Unexpected stereochemical outcome of activated 4,6-O-benzylidene derivatives of the 2-deoxy-2-trichloroacetamido-D-galacto series in glycosylation reactions during the synthesis of a chondroitin 6-sulfate trisaccharide methyl glycoside

Article abstract of DOI:10.1016/S0008-6215(99)00322-5

The synthesis of methyl (β-D-glucopyranosyluronic acid)-(1→3)-(2-acetamido-2-deoxy-6-O-sulfonato-β-D-galactopyranosyl)-(1→4)-(β-D-glucopyranosid)uronate trisodium salt, a chondroitin 6-sulfate trisaccharide derivative, is described. Loss of stereocontrol in glycosylation reactions involving activated 4,6-O-benzylidene derivatives of the 2-deoxy-2-trichloroacetamido-D-galacto series and D-glucuronic acid-derived acceptors was highlighted. This drawback was overcome through the use of phenyl 3,4,6-tri-O-acetyl-2-deoxy-1-thio-2-trichloroacetamido-β-D-galactopyranoside, which afforded the desired β-linked disaccharide derivative in high yield with an excellent stereoselectivity. This later was submitted to acid-catalyzed methanolysis, followed by benzylidenation, and condensed with methyl 2,3,4-tri-O-benzoyl-1-O-trichloroacetimidoyl-α-D-glucopyranuronate to afford the expected trisaccharide derivative. Subsequent transformation of the N-trichloroacetyl group into N-acetyl, mild acid hydrolysis, selective O-sulfonation at C-6 of the amino sugar moiety, and saponification afforded the target molecule as its sodium salt in high yield. Copyright (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0008-6215(99)00322-5

www.elsevier.nl/locate/carres
Carbohydrate Research 325 (2000) 93–106
Unexpected stereochemical outcome of activated
4,6-O-benzylidene derivatives of the
2-deoxy-2-trichloroacetamido- -galacto series in
D
glycosylation reactions during the synthesis of a
chondroitin 6-sulfate trisaccharide methyl glycoside
Fre´de´ric Be´lot, Jean-Claude Jacquinet *
Institut de Chimie Organique et Analytique, UPRES-A CNRS 6005, UFR Faculte´ des Sciences,
Uni6ersite´ d’Orle´ans, BP 6759, F-45067 Orle´ans, France
Received 5 October 1999; accepted 25 November 1999
Dedicated to Professor P. Sinay¨ on the occasion of his 62nd birthday.
Abstract
The synthesis of methyl (b-
topyranosyl)-(1“4)-(b- -glucopyranosid)uronate trisodium salt, a chondroitin 6-sulfate trisaccharide derivative, is
described. Loss of stereocontrol in glycosylation reactions involving activated 4,6-O-benzylidene derivatives of the
2-deoxy-2-trichloroacetamido- -galacto series and -glucuronic acid-derived acceptors was highlighted. This draw-
-galacto-
D
-glucopyranosyluronic acid)-(1“3)-(2-acetamido-2-deoxy-6-O-sulfonato-b-
D-galac-
D
D
D
back was overcome through the use of phenyl 3,4,6-tri-O-acetyl-2-deoxy-1-thio-2-trichloroacetamido-b-
D
pyranoside, which afforded the desired b-linked disaccharide derivative in high yield with an excellent stereoselectiv-
ity. This later was submitted to acid-catalyzed methanolysis, followed by benzylidenation, and condensed with methyl
2,3,4-tri-O-benzoyl-1-O-trichloroacetimidoyl-a-D-glucopyranuronate to afford the expected trisaccharide derivative.
Subsequent transformation of the N-trichloroacetyl group into N-acetyl, mild acid hydrolysis, selective O-sulfonation
at C-6 of the amino sugar moiety, and saponification afforded the target molecule as its sodium salt in high yield.
© 2000 Elsevier Science Ltd. All rights reserved.
