaccharides (1 and
2) has been attempted. For the preparation of compound 1, a di-
saccharide trichloroacetimidate glycosyl donor (11) was coupled
RO
RO
B
C
O
O
A
OMp
BnO
BnO
NPhth
98% b
OBn
12:R = Ac
13:R =H
with
a trisaccharide glycosyl acceptor (13) using Schmidt’s
c
11 84%
trichloroacetimidate glycosylation method.15 Glycosylation of
compound 5 with thioglycoside derivative 616 in the presence
of N-iodosuccinimide (NIS) and trimethylsilyl trifluoro-
methanesulfonate (TMSOTf)17 provided the disaccharide derivative
10 in 82% yield. Presence of signals in the 1H and 13C NMR spectra
confirmed the formation of 10. Oxidative removal of the anomeric
4-methoxyphenyl group of compound 10 using ammonium ceric
nitrate (CAN)18 furnished disaccharide hemiacetal, which was
treated with trichloroacetonitrile in the presence of DBU19 to
generate the disaccharide trichloroacetimidate derivative 11 in 85%
yield, which was used directly without further purification
(Scheme 1).
AcO
OBz
O
OAc AcO
OBn AcO OBn
OBn
O
O
D
O
O
E
O
O
C
B
BnO
AcO
O
O
A
BzO
HO
OMp
NPhth
BnO
NPhth
OBn
14
d, e,f 70%
1
Scheme 2. Reagents: (a) N-iodosuccinimide, TMSOTf, MS-4 Å, CH2Cl2, ꢁ30 ꢀC, 1 h; (b)
CH3ONa, CH3OH, rt, 30 min; (c) TMSOTf, CH2Cl2, ꢁ10 ꢀC, 1 h; (d) (i) NH2NH2$H2O, EtOH,
80 ꢀC, 6 h; (ii) Ac2O, pyridine, rt, 6 h; (e) CH3ONa, CH3OH, rt, 10 h; (f) H2, 20% Pd(OH)2–
C, CH3OH, rt, 24 h.
OBn
O
OBn
O
OBz
O
AcO
HO
AcO
HO
OBn
O
AcO
AcO
In another experiment, selective glycosylation of compound 724
with trisaccharide diol acceptor 13 furnished tetrasaccharide de-
rivative 15 in 87% yield. Spectral data of compound 15 supported its
formation. On treatment with hydrazine hydrate22 followed by N-
acetylation and saponification afforded tetrasaccharide tetraol 16
acceptor in 82% yield. In order to achieve stereo- and regioselective
glycosylation of compound 16 with sialic acid thioglycoside donor
8,25 a number of literature reported glycosylation condition were
explored.26 After a series of unsuccessful attempts, pentasaccharide
derivative 17 was obtained in moderate yield (48%) by condensa-
tion of compound 16 with compound 8 using NIS–TMSOTf as
O
OMp
SEt
OMp
Ph
BnO
BnO
BzO
NPhth
OBn
4
3
5
AcO
O
OAc
AcO
OAc
O
O
COOCH3
SPh
AcO
O
AcO
7
O
AcHN
AcO
AcO
SEt
SEt
NPhth
AcO
6
8
Figure 2. Suitably functionalized monosaccharide intermediates used for the syn-
thesis of pentasaccharides (1 and 2).
OAc
O
AcO
AcO
OBz
O
AcO
HO
a, b,c,d,e
80%
OMp
OMp
OAc
BzO
5
9
AcO
OBz
O
AcO
OAc
O
AcO
OBz
O
OAc AcO
f
g, h
83%
NH
O
CCl3
O
5 +6
A
B
A
O
NPhth
10
OMp
B
O
82%
AcO
AcO
BzO
BzO
NPhth
11
Scheme 1. Reagents: (a) CH3ONa, CH3OH, rt, 5 h; (b) 2,2-dimethoxypropane, p-TsOH, DMF, rt, 12 h; (c) benzoyl chloride, pyridine, rt, 6 h; (d) 80% AcOH, 80 ꢀC, 2 h; (e)
(i) CH3C(OC2H5)3, p-TsOH, DMF, 2 h; (ii) 80% AcOH, rt, 1 h; (f) N-iodosuccinimide, TMSOTf, MS-4 Å, CH2Cl2, ꢁ30 ꢀC, 1 h; (g) CAN, CH3CN, H2O, rt, 1.5 h; (h) CCl3CN, DBU, CH2Cl2,
ꢁ10 ꢀC, 1 h.

P.K. Mandal, A.K. Misra / Tetrahedron 64 (2008) 8685–8691
8687
thioglycoside activator in a mixed solvent (CH3CN–CH2Cl2 5:1 v/v).
Formation of compound 17 was confirmed from its spectral anal-
ysis. The presence of -linked sialic acid moiety in the compound 17
was supported by its 1H NMR spectrum, which was comparable
with the NMR signals of -linked sialic acid moiety in earlier re-
ports.26,27 In the 1H NMR spectrum of compound 17, appearance of
a signal at -ste-
2.74 (dd, J¼12.0, 4.8 Hz, H-3eE) indicated the
reochemistry of the C-2 of sialic acid moiety. In case of -linked
sialic acid this signal generally appears in upfield position. In ad-
dition, 1H NMR signals for H-4E
4.95–4.86), H-7E and H-8E
5.47–5.39) confirmed the presence of
-linked sialic acid moiety.27
4. Experimental
a
4.1. General procedure
a
General methods. All the reactions were monitored by thin layer
chromatography over silica gel coated TLC plates. The spots on TLC
were visualized by warming ceric sulfate (2% Ce(SO4)2 in 2 N
H2SO4) sprayed plates in hot plate. Silica gel 230–400 mesh was
used for column chromatography. 1H and 13C NMR, 2D COSY, HSQC
spectra were recorded on Brucker Advance DPX 300 and 400 MHz
using CDCl3 and D2O as solvents and TMS as internal reference
unless stated otherwise. Chemical shift value is expressed in
d
a
b
(d
(d
a
Hydrogenolysis followed by saponification of pentasaccharide
derivative 17 furnished target pentasaccharide 2 in 74% yield
d (ppm). ESI-MS were recorded on a MICROMASS QUTTRO II triple
(Scheme 3). Presence of signals at
H-1B, H-1D), 2.82 (dd, H-3eE), 1.70 (t, H-3aE) in the 1H NMR and
104.9 (2C, C-1B, C-1D), 103.1 (2C, C-1A, C-1C), 101.0 (C-2E) in the 13
NMR spectra supported the structure of compound 2 (Scheme 3).
