Convergent synthesis of a common pentasaccharide-repeating unit corresponding to the O-specific polysaccharide of Escherichia coli O4:K3, O4:K6, and O4:K12

Article abstract of DOI:10.1016/j.tetasy.2010.04.056

A convergent chemical synthesis of a pentasaccharide found in the O-specific polysaccharide of Escherichia coli O4:K3, O4:K6, and O4:K12 has been achieved in excellent yield. A [3+2] block synthetic strategy has been adopted to couple a disaccharide donor 11 with a trisaccharide acceptor 10 for the construction of the pentasaccharide derivative 12 which on deprotection furnished target pentasaccharide 1 as its 4-methoxyphenyl glycoside. Disaccharide thioglycoside donor 11 and trisaccharide acceptor 10 were prepared from suitably protected monosaccharide intermediates. Yields were excellent in all steps.

Full text of DOI:10.1016/j.tetasy.2010.04.056

Tetrahedron: Asymmetry 21 (2010) 859–863
Contents lists available at ScienceDirect
Tetrahedron: Asymmetry
journal homepage: www.elsevier.com/locate/tetasy
Convergent synthesis of a common pentasaccharide-repeating unit
corresponding to the O-specific polysaccharide of Escherichia coli O4:K3,
O4:K6, and O4:K12
*
Rajib Panchadhayee, Anup Kumar Misra
Bose Institute, Division of Molecular Medicine, P-1/12, C.I.T. Scheme VII-M, Kolkata 700 054, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A convergent chemical synthesis of a pentasaccharide found in the O-specific polysaccharide of
Escherichia coli O4:K3, O4:K6, and O4:K12 has been achieved in excellent yield. A [3+2] block synthetic
strategy has been adopted to couple a disaccharide donor 11 with a trisaccharide acceptor 10 for the con-
struction of the pentasaccharide derivative 12 which on deprotection furnished target pentasaccharide 1
as its 4-methoxyphenyl glycoside. Disaccharide thioglycoside donor 11 and trisaccharide acceptor 10
were prepared from suitably protected monosaccharide intermediates. Yields were excellent in all steps.
Ó 2010 Elsevier Ltd. All rights reserved.
Received 7 April 2010
Accepted 28 April 2010
Available online 1 June 2010
1. Introduction
→2)-α-L-Rhap-(1→6)-α-D-Glcp-(1→3)-α-L-FucpNAc-(1→3)-β-D-GlcpNAc-(1→
3
↑
1
Escherichia coli is an extremely diverse bacterial species, which
colonizes in numerous niches in both the environment and animal
hosts. Although, E. coli and other commensal intestinal microor-
ganisms form a beneficial symbiotic relationship with their host,1
some strains of E. coli behave in a pathogenic nature and cause
serious disease both within the intestinal tract and elsewhere
within the host.2 Among several virulent E. coli strains, Shiga-tox-
in-producing E. coli (STEC) has emerged as a major cause of food-
borne infections. They are associated with outbreaks or sporadic
cases of bloody diarrhea, hemorrhagic colitis (HC), hemolytic ure-
mic syndrome (HUS), and thrombotic thrombocytopenic purpura
(TTP).3 In the past, several epidemics arose due to the infection
of STEC strains of serotype O157:H7.4 Besides E. coli O157, a num-
ber of diarrhea-causing STEC strains have been characterized
which include, E. coli O4, O26, O55, O103, O111, and O145.5 Jann
et al. reported the structure of a pentasaccharide-repeating unit
present in the O-specific polysaccharide of E. coli O4:K3, O4:K6,
and O4:K12 (Fig. 1).6 O-Specific polysaccharides (O-antigens)
present in the outer membrane of Gram-negative bacteria plays
a critical role during the initial stage of infection and immune re-
sponses in the host. Therefore, glycoconjugates corresponding to
the O-antigen could be very useful in the immunochemical stud-
ies for their bioevaluation as possible glyco-vaccine candidates.7
For the extensive biochemical studies of glycoconjugates of the
bacterial O-antigens it is essential to have substantial quantities
of oligosaccharides in hand. Since, the natural source cannot pro-
vide a large quantity of the oligosaccharides, chemical synthesis of
α-D-Glcp
Figure 1. Structure of the pentasaccharide-repeating unit corresponding to the
O-specific polysaccharide of Escherichia coli O4:K3, O4:K6, and O4:K12.
oligosaccharides is extremely useful in this context. As a part of
the ongoing program on the synthesis of microbial oligosaccha-
rides,8 we describe herein a convergent chemical synthesis of
the pentasaccharide-repeating unit corresponding to the O-spe-
cific polysaccharide from enterohemorrhagic E. coli O4:K3,
O4:K6, and O4:K12 as its 4-methoxyphenyl (PMP) glycoside using
a block synthetic approach (Fig. 2). The PMP group has been cho-
sen as a temporary anomeric protecting group9 for its easy re-
moval at the end of the chemical synthesis under oxidative
condition to furnish hexasaccharide hemiacetal useful in the prep-
aration of glycoconjugates.
2. Results and discussion
Synthesis of the target pentasaccharide as its PMP glycoside
(Fig. 2) has been achieved using a [3+2] block synthetic strategy.
The synthetic strategy comprises a number of notable points,
which are (a)
derivative 3, prepared from
armed’ concept in the iodonium ion-mediated glycosylation of two
thioglycoside derivatives tuning one as donor and the other as
acceptor;10 (c) exclusively stereoselective glycosylation of a disac-
charide donor 11 with a trisaccharide acceptor 10, and (d) use of
the PMP group as a temporary anomeric protecting group.
a
-selective glycosylation of 2-azido-
L-fucosamine
L-fucose; (b) application of ‘armed–dis-
* Corresponding author. Tel.: +91 33 2569 3240; fax: +91 33 2355 3886.
E-mail address: akmisra69@gmail.com (A.K. Misra).
0957-4166/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2010.04.056

860
R. Panchadhayee, A. K. Misra / Tetrahedron: Asymmetry 21 (2010) 859–863
OH
O
Ph
O
O
O
HO
A
A
a
O
OPMP
O
OPMP
2 + 3
NPhth
NHAc
NHAc
O
B
O
B
N3
OR2
R1O
7: R1 = R2 = Ac
8: R1 = Ac; R2 = H
HO
HO
O
HO
HO
O
C
b
O
D
O
c
4
HO
HO
O
OH
Ph
O
HO
HO
E
O
O
A
O
PMP: 4-Methoxyphenyl
OC(NH)CCl3
1
O
OPMP
OH
NPhth
O
B
N3
O
AcO
BnO
BnO
C
Ph
O
BnO
O
O
O
O
N3
RO
HO
OPMP
NPhth
OAc
3
AcO
BnO
9: R = Ac
10: R = H
Phth: Phthaloyl
2
d
OAc
SPh
O
BnO
BnO
O
Scheme 1. Reagents and conditions: (a) TMSOTf, CH2Cl2, ꢁ20 °C, 45 min, 73%; (b)
(i) 0.01 M CH3ONa, CH3OH, room temperature, 30 min; (ii) triethylorthoacetate, p-
TsOH, DMF, room temperature, 2 h; (iii) 80% AcOH, 30 min, room temperature, 90%;
(c) NIS, TfOH, CH2Cl2, ꢁ40 °C, 30 min, 70%; (d) 0.01 M CH3ONa, CH3OH, room
temperature, 30 min, 96%.
