Synthesis of a tetrasaccharide corresponding to the teichoic acid from the cell wall of Streptomyces sp. VKM Ac-2275

Article abstract of DOI:10.1016/j.tetasy.2009.10.035

A concise chemical synthesis of a tetrasaccharide found in the teichoic acid from the cell wall of Streptomyces sp. VKM Ac-2275 was achieved in high yield. A [2+2] block synthetic strategy has been adopted for the construction of the target tetrasaccharid

Full text of DOI:10.1016/j.tetasy.2009.10.035

Tetrahedron: Asymmetry 20 (2009) 2688–2693
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Tetrahedron: Asymmetry
journal homepage: www.elsevier.com/locate/tetasy
Synthesis of a tetrasaccharide corresponding to the teichoic acid from the
cell wall of Streptomyces sp. VKM Ac-2275
*
Samir Ghosh, 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 concise chemical synthesis of a tetrasaccharide found in the teichoic acid from the cell wall of Strepto-
myces sp. VKM Ac-2275 was achieved in high yield. A [2+2] block synthetic strategy has been adopted for
the construction of the target tetrasaccharide by exploiting the orthogonal property of a thioglycoside.
For the first time, the 2-(4-methoxyphenoxy) ethyl group has been used as the anomeric protecting group
to make the glycone moiety with a readily available linker for its conjugation to a protein without
destroying the cyclic structure at the reducing end. Yields were high in all of the intermediate steps.
Ó 2009 Elsevier Ltd. All rights reserved.
Received 17 September 2009
Accepted 20 October 2009
Available online 24 November 2009
1. Introduction
β-D-Glcp
1
Potato scab, a commonly found infectious disease in potato,
causes serious damage in the agriculture industry.1 A group of bac-
teria, for example, Streptomyces sp., infect the potato and cause
parts of the vegetable to turn from a delicious vegetable into a
dry, corky substance that looks unpleasant and tastes worse. Strep-
tomyces scabiei is the most frequently known bacterial species for
causing potato scab.2 Among other potato scab-forming bacterial
species, Streptomyces sp. VKM-2275 is unique in nature as it does
not produce thaxtomin, a phytotoxin responsible for the inhibition
of cellulose biosynthesis in plants like others.3 In general, the cell
wall of plant pathogenic Streptomycetes species consists of differ-
ent polymers related to teichoic acids, such as teichuronic acids,
poly glycerol phosphates, poly ribitol phosphates, and Kdn poly-
mers4 Very often, these cell wall polymers are responsible for the
pathogenicity of the Streptomyces species.5 Recently, the structural
elucidation of the teichoic acid from the cell wall of Streptomyces
sp. VKM Ac-2275, isolated from the potato tubers infected by scab
lesions, has been reported by Streshinskaya et al. (Fig. 1).6 The cell
wall of Streptomyces sp. VKM Ac-2275 differs from that of other
scab-forming bacterial species, as it only contains anionic poly-
meric teichoic acid.
↓
6
→3)-β-D-Glcp-(1→1)-Gro
2
↑
1
α-L-Rhap (2-OAc)-(1→3)-β-D-GlcpNAc
Figure 1. Structure of the repeating unit of the teichoic acid of the cell wall of
Streptomyces sp. VKM Ac-2275.
jugates,7 we herein report a concise chemical synthesis of a
branched tetrasaccharide as its 2-(4-methoxyphenoxy) ethyl gly-
coside corresponding to the teichoic acid found in the cell wall of
the Streptomyces sp. VKM Ac-2275 (Fig. 2). The 2-(4-methoxyphen-
oxy) ethyl group at the anomeric position has been chosen for the
ready availability of an ethylene linker for its conjugation with a
suitable protein without destroying the cyclic structure at the
reducing end. A number of noteworthy features present in the syn-
thetic strategy, such as the use of (a) 2-(4-methoxyphenoxy) ethyl
group at the anomeric protecting group for the first time, (b) thio-
glycoside as an acceptor in the presence of thioglycoside as a gly-
cosyl donor under thioglycoside activation condition, (c) a block
synthetic strategy, and (d) one-pot multistep-protecting group
manipulation.
The development of anti-infective agents for controlling the
microbial infections in the crops has been an important concern
in the recent scenario. Since the pathogenicity emerges from the
bacterial cell wall teichoic acids, it is reasonable to synthesize oli-
gosaccharides related to them in order to study their role in the
pathogenicity. As a part of our program for the synthesis of com-
plex oligosaccharides for their use in the preparation of glycocon-
2. Results and discussion
In order to synthesize the target tetrasaccharide as its 2-(4-
methoxyphenoxy) ethyl glycoside 1, a block synthetic strategy
has been adopted. A disaccharide thioglycoside donor 14 was
* Corresponding author. Tel.: +91 33 2569 3240; fax: +91 33 2355 3886.
E-mail address: akmisra69@rediffmail.com (A.K. Misra).
0957-4166/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2009.10.035

S. Ghosh, A. K. Misra / Tetrahedron: Asymmetry 20 (2009) 2688–2693
2689
OH
O
disaccharide derivative 11 in 88% yield. Characteristic signals in
the NMR spectra confirmed the formation of compound 11. By
applying a one-pot deacetylation–benzylation protocol,16 com-
pound 11 was transformed into disaccharide derivative 12, which
on treatment with palladium chloride17 furnished disaccharide
acceptor 13 in 78% yield.
HO
HO
B
HO
HO
HO
O
O
A
O
In another experiment,
L-rhamnose-derived thioglycoside 6 was
HO
O
OMPE
allowed to glycosylate with
D-glucosamine-derived thioglycoside 5
C
in the presence of a NIS–TfOH combination exploiting the orthog-
onal properties of compound 5 to give disaccharide thioglycoside
derivative 14 in 80% yield. It is worth mentioning that the simulta-
neous use of thioglycosides as donors and acceptors minimized the
protecting group manipulations. The presence of signals in the
NMR spectra [d 5.39 (d, J = 10.6 Hz, H-1C), 4.54 (d, J = 1.5 Hz, H-
1D), 2.72–2.62 (m, 2H, SCH2CH3), 1.21 (t, J = 7.4 Hz, 3H, SCH2CH3)
in the 1H NMR and d 102.4 (PhCH), 98.5 (C-1D), 82.4 (C-1C) in the
13C NMR spectra] supported the formation of compound 14.