The stereocontrol of the glycosylation reactions was achieved using
judicious choice of protecting groups in the glycosyl donors and
acceptors.
d
4.82 (2d, H-1A, H-1C), 4.46 (2d,
quadrupole mass spectrometer. Elementary analysis was carried
out on Carlo ERBA-1108 analyzer. Optical rotations were measured
at 25 ꢀC on a Rudolf Autopol III polarimeter. Commercially available
grades of organic solvents of adequate purity are used in many
reactions.
d
C
4.1.1. 4-Methoxyphenyl 4-O-acetyl-2,6-di-O-benzoyl-b-D-
galactopyranoside (5)
A solution of compound 9 (10 g, 22 mmol) in 0.1 M CH3ONa
(150 mL) was allowed to stir at room temperature for 5 h. The re-
action mixture was neutralized with Amberlite-IR 120 (Hþ) resin,
filtered, and concentrated. To a solution of the deacetylated product
in anhydrous DMF (30 mL) were added 2,2-dimethoxypropane
(4 mL, 33 mmol) and p-TsOH (0.5 g), and the reaction mixture was
allowed to stir at room temperature for 12 h. The reaction mixture
was neutralized with Et3N (1.5 mL) and evaporated to dryness
under reduced pressure. To a solution of the dry mass in pyridine
(60 mL) was added benzoyl chloride (8 mL, 69 mmol) at 0 ꢀC and
the reaction mixture was allowed to stir at room temperature for
6 h. The excess reagents were quenched with CH3OH (5 mL) and the
solvents were removed under reduced pressure. A solution of the
crude mass in 80% AcOH (150 mL) was allowed to stir at 80 ꢀC for
2 h and the solvents were removed under reduced pressure to give
the crude diol, which was passed through a short pad of SiO2. To
a solution of the diol derivative in dry DMF (25 mL) were added
triethyl orthoacetate (15 mL, 82 mmol) and p-TsOH (0.5 g), and the
reaction mixture was allowed to stir at room temperature for 2 h.
The solvents were removed under reduced pressure and a solution
of the crude mass in 80% AcOH (100 mL) was stirred at room
temperature for 1 h. The reaction mixture was evaporated to
dryness and the crude mass was purified over SiO2 using hexane–
7 + 13
a
86%
Ph
O
O
OBn
O
OBn AcO
OBn
O
O
O
D
O
AcO
B
C
O
O
A
A
HO
OMp
OMp
AcO
BnO
BnO
NPhth
OBn
15
b
83%
Ph
O
O
OBn
O
OBn HO
OBn
O
O
O
D
O
HO
B
C
O
O
HO
HO
BnO
BnO
NHAc
16
OBn
c 48%
8
Ph
AcO
OAc
CO2CH3
O
AcO
O
OBn HO OBn
E
O
OBn
O
AcHN
O
O
O
D
O
O
AcO
B
BnO
C
O
NHAc
O
A
HO
17
OMp
HO
BnO
OBn
EtOAc (5:1) as eluant to furnish pure 5 (9.5 g, 80%). Rf 0.4 (hexane–
d, e 66%
25
EtOAc 3:1); white solid; mp 150–51 ꢀC; [
a
]
ꢁ4 (c 1.2, CHCl3); IR
D
(KBr): 2961, 1727, 1601, 1509, 1451, 1380, 1269, 1220, 1110, 1074, 829,
2
710 cmꢁ1 1H NMR (300 MHz, CDCl3):
;
d
8.07–8.0 (m, 4H, Ar–H),
Scheme 3. Reagents: (a) N-iodosuccinimide, TMSOTf, MS-4 Å, CH2Cl2, ꢁ30 ꢀC, 1 h; (b)
(i) NH2NH2$H2O, EtOH, 80 ꢀC, 6 h; (ii) Ac2O, pyridine, rt, 6 h; (iii) CH3ONa, CH3OH, rt,
2 h; (c) N-iodosuccinimide, TMSOTf, MS-4 Å, CH3CN–CH2Cl2 (5:1), ꢁ10 ꢀC, 16 h; (d) H2,
20% Pd(OH)2–C, CH3OH, rt, 24 h; (e) CH3ONa, CH3OH, rt, 8 h then few drops of water,
12 h.
7.59–7.38 (m, 6H, Ar–H), 6.90 (d, J¼9.0 Hz, 2H, Ar–H), 6.60 (d,
J¼9.0 Hz, 2H, Ar–H), 5.54 (br s, 1H, H-4), 5.51 (t, J¼8.0 Hz, 1H, H-2),
5.03 (d, J¼8.0 Hz, 1H, H-1), 4.50–4.43 (m, 2H, H-6a,b), 4.15–4.06 (m,
2H, H-3 and H-5), 3.68 (s, 3H, OCH3), 2.22 (s, 3H, COCH3); 13C NMR
(75 MHz, CDCl3): d 170.8 (COCH3), 166.7, 165.9 (2COPh), 155.6–114.4
(Ar–C), 100.8 (C-1), 73.2 (C-5), 71.5 (C-2), 71.4 (C-4), 69.8 (C-3), 62.4
(C-6), 55.4 (OCH3), 20.7 (COCH3); ESI-MS: m/z 559.1 [MþNa]þ. Anal.
Calcd for C29H28O10 (536.17): C, 64.92; H, 5.26. Found: C, 64.75; H,
5.50.
3. Conclusions
In summary, efficient syntheses of two pentasaccharides (1 and
2) corresponding to the a-chain of lipooligosaccharides of N. gon-
orrhoeae and N. meningitidis have been achieved in excellent yield.
Thioglycosides were used as glycosyl donors in most of the glyco-
sylation reactions. Synthesis of compound 1 was carried out fol-
lowing a block synthetic strategy and compound 2 was prepared
using sequential glycosylations. Both pentasaccharides contain 4-
methoxyphenyl group as a temporary anomeric protecting group,
which can be removed using standard reaction protocol for the
preparation of glycoconjugates.