SEt
BnO
HO
OAc
5
4
OBn
O
BnO
BnO
SEt
OBn
6
2,3,4,6-tetra-O-benzyl-1-thio-b-D a
-glucopyranoside 618 using
combination of NIS and TfOH16 applying ‘arm-disarmed’ strategy10
Figure 2. Chemical structure of the synthesized pentasaccharide as its PMP
glycoside (1).
5 + 6
The trisaccharide derivative 10 was synthesized by sequentially
assembling three suitably protected monosaccharide derivatives
2,11 3,12 and 4.13 4-Methoxyphenyl 4,6-O-benzylidene-2-deoxy-
a
SPh
2-N-phthalimido-b-
samine hydrochloride in five steps) was allowed to condense with
3,4-di-O-acetyl-2-azido-2-deoxy- /b- -fucopyranosyl trichloro-
D-glucopyranoside 2 (prepared from D-gluco-
O
D
BnO
O
OAc
a
L
BnO
acetimidate 3 (prepared from L-fucose in four steps following
BnO
BnO
E
Roy et al.12) under Schmidt’s glycosylation condition14 to furnish
O
OBn
exclusively 4-methoxyphenyl (3,4-di-O-acetyl-2-azido-2-deoxy-
11
a-
L-fucopyranosyl)-(1?3)-4,6-O-benzylidene-2-deoxy-2-N-phtha-
limido-b- -glucopyranoside 7 in 73% yield. Presence of signals in
D
a
10
the NMR spectra [d 5.66 (d, J = 8.5 Hz, H-1A), 5.55 (s, PhCH), 4.66
(d, J = 3.6 Hz, H-1B) in the 1H NMR and d 102.9 (PhCH), 99.3 (C-
1B) and 98.7 (C-1A) in the 13C NMR spectra] unambiguously con-
firmed the formation of compound 7. Saponification of compound
7 followed by orthoesterification15 and hydrolysis of the resulting
orthoester resulted in the formation of 4-methoxyphenyl (4-O-
Ph
O
O
O
A
O
OPMP
NPhth
B
O
N3
O
AcO
BnO
acetyl-2-azido-2-deoxy-
idene-2-deoxy-2-N-phthalimido-b-
a
-
L
-fucopyranosyl)-(1?3)-4,6-O-benzyl-
-glucopyranoside in 90%
BnO
C
D
8
BnO
O
yield. Iodonium ion-mediated glycosylation of compound 8 with
thioglycoside donor 4 in the presence of a combination of N-iodo-
succinimide (NIS) and trifluoromethanesulfonic acid (TfOH)16
O
O
D
BnO
BnO
O
OAc
furnished 4-methoxyphenyl (6-O-acetyl-2,3,4-tri-O-benzyl-
glucopyranosyl)-(1?3)-(4-O-acetyl-2-azido-2-deoxy- -fucopyr-
anosyl)-(1?3)-4,6-O-benzylidene-2-deoxy-2-N-phthalimido-b-
-glucopyranoside 9 in 70% yield together with minor amount of
a-D-
BnO
BnO
E
a
-L
12
b, c, d, e
O
OBn
D
its b-isomer (ꢀ10%), which on deacetylation afforded the trisac-
charide derivative 10 in 96% yield. Formation of compound 9
was confirmed through spectral analysis [d 5.68 (d, J = 8.5 Hz,
H-1A), 5.55 (s, PhCH), 4.87 (br s, H-1B), 4.74 (d, J = 3.7 Hz, H-1C)
in the 1H NMR and d 103.0 (PhCH), 100.0 (C-1B), 99.8 (C-1C), 98.7
(C-1A) in the 13C NMR spectra] (Scheme 1).
1
Scheme 2. Reagents and conditions: (a) NIS, TfOH, CH2Cl2, ꢁ40 °C, 30 min, 81%
for 11 and 76% for 12; (b) ethylene diamine, n-BuOH, 90 °C, 8 h; (c) acetic
anhydride, pyridine, room temperature, 3 h; (d) H2, 20% Pd(OH)2–C, CH3OH–
AcOH, room temperature, 24 h; (e) (i) acetic anhydride, pyridine, room temper-
ature, 3 h; (ii) 0. 1 M CH3ONa, CH3OH, room temperature, 3 h, over all 70%.