The stereoselective glycosylation of disaccharide acceptor 13
and thioglycoside disaccharide donor 14 in the presence of a
NIS–TfOH combination furnished the tetrasaccharide derivative
15 in 75% yield. The appearance of signature signals in the NMR
spectra supported the formation of compound 15. Compound 15
was subjected to a series of functional group transformations
involving hydrazinolysis of the N-phthalimido group; acetylation
and hydrogenolysis over Pearlman’s catalyst17 furnished the target
tetrasaccharide as its 2-(4-methoxyphenoxy) ethyl glycoside in
71% yield. The structure of compound 1 was unambiguously sup-
ported by its 1D and 2D NMR spectroscopic analysis [d 4.92–4.87
(m, 1H, H-2D), 4.86 (d, J = 8.0 Hz, H-1C), 4.81 (br s, 1H, H-1D), 4.51
(d, J = 7.43 Hz, H-1A), 4.36 (d, J = 7.8 Hz, H-1B) in the 1H NMR and
d 103.9 (C-1B), 102.4 (C-1A), 101.1 (C-1C), 99.4 (C-1D) in the 13C
NMR spectra]. The 4-methoxyphenyl group of the anomeric linker
of compound 1 can be removed by treatment with ammonium ce-
ric nitrate (CAN) in methanol to produce the tetrasaccharide with a
hydroxyethyl linker at the reducing end without destroying the
cyclic structure of the reducing end (see Schemes 1 and 2).
HO
NHAc
O
O
1
D
O
OCH3
MPE:
HO
OAc
OH
OH
O
OCH3
O
BnO
BnO
HO
OMPE
2
OAll
O
3
OAc
Ph
O
O
O
AcO
AcO
SEt
SEt
HO
OAc
NPhth
4
5
SEt
O
BnO
BnO
OAc
6
Figure 2. Structure of the synthesized tetrasaccharide as its 2-(4-methoxyphenoxy)
ethyl glycoside corresponding to the teichoic acid of the cell wall of Streptomyces sp.
VKM Ac-2275.
prepared using the two thioglycosides 5 and 6 by selective activa-
tion of compound 6 in the presence of compound 5 tuning the
reactivity differences of the two thioglycosides under iodonium
ion-mediated glycosylation conditions. Compound 5 behaves as
an orthogonal thioglycoside donor by acting as a glycosyl acceptor.
Another disaccharide derivative 13 was prepared with a 2-(4-
methoxyphenoxy) ethyl group at the anomeric position. Finally
the stereoselective condensation of two disaccharide derivatives
13 and 14 furnished tetrasaccharide derivative 15, which was
deprotected to give the target tetrasaccharide as its 2-(4-methoxy-
phenoxy) ethyl glycoside 1. For this purpose, suitably protected 2-
(4-methoxyphenoxy) ethyl glucoside derivative 3 was prepared
OAc
O
OAc
O
2
b, c, d
AcO
AcO
AcO
AcO
OAc
OMPE
a
OAc
OAc
7
8
Ph
OH
O
O
O
O
f
BnO
BnO
BnO
OMPE
OMPE
OR
9: R = H
10: R = All
OAll
e
3
MPE:
OCH3
from
D-glucose penta-O-acetate 7 via a number of steps. Three
O
other monosaccharide derivatives 4,8 59, and 610 were prepared
following the literature-reported synthetic methodologies. Treat-
Scheme 1. Reagents and conditions: (a) 2-(4-methoxyphenoxy) ethanol, BF3ꢀOEt2,
CH2Cl2, 5 °C, 12 h, 82%; (b) 0.1 N CH3ONa, CH3OH, room temperature, 4 h; (c)
PhCH(OCH3)2, p-TsOH, CH3CN, room temperature, 12 h; (d) (i) Bu2SnO, CH3OH,
80 °C, 2 h; (ii) benzyl bromide, CsF, DMF, room temperature, 16 h, 72% in three
steps; (e) allyl bromide, NaOH, DMF, room temperature, 4 h, 93%; (f) LiAlH4, AlCl3,
CH2Cl2, Et2O, 1.5 h, 76%.
ment of penta-O-acetyl-b-
phenoxy) ethanol 211 in the presence of borontrifluoride etherate
furnished 2-(4-methoxyphenoxy) ethyl 2,3,4,6-tetra-O-acetyl-b-
D-glucopyranose 7 with 2-(4-methoxy-
D
-
glucopyranoside 8 in 82% yield. Compound 8 was converted to
compound 9 in 72% overall yield following a sequence of reactions
involving (a) saponification, (b) benzylidene acetal formation,12
and (c) selective benzylation13 via stannylidene acetal formation.
Allylation of compound 9 using allyl bromide in the presence of so-
dium hydroxide followed by regioselective ring opening of the
benzylidene acetal14 using lithium aluminim hydride–aluminim
chloride combination furnished compound 3 in 76% yield. Iodoni-
um ion-promoted stereoselective glycosylation of compound 3
with thioglycoside derivative 4 in the presence of N-iodosuccini-
mide (NIS) and trifluoromethanesulfonic acid (TfOH)15 afforded
3. Conclusion
In conclusion, the chemical synthesis of a tetrasaccharide re-
lated to the teichoic acid of the cell wall of Streptomyces sp. VKM
Ac-2275 as its 2-(4-methoxyphenoxy) ethyl glycoside was
achieved in excellent yield. The 2-(4-methoxyphenoxy) ethyl
group, which was used as the anomeric protecting group was
introduced for the first time to provide the oligosaccharide moiety
readily attached to an ethylene linker useful for the preparation of

2690
S. Ghosh, A. K. Misra / Tetrahedron: Asymmetry 20 (2009) 2688–2693
OAc
on a hot plate. Silica gel 230–400 mesh was used for column chro-
matography. 1H and 13C NMR, 2D COSY, HMQC spectra were re-
corded on Bruker Avance DRX 500 MHz using CDCl3 and D2O as
solvents and TMS as an internal reference unless stated otherwise.
Chemical shift value is expressed in d ppm. ESI-MS were recorded
on a Micromass Quttro II triple quadrupole mass spectrometer. Ele-
mentary analysis was carried out on Carlo ERBA-1108 analyzer.
Optical rotations were measured at 25 °C on a Perkin–Elmer 341
polarimeter. Commercially available grades of organic solvents of
adequate purity were used in many reactions.