4.1.2. 4-Methoxyphenyl (3,4,6-tri-O-acetyl-2-deoxy-2-N-
phthalimido-
b
-D-galactopyranosyl)-(1/3)-4-O-acetyl-
2,6-di-O-benzoyl-
b-D-galactopyranoside (10)
To a solution of compound 5 (3 g, 5.6 mmol) and thioglycoside
donor 6 (3.2 g, 6.7 mmol) in CH2Cl2 (30 mL) was added MS-4 Å (3 g)
and the reaction mixture was allowed to stir at room temperature
under argon for 30 min. The reaction mixture was cooled to ꢁ30 ꢀC
and N-iodosuccinimide (1.8 g, 8 mmol) and TMSOTf (50 mL) were

8688
P.K. Mandal, A.K. Misra / Tetrahedron 64 (2008) 8685–8691
added to it. After stirring the reaction mixture at the same tem-
perature for 1 h, it was filtered through a CeliteÒ bed and washed
with CH2Cl2 (100 mL). The organic layer was washed with 5%
Na2S2O3 (100 mL), satd NaHCO3 (100 mL), and water (100 mL) in
succession, dried (Na2SO4), and evaporated to dryness. The crude
mass was purified over SiO2 using hexane–EtOAc (5:1) as eluant to
neutralized with Amberlite-IR 120 (Hþ) resin. The reaction mixture
was filtered and evaporated to dryness to give the crude product,
which was passed through a short column of SiO2 using hexane–
EtOAc (2:1) as eluant to give pure 13 (6 g, 98%). Rf 0.3 (hexane–
EtOAc 1:1); colorless syrup; IR (neat): 2923, 2372, 2142, 1661, 1591,
25
1055, 611 cmꢁ1; [
a
]
D
ꢁ10 (c 1.2, CHCl3); 1H NMR (300 MHz, CDCl3):
furnish pure 10 (4.4 g, 82 %). Rf 0.3 (hexane–EtOAc 3:1); white solid;
d 7.41–7.0 (m, 34H, Ar–H), 6.92–6.60 (m, 4H, Ar–H), 5.42 (d,
25
mp 181–83 ꢀC; [
a]
þ35 (c 1.52, CHCl3); IR (KBr): 2924, 2142, 1727,
J¼2.0 Hz, 1H, H-4B), 5.28 (d, J¼8.1 Hz, 1H, H-1C), 4.95–4.65 (m, 4H,
PhCH2), 4.63 (d, J¼7.6 Hz, 1H, H-1A), 4.59–4.50 (m, 2H, PhCH2),
4.46–4.30 (m, 2H, PhCH2), 4.27–4.15 (m, 4H, H-1B, H-3C, and
PhCH2), 4.10–3.95 (m, 4H, H-2C, H-4C, and PhCH2), 3.90–3.80 (m,
2H, H-3A and H-6aA), 3.76 (s, 3H, OCH3), 3.75–3.71 (m, 1H, H-6bA),
3.59–3.49 (m, 4H, H-2A, H-3B, and H-6a,bC), 3.46–3.33 (m, 4H, H-2B,
H-5B, and H-6a,bB), 3.28–3.22 (m, 2H, H-4A and H-5C), 3.15–3.0 (m,
D
1593, 1379, 1226, 1114, 855, 773, 505 cmꢁ1
;
1H NMR (300 MHz,
CDCl3): 8.07–8.05 (m, 2H, Ar–H), 7.65–7.25 (m,12H, Ar–H), 6.74 (d,
d
J¼9.0 Hz, 2H, Ar–H), 6.50 (d, J¼9.0 Hz, 2H, Ar–H), 5.67 (dd, J¼11.5,
3.3 Hz, H-3B), 5.63 (d, J¼3.6 Hz,1H, H-4A), 5.51 (dd, J¼8.1, 8.1 Hz,1H,
H-2A), 5.45 (d, J¼8.3 Hz, 1H, H-1B), 5.41 (d, J¼3.1 Hz, H-4B), 4.87 (d,
J¼8.0 Hz, 1H, H-1A), 4.58–4.36 (m, 3H, H-2B and H-6a,bA), 4.25–4.18
(m, 2H, H-6a,bB), 4.15–4.02 (m, 3H, H-3A, H-5A, and H-5B), 3.63 (s,
3H, OCH3), 2.24, 2.20, 2.05, 1.76 (4s, 12H, 4COCH3); 13C NMR
1H, H-5A), 2.01 (s, 3H, COCH3); 13C NMR (75 MHz, CDCl3):
d 170.2
(COCH3), 167.9 (2C, COPhth), 155.0–110.9 (Ar–C), 102.6 (C-1A), 101.9
(C-1B), 98.7 (C-1C), 82.5 (C-2A), 81.2 (C-3B), 78.9 (C-5A), 78.1 (C-5C),
77.3 (C-5B), 75.5 (C-2B), 75.2 (C-3A), 75.1, 74.9, 74.5, 73.5, 73.4, 73.0
(6PhCH2), 72.4 (2C, C-3C and C-4C), 71.0 (C-4A), 70.5 (C-4B), 69.9 (C-
6C), 68.1 (2C, C-6A and C-6B), 56.9 (C-2C), 56.6 (OCH3), 20.7 (COCH3);
ESI-MS: m/z 1344.6 [MþNa]þ. Anal. Calcd for C77H79NO19 (1321.52):
C, 69.93; H, 6.02. Found: C, 69.74; H, 6.25.
(75 MHz, CDCl3):
d 170.8, 170.7, 170.5, 170.1 (4COCH3), 168.0, 167.4
(COPhth), 166.4, 165.0 (2COPh), 155.8–114.2 (Ar–C), 100.9 (C-1A),
98.8 (C-1B), 77.3 (C-5A), 71.8 (C-5B), 70.8 (2C, C-2A and C-3A), 69.2
(C-3B), 67.5 (C-4A), 66.4 (C-4B), 62.8 (C-6A), 61.1 (C-6B), 55.4 (OCH3),
51.2 (C-2B), 20.7, 20.6 (2C), 20.3 (4COCH3); ESI-MS: m/z 976.2
[MþNa]þ. Anal. Calcd for C49H47NO19 (953.27): C, 61.70; H, 4.97.