In another experiment, phenyl 2-O-acetyl-4-O-benzyl-1-thio-
a-
L
-rhamnopyranoside 517 was allowed to condense with ethyl

R. Panchadhayee, A. K. Misra / Tetrahedron: Asymmetry 21 (2010) 859–863
861
to furnish phenyl (2,3,4,6-tetra-O-benzyl-
a
-
D
-glucopyranosyl)-
temperature for 45 min. The reaction was quenched with Et3N
(0.1 mL) and the reaction mixture was diluted with CH2Cl2
(50 mL). The organic layer was successively washed with satd NaH-
CO3 and water, dried (Na2SO4), and concentrated under reduced
pressure. The crude product was purified over SiO2 using hexane–
EtOAc (6:1) as eluant to give pure compound 7 (2.2 g, 73%). Color-
(1?3)-2-O-acetyl-4-O-benzyl-1-thio- -rhamnopyranoside 11 in
a-L
81% yield together with its b-isomer (<10%). Stereoselective forma-
tion of compound 11 was confirmed through spectral analysis [d
5.37 (br s, H-1D), 5.14 (d, J = 3.4 Hz, H-1E), 1.37 (d, J = 6.2 Hz,
CCH3) in the 1H NMR and d 93.0 (C-1E), 86.4 (C-1D), 18.2 (CCH3) in
the 13C NMR spectra of compound 11]. Stereoselective glycosyla-
tion of trisaccharide derivative 10 with disaccharide thioglycoside
11 in the presence of a combination of NIS and TfOH furnished
less oil; ½a 2D5
ꢂ
¼ ꢁ16:8 (c 1.0, CHCl3); mmax (neat): 2937, 2111,
1751, 1715, 1507, 1389, 1220, 1101, 1036, 967, 722 cmꢁ1
;
1H
NMR (500 MHz, CDCl3): d 7.87–7.84 (m, 9H, Ar-H), 6.81 (d,
J = 9.0 Hz, 2H, Ar-H), 6.71 (d, J = 9.0 Hz, 2H, Ar-H), 5.66 (d,
J = 8.5 Hz, 1H, H-1A), 5.55 (s, 1H, PhCH), 5.15 (dd, J = 11.0, 3.2 Hz,
1H, H-3B), 5.06 (d, J = 2.6 Hz, 1H, H-4B), 4.70 (t, J = 10.4 Hz each,
1H, H-3A), 4.66 (d, J = 3.6 Hz, 1H, H-1B), 4.54 (dd, J = 8.5, 8.5 Hz,
1H, H-2A), 4.39 (dd, J = 10.8, 3.9 Hz, 1H, H-6aA), 4.17–4.16 (m, 1H,
H-5B), 3.86 (t, J = 10.6 Hz each, 1H, H-6bA), 3.78–3.74 (m, 2H, H-
5A, H-4A), 3.70 (s, 3H, OCH3), 3.45 (dd, J = 11.0, 3.6 Hz, 1H, H-2B),
2.0 (s, 3H, COCH3), 1.93 (s, 3H, COCH3), 0.41 (d, J = 6.5 Hz, 3H,
CCH3); 13C NMR (125 MHz, CDCl3): d 170.4, 169.8 (2COCH3),
167.0, 167.1 (Phth), 156.0–114.9 (Ar-C), 102.9 (PhCH), 99.3 (C-1B),
98.7 (C-1A), 80.7 (C-4A), 75.8 (C-3A), 71.0 (C-4B), 69.7 (C-3B), 69.1
(C-6A), 67.1 (C-5A), 65.5 (C-5B), 58.1 (C-2B), 55.8 (C-2A), 53.1
(OCH3), 20.9, 20.8 (2COCH3), 10.6 (CCH3); ESI-MS: m/z 781.2
[M+Na]+; Anal. Calcd for C38H38N4O13 (758.24): C, 60.15; H, 5.05.
Found: C, 60.0; H, 5.30.
4-methoxyphenyl (2,3,4,6-tetra-O-benzyl-
(1? 3)-(2-O-acetyl-4-O-benzyl- -rhamnopyranosyl)-(1?6)-
(2,3, 4-tri-O-benzyl- -glucopyranosyl)-(1?3)-(4-O-acetyl-2-azi-
do-2-deoxy- -fucopyranosyl)-(1?3)-4,6-O-benzylidene-2-deoxy-
2-N-phthalimido-b- -glucopyranoside 12 in 76% yield. Spectral
a-D-glucopyranosyl)-
a
-L
a
-D
a-L
D
analysis of compound 12 confirmed its formation [d 5.71 (d,
J = 8.4 Hz, H-1A), 5.53 (s, PhCH), 5.15 (d, J = 3.4 Hz, H-1E), 4.79 (d,
J = 3.5 Hz, H-1C), 4.76 (d, J = 3.5 Hz, H-1B), 4.66 (br s, H-1D) in the 1H
NMR and d 102.8 (PhCH), 99.8 (C-1C), 99.7 (C-1B), 98.7 (C-1D), 98.6
(C-1A), 93.2 (C-1E) in the 13C NMR spectra of compound 12]. Finally,
transformation of N-phthalimido and azido groups to acetamido
group19,20 followed by deprotection of the pentasaccharide deriva-
tive furnished target compound 1 in 70% yield. Compound 1 was
characterized by the appearance of signals in the 1H NMR [d 4.87
(br s, H-1E), 4.85 (br s, H-1C), 4.82 (br s, H-1B), 4.68 (br s, H-1D),
4.65 (br s, H-1A)] and in the 13C NMR spectra [d 102.0 (C-1B),
100.4 (3C, C-1A, C-1C, C-1D), 95.3 (C-1E)] (Scheme 2).
4.3. 4-Methoxyphenyl (4-O-acetyl-2-azido-2-deoxy-
fucopyranosyl)-(1?3)-4,6-O-benzylidene-2-deoxy-2-N-
phthalimido-b- -glucopyranoside 8
a-L-
D
3. Conclusion
A solution of compound 7 (2.0 g, 2.63 mmol) in 0.01 M CH3ONa
in CH3OH (25 mL) was allowed to stir at room temperature for
30 min. The reaction mixture was neutralized with Dowex 50W
X-8 (H+) resin, filtered, and evaporated to dryness. To a solution
of the dry mass in dry DMF (10 mL) were added triethylorthoace-
tate (3.0 mL, 16.36 mmol) and p-TsOH (100 mg) and the reaction
mixture was allowed to stir at room temperature for 2 h. It was neu-
tralized with Et3N (1.0 mL) and the solvents were removed under
reduced pressure. A solution of the crude mass in 80% aq AcOH
(20 mL) was allowed to stir at room temperature for 30 min. The
reaction mixture was evaporated and co-evaporated with toluene
to give the crude product, which was purified over SiO2 using hex-
ane–EtOAc (5:1) as eluant to furnish pure compound 8 (1.7 g, 90%).
In summary, a convergent synthetic strategy for the preparation
of the common pentasaccharide-repeating unit corresponding to
the O-specific polysaccharide of E. coli O4:K3, O4:K6, and O4:K12
has been developed successfully. A successful stereoselective
[3+2] glycosylation allowed to achieve the target pentasaccharide
in minimum number of steps. A ‘armed–disarmed’ approach has
been applied for the preparation of disaccharide thioglycoside
derivative. All intermediate steps were reasonably high yielding
and reproducible for a scale-up preparation.