O
AcO
AcO
B
O
a
AcO
BnO
BnO
3 + 4
O
A
OMPE
OAll
11
OBn
O
BnO
BnO
B
O
b
BnO
BnO
BnO
4.1.1. 2-(4-Methoxyphenoxy) ethyl 2,3,4,6-tetra-O-acetyl-b-D-
glucopyranoside 8
O
OMPE
A
To a solution of compound 7 (10 g, 25.64 mmol) and 2-(4-
methoxyphenoxy) ethanol (7 g, 41.62 mmol) in anhydrous CH2Cl2
(100 mL) was added MS 4 Å (5 g) and the reaction mixture was al-
lowed to stir at room temperature for 1 h. To the reaction mixture
was added BF3ꢀOEt2 (6.5 mL, 52.66 mmol) and it was allowed to
stir at 5 °C for 12 h. The reaction mixture was filtered through a
CeliteÒ bed and washed with CH2Cl2 (200 mL). The organic layer
was successively washed with satd NaHCO3 and H2O, dried
(Na2SO4), and concentrated under reduced pressure. The crude
product was purified over SiO2 using hexane/EtOAc (5:1) as eluant
OR
12: R = All
13: R = H
c
O
Ph
O
C
O
a
SEt
5 + 6
O
NPhth
O
D
to give pure
¼ ꢂ20:4 (c 1.0, CHCl3); IR (KBr): 3468, 2918, 2849, 1741,
1755, 1513, 1453, 1385, 1370, 1260, 1247, 1226, 1172, 1058,
1035, 901, 822 cmꢂ1 1H NMR (500 MHz, CDCl3): d 6.82–6.81 (m,
8 (10.5 g, 82%). White solid; mp 99–100 °C;
BnO
½ ꢁ
a 2D5
BnO
OAc
14
;
4H, Ar–H), 5.22 (t, J = 9.5 Hz, 1H, H-3), 5.10 (t, J = 9.8 Hz, 1H, H-
2), 5.04–5.00 (m, 1H, H-4), 4.68 (d, J = 8.0 Hz, 1H, H-1), 4.28–4.24
(dd, J = 4.7, 12.3 Hz, 1H, H-6a), 4.14–4.06 (m, 4H, H-6b, 2H–OCH2,
H–OCH2a), 3.94–3.90 (m, 1H, H–OCH2b), 3.76 (s, 3H, OCH3), 3.73–
3.70 (m, 1H, H-5), 2.10 (s, 3H, COCH3), 2.03 (s, 3H, COCH3), 2.00
(s, 3H, COCH3), 1.94 (s, 3H, COCH3); 13C NMR (125 MHz, CDCl3): d
171.1, 170.7, 169.8, 169.8 (4C, COCH3), 154.5–115.1 (Ar–C), 101.5
(C-1), 73.2 (C-2), 72.3 (C-3), 71.6 (C-5), 68.8 (2C, C-6, C-4), 68.4
(OCH2), 62.3 (OCH2), 56.1 (OCH3), 21.1, 21.0, 21.0, 20.9 (4C,
4COCH3); ESI-MS: 521.1 [M+Na]+. Anal. Calcd for C23H30O12
(498.17): C, 55.42; H, 6.07. Found: C, 55.25; H, 6.30.
OBn
O
BnO
BnO
B
BnO
O
BnO
BnO
d
a
13 + 14
1
A
O
O
OMPE
O
O
O
Ph
C
NPhth
O
4.1.2. 2-(4-Methoxyphenoxy) ethyl 3-O-benzyl-4,6-O-
benzylidene-b-D-glucopyranoside 9
O
D
BnO
OAc
A solution of compound 8 (10 g, 20.06 mmol) in 0.1 M CH3ONa
(150 mL) was allowed to stir at room temperature for 4 h and neu-
tralized with Amberlite IR-120 (H+) resin. The reaction mixture
was filtered and evaporated to dryness. To a solution of the crude
mass in CH3CN (50 mL) were added benzaldehyde dimethylacetal
(6 mL, 40 mmol) and p-TsOH (500 mg) and the reaction mixture
was allowed to stir at room temperature for 12 h. The reaction
was quenched with Et3N (2 mL) and the solvents were removed
under reduced pressure. To a solution of the crude product in
CH3OH (100 mL) was added dibutyltin oxide (7.5 g, 30.13 mmol)
and the reaction mixture was allowed to stir at 80 °C for 2 h. The
solvents were removed under reduced pressure and the crude
stannylidene acetal derivative was dissolved in anhydrous DMF
(50 mL). To the reaction mixture were added CsF (3.1 g, 20.4 mmol)
and benzyl bromide (4.8 mL, 40.36 mmol) and it was allowed to
stir at room temperature for 16 h. The solvents were removed un-
der reduced pressure and the crude mass was dissolved in EtOAc
(200 mL). The organic layer was washed with satd NaHCO3 and
H2O, dried (Na2SO4), and concentrated. The crude product was
purified over SiO2 using hexane/EtOAc (4:1) as eluant to give pure
OBn
15
Scheme 2. Reagents and conditions: (a) N-iodosuccinimide (NIS), trifluorometh-
anesulfonic acid (TfOH), CH2Cl2, ꢂ40 °C, 1 h, 88% for 11, 80% for 14 and 75% for 15;
(b) benzyl bromide, NaOH, TBAB, THF, room temperature, 4 h, 86%; (c) PdCl2,
CH3OH, room temperature, 2 h, 78%; (d) (i) NH2NH2ꢀH2O, C2H5OH, 80 °C, 4 h; (ii)
acetic anhydride, pyridine, room temperature, 2 h; (iii) H2, 20% Pd(OH)2–C, CH3OH,
room temperature, 24 h, 71% in three steps.
glycoconjugates without destroying the cyclic structure of the
monosaccharide of the reducing end. The use of a thioglycoside
as an orthogonal glycosyl acceptor under the thioglycoside activa-
tion conditions allowed us to obtain the target compound in the
minimum number of steps. Finally a block synthetic strategy has
been adopted for the preparation of a tetrasaccharide derivative.
Yields were excellent in all intermediate steps and reproducible.
4. Experimental
9 (7.3 g, 72%). White solid; mp 106–108 °C; ½a D25
¼ ꢂ31:1 (c 1.0,
ꢁ
4.1. General methods
CHCl3); IR (KBr): 3496, 2922, 2853, 1511, 1455, 1367, 1235,
1101, 1066, 1029, 822, 744, 735 cmꢂ1 1H NMR (500 MHz, CDCl3):
;
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
d 7.50–6.82 (m, 14H, Ar–H), 5.57 (s, 1H, PhCH), 4.95 (d, J = 11.7 Hz,
1H, PhCH2), 4.83 (d, J = 11.7 Hz, 1H, PhCH2), 4.50 (d, J = 7.6 Hz, 1H,

S. Ghosh, A. K. Misra / Tetrahedron: Asymmetry 20 (2009) 2688–2693
2691
H-1), 4.33–4.31 (dd, J = 4.9, 10.5 Hz, 1H, H-6a), 4.20–4.10 (m, 3H, H-
6b, OCH2a,b), 3.98–3.94 (m, 1H, OCH2a), 3.79 (t, J = 10.2 Hz, 1H, H-4),
3.76 (s, 3H, OCH3), 3.70–3.68 (m, 2H, H-3, H–OCH2b), 3.62 (t, J = 7.9,
7.9 Hz, 1H, H-2), 3.48–3.43 (m, 1H, H-5); 13C NMR (125 MHz,
CDCl3): d 138.8–115.1 (Ar–C), 104.3 (C-1), 101.7 (PhCH), 81.7 (C-
2), 80.6 (PhCH2), 75.0 (C-3), 74.8 (C-5), 69.2 (C-6), 69.1 (C-4),
68.3 (OCH2), 67.0 (OCH2), 56.1 (OCH3); ESI-MS: 531.2 [M+Na]+.