Found: C, 61.51; H, 5.20.
4.1.5. 4-Methoxyphenyl (3,4,6-tri-O-acetyl-2-deoxy-2-
4.1.3. 4-Methoxyphenyl (3,4-di-O-acetyl-6-O-benzyl-2-deoxy-
phthalimido-
benzoyl- -galactopyranosyl)-(1/4)-(6-O-benzyl-2-deoxy-2-
phthalimido- -glucopyranosyl)-(1/3)-(4-O-acetyl-2,6-di-O-
benzyl- -galactopyranosyl)-(1/4)-2,3,6-tri-O-benzyl-
glucopyranoside (14)
b-D-galactopyranosyl)-(1/3)-(4-O-acetyl-2,6-di-O-
2-phthalimido-
di-O-benzyl-
benzyl- -glucopyranoside (12)
b
-D
-glucopyranosyl)-(1/3)-(4-O-acetyl-2,6-
b-D
b
-D-galactopyranosyl)-(1/4)-2,3,6-tri-O-
b-D
b-
D
b
-D
b-D-
To a solution of compound 3 (5 g, 5.3 mmol) and thioglycoside
donor 4 (3.4 g, 6.4 mmol) in anhydrous CH2Cl2 (60 mL) was added
MS-4 Å (5 g) and the reaction mixture was allowed to stir at room
temperature under argon for 30 min. The reaction mixture was
cooled to ꢁ30 ꢀC and N-iodosuccinimide (1.7 g, 7.5 mmol) and
To a solution of compound 10 (3 g, 3.14 mmol) in CH3CN–H2O
(25 mL, 4:1 v/v) was added ammonium cerium nitrate (CAN, 2.6 g,
4.7 mmol) and the reaction mixture was allowed to stir at room
temperature for 2 h. The reaction mixture was diluted with CH2Cl2
(100 mL) and the organic layer was washed with satd NaHCO3
(2ꢂ100 mL) and water (100 mL), dried (Na2SO4), and evaporated to
dryness to give disaccharide hemiacetal. To a solution of the
hemiacetal in anhydrous CH2Cl2 (30 mL) was added tri-
chloroacetonitrile (2.5 mL, 24.9 mmol) and the reaction mixture was
cooled to ꢁ10 ꢀC. To the cooled reaction mixture was added DBU
(0.2 mL, 1.3 mmol) and it was allowed to stir at ꢁ10 ꢀC for 1 h. The
reaction mixture was evaporated to dryness and the crude product
was passed through a short pad of SiO2 to furnish 3,4,6-tri-O-ace-
TMSOTf (50 mL) were added to it. After stirring the reaction mixture
at the same temperature for 1 h, it was filtered through a CeliteÒ
bed and washed with CH2Cl2 (100 mL). The organic layer was
washed with 5% Na2S2O3 (100 mL), satd NaHCO3 (100 mL), and
water (100 mL) in succession, dried (Na2SO4), and evaporated to
dryness. The crude mass was purified over SiO2 using hexane–
EtOAc (4:1) as eluant to furnish pure 12 (6.7 g, 90%). Rf 0.3 (hexane–
25
EtOAc 3:1); colorless syrup; [
a]
þ7.3 (c 1.2, CHCl3); IR (neat): 3021,
D
2925, 1749, 1720, 1488, 1385, 1219, 1064, 757, 669 cmꢁ1
;
1H NMR
(300 MHz, CDCl3): 7.48–7.0 (m, 34H, Ar–H), 6.90–6.62 (m, 4H, Ar–
d
tyl-2-deoxy-2-phthalimido-
b
-D-galactopyranosyl-(1/3)-4-O-ace-
H), 5.81 (t, J¼9.2 Hz, 1H, H-3C), 5.51 (d, J¼8.4 Hz, 1H, H-1C), 5.43 (br
s, 1H, H-4B), 5.18 (t, J¼9.8 Hz, 1H, H-4C), 4.95–4.70 (m, 3H, PhCH2),
4.66 (d, J¼7.3 Hz, 1H, H-1A), 4.65–4.42 (m, 5H, PhCH2), 4.30–4.14
(m, 2H, H-1B and PhCH2), 4.10–4.03 (m, 1H, H-2C), 3.92–3.80 (m, 3H,
H-3A, H-4A, and H-5C), 3.78 (s, 3H, OCH3), 3.66–3.62 (m, 2H, H-
tyl-2,6-di-O-benzoyl- -galactopyranosyl
b-D
trichloroacetimidate
(11, 2.6 g, 83%). A solution of compound 13 (1.5 g, 1.1 mmol) and
compound 11 (1.4 g, 1.4 mmol) in anhydrous CH2Cl2 (25 mL) was
cooled to ꢁ10 ꢀC. To the cooled reaction mixture was added
TMSOTf (100
m
L) and it was allowed to stir at ꢁ10 ꢀC for 1 h. The
6
6
a,bC), 3.55–3.49 (m,1H, H-3B), 3.46–3.36 (m, 3H, H-2A, H-5B, and H-
aA), 3.33–3.22 (m, 4H, H-2B, H-6bA, and H-6a,bB), 3.02–2.97 (m, 1H,
reaction mixture was diluted with CH2Cl2 (50 mL) and the organic
layer was washed with satd NaHCO3 (100 mL) and water (100 mL)
in succession, dried (Na2SO4), and evaporated to dryness. The crude
product was purified over SiO2 using hexane–EtOAc (4:1) as eluant
to give pure 14 (2 g, 84%). Rf 0.5 (hexane–EtOAc 1:1); white solid;
H-5A), 2.05, 1.91, 1.81 (3s, 9H, 3COCH3); 13C NMR (75 MHz, CDCl3):
d
169.9, 169.6, 169.3 (3COCH3), 167.5, 167.3 (COPhth), 154.0–110.9
(Ar–C), 102.5 (C-1A), 101.9 (C-1B), 98.5 (C-1C), 82.4 (C-2A), 81.2 (C-
3B), 79.3 (C-5C), 78.7 (C-5A), 77.2 (C-5B), 75.5 (C-2B), 75.2, 74.8, 74.4,
73.6 (2C), 73.4 (6PhCH2), 73.3 (C-3A), 73.1 (C-4A), 72.6 (C-4C), 70.6
(C-3C), 69.9 (C-6C), 69.8 (C-4B), 68.9 (C-6B), 68.3 (C-6A), 56.6 (OCH3),
54.9 (C-2C), 20.7, 20.6, 20.4 (3COCH3); ESI-MS: m/z 1428.5 [MþNa]þ.