4. Experimental
Colorless oil; ½a D25
¼ ꢁ19:4 (c 1.0, CHCl3); mmax (neat): 2936, 2112,
ꢂ
4.1. General methods
1776, 1744, 1714, 1508, 1396, 1230, 1102, 1032, 966, 756 cmꢁ1
;
1H NMR (500 MHz, CDCl3): d 7.75–7.34 (m, 9H, Ar-H), 6.84 (d,
J = 9.0 Hz, 2H, Ar-H), 6.74 (d, J = 9.0 Hz, 2H, Ar-H), 5.72 (d,
J = 8.5 Hz, 1H, H-1A), 5.56 (s, 1H, PhCH), 4.97 (d, J = 2.5 Hz, 1H, H-
4B), 4.69 (t, J = 10.3 Hz each, 1H, H-3A), 4.67 (d, J = 3.8 Hz, 1H, H-
1B), 4.55 (dd, J = 8.5, 8.5 Hz, 1H, H-2A), 4.42 (dd, J = 10.5, 3.9 Hz,
1H, H-6aA), 4.15–4.08 (m, 2H, H-5B, H-3B), 3.90–3.86 (m, 1H, H-
6bA), 3.77–3.75 (m, 2H, H-4A, H-5A), 3.71 (s, 3H, OCH3), 3.29 (dd,
J = 10.5, 3.5 Hz, 1H, H-2B), 2.04 (s, 3H, COCH3), 0.50 (d, J = 6.5 Hz,
3H, CH3); 13C NMR (125 MHz, CDCl3): d 171.6 (COCH3), 167.1,
167.2 (Phth), 156.0–114.9 (Ar-C), 102.7 (PhCH), 99.6 (C-1B), 98.7
(C-1A), 81.2 (C-4A), 76.2 (C-3A), 73.8 (C-4B), 69.0 (C-6A), 68.2 (C-
3B), 67.1 (C-5B), 65.8 (C-5A), 61.2 (C-2B), 56.2 (C-2A), 55.8 (OCH3),
21.0 (COCH3), 15.6 (CCH3); ESI-MS: m/z 739.2 [M+Na]+; Anal. Calcd
for C36H36N4O12 (716.23): C, 60.33; H, 5.06. Found: C, 60.10; H, 5.38.
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
on a hot plate. Silica gel 230–400 mesh was used for column chro-
matography. 1H and 13C NMR, DEPT 135, 2D COSY, and HMQC
spectra were recorded on Brucker Avance DRX 500 MHz using
CDCl3 and CD3OD as solvents and TMS as internal reference unless
stated otherwise. Chemical shift values are expressed in d ppm.
ESI-MS were recorded on a Micromass Quttro II mass spectrome-
ter. Elementary analysis was carried out on Carlo Erba-1108 ana-
lyzer. Optical rotations were measured at 25 °C on a Perkin Elmer
341 polarimeter. Commercially available grades of organic solvents
of adequate purity are used in many reactions.
4.2. 4-Methoxyphenyl (3,4-di-O-acetyl-2-azido-2-deoxy-
a-L-
fucopyranosyl)-(1?3)-4,6-O-benzylidene-2-deoxy-2-N-
4.4. 4-Methoxyphenyl (6-O-acetyl-2,3,4-tri-O-benzyl-
a-D-glucopy-
phthalimido-b-D-glucopyranoside 7
ranosyl)-(1?3)-(4-O-acetyl-2-azido-2-deoxy- -fucopyranosyl)-
a
-L
(1?3)-4,6-O-benzylidene-2-deoxy-2-N-phthalimido-b-D-gluco-
To a solution of compound 2 (2.0 g, 3.97 mmol) and compound 3
pyranoside 9
(2.0 g, 4.76 mmol) in anhydrous CH2Cl2 (15 mL) was added trimeth-
ylsilyl trifluoromethane sulfonate (TMSOTf; 50
argon and the reaction mixture was allowed to stir at the same
l
L) at ꢁ20 °C under
To a solution of compound 8 (1.2 g, 1.67 mmol) and compound
4 (1.1 g, 2.05 mmol) in anhydrous CH2Cl2 (10 mL) was added MS

862
R. Panchadhayee, A. K. Misra / Tetrahedron: Asymmetry 21 (2010) 859–863
4 Å (1 g) and the reaction mixture was allowed to stir at room tem-
perature for 30 min under argon. It was cooled to ꢁ40 °C and N-
iodosuccinimide (NIS; 550 mg, 2.44 mmol) followed by TfOH
4.6. Phenyl (2,3,4,6-tetra-O-benzyl-
a-D-glucopyranosyl)-(1?3)-
2-O-acetyl-4-O-benzyl-1-thio- -rhamnopyranoside 11
a
-L
(5
l
L) was added to it. After stirring at the same temperature for
To a solution of compound 5 (1.0 g, 2.57 mmol) and compound
6 (1.6 g, 2.74 mmol) in anhydrous CH2Cl2 (10 mL) was added MS
4 Å (1 g) and the reaction mixture was allowed to stir at room
temperature for 30 min under argon. It was cooled to ꢁ40 °C
and N-iodosuccinimide (NIS; 620 mg, 2.75 mmol) followed by
30 min, the reaction was quenched with Et3N (50
lL) and the reac-
tion mixture was filtered through a CeliteÒ bed and washed with
CH2Cl2 (50 mL). The combined organic layer was washed with 5%
Na2S2O3, satd NaHCO3, water in succession, dried (Na2SO4), and
concentrated under reduced pressure. The crude product was puri-
fied over SiO2 using hexane–EtOAc (8:1) as eluant to give pure 9
TfOH (5
lL) was added to it. After stirring at the same tempera-
ture for 30 min, the reaction was quenched with Et3N (50
l
L)
(1.4 g, 70%). Colorless oil; ½a D25
ꢂ
¼ þ15:2 (c 1.0, CHCl3); mmax (neat):
and the reaction mixture was filtered through a CeliteÒ bed and
washed with CH2Cl2 (50 mL). The combined organic layer was
washed with 5% Na2S2O3, satd NaHCO3, water in succession, dried
(Na2SO4), and concentrated under reduced pressure. The crude
product was purified over SiO2 using hexane–EtOAc (8:1) as
2925, 2112, 1744, 1713, 1507, 1392, 1227, 1100, 1027, 827 cmꢁ1
;
1H NMR (500 MHz, CDCl3): d 7.49–7.21 (m, 24H, Ar-H), 6.83 (d,
J = 9.0 Hz, 2H, Ar-H), 6.73 (d, J = 9.0 Hz, 2H, Ar-H), 5.68 (d,
J = 8.5 Hz, 1H, H-1A), 5.55 (s, 1H, PhCH), 5.04 (d, J = 2.4 Hz, 1H,
H-4B), 4.89 (d, J = 11.2 Hz, 1H, PhCH2), 4.87 (br s, 1H, H-1B), 4.78
(t, J = 10.8 Hz each, 1H, H-3A), 4.74 (d, J = 3.7 Hz, 1H, H-1C), 4.72–
4.69 (m, 3H, PhCH2), 4.66 (m, 1H, PhCH2), 4.62 (dd, J = 8.5, 8.5 Hz,
1H, H-2A), 4.52 (d, J = 11.1 Hz, 1H, PhCH2), 4.42 (dd, J = 12.5,
3.9 Hz, 1H, H-6aA), 4.18 (m, 1H, H-6abC), 4.05 (m, 1H, H-5B), 3.88
(m, 2H, H-3B, H-6bA), 3.80–3.77 (m, 3H, H-4A, H-4C, H-5A), 3.72
(m, 1H, H-5C), 3.71 (s, 3H, OCH3), 3.47 (dd, J = 10.7, 3.5 Hz, 1H,
H-2B), 3.44 (m, 2H, H-2C, H-3C), 2.0 (s, 3H, COCH3), 1.9 (s, 3H,
COCH3), 0.36 (d, J = 6.5 Hz, 3H, CCH3); 13C NMR (125 MHz, CDCl3):
d 171.0, 170.6 (2COCH3), 167.0, 167.1 (Phth), 156.1–114.9 (Ar-C),
103.0 (PhCH), 100.0 (C-1B), 99.8 (C-1C), 98.7 (C-1A), 81.7 (C-4A),
81.1 (C-4C), 79.5 (C-3C), 77.0 (C-2C), 76.1 (C-3A), 75.9 (C-3B), 75.8,
75.0, 73.2 (3PhCH2), 73.0 (C-4B), 70.0 (C-5C), 69.2 (C-6A), 67.1 (C-
5A), 66.4 (C-5B), 63.0 (C-6C), 60.9 (C-2B), 56.2 (C-2A), 56.0 (OCH3),
21.2, 21.1 (2COCH3), 15.7 (CCH3); ESI-MS: m/z 1213.4 [M+Na]+;
Anal. Calcd for C65H66N4O18 (1190.43): C, 65.54; H, 5.58. Found:
C, 65.35; H, 5.82.