Keywords: Glycosylation reactions; 2-Deoxy-2-trichloroacetamido-D-galactose derivatives; Chondroitin 6-sulfate trisaccharide
(GAGs). Chondroitins are built from dimeric
units composed of -glucuronic acid (GlcA)
and 2-acetamido-2-deoxy- -galactose (Gal-
NAc), namely [4)-b- -GlcpA-(1“3)-b-
GalpNAc-(1“]n, and contain, on average,
one sulfate group per disaccharide unit either
at C-4 or C-6 of the amino sugar moiety, but
several types having sulfate(s) at various posi-
tions are known [1]. They are located on the
cell surface and in the extracellular matrix,
and are involved in numerous important bio-
D
1. Introduction
D
D
D-
Chondroitin sulfates belong to a family of
structurally complex, microheterogeneous, lin-
ear polysaccharides called glycosaminoglycans
* Corresponding author. Tel.: +33-2-38417072; fax: +33-
2-38417281.
E-mail address: jean-claude.jacquinet@univ-orleans.fr (J.-
C. Jacquinet)
0008-6215/00/$ - see front matter © 2000 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(99)00322-5

94
F. Be´lot, J.-C. Jacquinet / Carbohydrate Research 325 (2000) 93–106
logical processes. In the case of chondroitin
6-sulfate, they, for example, play a role in
inhibition of human C1q factor [2], could be a
potent ligand for NKR-P1 proteins of NK
cells [3], and were found at increased levels in
human colon carcinoma [4] or articular carti-
lage of older individuals [5]. In order to study
these biological functions in more detail at the
molecular level, and since it is quite difficult to
get chemically pure fragments by chemical or
enzymatic degradation, the availability of syn-
thetic fragments is of prime importance.
the direct glycosylation of the low-reactive
4-OH group of -glucuronic acid derivatives
[12], is particularly well suited for the con-
struction of chondroitin fragments [9].
D
We first focused on the preparation of thio-
glycosides 4–6. Treatment with benzaldehyde
and trifluoroacetic acid of phenyl 2-deoxy-1-
thio-2-trichloroacetamido-b-
oside (2), easily prepared [11] from the corre-
sponding -gluco analogue through a high-
D
-galactopyran-
D
yielding three-step sequence, gave the
crystalline 4,6-O-benzylidene derivative 3 in
90% yield. Temporary protection at O-3 was
then achieved through chloroacetylation to
give crystalline 4 in 75% yield, and silylation
to give 5 in 92% yield. Acetylation of 2 with
acetic anhydride–pyridine gave crystalline 6 in
92% yield (Scheme 1).
Several syntheses of chondroitin 6-sulfate
fragments have been reported, such as those
of the basic reducing disaccharide [6], its
methyl glycoside [7] or its 4-methoxyphenyl
glycoside [8], or those of 4-methoxyphenyl
glycosides of the tri- and tetrasaccharide [8].
In all these syntheses, monosaccharide syn-
Another sequence was attempted starting
thons derived from -galactosamine were used
D
from inexpensive
D
-glucosamine with a view
as the amino sugar moiety. We also reported
[9] another approach based on selective inver-
sion of the configuration at C-4 of a glu-
cosamine-containing trisaccharide. We now
report on the use and the unexpected stereo-
chemical outcome of activated 4,6-O-benzyli-
dene derivative of the 2-deoxy-2-trichloro-
to preparing the corresponding trichloroace-
timidates. Treatment of 1,3,4,6-tetra-O-acetyl-
2-deoxy-2-trichloroacetamido-b- -glucopyran-
D
ose (7) [12] with 4-methoxyphenol and triflic
acid afforded crystalline 8 in 87% yield, which
was O-deacetylated with methanolic sodium
methoxide to give quantitatively the crys-
talline triol 9. Treatment of 9 with pivaloyl
chloride in pyridine afforded the crystalline
3,6-di-O-pivaloyl derivative 10a in 89% yield,
along with its 4,6-isomer 10b (9%). Inversion
of configuration at C-4 was then achieved [11]
through treatment of 10a with triflic anhy-
dride and pyridine in 1,2-dichloroethane at
−15 °C, followed by addition of water and
heating at 85 °C to give a mixture of 4,6- and
acetamido- -galacto series in the synthesis of
D
chondroitin 6-sulfate trisaccharide methyl gly-
coside 1.