Anal. Calcd for C81H83NO21 (1405.55): C, 69.17; H, 5.95. Found: C,
68.96; H, 6.20.
mp 106–108 ꢀC; IR (KBr): 2922, 1721, 1459, 1371, 1230, 1070, 766,
717 cmꢁ1; [
a
]
þ24 (c 1.5, CHCl3); 1H NMR (300 MHz, CDCl3):
25
D
d
7.99–7.96 (m, 2H, Ar–H), 7.65–7.0 (m, 44H, Ar–H), 6.96–6.60 (m,
6H, Ar–H), 5.67 (dd, J¼11.5, 3.3 Hz, 1H, H-3E), 5.57 (d, J¼3.1 Hz, 1H,
H-4D), 5.49–5.37 (m, 3H, H-1E, H-4B, and H-4E), 5.34–5.28 (m, 1H,
H-2D), 5.20 (d, J¼8.4 Hz, 1H, H-1C), 5.0–4.83 (m, 2H, PhCH2), 4.76–
4.52 (m, 5H, H-1A, H-1D, H-6a,bD, and PhCH2), 4.44–4.28 (m, 6H, H-
4.1.4. 4-Methoxyphenyl (6-O-benzyl-2-deoxy-2-N-phthalimido-
2E and PhCH2), 4.25–4.10 (m, 8H, H-1B, H-2C, H-4C, H-6aC, H-6a,bE,
b
-
D
-glucopyranosyl)-(1/3)-(4-O-acetyl-2,6-di-O-benzyl-
b
-
D
-
and PhCH2), 4.08–3.94 (m, 7H, H-3C, H-3D, H-5D, H-5E, H-6bC, and
PhCH2), 3.89–3.79 (m, 1H, H-3A), 3.77 (s, 3H, OCH3), 3.64–3.59 (m,
1H, H-2A), 3.53–3.32 (m, 5H, H-2B, H-3B, H-4A, H-5B, and H-5C),
3.28–3.19 (m, 4H, H-6a,bA and H-6a,bB), 3.09–2.98 (m, 1H, H-5A),
2.20, 2.18, 2.04, 1.97, 1.74 (5s, 15H, 5COCH3); 13C NMR (75 MHz,
galactopyranosyl)-(1/4)-2,3,6-tri-O-benzyl-
glucopyranoside (13)
b-D-
A solution of compound 12 (6.5 g, 4.6 mmol) in 0.05 M CH3ONa
(130 mL) was allowed to stir at room temperature for 30 min and

P.K. Mandal, A.K. Misra / Tetrahedron 64 (2008) 8685–8691
8689
CDCl3):
d
170.3, 170.2, 169.7 (2C), 169.5 (5COCH3), 167.7 (2C), 166.8
(Hþ) resin. The reaction mixture was filtered and concentrated to
give the crude product, which was purified over SiO2 using hexane–
EtOAc (1:2) as eluant to furnish pure 16 (1.8 g, 83%). Rf 0.2 (hexane–
(2C) (2COPhth), 166.1, 164.2 (2COPh), 153.9–110.9 (Ar–C), 102.4 (C-
1A), 101.7 (C-1B), 101.4 (C-1D), 98.6 (2C, C-1C and C-1E), 82.3 (C-2B),
82.1 (C-5C), 81.2 (C-5B), 78.8 (2C, C-2A and C-3B), 77.2 (C-3A), 75.0
(PhCH2), 74.7 (C-4A), 74.4 (PhCH2), 73.7 (C-4C), 73.3 (2C), 72.9, 72.6
(4PhCH2), 72.5 (C-3D), 72.2 (C-3C), 70.8 (C-4E), 70.5 (C-4B), 69.9 (C-
2D), 69.2 (C-5D), 69.0 (C-5A), 68.2 (C-6B), 67.7 (C-6A), 67.3 (2C, C-3E
and C-4D), 66.3 (C-5E), 62.9 (C-6D), 61.2 (C-6C and C-6E), 56.6
(OCH3), 56.0 (C-2C), 51.1 (C-2E), 20.6 (2C), 20.5 (2C), 20.2 (5COCH3);
ESI-MS: m/z 2173.8 [MþNa]þ. Anal. Calcd for C119H118N2O36
(2150.75): C, 66.41; H, 5.53. Found: C, 66.20; H, 5.77.