eluant to give pure 11 (1.9 g, 81%). Colorless oil; ½a D25
¼ þ3:2 (c
ꢂ
1.0, CHCl3); mmax (neat): 2918, 1742, 1584, 1496, 1454, 1367,
1234, 1216, 1090, 911, 847, 748 cmꢁ1 1H NMR (500 MHz, CDCl3):
;
d 7.33–7.04 (m, 30H, Ar-H), 5.58 (br s, 1H, H-2D), 5.37 (br s, 1H, H-
1D), 5.14 (d, J = 3.4 Hz, 1H, H-1E), 4.97 (d, J = 11.0 Hz, 1H, PhCH2),
4.91 (d, J = 10.2 Hz, 1H, PhCH2), 4.84 (d, J = 11.0 Hz, 1H, PhCH2),
4.80 (d, J = 10.9 Hz, 1H, PhCH2), 4.67–4.63 (2d, J = 12.2 Hz, 2H,
PhCH2), 4.60–4.58 (m, 2H, PhCH2), 4.45 (d, J = 10.9 Hz, 1H, PhCH2),
4.34 (d, J = 12.0 Hz, 1H, PhCH2), 4.21–4.18 (m, 1H, H-5D), 4.13 (dd,
J = 9.4, 3.1 Hz, 1H, H-3D), 4.04 (t, J = 9.3 Hz each, 1H, H-4E), 4.02–
3.99 (m, 1H, H-5E), 3.69 (t, J = 9.4 Hz each, H-3E), 3.62–3.52 (m,
4H, H-2E, H-4D, H-6abE), 1.9 (s, 3H, COCH3), 1.37 (d, J = 6.2 Hz,
3H, CCH3); 13C NMR (125 MHz, CDCl3): d 170.5 (COCH3), 139.0–
127.8 (Ar-C), 93.0 (C-1E), 86.4 (C-1D), 82.4 (C-4E), 80.2 (C-2E),
79.6 (C-4D), 78.2 (C-3E), 76.6, 75.9, 75.3, 73.6, 73.4 (5PhCH2),
72.9 (C-3D), 70.6 (C-5E), 69.7 (C-2D), 69.6 (C-5D), 68.6 (C-6E),
21.2 (COCH3), 18.2 (CCH3); ESI-MS: m/z 933.3 [M+Na]+; Anal. Calcd
for C55H58O10S (910.37): C, 72.50; H, 6.42. Found: C, 72.27; H, 6.60.
4.5. 4-Methoxyphenyl (2,3,4-tri-O-benzyl-a-D-glucopyranosyl)-
(1?3)-(4-O-acetyl-2-azido-2-deoxy- -fucopyranosyl)-(1?3)-
a
-
L
4.7. 4-Methoxyphenyl (2,3,4,6-tetra-O-benzyl-
anosyl)-(1?3)-(2-O-acetyl-4-O-benzyl- -rhamnopyranosyl)-
(1?6)-(2,3,4-tri-O-benzyl- -glucopyranosyl)-(1?3)-(4-O-acetyl-
2-azido-2-deoxy- -fucopyranosyl)-(1?3)-4,6-O-benzylidene-
2-deoxy-2-N-phthalimido-b- -glucopyranoside 12
a-D-glucopyr-
4,6-O-benzylidene-2-deoxy-2-N-phthalimido-b-
D
-
a-L
glucopyranoside 10
a-D
a-L
A solution of compound 9 (1.2 g, 1.0 mmol) in 0.01 M CH3ONa
in CH3OH (20 mL) was allowed to stir at room temperature for
30 min. The reaction mixture was neutralized with Dowex 50W
X-8 (H+) resin, filtered, and evaporated to dryness. The crude prod-
uct was passed through a short pad of SiO2 using hexane–EtOAc
(4:1) as eluant to give pure compound 10 (1.1 g, 96%). Colorless
D
To a solution of compound 10 (1.0 g, 0.87 mmol) and compound
11 (950 mg, 1.04 mmol) in anhydrous CH2Cl2 (10 mL) was added
MS 4 Å (1 g) and the reaction mixture was allowed to stir at room
temperature for 30 min under argon. It was cooled to ꢁ40 °C and
N-iodosuccinimide (NIS; 260 mg, 1.15 mmol) followed by TfOH
oil; ½a 2D5
ꢂ
¼ ꢁ1:6 (c 1.0, CHCl3); mmax (neat): 2931, 2112, 1715,
1507, 1390, 1230, 1100, 1029, 970, 722 cmꢁ1
;
1H NMR (500 MHz,
(3
lL) was added to it. After stirring at the same temperature for
CDCl3): d 7.50–7.25 (m, 24H, Ar-H), 6.83 (d, J = 9.0 Hz, 2H, Ar-H),
6.72 (d, J = 9.0 Hz, 2H, Ar-H), 5.71 (d, J = 8.5 Hz, 1H, H-1A), 5.55 (s,
1H, PhCH), 5.07 (d, J = 2.5 Hz, 1H, H-4B), 4.86 (d, J = 10.9 Hz, 1H,
PhCH2), 4.81 (d, J = 11.1 Hz, 1H, PhCH2), 4.77 (d, J = 3.6 Hz, 1H, H-
1B), 4.75 (d, J = 3.6 Hz, 1H, H-1C), 4.70 (d, J = 11.1 Hz, 1H, PhCH2),
4.71–4.66 (m, 1H, H-3A), 4.66–4.65 (m, 2H, PhCH2), 4.61 (t,
J = 8.5, 8.5 Hz, 1H, H-2A), 4.56 (d, J = 11.1 Hz, 1H, PhCH2), 4.41
(dd, J = 10.5, 3.9 Hz, 1H, H-6aA), 4.07–4.05 (m, 1H, H-5B), 3.91–
3.88 (m, 2H, H-3B, H-6bA), 3.81 (t, J = 9.3, 9.3 Hz, 1H, H-4C), 3.77–
3.72 (m, 3H, H-4A, H-5A, H-6aC), 3.71 (s, 3H, OCH3), 3.55–3.51 (m,