3,4-di-O-pivaloyl- -galacto intermediates in a
D
1
ꢀ12:1 ratio (determined by integrated H
NMR, details not presented in Section 3),
which was directly O-deacylated to give the
crystalline triol 11 in 94% overall yield. Treat-
ment of 11, as described for 3, gave the crys-
talline 4,6-O-benzylidene derivative 12 in 85%
yield, which was then chloroacetylated at O-3
to afford 13 in 90% yield. Introduction of the
trichloroacetimidoyl group at C-1 was then
achieved by selective oxidative removal of the
anomeric 4-methoxyphenyl group using ceric
ammonium nitrate in toluene–acetonitrile–
water [13], followed by treatment with
trichloroacetonitrile and 1,8-diazabicyclo-
2. Results and discussion
The preparation of
D-galactosamine deriva-
tives, which could serve initially as glycosyl
donors and then as glycosyl acceptors after
coupling, was first examined. We demon-
strated [10] that 2-deoxy-2-trichloroacet-
amido-
glycosyl donors for the synthesis of 1,2-trans-
2-amino-2-deoxy- -glucosides, and that the
D
-glucose derivatives are very efficient
D
N-trichloroacetyl group in the products could
be easily transformed into N-acetyl under
neutral conditions. This method, which allows

F. Be´lot, J.-C. Jacquinet / Carbohydrate Research 325 (2000) 93–106
95
[5,4,0]-undec-7-ene (DBU) to give the crys-
talline a-imidate 14 in 61% overall yield.
Acetylation of 11 gave crystalline 15 in 85%
yield, which was similarly transformed into
the crystalline a-imidate 16 in 70% overall
yield. The physical data for 16 are in full
agreement with those reported [14] for a
disaccharide derivatives in a ꢀ3:1 ratio in
65% overall yield (Entry 1). Lowering the
temperature (Entry 2), or varying the nature
of the solvent (Entry 3) did not significantly
change the product distribution. Condensa-
tion of 5, bearing a bulky substituent at O-3,
with 20 under the same conditions (Entry 5)
afforded an inseparable mixture of disaccha-
rides in which the a-linked isomer was pre-
dominant (determined by integrated 1H
NMR, details not presented in Section 3).
Similar results were obtained when the imi-
date 14 and the alcohol 20 were condensed in
dichloromethane (Entry 6) or toluene (Entry
7) under the catalysis of trimethylsilyl triflate.
However, coupling of the O-acetylated thio-
glycoside 6 with 20 (Entry 8) or 19 (Entry 9),
or coupling of the O-acetylated trichloroace-
timidate 16 with 20 (Entry 10) afforded exclu-
sively the crystalline b-linked disaccharide
derivative prepared from 2-amino-2-deoxy-
galactose.
D
-
Coupling reactions that involved the donors
4–6, 14 and 16 and the acceptors methyl
(methyl 2,3 - di - O - benzoyl - b - - glucopyran-
D
osid)uronate (19) [9] and its 4-methoxyphenyl
glycoside analogue 20 [10] were then studied
(Table 1). Condensation of the thioglycoside
4 (1 equivalent) with the alcohol 20 in
dichloromethane at room temperature in the
presence of N-iodosuccinimide (NIS) and a
catalytical amount of trimethylsilyl triflate af-
forded a mixture of b- (21) and a-linked (25)
Scheme 1.

96
F. Be´lot, J.-C. Jacquinet / Carbohydrate Research 325 (2000) 93–106
Table 1
Coupling reactions between donors 4–6, 14 and 16 and acceptors 19 and 20
a
Entry
Reactants
Catalyst
Solvent b
Coupling d
b,a-ratio
Products
1
2
3
4
5
6
7
8
9
4+20
4+20
4+20
4+MeOH
5+20
14+20
14+20
6+20
6+19
16+20
16+MeOH
A
A
A
A
A
B
B
A
A
B
B
CH2Cl2
CH2Cl2
65
46
68
74
80
65
52
77
76
83
94
3:1
5:1
3:1
b
21, 25
21, 25
21, 25
17
c
toluene
CH2Cl2
CH2Cl2
CH2Cl2
toluene
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
1:2 e
2:1
3:1
b
21, 25
21, 25
22
23
22
b
10
11
b
b
18
a Catalysis with A, N-iodosuccinimide–trimethylsilyl triflate; B, trimethylsilyl triflate.
b Reactions at room temperature.
c Reaction at −20 °C.
d Yields (%) refer to isolated products.