Anal. Calcd for C29H32O8 (508.21): C, 68.49; H, 6.34. Found: C,
68.30; H, 6.50.
[M+Na]+. Anal. Calcd for C32H38O8 (550.26): C, 69.80; H, 6.96.
Found: C, 69.62; H, 7.20.
4.1.5. 2-(4-Methoxyphenoxy) ethyl (2,3,4,6-tera-O-acetyl-b-D-
glucopyranosyl)-(1?6)-2-O-allyl-3,4-di-O-benzyl-b-D-
glucopyranoside 11
To a solution of compound 3 (1.5 g, 2.72 mmol) and compound
4 (1.3 g, 3.31 mmol) in CH2Cl2 (15 mL) was added MS 4 Å (3 g) and
the reaction mixture was allowed to stir under argon at room tem-
perature for 1 h. The reaction mixture was cooled to ꢂ40 °C and to
the cooled reaction mixture were added N-iodosuccinimide (NIS;
4.1.3. 2-(4-Methoxyphenoxy) ethyl 2-O-allyl-3-O-benzyl-4,6-O-
benzylidene-b-
D
-glucopyranoside 10
900 mg, 4 mmol) and trifluoromethanesulfonic acid (TfOH; 10 lL)
To a solution of compound 9 (5 g, 9.83 mmol) in THF (20 mL)
were added allyl bromide (1.7 mL, 19.64 mmol), powdered NaOH
(1.2 g, 30 mmol), and TBAB (200 mg, 0.62 mmol) and the reaction
mixture was allowed to stir at room temperature for 4 h. The reac-
tion mixture was diluted with CH2Cl2 (100 mL) and the organic
layer was washed with H2O, dried (Na2SO4), and concentrated un-
der reduced pressure. The crude product was purified over SiO2
using hexane/EtOAc (6:1) as eluant to give pure 10 (5 g, 93%).
and the reaction mixture was allowed to stir at the same temper-
ature for 1 h. The reaction mixture was filtered through a CeliteÒ
bed and washed with CH2Cl2 (100 mL). The organic layer was
washed with 5% Na2S2O3, satd NaHCO3 and H2O, dried (Na2SO4),
and concentrated under reduced pressure. The crude product was
purified over SiO2 using hexane/EtOAc (4:1) to give pure 11
(2.1 g, 88%). White solid; mp 105–107 °C; ½a D25
¼ ꢂ15:2 (c 1.0,
ꢁ
CHCl3); IR (KBr): 3473, 2932, 1747, 1510, 1381, 1234, 1178,
White solid; mp 95–97 °C; ½a D25
ꢁ
¼ ꢂ40:8 (c 1.0, CHCl3); IR (KBr):
1060, 914, 821, 749, 699 cmꢂ1 1H NMR (500 MHz, CDCl3): d
;
3446, 2917, 2873, 1510, 1365, 1235, 1096, 1073, 811, 744,
7.35–6.82 (m, 14H, Ar–H), 5.94–5.89 (m, 1H, CH2@CH–CH2),
5.26–5.22 (m, 2H, CH2@CH–CH2), 5.16 (t, J = 9.1 Hz, 1H, H-3B),
5.10 (t, J = 9.6 Hz, 1H, H-2B), 5.02 (m, 1H, H-4B), 4.94 (d,
J = 10.9 Hz, 1H, PhCH2), 4.85 (d, J = 10.9 Hz, 1H, PhCH2), 4.76 (d,
J = 10.9 Hz, 1H, PhCH2), 4.63 (d, J = 8.0 Hz, 1H, H-1B), 4.53 (d,
J = 10.9 Hz, 1H, PhCH2), 4.45–4.43 (m, 1H, CH2a–CH@CH2) 4.41 (d,
693 cmꢂ1 1H NMR (500 MHz, CDCl3): d 7.50–6.81 (m, 14H, Ar–
;
H), 5.96–5.90 (m, 1H, –CH2–CH@CH2), 5.55 (s, 1H, PhCH), 5.27–
5.13 (m, 2H, –CH2–CH@CH2), 4.89 (d, J = 11.5 Hz, 1H, PhCH2),
4.81 (d, J = 11.5 Hz, 1H, PhCH2), 4.54 (d, J = 7.7 Hz, 1H, H-1), 4.41–
4.39 (m, 1H, CH2a–CH@CH2), 4.33–4.30 (dd, J = 5.0, 10.5 Hz, 1H,
H-6a), 4.25–4.22 (m, 1H, CH2b–CH@CH2), 4.12–4.10 (m, 3H, H-6b,
OCH2a,b), 3.95–3.92 (m, 1H, OCH2a), 3.77 (t, J = 10.4 Hz, 1H, H-4),
3.76 (s, 3H, OCH3), 3.69–3.64 (m, 2H, H-3, OCH2b), 3.41–3.36 (m,
2H, H-5, H-2); 13C NMR (125 MHz, CDCl3): d 154.8–115.1 (Ar–C),
129.6 (CH2–CH@CH2), 117.4 (CH2–CH@CH2), 104.8 (C-1), 101.6
(PhCH), 82.2 (C-2), 81.6 (PhCH2), 81.1 (C-3), 75.5 (C-4), 74.4 (C-
5), 69.3 (C-6), 69.2 (CH2–CH@CH2), 68.1 (OCH2), 66.5 (OCH2), 56.1
(OCH3); ESI-MS: 571.2 [M+Na]+. Anal. Calcd for C32H36O8
(548.24): C, 70.06; H, 6.61. Found: C, 69.84; H, 6.85.