3H, H-2B, H-5C, H-6bC), 3.40 (dd, J = 9.8, 3.4 Hz, 1H, H-2C), 3.38 (t,
J = 10.4, 10.4 Hz, 1H, H-3C), 2.0 (s, 3H, COCH3), 0.43 (d, J = 6.5 Hz,
3H, CCH3); 13C NMR (125 MHz, CDCl3): d 171.2 (COCH3), 167.0,
167.1 (Phth), 156.1–114.9 (Ar-C), 102.8 (PhCH), 99.8 (C-1B), 99.6
(C-1C), 98.7 (C-1A), 81.5 (C-4A), 81.2 (C-4C), 79.9 (C-3C), 77.8 (C-
2C), 76.2 (C-3A), 75.8 (PhCH2), 75.7 (C-3B), 75.1, 73.3 (2PhCH2),
73.0 (C-4B), 72.5 (C-5C), 69.1 (C-6A), 67.1 (C-5A), 66.4 (C-5B), 62.5
(C-6C), 60.9 (C-2B), 56.1 (C-2A), 56.0 (OCH3), 21.2 (COCH3), 15.8
(CCH3); ESI-MS: m/z 1171.4 [M+Na]+; Anal. Calcd for C63H64N4O17
(1148.43): C, 65.84; H, 5.61. Found: C, 65.63; H, 5.86.
30 min the reaction was quenched with Et3N (50
l
L) and the reac-
tion mixture was filtered through a CeliteÒ bed and washed with
CH2Cl2 (50 mL). The combined organic layer was washed with 5%
Na2S2O3, satd NaHCO3, water in succession, dried (Na2SO4), and
concentrated under reduced pressure. The crude product was puri-
fied over SiO2 using hexane–EtOAc (8:1) as eluant to give pure 12
(1.3 g, 76%). Colorless oil; ½a D25
¼ þ10:8 (c 1.0, CHCl3); mmax (neat):
ꢂ
2928, 2870, 2111, 1779, 1745, 1716, 1508, 1388, 1233, 1100, 1028,
915, 738 cmꢁ1 1H NMR (500 MHz, CDCl3): d 7.36–7.05 (m, 49H,
;
Ar-H), 6.82 (d, J = 9.0 Hz, 2H, Ar-H), 6.74 (d, J = 9.0 Hz, 2H, Ar-H),
5.71 (d, J = 8.4 Hz, 1H, H-1A), 5.53 (s, 1H, PhCH), 5.30 (s, 1H, H-
2D), 5.15 (d, J = 3.4 Hz, 1H, H-1E), 5.04 (d, J = 3.1 Hz, 1H, H-4B),
4.99–4.80 (m, 7H, PhCH2), 4.79 (d, J = 3.5 Hz, 1H, H-1C), 4.76 (d,
J = 3.5 Hz, 1H, H-1B), 4.70–4.68 (m, 1H, H-3A), 4.66 (br s, 1H, H-
1D), 4.71–4.52 (m, 8H, H-2A, PhCH2), 4.44–4.26 (m, 2H, H-5B,
PhCH2), 4.26 (d, J = 11.2 Hz, 1H, PhCH2), 4.18 (dd, J = 9.1, 3.0 Hz,
1H, H-3D), 4.10–4.07 (m, 2H, H-4E, H-5D), 4.05–4.00 (m, 1H,
H-5E), 3.85–3.68 (m, 8H, H-3B, H-3E, H-4A, H-4C, H-5A, H-6aC
H-6abA), 3.69 (s, 3H, OCH3), 3.58–3.51 (m, 7H, H-2B, H-2E, H-4D,
H-5C, H-6bC, H-6abE), 3.52–3.50 (m, 1H, H-3C), 3.42 (dd, J = 9.5,
,

R. Panchadhayee, A. K. Misra / Tetrahedron: Asymmetry 21 (2010) 859–863
863
3.5 Hz, 1H, H-2C), 1.98 (s, 3H, COCH3), 1.92 (s, 3H, COCH3), 1.37 (d,
J = 6.3 Hz, 3H, CCH3), 0.44 (d, J = 6.4 Hz, 3H, CCH3); 13C NMR
(125 MHz, CDCl3): d 170.8, 170.6 (2COCH3), 167.0, 167.1 (Phth),
156.1–114.9 (Ar-C), 102.8 (PhCH), 99.8 (C-1C), 99.7 (C-1B), 98.7
(C-1D), 98.6 (C-1A), 93.2 (C-1E), 82.5 (C-4E), 81.6 (C-4A), 81.2 (C-
4C), 80.5 (C-2E), 80.1 (C-3C), 79.6 (C-4D), 78.1 (C-3E), 77.6 (C-2C),
76.6 (PhCH2), 76.2 (C-3A), 75.9 (PhCH2), 75.8 (C-3B), 75.7, 75.3,
75.1, 73.7, 73.4, 73.3 (6PhCH2), 73.0 (C-4B), 72.7 (C-5C), 71.2 (C-
3D), 70.6 (C-5E), 69.1 (C-6C), 68.8 (C-6A), 68.6 (C-6E), 68.3 (C-5A),
68.1 (C-5B), 67.1 (C-2D), 66.5 (C-5D), 61.0 (C-2B), 56.1 (C-2A), 56.0
(OCH3), 21.3, 21.2 (2COCH3), 18.2, 15.9 (2CCH3); MALDI-MS: m/z
1971.8 [M+Na]+; Anal. Calcd for C112H116N4O27 (1948.78): C,
68.98; H, 6.00. Found: C, 68.80; H, 6.30.
Department of Science and Technology, New Delhi (SR/S1/RFPC-
06/2006) and Bose Institute, Kolkata.
References
1. Yan, F.; Polk, D. B. Curr. Opin. Gastroenterol. 2004, 20, 565–571.
2. (a) Kaper, J. B.; Nataro, J. P.; Mobley, H. L. T. Nat. Rev. Microbiol. 2004, 2, 123–
140; (b) Russo, T. A.; Johnson, J. R. J. Infect. Dis. 2000, 181, 1753–1754.