1
e Determined by integrated H NMR
derivatives 22 and 23 in 77, 76, and 83%
yields, respectively. Surprisingly, with respect
to the above results, coupling of 4 with
methanol (Entry 4) gave exclusively the corre-
sponding b-glycoside, as was the case with the
imidate 16 (Entry 11).
analogue of 14 and 20 gave the corresponding
b-linked disaccharide derivative in 89% yield
[10]. Consequently, the loss of stereocontrol in
the coupling reactions was apparently not due,
as postulated, to a lack of anchimeric assis-
tance of the 2-acylamido group, but more
certainly to a mismatched pair formed in the
transition state of the b-coupling caused by
steric factors induced by the rigid 4(axial),6-
Such an unexpected stereochemical out-
come has still been reported [15] with acti-
vated 4,6-O-benzylidene derivatives of the
2-acetamido-2-deoxy-D-galacto series during a
dioxolane ring in the 4,6-O-benzylidene- -
D
synthesis of the Thomsen–Friedenreich anti-
gen. It was postulated that the 1,3-dioxolane
ring system in the 4,6-O-benzylidene deriva-
tive prevented the participation of the 2-ac-
etamido group. As a matter of fact, when
donors 5 and 6 were treated with NIS–
trimethylsilyl triflate for a short period in the
absence of acceptor, the corresponding un-
stable silylated oxazoline 27 and the known
[14] acetylated oxazoline 26 were isolated, re-
spectively, as the major product, thus indicat-
ing that participation of the 2-trichloro-
acetamido group is quite effective in both
galacto derivatives. Whether this phenomenon
is general or not remains to be established
(Scheme 2).
Since the amino sugar moiety could not be
suitably protected before coupling, we tried to
transform the easily available disaccharide
derivative 23 into an acceptor having its 3%-
OH group free, thus allowing further elonga-
tion at the non reducing end. Acid-catalyzed
methanolysis [16] of 23 readily afforded the
corresponding triol, which was treated directly
with benzaldehyde and trifluoroacetic acid to
give the crystalline acceptor 24 in 79% yield.
We have previously reported [17] that O-
1
cases. Comparison of the H NMR spectra of
27 (Table 2) with those reported [14] for 26
showed very little differences (50.5 Hz) for
benzoylated derivatives of
D
-glucuronic acid
activated through their corresponding tri-
chloroacetimidates were very efficient donors
3
the values of the JH,H coupling constants for
H-1 to H-4, thus indicating that both oxazo-
line derivatives, which are assumed to be the
major intermediates in the coupling reaction,
have at least very similar conformations. It
for the preparation of b-
D
-glucuronides. Con-
densation of methyl 2,3,4-tri-O-benzoyl-1-O-
trichloroacetimidoyl - a - - glucopyranuronate
D
28 [9] (1.5 equivalents) with the alcohol 24 in
should be noted that coupling of the
D-gluco
the presence of trimethylsilyl triflate afforded

Table 2
1H NMR data: carbohydrate ring protons for monosaccharide derivatives 3-6, 8-15, 17-18, and 27 a
b
Proton
3
4
5
6
8
9
10a
10b
11 b
4.87
8.5
4.00
10.0
3.50
3.5
12 b
5.02
8.0
3.92
10.0
4.05
3.5
13
14
15
5.10
8.5
4.30
10.5
5.39
3.5
17
18
4.61
8.5
4.05
11.0
5.32
3.5
27
H-1
J1,2
H-2
J2,3
H-3
J3,4
5.04
10.0
3.75
10.0
4.10
3.5
5.18
10.0
4.09
10.0
5.51
3.5
5.40
10.0
3.69
10.0
4.54
3.5
4.92
10.0
4.15
10.5