J = 7.7 Hz, 1H, H-1A), 4.22–4.10 (m, 7H, OCH2, OCH2a, H-6aB
,
CH2b–CH@CH2, H-6abA), 3.91–3.89 (m, 1H, OCH2b), 3.76 (s, 3H,
OCH3), 3.67–3.59 (m, 3H, H-5A, H-6bB, H-4A), 3.48 (m, 1H, H-5B),
3.39–3.31 (m, 2H, H-3A, H-2A), 2.04, 2.01, 1.99, 1.98 (4s, 12H,
4COCH3); 13C NMR (125 MHz, CDCl3): d 171.1, 170.7, 169.8, 169.5
(4C, 4COCH3), 154.4–115.1 (Ar–C), 128.9 (CH2–CH@CH2), 117.4
(CH2–CH@CH2), 104.1 (C-1A), 101.3 (C-1B), 84.9 (C-4A), 82.2 (C-
2A), 78.1 (C-3A), 76.1 (PhCH2), 75.3 (PhCH2), 75.2 (C-5B), 73.9
(CH2–CH@CH2), 73.4 (C-3B), 72.2 (C-4B), 71.7 (C-5A), 68.9 (C-6B),
68.8 (C-6A), 68.7 (C-2B), 68.2 (OCH2), 62.3 (OCH2), 56.1 (OCH3),
21.1, 21.1, 21.0, 20.9 (4C, 4COCH3); ESI-MS: 903.3 [M+Na]+. Anal.
Calcd for C46H56O17 (880.35): C, 62.72; H, 6.41. Found: C, 62.55;
H, 6.27.
4.1.4. 2-(4-Methoxyphenoxy) ethyl 2-O-allyl-3,4-di-O-benzyl-b-
D
-glucopyranoside 3
To a solution of compound 10 (3 g, 5.47 mmol) in CH2Cl2/Et2O
(60 mL, 1:1 v/v) was added LiAlH4 (1 g, 26.35 mmol) portionwise
and the reaction mixture was allowed to stir at 40 °C. To the stirred
reaction mixture was slowly added AlCl3 (3 g, 22.5 mmol) sus-
pended in Et2O (50 mL) for30 min and the reaction mixture was al-
lowed to stir at the same temperature for 1.5 h. The reaction
mixture was cooled and excess LiAlH4 was decomposed by EtOAc
(10 mL) and extracted with Et2O (100 mL). The organic layer was
washed with H2O, dried (Na2SO4), and evaporated to dryness.
The crude product was purified over SiO2 using hexane/EtOAc
4.1.6. 2-(4-Methoxyphenoxy) ethyl (2,3,4,6-tera-O-benzyl-b-D-
glucopyranosyl)-(1?6)-2-O-allyl-3,4-di-O-benzyl-b-D-
glucopyranoside 12
To a solution of compound 11 (2 g, 2.27 mmol) in THF (30 mL)
were added powdered NaOH (1 g, 25 mmol), benzyl bromide
(2 mL, 16.81 mmol), and n-Bu4NBr (200 mg, 0.62 mmol) and the
reaction mixture was allowed to stir at room temperature for
4 h. The reaction mixture was diluted with H2O (100 mL) and ex-
tracted with CH2Cl2 (100 mL). The organic layer was washed with
H2O, dried (Na2SO4), and concentrated under reduced pressure.
The crude product was purified over SiO2 using hexane/EtOAc
(4:1) to give pure 3 (2.3 g, 76%). Colorless oil; ½a D25
¼ ꢂ9:6 (c 1.0,
ꢁ
CHCl3); IR (neat): 3572, 3462, 3030, 2928, 2895, 2851, 1738,
1633, 1509, 1464, 1453, 1361, 1291, 1281, 1234, 1149, 1114,
1070, 1047, 1016, 1001, 914, 820, 754, 736, 699 cmꢂ1
;
1H NMR
(7:1) to give pure 12 (2.1 g, 86%). Yellow oil; ½a D25
¼ þ6:5 (c 1.0,
ꢁ
(500 MHz, CDCl3): d 7.36–6.81 (m, 14H, Ar–H), 5.94–5.86 (m, 1H,
CH2@CH–CH2), 5.26–5.12 (m, 2H, CH2@CH–CH2), 4.95 (d,
J = 10.9 Hz, 1H, PhCH2), 4.86 (d, J = 10.9 Hz, 1H, PhCH2), 4.80 (d,
J = 10.9 Hz, 1H, PhCH2), 4.63 (d, J = 10.9 Hz, 1H, PhCH2), 4.47 (d,
J = 7.8 Hz, 1H, H-1), 4.45–4.41 (m, 1H, CH2a–CH@CH2), 4.41–4.14
(m, 2H, CH2b–CH@CH2, OCH2a), 4.12–4.10 (m, 2H, OCH2a,b), 3.93–
3.91 (m, 1H, OCH2b), 3.85–3.82 (m, 1H, H-6a), 3.76 (s, 3H, OCH3),
3.71–3.70 (m, 1H, H-6b), 3.63 (t, J = 9.1 Hz, 1H, H-3), 3.54 (t,
J = 9.4 Hz, 1H, H-4), 3.38–3.21 (m,, 2H, H-5, H-2); 13C NMR
(125 MHz, CDCl3): d 154.5–115.1 (Ar–C), 128.9 (CH2–CH@CH2),
117.4 (CH2–CH@CH2), 104.3 (C-1), 84.8 (C-2), 82.3 (PhCH2), 77.8
(PhCH2), 76.1 (C-3), 75.5 (2C, C-5, C-4), 74.1 (C-6), 69.1 (CH2–
CH@CH2), 68.3 (OCH2), 62.4 (OCH2), 56.1 (OCH3); ESI-MS: 573.2
CHCl3); IR (neat): 3449, 3063, 3031, 2907, 1509, 1454, 1358,
1237, 1069, 913, 825, 747, 697 cmꢂ1 1H NMR (500 MHz, CDCl3):
;
d 7.33–6.78 (m, 34H, Ar–H), 5.95–5.87 (m, 1H, CH2@CH–CH2),
5.27–5.10 (m, 2H, CH2@CH–CH2), 4.97 (d, J = 11.1 Hz, 1H, PhCH2),
4.94 (d, J = 10.9 Hz, 1H, PhCH2), 4.89 (d, J = 10.9 Hz, 1H, PhCH2),
4.80 (d, J = 10.4 Hz, 1H, PhCH2), 4.77–4.71 (m, 4H, PhCH2), 4.60
(d, J = 12.0 Hz, 1H, PhCH2), 4.54–4.51 (m, 3H, PhCH2), 4.47 (d,
J = 7.8 Hz, 1H, H-1B), 4.43–4.39 (m, 1H, CH2a@CH–CH2), 4.34 (d,
J = 7.8 Hz, 1H, H-1A), 4.21–4.18 (m, 1H, H-6aA), 4.17–4.13 (m, 1H,
CH2b@CH–CH2), 4.06–4.02 (m, 1H, OCH2a), 3.95–3.87 (m, 2H,
OCH2ab), 3.72 (s, 3H, OCH3), 3.71–3.67 (m, 4H, H-6bA, H-6abB
,
OCH2b), 3.66–3.57 (m, 4H, H-2B, H-3B, H-4A, H-5A), 3.46–3.42 (m,
2H, H-5B, H-4B), 3.38 (m, 1H, H-3A), 3.32 (m, 1H, H-2A); 13C NMR

2692
S. Ghosh, A. K. Misra / Tetrahedron: Asymmetry 20 (2009) 2688–2693
(125 MHz, CDCl3): d 154.3–115.0 (Ar–C), 128.8 (CH2–CH@CH2),
117.4 (CH2–CH@CH2), 104.5 (C-1B), 103.9 (C-1A), 85.2 (C-2B), 85.0
(C-3B), 82.6 (C-2A), 82.4 (C-3A), 78.5 (C-4A), 78.2 (C-5A), 76.1
(PhCH2), 76.0 (PhCH2), 75.4 (C-5B), 75.4 (2C, 2 PhCH2), 75.3 (C-
4B), 75.1 (CH2–CH@CH2), 74.0 (PhCH2), 73.9 (PhCH2), 69.3 (C-6A),
69.2 (C-6B), 68.8 (OCH2), 68.0 (OCH2), 56.1 (OCH3); ESI-MS:
1095.5 [M+Na]+. Anal. Calcd for C66H72O13 (1072.50): C, 73.86; H,
6.76. Found: C, 73.65; H, 7.0.
(PhCH2), 71.3 (C-4C), 69.4 (C-2D), 69.1 (C-6C), 68.4 (C-5C), 55.8 (C-
2C), 24.7 (SCH2CH3), 21.1 (COCH3), 17.6 (SCH2CH3), 15.3 (CCH3);
ESI-MS: 832.2 [M+Na]+. Anal. Calcd for C45H47NO11S (809.29): C,
66.73; H, 5.85. Found: C, 66.55; H, 6.10.
4.1.9. 2-(4-Methoxyphenoxy) ethyl (2-O-acetyl-3,4-di-O-benzyl-
a
-
L
-rhamnopyranosyl)-(1?3)-4,6-O-benzylidene-2-deoxy-2-N-
phthalimido-b- -glucopyranosyl)-(1?2)-[(2,3,4,6-tera-O-
benzyl-b- -glucopyranosyl)-(1?6)]-3,4-di-O-benzyl-b-
glucopyranoside 15
D
D
D-
4.1.7. 2-(4-Methoxyphenoxy) ethyl (2,3,4,6-tera-O-benzyl-b-
D-
glucopyranosyl)-(1?6)-3,4-di-O-benzyl-b- -glucopyranoside 13
D
To a solution of compound 13 (1 g, 0.97 mmol) and compound
14 (940 mg, 1.16 mmol) in anhydrous CH2Cl2 (15 mL) was added
MS 4 Å (2 g) and the reaction mixture was allowed to stir under
argon at room temperature for 1 h. The reaction mixture was
To a solution of compound 12 (2 g, 1.86 mmol) in CH3OH
(30 mL) was added PdCl2 (200 mg, 1.13 mmol) and the reaction
mixture was allowed to stir at room temperature for 2 h. The sol-
vent was removed and the reaction mixture was diluted with
CH2Cl2 (100 mL). The organic layer was washed with satd NaHCO3,
dried (Na2SO4), and evaporated to dryness. The crude product was
purified over SiO2 using hexane/EtOAc (5:1) to give pure 13 (1.5 g,
cooled to ꢂ40 °C and NIS (300 g, 1.33 mmol) and TfOH (5
lL)
were added to it. After stirring at the same temperature for 1 h,
the reaction mixture was filtered through a CeliteÒ bed and
washed with CH2Cl2 (50 mL). The organic layer was washed with
5% Na2S2O3, satd NaHCO3 and H2O, dried (Na2SO4), and concen-
trated. The crude product was purified over SiO2 using hexane/
EtOAc (5:1) as eluant to give pure 15 (1.3 g, 75%). White solid;
78%). Colorless oil; ½a D25
¼ þ8:5 (c 1.0, CHCl3); IR (neat): 3581,
ꢁ
3494, 3060, 3031, 2907, 2861, 1509, 1454, 1382, 1358, 1234,
1178, 1069, 919, 826, 752, 735, 699 cmꢂ1 1H NMR (500 MHz,
;
CDCl3): d 7.33–6.79 (m, 34H, Ar–H), 4.97 (d, J = 11.1 Hz, 1H, PhCH2),
4.96 (d, J = 11.2 Hz, 1H, PhCH2), 4.89 (d, J = 10.9 Hz, 1H, PhCH2),
4.80 (d, J = 10.4 Hz, 1H, PhCH2), 4.79 (d, J = 11.2 Hz, 1H, PhCH2),
4.77–4.72 (m, 3H, PhCH2), 4.60 (d, J = 12.0 Hz, 1H, PhCH2), 4.55–
4.51 (m, 3H, PhCH2), 4.46 (d, J = 7.8 Hz, 1H, H-1B), 4.26 (d,
J = 7.5 Hz, 1H, H-1A), 4.22–4.20 (m, 1H, H-6aA), 4.03–3.99 (m, 1H,
OCH2a), 3.96–3.93 (m, 1H, OCH2a), 3.90–3.88 (m, 1H, OCH2b), 3.72
(s, 3H, OCH3), 3.71–3.66 (m, 4H, H-6bA, H-6abB, OCH2b), 3.63–3.54
(m, 5H, H-2B, H-3B, H-4A, H-5A, H-5B), 3.48–3.41 (m, 3H, H-2A H-
3A, H-4B); 13C NMR (125 MHz, CDCl3): d 154.5–115.1 (Ar–C),
103.4 (C-1B), 102.2 (C-1A), 85.2 (C-2B), 84.9 (C-3B), 82.6 (C-3A),
78.3 (C-4A), 78.2 (C-5A), 76.1 (PhCH2), 75.8 (C-5B), 75.5 (PhCH2),
75.4 (2C, PhCH2), 75.3 (C-2A), 75.2 (C-4B), 75.1 (PhCH2), 73.9
(PhCH2), 69.3 (C-4B), 69.2 (C-6A), 68.8 (OCH2), 68.2 (OCH2), 56.1
(OCH3); ESI-MS: 1055.4 [M+Na]+. Anal. Calcd for C63H68O13
(1032.47): C, 73.24; H, 6.63. Found: C, 73.05; H, 6.90.