3. (a) Nataro, J. P.; Kaper, J. B. Clin. Microbiol. Rev. 1998, 11, 142–201; (b) Karmali,
M. A. Clin. Microbiol. Rev. 1989, 2, 15–38; (c) Tarr, P. I. Clin. Infect. Dis. 1994, 20,
1–10; (d) Paton, J. C.; Paton, A. W. Clin. Microbiol. Rev. 1998, 1, 450–479; (e)
Griffin, P. M.; Tauxe, R. V. Epidemiol. Rev. 1991, 13, 60–98; (f) Levine, M. M. J.
Infect. Dis. 1987, 155, 377–389.
4. (a) Keene, W. E.; McAnulty, J. M.; Hoesly, F. C.; Williams, L. P.; Hedberg, K.;
Oxman, G. L.; Barrett, T. J.; Pfaller, M. A.; Fleming, D. W. N. Eng. J. Med. 1994, 331,
579–584; (b) Heuvelink, A. E.; Wernars, K.; de Boer, E. J. Food Prot. 1996, 59,
1267–1272; (c) Pierard, D.; Van Damme, L.; Moriau, L.; Stevens, D.; Lauwers, S.
Appl. Environ. Microbiol. 1997, 63, 4585–4587; (d) Lindqvist, R.; Antonsson, A.
K.; Norling, B.; Persson, L.; Ekstrom, A. C.; Fager, U.; Eriksson, E.; Lofdahl, S.;
Norberg, P. Food Microbiol. 1998, 15, 591–601; (e) Abdulmawjood, A.; Bulte, M.;
Cook, N.; Roth, S.; Schonenbrucher, H.; Hoorfar, J. J. Microbiol. Methods 2003, 55,
775–786.
4.8. 4-Methoxyphenyl (
pyranosyl)-(1?6)-( -glucopyranosyl)-(1?3)-(2-acetamido-2-
deoxy- -fucopyranosyl)-(1?3)-2-acetamido-2-deoxy-b-
glucopyranoside 1
a-D-glucopyranosyl)-(1?3)-(a-L-rhamno-
a-D
a
-
L
D-
5. (a) Tozzi, A. E.; Caprioli, A.; Minelli, F.; Gianviti, A.; De Petris, L.; Edefanti, A.;
Montini, G.; Ferretti, A.; De Palo, T.; Gaido, M.; Rizzoni, G. Emerg. Infect. Dis.
2003, 9, 106–108; (b) Scotland, S. M.; Willshaw, G. A.; Smith, H. R.; Said, B.;
Stokes, N.; Rowe, B. Epidemiol. Infect. 1993, 111, 429–438.
To a solution of compound 12 (1.0 g, 0.51 mmol) in n-butanol
(10 mL) was added ethylene diamine (0.2 mL) and the reaction
mixture was allowed to stir at 90 °C for 8 h. The solvents were re-
moved under reduced pressure and a solution of the crude product
in acetic anhydride-pyridine (2 mL; 1:1 v/v) was kept at room tem-
perature for 3 h. The reaction mixture was evaporated and co-
evaporated with toluene and passed through a short pad of SiO2
using hexane–EtOAc (1:1) as eluant. To a solution of the crude
product in CH3OH–AcOH (10 mL; 8:1 v/v) was added 20%
Pd(OH)2–C (150 mg) and the reaction mixture was allowed to stir
at room temperature under a positive pressure of hydrogen for
24 h. It was filtered through a CeliteÒ bed and evaporated to dry-
ness. A solution of the crude product in acetic anhydride–pyridine
(2 mL; 1:1 v/v) was kept at room temperature for 3 h. The reaction
mixture was evaporated and co-evaporated with toluene and
passed through a short pad of SiO2 using hexane–EtOAc (1:1) as
eluant. Finally, a solution of the product in 0.1 M CH3ONa (5 mL)
was allowed to stir at room temperature for 3 h, neutralized using
Dowex 50W X-8 (H+) resin, filtered, and concentrated under re-
duced pressure. The crude product was purified over SephadexÒ
LH-20 column using CH3OH–H2O (8:1 v/v) as eluant to give pure
6. Jann, B.; Shashkov, A. S.; Kochanowski, H.; Jann, K. Carbohydr. Res. 1993, 248,
241–250.
7. (a) Roy, R. Drug Discovery Today: Technol. 2004, 1, 327–336. and references cited
therein; (b) Pozsgay, V. Angew. Chem., Int. Ed. 1998, 37, 138–142; (c)
Tamborrini, M.; Werz, D. B.; Frey, J.; Pluschke, G.; Seeberger, P. H. Angew.
Chem., Int. Ed. 2006, 45, 6581–6582; (d) Verez-Bencomo, V.; Fernández-
Santana, V.; Hardy, E.; Toledo, M. E.; Rodríguez, M. C.; Heynngnezz, L.;
Rodriguez, A.; Baly, A.; Herrera, L.; Izquierdo, M.; Villar, A.; Valdés, Y.; Cosme,
K.; Deler, M. L.; Montane, M.; Garcia, E.; Ramos, A.; Aguilar, A.; Medina, E.;
Toraño, G.; Sosa, I.; Hernandez, I.; Martínez, R.; Muzachio, A.; Carmenates, A.;
Costa, L.; Cardoso, F.; Campa, C.; Diaz, M.; Roy, R. Science 2004, 305, 522–525;
(e) Jansen, W. T. M.; Hogenboom, S.; Thijssen, M. J. L.; Kamerling, J. P.;
Vliegenthart, J. F. G.; Verhoef, J.; Snippe, H.; Verheul, A. F. Infect. Immun. 2001,
69, 787–793; (f) Meeks, M. D.; Saksena, R.; Ma, X.; Wade, T. K.; Taylor, R. K.;
Kovác, P.; Wade, W. F. Infect. Immun. 2004, 72, 4090–4101; (g) Taylor, R. K.;
Kirn, T. J.; Bose, N.; Stonehouse, E.; Tripathi, S. A.; Kovác, P.; Wade, W. F. Chem.
Biodivers. 2004, 1, 2036–2057.
8. (a) Mandal, P. K.; Misra, A. K. Bioorg. Chem. 2010, 38, 56–61; (b) Guchhait, G.;
Misra, A. K. Tetrahedron: Asymmetry 2009, 20, 1791–1797; (c) Ghosh, S.; Misra,
A. K. Tetrahedron: Asymmetry 2009, 20, 2688–2693; (d) Pandey, S.; Ghosh, S.;
Misra, A. K. Synthesis 2009, 2584–2590; (e) Panchadhayee, R.; Misra, A. K.