EtOAc: 1:2); white solid; mp 86–88 ꢀC; IR (KBr): 2922, 2864, 2361,
25
1711, 1649, 1511, 1460, 1389, 1229, 1069, 750, 699 cmꢁ1; [
a
]
D
þ8 (c
1.2, CHCl3); 1H NMR (300 MHz, CDCl3):
d 7.48–7.13 (m, 35H, Ar–H),
6.93–6.66 (m, 4H, Ar–H), 5.42 (s,1H, PhCH), 5.36 (d, J¼8.3 Hz,1H, H-
1C), 4.93 (d, J¼9.0 Hz, 1H, H-1A), 4.89 (d, J¼11.2 Hz, 1H, PhCH2),
4.76–4.56 (m, 5H, PhCH2), 4.48–4.38 (m, 4H, H-1B, H-1D, and
PhCH2), 4.32–4.26 (m, 4H, H-3C, H-4C, and PhCH2), 4.22–4.11 (m,
5H, H-3A, H-6a,bA, and PhCH2), 4.08–4.04 (m, 2H, H-2D and H-3D),
3.95–3.82 (m, 5H, H-2C, H-4B, H-4D, and H-6a,bD), 3.73 (s, 3H, OCH3),
3.72–3.58 (m, 4H, H-2A, H-3B, and H-6a,bC), 3.56–3.42 (m, 4H, H-2B,
H-5D, and H-6a,bB), 3.39–3.30 (m, 3H, H-4A, H-5B, and H-5C), 3.15–
3.07 (m, 1H, H-5A), 2.05 (s, 3H, COCH3); 13C NMR (75 MHz, CDCl3):
4.1.6. 4-Methoxyphenyl (2,3-di-O-acetyl-4,6-O-benzylidene-
galactopyranosyl)-(1/4)-(6-O-benzyl-2-deoxy-2-phthalimido-
-glucopyranosyl)-(1/3)-(4-O-acetyl-2,6-di-O-benzyl-
galactopyranosyl)-(1/4)-2,3,6-tri-O-benzyl-
-glucopyranoside (15)
To a solution of compound 13 (2.5 g, 1.9 mmol) and thioglyco-
b
-D-
b
-
D
b-D-
d
169.9 (NHCOCH3), 167.7 (2C, COPhth), 155.2–114.4 (Ar–C), 103.7
b
-D
(C-1A), 102.8 (C-1B), 101.9 (C-1D), 101.0 (PhCH), 98.7 (C-1C), 82.5 (C-
2A), 81.9 (C-3B), 81.4 (C-3D), 78.9 (2C, C-5B and C-5D), 75.7 (C-2D),
75.1 (PhCH2), 75.0 (2C, C-5A and PhCH2), 74.9 (C-5C), 74.5 (PhCH2),
74.0 (C-2B), 73.4 (2C, PhCH2), 73.0 (PhCH2), 72.6 (C-3A), 72.5 (C-4C),
71.1 (C-3C), 70.1 (C-4A), 69.0 (C-4B), 68.8 (C-6D), 68.6 (C-6C), 68.2 (C-
6A), 67.7 (C-6B), 66.7 (C-4D), 56.5 (C-2C), 55.4 (OCH3), 20.8
(NHCOCH3); ESI-MS: m/z 1464.6 [MþNa]þ. Anal. Calcd for
side donor 7 (900 mg, 2.3 mmol) in anhydrous CH2Cl2 (25 mL) was
added MS-4 Å (2 g) and the reaction mixture was allowed to stir at
room temperature under argon for 30 min. The reaction mixture
was cooled to ꢁ30 ꢀC and N-iodosuccinimide (625 mg, 2.7 mmol)
and TMSOTf (10 mL) were added to it. After stirring the reaction
mixture at the same temperature for 1 h, it was filtered through
a CeliteÒ bed and washed with CH2Cl2 (50 mL). The organic layer
was washed with 5% Na2S2O3 (50 mL), satd NaHCO3 (100 mL), and
water (100 mL) in succession, dried (Na2SO4), and evaporated to
dryness. The crude mass was purified over SiO2 using hexane–
EtOAc (4:1) as eluant to furnish pure 15 (2.7 g, 86%). Rf 0.4 (hexane–
C82H91NO22 (1441.60): C, 68.27; H, 6.36. Found: C, 68.06; H, 6.55.
4.1.8. 4-Methoxyphenyl (methyl 5-acetamido-4,7,8,9-tetra-O-
acetyl-3,5-dideoxy- -glycero- -galacto-2-nonulopyrano-
sylonate)-(2/3)-(4,6-O-benzylidene- -galacto-
pyranosyl)-(1/4)-(2-acetamido-6-O-benzyl-2-deoxy-
pyranosyl)-(1/3)-(2,6-di-O-benzyl- -galactopyranosyl)-
(1/4)-2,3,6-tri-O-benzyl- -glucopyranoside (17)
D
a-D
b-D
b-D-gluco-
EtOAc 2:1); white solid; mp 95–97 ꢀC; IR (KBr): 2924, 2856, 2363,
b-D
25
1654, 1649, 1515, 1460, 1218, 1072, 759, 671 cmꢁ1; [
a
]
þ16.3 (c 1.2,
b-D
D
CHCl3); 1H NMR (300 MHz, CDCl3):
d
7.48–7.11 (m, 39H, Ar–H),
To a solution of compound 16 (1.5 g, 1 mmol) and thioglycoside
donor 8 (1.1 g, 1.9 mmol) in anhydrous CH3CN–CH2Cl2 (20 mL, 5:1
v/v) was added MS-3 Å (2 g) and the reaction mixture was allowed
to stir at room temperature under argon for 30 min. The reaction
mixture was cooled to ꢁ10 ꢀC and N-iodosuccinimide (500 mg,
6.92–6.69 (m, 4H, Ar–H), 5.44 (d, J¼3.3 Hz, 1H, H-4B), 5.39 (s, 1H,
PhCH), 5.35 (d, J¼8.0 Hz, 1H, H-1C), 5.30 (dd, J¼7.8 Hz, 1H, H-2D),
4.92–4.84 (m, 3H, H-3D and PhCH2), 4.82–4.75 (m, 2H, PhCH2), 4.71
(d, J¼8.7 Hz, 1H, H-1A), 4.68–4.57 (m, 2H, PhCH2), 4.55 (d, J¼7.9 Hz,
1H, H-1D), 4.53–4.38 (m, 3H, PhCH2), 4.29 (d, J¼7.5 Hz, 1H, H-1B),
4.29–4.23 (m, 2H, PhCH2), 4.21–4.17 (m, 3H, H-3C and H-6a,bD),
4.16–4.04 (m, 2H, H-2C and H-4D), 3.98–3.80 (4H, H-2A, H-3A, H-4C,
and H-6aA), 3.73 (s, 3H, OCH3), 3.67–3.57 (m, 2H, H-3B and H-6bA),
2.2 mmol) and TMSOTf (15 mL) were added to it. After stirring the
reaction mixture at the same temperature for 16 h, it was filtered
through a CeliteÒ bed and washed with CH2Cl2 (100 mL). The or-
ganic layer was washed with 5% Na2S2O3 (100 mL), satd NaHCO3
(100 mL), and water (100 mL) in succession, dried (Na2SO4), and
evaporated to dryness. The crude mass was purified over SiO2 using
toluene–EtOAc (1:2) as eluant to furnish pure 17 (920 mg, 48%). Rf
3.55–3.49 (m, 2H, H-2B and H-6aC), 3.47–3.40 (m, 4H, H-5B, H-6bC
,
and H-6a,bB), 3.37–3.26 (m, 3H, H-4A, H-5C, and H-5D), 3.12–2.98 (m,
1H, H-5A), 2.07, 2.06, 2.0 (3s, 9H, 3COCH3); 13C NMR (75 MHz,
CDCl3):
d
170.2, 169.7, 168.6 (3COCH3), 167.7 (2C, COPhth), 155.3–
0.2 (toluene–EtOAc 1:3); colorless syrup; IR (neat): 2925, 2339,
25
114.4 (Ar–C), 102.7 (C-1A), 101.9 (C-1B), 101.2 (C-1D), 100.9 (PhCH),
98.8 (C-1C), 82.5 (C-2A), 81.4 (C-3B), 80.8 (C-3D), 79.2 (C-5B), 78.8 (C-
5D), 75.7 (C-2D), 75.1, 75.0 (2PhCH2), 74.8 (C-5C), 74.4 (PhCH2), 74.3
(C-2B), 73.6, 73.4 (2PhCH2), 72.9 (2C, C-3A and PhCH2), 72.6 (C-3C),
71.6 (C-5A), 69.9 (C-4C), 68.9 (C-4A), 68.6 (C-4B), 68.2 (2C, C-6C and
C-6D), 67.8 (C-6A), 67.6 (C-6B), 66.5 (C-4D), 56.3 (C-2C), 55.4 (OCH3),
20.7 (2C), 20.6 (3COCH3); ESI-MS: m/z 1673.4 [MþNH4]þ. Anal.