mp 126–127 °C;
3031, 2924, 1775, 1745, 1717, 1508, 1454, 1387, 1234, 1070,
1028, 737, 697 cmꢂ1 1H NMR (500 MHz, CDCl3): d 7.46–6.80
½
a 2D5
ꢁ
¼ þ6:9 (c 1.0, CHCl3); IR (KBr): 3460,
;
(m, 53H, Ar–H), 5.71 (d, J = 8.6 Hz, 1H, H-1C), 5.47 (s, 1H, PhCH),
4.93 (d, J = 11.0 Hz, 1H, PhCH2), 4.88 (d, J = 10.9 Hz, 1H, PhCH2),
4.81–4.80 (m, 1H, H-2D), 4.78–4.70 (m, 4H, 4 PhCH2), 4.64 (d,
J = 12.0 Hz, 1H, PhCH2), 4.59 (d, J = 12.1 Hz, 1H, PhCH2), 4.54–
4.49 (m, 3H, 3 PhCH2), 4.45–4.39 (m, 8H, H-1A, H-1B, H-1D, H-
3C, 4 PhCH2), 4.34 (d, J = 11.2 Hz, 1H, PhCH2), 4.31 (t, J = 10.1 Hz,
1H, H-2C), 4.12–4.10 (m, 1H, H-6aA), 4.05–4.02 (m, 2H, OCH2),
3.84–3.82 (m, 2H, OCH2), 3.78–3.76 (m, 3H, H-6bA, H-6abC),
3.70–3.65 (m, 3H, H-4B, H-3D, H-5D), 3.69 (s, 3H, OCH3), 3.59–
3.51 (m, 7H, H-2B, H-3B, H-4A, H-5B, H-3A, H-6abB), 3.43–3.40
(m, 2H, H-2A, H-5A), 3.31 (t, J = 9.1 Hz, 1H, H-4C), 3.17 (t,
J = 9.5 Hz, 1H, H-4D), 1.73 (s, 3H, COCH3), 0.71 (d, J = 6.2 Hz, 3H,
CCH3); 13C NMR (125 MHz, CDCl3): d 169.8 (COCH3), 154.4–
115.1 (Ar–C), 104.4 (C-1D), 102.4 (2C, PhCH, C-1C), 98.6 (2C, C-
1B, C-1A), 85.1 (C-4A), 84.3 (C-5B), 82.5 (C-2A), 82.2 (C-5A), 80.9
(C-2B), 80.3 (C-3B), 78.5 (C-5C), 78.2 (C-4C), 78.0 (C-4D), 76.1
(PhCH2), 75.9 (C-5D), 75.4 (PhCH2), 75.3 (PhCH2), 75.2 (3C, 3
PhCH2), 75.1 (C-3A), 75.0 (C-4B), 73.9 (PhCH2), 71.8 (PhCH2),
69.3 (C-6C), 69.2 (C-3D), 69.1 (C-3C), 69.0 (C-6A), 68.5 (C-6B),
68.3 (2C, 2OCH2), 66.7 (C-2D), 57.3 (C-2C), 56.1 (OCH3), 21.0
(COCH3), 17.6 (CCH3); MALDI-TOF: 1802.7 [M+Na]+. Anal. Calcd
for C106H109NO24 (1779.73): C, 71.48; H, 6.17. Found: C, 71.26;
H, 6.40.
4.1.8. Ethyl (2-O-acetyl-3,4-di-O-benzyl-a-L-rhamnopyranosyl)-
(1?3)-4,6-O-benzylidene-2-deoxy-2-N-phthalimido-1-thio-b-D-
glucopyranoside 14
To a solution of compound 5 (1.5 g, 3.39 mmol) and compound
6 (1.6 g, 3.72 mmol) in anhydrous CH2Cl2 (25 mL) was added MS
4 Å (3 g) and the reaction mixture was allowed to stir at room tem-
perature for 1 h. The reaction mixture was cooled to ꢂ40 °C and
NIS (850 mg, 3.77 mmol) and TfOH (10 lL) were added to it. After
stirring at the same temperature for 1 h, the reaction mixture was
filtered through a CeliteÒ bed and washed with CH2Cl2 (100 mL).
The organic layer was washed with 5% Na2S2O3, satd NaHCO3
and H2O, dried (Na2SO4), and concentrated. The crude product
was purified over SiO2 using hexane/EtOAc (5:1) as eluant to give
4.1.10. 2-(4-Methoxyphenoxy) ethyl (
(1?3)-2-acetamido-2-deoxy-b- -glucopyranosyl)-(1?2)-[b-
glucopyranosyl)-(1?6)]-b- -glucopyranoside 1
To a solution of compound 15 (1 g, 0.56 mmol) in C2H5OH
(20 mL) was added NH2NH2ꢀH2O (150 L, 3.1 mmol) and the reac-
a-L-rhamnopyranosyl)-
D
D-
D
pure 14 (2.2 g, 80%). White solid; mp 143–145 °C; ½a D25
¼ ꢂ7:1 (c
ꢁ
1.0, CHCl3); IR (KBr): 3474, 3376, 2977, 2930, 2869, 1775, 1746,
1713, 1468, 1456, 1389, 1232, 11445, 1096, 1060, 1011, 994,
l
tion mixture was allowed to stir at 80 °C for 4 h. The solvents were
removed under reduced pressure and a solution of the crude prod-
uct in acetic anhydride–pyridine (5 mL, 1:1, v/v) was kept at room
temperature for 2 h. The solvents were removed under reduced
pressure and the crude product was passed through a short pad
of SiO2 using EtOAc as an eluant. To a solution of the crude product
in CH3OH (10 mL) was added 20% Pd(OH)2–C (200 mg) and the
reaction mixture was allowed to stir at room temperature under
a positive pressure of hydrogen for 24 h. The reaction mixture
was filtered through a CeliteÒ bed and evaporated to dryness.
The crude product was purified by passing through a column of
963, 917, 873, 745, 723, 699 cmꢂ1 1H NMR (500 MHz, CDCl3): d
;
7.50–7.21 (m, 19H, Ar–H), 5.54 (s, 1H, PhCH), 5.39 (d, J = 10.6 Hz,
1H, H-1C), 4.88–4.79 (m, 1H, H-2D), 4.78 (d, J = 10.9 Hz, 1H, PhCH2),
4.62 (t, J = 9.4 Hz, 1H, H-3C), 4.54 (d, J = 1.5 Hz, 1H, H-1D), 4.50–4.49
(m, 2H, 2-PhCH2), 4.42–4.39 (m, 2H, H-6aC, PhCH2), 4.36 (t,
J = 10.3 Hz, 1H, H-2C), 3.90–3.88 (m, 1H, 6bC), 3.83–3.80 (m, 2H,
H-3D, H-5D), 3.76–3.73 (m, 1H, H-5C), 3.65 (t, J = 9.1 Hz, 1H, H-
4C), 3.23 (t, J = 9.6 Hz, 1H, H-4D), 2.72–2.62 (m, 2H, SCH2CH3),
1.78 (s, 3H, COCH3), 1.21 (t, J = 7.4 Hz, 3H, SCH2CH3), 0.77 (d,
J = 6.2 Hz, 3H, CCH3); 13C NMR (125 MHz, CDCl3): d 170.0 (COCH3),
138.9–126.9 (Ar–C), 102.4 (PhCH), 98.5 (C-1D), 82.4 (C-1C), 80.8 (C-
4D), 80.4 (C-3D), 77.9 (C-3C), 76.3 (C-5D), 75.5 (PhCH2), 72.0
Sephadex LH-20 using CH3OH as an eluant to give pure
1
(350 mg, 71%). White powder; ½a D25
¼ ꢂ38 (c 1.0, CH3OH); IR
ꢁ

S. Ghosh, A. K. Misra / Tetrahedron: Asymmetry 20 (2009) 2688–2693
2693
4. (a) Shashkov, A. S.; Tulskaya, E. M.; Evtushenko, L. I.; Denisenko, V. A.; Ivanyuk,
V. G.; Stomakhin, A. A.; Naumova, I. B. Carbohydr. Res. 2002, 337, 2255–2261;
(b) Shashkov, A. S.; Kosmachevskaya, L. N.; Streshinskaya, G. M.; Evtushenko, L.