5.27
3.5
5.05
8.5
4.15
10.0
5.37
9.5
4.91
8.0
3.50
10.0
3.65
9.0
4.99
8.5
4.18
5.26
8.5
4.25
5.36
8.5
4.35
6.59
3.5
4.94
4.86
8.5
4.09
10.0
5.53
3.5
6.48
6.0
4.23
7.5
10.0
10.0
10.0
11.0
/
5.45
9.0
3.68
9.0
5.59
3.5
5.49
3.5
3.80
3.0
H-4
J4,5
4.20
1.0
4.40
1.0
4.09
1.0
5.37
1.0
5.15
9.5
3.15
3.55
9.0
4.84
9.5
3.68
1.0
4.15
1.0
4.47
1.0
4.48
1.0
5.40
1.0
4.40
1.0
5.35
1.0
4.18
2.5
H-5
J5,6a
J5,6b
H-6a
J6a,6b
H-6b
NH
J2,NH
3.57
1.5
1.5
3.68
2.0
2.0
3.57
1.5
1.5
3.93
6.0
7.0
3.80
2.5
5.0
3.15
3.50
3.75
2.0
6.0
3.81
2.0
6.0
3.40
4.05
3.66
2.0
2.0
3.94
1.5
1.5
4.01
6.0
6.0
3.60
1.5
1.5
3.92
7.0
7.0
3.88
2.0
2.0
4.37
4.38
4.38
4.18
4.29
4.46
4.25
3.50
4.05
4.35
4.35
4.15
4.34
4.10
4.40
−12.5
4.01
−12.5
4.03
−12.5
4.02
−12.0
4.12
−12.0
4.14
−12.0
4.30
−12.0
4.09
−12.0
4.08
−12.0
4.07
−12.5
4.08
−12.5
4.07
325
3.65
8.77
9.0
3.50
8.70
9.0
4.05
8.78
9.0
4.15
6.79
8.0
4.10
6.85
8.5
)
6.81
8.0
6.64
8.5
6.78
7.5
6.75
8.5
6.80
7.5
7.24
9.0
7.01
7.0
6.81
8.0
6.80
9.0
7.01
8.0
9
a Chemical shifts (l, ppm) and coupling constants (J, in Hz) for solutions in CDCl3, unless otherwise stated.
106
b (CD3)2SO.

98
F. Be´lot, J.-C. Jacquinet / Carbohydrate Research 325 (2000) 93–106
the crystalline trisaccharide derivative 29 in
85% yield. The N-trichloroacetyl group in 29
was readily transformed into N-acetyl with
tributyltin hydride and azobisisobutyronitrile
(AIBN) to give the crystalline acetamide 30 in
82% yield. Treatment of 30 with aqueous
acetic acid at 100 °C gave the crystalline diol
31 in 80% yield.
Preparation of the target molecule 1 was
then achieved as follows. Treatment of the
diol 31 with the sulfur trioxide–trimethyl-
amine complex (3 equivalents) in N,N-
dimethylformamide at 50 °C for 4 h, followed
by ion-exchange chromatography, afforded
the crystalline sodium salt 32 in 72% yield.
Minor amounts of unreacted starting material
and of the corresponding 4,6-disulfated
derivative were also obtained, but easily sepa-
rated from 32 by chromatography. These re-
sults were in accord with those previously
reported [6], and no formation of imine-like
products [8] coming from O-sulfonation of the
tautomeric form of the amide was observed.
Comparison of the NMR spectra of 32 and 31
1
showed for H (Table 4) the expected [7]
downfield shift (0.6 ppm) of the signals for
Scheme 2.

F. Be´lot, J.-C. Jacquinet / Carbohydrate Research 325 (2000) 93–106
99
Table 3
1H NMR data: carbohydrate ring protons for disaccharide derivatives 21–25 a
Proton
21
25
22
23
24
H-1I
J1,2
5.23
7.0
5.57
9.0
5.76
9.0
4.52
9.0
4.25
5.07
8.0
4.15
11.0
5.30
7.0
5.61
9.0
5.78
9.0
4.77
9.0
4.34
5.37
3.5
4.72
11.0
5.22
7.0
5.58
9.0
5.71
9.0
4.41
9.0
4.22
4.95
8.5
3.97
10.5
4.65
7.0
5.35
9.5
5.64
9.5
4.29
9.5
4.12
4.91
8.5
3.94
11.0
4.66
7.0
5.34
9.0
5.67
9.0
4.34
9.0
4.14
4.86
8.0
3.87
11.0
H-2I
J2,3
H-3I
J3,4
H-4I
J4,5
H-5I
H-1II
J1,2
H-2II
J2,3
H-3II
J3,4
5.22
3.5
4.18
1.0
5.24
3.5
4.39
1.0
5.09
3.5
5.13
1.0
5.09
3.5
5.11
1.0
3.81
3.5
3.97
1.0
H-4II
J4,5
H-5II
J5,6a
J5,6b
H-6aII
J6a,6b
H-6bII
NH
3.33
1.5
1.5
3.75
1.5
1.5
3.71
6.0
7.5
3.69
6.0
7.0
3.24
1.5
1.5
3.65
4.32
3.32
3.25
3.61
−12.0
3.55
−12.0
3.98
−11.5
3.25
−12.0
3.25
−12.5
3.43
6.78
8.0
6.62
9.0
6.68
8.5
6.74
8.5
7.00
7.5
J2,NH
a Chemical shifts (l, ppm) and coupling constants (J, in Hz) for solutions in CDCl3.