Calcd for C94H97NO26 (1655.63): C, 68.15; H, 5.90. Found: C, 67.94;
H, 6.14.
1750, 1663, 1595, 1440, 1373, 1222, 1048, 760 cmꢁ1; [
a
]
þ10 (c 1.2,
D
CHCl3); 1H NMR (400 MHz, CDCl3):
d 7.42–7.14 (m, 35H, Ar–H),
6.95–6.69 (m, 4H, Ar–H), 5.47–5.39 (m, 2H, H-7E and H-8E), 5.33 (s,
1H, PhCH), 5.30 (d, J¼9.3 Hz, 2H, H-1C and NHCOCH3), 4.95–4.86
(m, 2H, H-4E and PhCH2), 4.80 (d, J¼10.8 Hz, 1H, H-1A), 4.77–4.62
(m, 4H, PhCH2), 4.52 (d, J¼7.5 Hz, 1H, H-1B), 4.50–4.36 (m, 3H,
PhCH2), 4.32 (d, J¼8.6 Hz, 1H, H-1D), 4.30–4.15 (m, 8H, H-3C, H-4C,
H-6a,bA, H-9aE, and PhCH2), 4.13–4.08 (m, 4H, H-3A, H-4B, H-9bE, and
PhCH2), 4.06–4.04 (m, 2H, H-2D and H-5E), 4.02–3.86 (m, 5H, H-3D,
H-4D, H-6E, and H-6a,bD), 3.83–3.76 (m, 2H, H-2C and H-3B), 3.74 (s,
3H, OCH3), 3.59 (s, 3H, OCH3), 3.54–3.50 (m, 2H, H-2A and H-6aB),
3.48–3.38 (m, 4H, H-2B, H-5D, and H-6a,bC), 3.36–3.28 (m, 4H, H-4A,
H-5B, H-5C, and H-6bB), 3.18–3.06 (m, 1H, H-5A), 2.74 (dd, J¼12.0,
4.8 Hz, 1H, H-3eE), 2.16, 2.14, 2.04, 2.02, 2.0, 1.89 (6s, 18H, 6COCH3),
4.1.7. 4-Methoxyphenyl (4,6-O-benzylidene-
(1/4)-(2-acetamido-6-O-benzyl-2-deoxy-
(1/3)-(2,6-di-O-benzyl- -galactopyranosyl)-(1/4)-2,3,6-
tri-O-benzyl- -glucopyranoside (16)
To a solution of compound 15 (2.5 g, 1.5 mmol) in EtOH (70 mL)
was added hydrazine monohydrate (0.4 mL, 8.2 mmol) and the
reaction mixture was allowed to stir at 80 ꢀC for 6 h. The solvents
were removed under reduced pressure and a solution of the crude
mass in acetic anhydride–pyridine (10 mL, 1:1 v/v) was kept at
room temperature for 6 h and evaporated to dryness. A solution of
the acetylated product in 0.1 M CH3ONa (60 mL) was allowed to stir
at room temperature for 2 h and neutralized with Amberlite-IR 120
b
-D
-galactopyranosyl)-
b-D-glucopyranosyl)-
b-D
b-D
1.99–1.97 (m, 1H, H-3aE); 13C NMR (100 MHz, CDCl3):
d 170.6 (2C),
170.3 (2C), 170.1 (2C) (6COCH3), 168.3 (COOCH3), 155.3–114.4 (Ar–
C), 103.6 (C-1B), 102.6 (C-1A), 101.8 (C-1D), 100.7 (PhCH), 98.7 (C-1C),
97.2 (C-2E), 82.5 (C-2A), 82.0 (C-3B), 81.5 (C-3D), 78.8 (C-5B), 78.7 (C-
5D), 78.7 (C-2D), 75.6 (C-5A), 75.1 (2C, PhCH2), 74.6 (2C, C-2B and C-
5C), 74.2 (2C, C-3A and PhCH2), 73.3 (2C, PhCH2), 72.9 (2C, C-4B and
PhCH2), 72.6 (2C, C-4D and C-5E), 70.8 (C-4C), 70.1 (C-3C), 69.0 (C-
4E), 68.7 (2C, C-6D and C-7E), 68.5 (2C, C-6C and C-8E), 68.3 (2C, C-6A

8690
P.K. Mandal, A.K. Misra / Tetrahedron 64 (2008) 8685–8691
25
and C-6B), 67.1 (C-4A), 62.4 (C-9E), 56.4 (C-6E), 55.5 (OCH3), 52.8
(COOCH3), 49.5 (C-2C), 38.3 (C-3E), 23.0, 22.6, 20.7 (4C) (6COCH3);
ESI-MS: m/z 1937.7 [MþNa]þ. Anal. Calcd for C102H118N2O34
(1914.76): C, 63.94; H, 6.21. Found: C, 63.76; H, 6.45.