I.; Bueva, O. V.; Denisenko, V. A.; Naumova, I. B.; Stackebrandt, E. Eur. J. Biochem.
2002, 269, 6020–6025; (c) Shashkov, A. S.; Streshinskaya, G. M.;
Kosmachevskaya, L. N.; Senchenkova, S. N.; Evtushenko, L. I.; Naumova, I. B.
Carbohydr. Res. 2003, 338, 2021–2024.
5. Shashkov, A. S.; Streshinskaya, G. M.; Kosmachevskaya, L. N.; Evtushenko, L. I.;
Naumova, I. B. Mendeleev Commun. 2000, 167–168.
6. Streshinskaya, G. M.; Shashkov, A. S.; Senchenkova, S. N.; Bueva, O. V.; Stuparc,
O. S.; Evtushenko, L. I. Carbohydr. Res. 2007, 342, 659–664.
7. (a) Guchhait, G.; Misra, A. K. Tetrahedron: Asymmetry 2009, 20, 1791–1797; (b)
Pandey, S.; Ghosh, S.; Misra, A. K. Synthesis 2009, 2584–2590; (c)
Panchadhayee, R.; Misra, A. K. Tetrahedron: Asymmetry 2009, 20, 1550–1555;
(d) Mandal, P. K.; Misra, A. K. Synthesis 2009, 1348–1354; (e) Mukherjee, C.;
Misra, A. K. Tetrahedron: Asymmetry 2009, 20, 473–477; (f) Mandal, P. K.; Misra,
A. K. Tetrahedron 2008, 64, 8685–8691; (g) Mandal, P. K.; Misra, A. K.
Glycoconjugate J. 2008, 25, 713–722; (h) Mukherjee, C.; Misra, A. K.
Tetrahedron: Asymmetry 2008, 19, 2746–2751; (i) Panchadhayee, R.; Misra, A.
K. Glycoconjugate J. 2008, 25, 817–826; (j) Kumar, R.; Maulik, P. R.; Misra, A. K.
Glycoconjugate J. 2008, 25, 511–519; (k) Mukherjee, C.; Misra, A. K.
Glycoconjugate J. 2008, 25, 611–624; (l) Tiwari, P.; Misra, A. K. Glycoconjugate
J. 2008, 25, 85–99; (m) Mukherjee, C.; Misra, A. K. Glycoconjugate J. 2008, 25,
111–119; (n) Mandal, P. K.; Misra, A. K. Synthesis 2007, 2660–2666; (o)
Agnihotri, G.; Mandal, P. K.; Misra, A. K. Tetrahedron 2007, 63, 7240–7245; (p)
Agnihotri, G.; Misra, A. K. Tetrahedron Lett. 2006, 47, 8493–8497.
8. Vic, G.; Hasting, J. J.; Howarth, O. W.; Crout, D. H. G. Tetrahedron: Asymmetry
1996, 7, 709–720.
(KBr): 3407, 2926, 1736, 1649, 1554, 1510, 1459, 1377, 1236, 1057,
832, 609 cmꢂ1 1H NMR (500 MHz, CD3OD): d 6.92–6.83 (m, 4H,
;
Ar–H), 4.92–4.87 (m, 1H, H-2D), 4.86 (d, J = 8.0 Hz, 1H, H-1C), 4.81
(br s, 1H, H-1D), 4.51 (d, J = 7.43 Hz, 1H, H-1A), 4.36 (d, J = 7.8 Hz,
1H, H-1B), 4.17–4.11 (m, 4H, H-6abA, H-6aC, H-3A), 4.05–3.92 (m,
2H, H-6bC, H-5D), 3.88–3.80 (m, 2H, H-4B, H-6aB), 3.78–3.73 (m,
2H, H-2C, H-6bB), 3.74 (s, 3H, OCH3), 3.69–3.64 (m, 3H, H-3C, H-
3D, H-4A), 3.48–3.43 (m, 2H, H-3A, H-4C), 3.38–3.28 (m, 6H, H-2A,
H-3B, H-4D, H-5A, H-5B, H-5C), 3.23–3.20 (m, 1H, H-2B), 2.07, 2.03
(2s, 6H, 2COCH3), 1.26 (d, J = 6.1 Hz, 3H, CCH3); 13C NMR
(125 MHz, CD3OD): d 173.8 (NHCOCH3), 171.1 (COCH3) 154.6–
114.8 (Ar–C), 103.9 (C-1B), 102.4 (C-1A), 101.1 (C-1C), 99.4 (C-1D),
81.1 (C-3C), 77.0 (4C, C-3A, C-3B, C-5B, C-5C), 76.7 (C-2A), 75.8 (C-
2B), 74.1 (2C, C-2D, C-5A), 73.5 (C-4D), 73.1 (C-4C), 70.6 (C-4A),
70.3 (C-4B), 69.5 (C-5D), 69.2 (C-3D), 68.9 (C-6A), 68.7 (C-6C), 68.5
(C-6B), 61.8 (2C, OCH2), 56.4 (C-2C), 55.4 (OCH3), 20.1 (NHCOCH3),
19.9 (COCH3), 16.8 (CCH3); ESI-MS: 906.3 [M+Na]+. Anal. Calcd
for C37H57NO23 (883.33): C, 50.28; H, 6.50. Found: C, 50.05; H, 6.76.
Acknowledgments
S.G. thanks UGC, New Delhi, for providing a Senior Research Fel-
lowship. This work was supported by Ramanna Fellowship
(A.K.M.), Department of Science and Technology, New Delhi (SR/
S1/RFPC-06/2006).
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