H-6aII and H-6bII in 32, and for 13C the
expected [7] downfield shift (6.7 ppm) of the
signal for C-6II in 32, respectively. Saponifica-
tion of the ester groups was then achieved by
treatment of 32 with lithium hydroperoxide in
aqueous tetrahydrofuran at −5 °C [18], fol-
lowed by methanolic sodium hydroxide to af-
ford the target molecule 1 in 81% yield. The
3. Experimental
General methods.—Melting points were de-
termined in capillary tubes with a Bu¨chi ap-
paratus and are uncorrected. Optical rotations
were measured at 20–25 °C with a Perkin–
Elmer 241 polarimeter. H and 13C NMR
1
spectra were recorded at 25 °C with a Bruker
DPX-250 spectrometer operating at 250 and
63 MHz, respectively, with Me4Si as internal
standard, unless otherwise stated. Assign-
ments were based on homo- and heteronuclear
correlations using the supplier’s software.
Mass spectra were obtained on a Perkin–
Elmer SCIEX API 300 spectrometer operating
in the ion-spray (IS) mode. Flash-column
chromatography was performed on Silica Gel
(E. Merck, 40–63 mm). Elemental analyses
were performed by the Service Central de
Microanalyse du CNRS (Vernaison, France).
Phenyl 4,6-O-benzylidene-2-deoxy-1-thio-
13
1H (Table 4) and C NMR spectra of 1 are in
full agreement with the expected structure,
and in accord with those reported for syn-
thetic trisaccharide derivatives [8,9] and poly-
meric chondroitin 6-sulfate [19].
In summary, unfavorable interactions in the
transition state between 4,6-O-benzylidene-2-
deoxy-2-trichloroacetamido-
D
-galacto-derived
glycosyl donors and -glucuronic acid-derived
D
acceptors may lead to a dramatic loss of
stereoselectivity in the coupling reaction.
However, this drawback should be overcome
through the use of more flexible and less
strerically hindered species, thus allowing the
high-yielding preparation of a chondroitin 6-
sulfate trisaccharide derivative.
2 - trichloroacetamido - i -
(3).—A mixture of phenyl 2-deoxy-1-thio-2-
D
- galactopyranoside

100
F. Be´lot, J.-C. Jacquinet / Carbohydrate Research 325 (2000) 93–106
NMR (CDCl3): carbohydrate ring protons
trichloroacetamido-b- -galactopyranoside (2)
D
(see Table 2); 7.65–7.15 (m, 10 H, Ph), 5.52 (s,
1 H, PhCH), 2.75 (bs, 1 H, HO-3). Anal.
Calcd for C21H20Cl3NO5S·H2O: C, 48.24; H,
4.24; N, 2.68. Found: C, 48.42; H, 4.19; N,
2.74.
[11] (5.12 g, 12.2 mmol), benzaldehyde (40
mL), and CF3COOH (2 mL) was stirred for
1.5 h at room temperature (rt). The solution
was then cooled to 0 °C, and Et3N (5 mL) was
added. The mixture was then diluted with
CH2Cl2 (250 mL), washed with water, dried
(MgSO4), and concentrated. The residue was
eluted from a column (100 g) of silica gel with
1:1“2:1 EtOAc–petroleum ether, and crys-
tallized from hot EtOH to give 3 (5.5 g, 90%);
Phenyl 4,6-O-benzylidene-3-O-chloroacetyl-
2 - deoxy - 1 - thio - 2 - trichloroacetamido - i - -
D
galactopyranoside (4).—Chloroacetic anhyd-
ride (76 mg, 0.44 mmol) was added at 0 °C to
a solution of 3 (0.15 g, 0.29 mmol) in anhyd
CH2Cl2 (6 mL) and pyridine (0.6 mL), and the
mixture was stirred for 1.5 h at this tempera-
ture. Ice-cold water (1 mL) was then added,
and the mixture was diluted with CH2Cl2 (10
mL), washed with water, 5% aq KHSO4, satd
aq NaHCO3, and water, dried (MgSO4), and
concentrated. The residue was eluted from a
column (10 g) of silica gel with 1:1 EtOAc–
petroleum ether, and crystallized from the
same mixture of solvents to give 4 (129 mg,
75%); mp 209–210 °C; [h]D +1° (c1, CHCl3);
1H NMR (CDCl3): carbohydrate ring protons
(see Table 2); 7.66–7.20 (m, 10 H, Ph), 5.49 (s,
1 H, PhCH), 3.98 (ABq, 2 H, COCH2Cl).
Anal. Calcd for C23H21Cl4NO6S: C, 47.52; H,
3.64; N, 2.41. Found: C, 47.72; H, 3.69; N,
2.49.