Tetrahedron: Asymmetry 2009, 20, 1550–1555; (f) Mandal, P. K.; Misra, A. K.
Synthesis 2009, 1348–1354; (g) Mukherjee, C.; Misra, A. K. Tetrahedron:
Asymmetry 2009, 20, 473–477; (h) Mandal, P. K.; Misra, A. K. Tetrahedron
2008, 64, 8685–8691; (i) Mandal, P. K.; Misra, A. K. Glycoconjugate J. 2008, 25,
713–722; (j) Mukherjee, C.; Misra, A. K. Tetrahedron: Asymmetry 2008, 19,
2746–2751; (k) Panchadhayee, R.; Misra, A. K. Glycoconjugate J. 2008, 25, 817–
826; (l) Kumar, R.; Maulik, P. R.; Misra, A. K. Glycoconjugate J. 2008, 25, 511–
519; (m) Mukherjee, C.; Misra, A. K. Glycoconjugate J. 2008, 25, 611–624; (n)
Tiwari, P.; Misra, A. K. Glycoconjugate J. 2008, 25, 85–99; (o) Mukherjee, C.;
Misra, A. K. Glycoconjugate J. 2008, 25, 111–119; (p) Mandal, P. K.; Misra, A. K.
Synthesis 2007, 2660–2666.
9. (a) Yan, S.; Liang, X.; Diao, P.; Yang, Y.; Zhang, J.; Wang, D.; Kong, F. Carbohydr.
Res. 2008, 343, 3107–3111; (b) Tamura, J.; Nakada, Y.; Taniguchi, K.; Yamane,
M. Carbohydr. Res. 2008, 343, 39–47; (c) Comegna, D.; Bedini, E.; Parrilli, M.
Tetrahedron 2008, 64, 3381–3391; (d) Attolino, E.; Rising, T. W. D. F.; Heidecke,
C. D.; Fairbanks, A. J. Tetrahedron: Asymmetry 2007, 18, 1721–1734.
10. (a) Mootoo, D. R.; Konradsson, P.; Fraser-Reid, B. J. Am. Chem. Soc. 1989, 111,
8540–8542; (b) Mootoo, D. R.; Konradsson, P.; Udodong, U.; Fraser-Reid, B. J.
Am. Chem. Soc. 1988, 110, 5583–5584.
11. Nakano, T.; Ito, Y.; Ogawa, T. Tetrahedron Lett. 1990, 31, 1597–1600.
12. Sarkar, K.; Mukherjee, I.; Roy, N. J. Carbohydr. Chem. 2003, 22, 95–107.
13. Ray, A. K.; Roy, N. Carbohydr. Res. 1990, 196, 95–100.
14. (a) Schmidt, R. R.; Jung, K.-H. In Preparative Carbohydrate Chemistry;
Hanessaian, S., Ed.; Marcel Dekker: New York, 1997. pp 283–312; (b)
Schmidt, R. R. Angew. Chem., Int. Ed. Engl. 1986, 25, 212–235.
compound 1 (350 mg, 70%). Glass; [
(KBr): 2926, 2372, 1738, 1661, 1550, 1516, 1429, 1377, 1030,
679 cmꢁ1 1H NMR (500 MHz, CD3OD): d 6.75–6.63 (m, 4H, Ar-
a]D = +9.2 (c 1.0, CH3OH); mmax
;
H), 4.87 (br s, 1H, H-1E), 4.85 (br s, 1H, H-1C), 4.82 (br s, 1H, H-
1B), 4.68 (br s, 1H, H-1D), 4.65 (br s, 1H, H-1A), 4.55–4.36 (m, 2H,
H-2A, H-3A), 4.35–4.21 (m, 2H, H-3B, H-3D), 4.11 (br s, 1H, H-4B),
4.05–3.76 (m, 5H, H-2D, H-3C, H-5C, H-6aA, H-6aC), 3.70–3.58 (m,
9H, H-2E, H-3E, H-4A, H-5D, H-5E, H-6bA, H-6bC, H-6abE), 3.57 (s,
3H, OCH3), 3.56–3.21 (m, 7H, H-2B, H-2C, H-4C, H-4D, H-4E, H-5A,
H-5B), 2.08, 1.91 (2s, 6H, 2COCH3), 1.32, 1.20 (2d, J = 6.0 Hz, 6H,
2CCH3); 13C NMR (125 MHz, CD3OD): d 169.6 (2C, 2COCH3),
156.0–114.7 (Ar-C), 102.0 (C-1B), 100.4 (3C, C-1A, C-1C, C-1D),
95.3 (C-1E), 80.4 (C-3A), 77.6 (C-3B), 77.4 (C-5A), 76.6 (C-3D), 73.9
(3C, C-2D, C-3C, C-3E), 72.5 (C-2E), 72.4 (3C, C-4D, C-4E, C-5E), 72.3
(2C, C-4B, C-5C), 72.0 (C-2C), 71.0 (C-4A), 70.6 (C-5D), 70.2 (C-5B),
68.5 (C-4C), 67.0 (C-6C), 61.5 (2C, C-6A, C-6E), 56.9 (C-2A), 55.1
(OCH3), 48.5 (C-2B), 20.2 (2C, 2COCH3), 17.2, 15.2 (2CCH3); ESI-
MS: m/z 1007.38 [M+Na]+; Anal. Calcd for C41H64N2O25 (984.38):
C, 50.00; H, 6.55. Found: C, 49.77; H, 6.81.
15. Field, R. A.; Otter, A.; Fu, W.; Hindsgaul, O. Carbohydr. Res. 1995, 276, 347–363.
16. (a) Veeneman, G. H.; van Leeuwen, S. H.; van Boom, J. H. Tetrahedron Lett. 1990,
31, 1331–1334; (b) Konradsson, P.; Udodong, U. E.; Fraser-Reid, B. Tetrahedron
Lett. 1990, 31, 4313–4316.
17. Zuurmond, H. M.; van der Laan, S. C.; van der Marel, G. A.; van Boom, J. H.
Carbohydr. Res. 1991, 215, C1–C3.
18. Boons, G. J.; Stauch, T. Synlett 1996, 906–908.
Acknowledgments
19. Spijker, N. M.; Keuning, C. A.; Hooglugt, M.; Veeneman, G. H.; van Boeckel, C. A.
A. Tetrahedron 1996, 52, 5945–5960.
20. Perlman, W. M. Tetrahedron Lett. 1967, 8, 1663–1664.
R.P. thanks CSIR, New Delhi, for providing a Senior Research Fel-
lowship. This work was supported by Ramanna Fellowship (AKM),