0.2 (CH3CN–CH3OH–H2O 1:1:0.5); [
a
]
D
ꢁ9.0 (c 1.1, H2O); IR (KBr):
3021, 2361, 1730, 1217, 1046, 763 cmꢁ1
;
1H NMR (400 MHz, D2O):
d
7.06 (d, J¼8.8 Hz, 2H, Ar–H), 6.84 (d, J¼8.8 Hz, 2H, Ar–H), 4.82 (2d,
J¼7.5 Hz, 2H, H-1A, H-1C), 4.46 (2d, J¼7.8 Hz, 2H, H-1B, H-1D), 4.18–
4.0 (m, 4H, H-3C, H-4B, H-4D, H-8E), 3.98–3.80 (m, 9H, H-3A, H-3B,
H-3D, H-4A, H-4C, H-6a,bA, H-6E, H-7E), 3.79–3.70 (m, 8H, H-4E, H-5E,
H-6a,bB, H-6aC, OCH3), 3.68–3.57 (m, 8H, H-2C, H-2D, H-5A, H-6bC, H-
4.1.9. 4-Methoxyphenyl (2-acetamido-2-deoxy-
pyranosyl)-(1/3)-( -galactopyranosyl)-(1/4)-(2-acetamido-
2-deoxy- -glucopyranosyl)-(1/3)-( -galactopyranosyl)-
(1/4)- -glucopyranoside (1)
b-D-galacto-
b-D
b
-D
b
-D
6a,bD, H-9a,bE), 3.56–3.43 (m, 5H, H-2A, H-2B, H-5B, H-5C, H-5D), 2.82
b
-D
(dd, J¼12.2, 3.3 Hz, 1H, H-3eE), 2.02 (s, 6H, 2NHCOCH3), 1.70 (t,
To a solution of compound 14 (1.5 g, 0.7 mmol) in EtOH
(50 mL) was added hydrazine monohydrate (1 mL, 20.6 mmol)
and the reaction mixture was allowed to stir at 80 ꢀC for 6 h. The
solvents were removed under reduced pressure and a solution of
the crude mass in acetic anhydride–pyridine (10 mL, 1:1 v/v) was
kept at room temperature for 6 h and evaporated to dryness. A
solution of the acetylated product in 0.1 M CH3ONa (50 mL) was
allowed to stir at room temperature for 10 h and neutralized with
Dowex 50W X8 (Hþ) resin. The reaction mixture was filtered and
concentrated. To a solution of the deacetylated product in CH3OH
(20 mL) was added 20% Pd(OH)2–C (400 mg) and the reaction
mixture was allowed to stir at room temperature for 24 h under
positive pressure of hydrogen. The reaction mixture was filtered
through a CeliteÒ bed, concentrated, and purified by passing
through a column of Sephadex LH-20 using CH3OH–H2O (4:1) as
J¼12.2 Hz, 1H, H-3aE); 13C NMR (100 Hz, D2O):
d 175.5 (2C, COONa,
NHCOCH3), 174.8 (NHCOCH3), 156.6–115.7 (Ar–C), 104.9 (2C, C-1B,
C-1D), 103.1 (2C, C-1A, C-1C), 101.0 (C-2E), 80.5 (2C, C-2D, C-5A), 77.5
(C-2A), 77.0 (C-2B), 76.5 (4C, C-3C, C-4A, C-5B, C-5D), 76.1 (C-5C), 74.8
(C-3A), 74.6 (2C, C-3B, C-4B), 72.9 (C-6E), 71.2 (C-4C), 70.6 (C-7E), 70.0
(2C, C-3D, C-8E), 69.6 (C-4D), 69.2 (C-4E), 64.4 (C-9E), 62.7 (C-6A),
62.4 (C-6C), 61.7 (2C, C-6B, C-6D), 56.1 (OCH3), 53.6 (2C, C-2C, C-5E),
42.1 (C-3E), 22.1 (2C, NHCOCH3); ESI-MS: m/z 1127.2 [Mþ1]þ. Anal.
Calcd for C44H67N2NaO30 (1126.37): C, 46.89; H, 5.99. Found: C,
46.67; H, 6.25.
Acknowledgements
Instrumentation facilities from SAIF, CDRI is gratefully ac-
knowledged. P.K.M. thanks CSIR, New Delhi for providing a Senior
Research fellowship. A.K.M. thanks Department of Science and
Technology (DST), New Delhi for providing Ramanna Fellowship
(SR/S1/RFPC-06/2006).
eluant to give compound 1 (500 mg, 70%). Rf 0.3 (CHCl3–CH3OH–
25
H2O 2:1:0.4); white powder; [
a
]
ꢁ10 (c 1.2, H2O); IR (KBr): 3445,
D
2361, 1670, 1649, 1541, 1462, 1026, 767 cmꢁ1
D2O):
;
1H NMR (400 MHz,
d
7.20 (d, J¼9.0 Hz, 2H, Ar–H), 7.04 (d, J¼9.0 Hz, 2H, Ar–H),
5.08 (d, J¼7.8 Hz, 1H, H-1D), 4.74 (d, J¼8.4 Hz, 1H, H-1C), 4.66 (d,
J¼8.1 Hz, 1H, H-1E), 4.51 (2d, J¼7.7 Hz, 2H, H-1A and H-1B), 4.19
(br s, 2H, H-4B and H-4D), 4.07–3.95 (m, 4H, H-2E, H-3C, H-4E, and
H-6aE), 3.90–3.86 (m, 2H, H-2C and H-6bE), 3.85 (s, 3H, OCH3),
3.84–3.72 (m, 15H, H-3A, H-3B, H-3D, H-3E, H-4A, H-4C, H-5C, H-
Supplementary data
Supplementary data associated with this article can be found in
the online version, at doi:10.1016/j.tet.2008.07.004.
6
a,bA, H-6a,bB, H-6a,bC, and H-6a,bD), 3.71–3.67 (m, 2H, H-5A and H-
5E), 3.66–3.60 (m, 5H, H-2A, H-2B, H-2D, H-5B, and H-5D), 2.07 (s,
6H, 2NHCOCH3); 13C NMR (100 Hz, D2O):
174.2 (2C, 2NHCOCH3),
References and notes
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