1
mp 167–168 °C; [h]D −11° (c1, CHCl3); H
Table 4
1H NMR data: carbohydrate ring protons for trisaccharide
derivatives 29–32 and 1 a
b
Proton 29
30
31
4.62
7.0
5.33
9.0
5.58
9.0
4.30
9.0
4.07
4.94
8.0
3.04
11.0
4.59
3.5
3.91
1.0
3.28
5.0
6.0
32
1 c
H-1I
J1,2
4.66
7.0
5.28
9.0
5.67
9.0
4.54
9.0
4.61
7.0
5.26
9.0
5.64
9.0
4.38
9.0
4.54
7.0
5.26
9.0
5.66
9.0
4.43
9.0
4.19
4.79
8.0
3.90
10.5
3.94
3.5
4.19
1.0
4.38
7.5
3.24
9.0
3.37
9.0
3.60
9.0
H-2I
J2,3
H-3I
J3,4
H-4I
J4,5
H-5I
H-1II
J1,2
4.13
5.21
8.0
4.17
5.13
8.0
3.60
4.44
8.0
H-2II
J2,3
3.65
3.20
3.91
Phenyl 4,6-O-benzylidene-2-deoxy-3-O-tert-
butyldimethylsilyl-1-thio-2-trichloroacetamido-
11.0
11.0
10.5
H-3II
J3,4
4.58
3.5
4.33
1.0
3.24
1.0
1.5
4.69
3.5
4.14
1.0
2.91
1.0
1.0
3.88
3.5
4.12
1.0
i- -galactopyranoside (5).—A mixture of 3
D
H-4II
J4,5
(80 mg, 0.16 mmol), imidazole (68 mg, 1
mmol), and tert-butyldimethylsilyl chloride
(72 mg, 0.48 mmol) in dry DMF (2 mL) was
stirred for 2 h at 80 °C, then cooled to 0 °C.
Methanol (0.2 mL) was then added, and the
mixture was diluted with CH2Cl2 (20 mL),
washed with water, dried (MgSO4), and con-
centrated. The residue was eluted from a
column (10 g) of silica gel with 10:1 toluene–
EtOAc to give amorphous 5 (90 mg, 92%);
H-5II
J5,6a
J5,6b
H-6aII
3.59
3.76
3.92
3.74
3.15
3.75
3.75
4.12
J6a,6b −12.0
−12.0
3.56
−12.0
4.12
H-6bII
NH
3.76
7.04
7.0
5.15
7.5
5.48
9.0
5.76
9.0
5.61
9.5
3.15
5.37
6.0
4.92
7.5
5.48
9.0
5.84
9.0
5.51
7.0
5.08
7.5
5.46
9.0
5.80
9.0
J2,NH
H-1III
J1,2
5.31
7.5
5.54
9.0
6.02
9.0
5.57
9.5
4.28
8.0
3.24
9.0
3.37
9.0
3.51
9.0
H-2III
J2,3
1
[h]D +18° (c1, CHCl3); H NMR (CDCl3):
carbohydrate ring protons (see Table 2); 7.65–
7.15 (m, 10 H, Ph), 5.49 (s, 1 H, PhCH), 0.82
(s, 9 H, (CH3)3C), 0.10 (s, 6 H, CH3Si). Anal.
Calcd for C27H34Cl3NO5SSi: C, 52.38; H, 5.54;
N, 2.26. Found: C, 52.47; H, 5.50; N, 2.10.
H-3III
J3,4
H-4III
J4,5
5.62
9.5
4.24
5.55
9.5
4.26
H-5III
4.27
4.67
3.60
Phenyl
2 - trichloroacetamido - i -
3,4,6-tri-O-acetyl-2-deoxy-1-thio-
- galactopyranoside
a Chemical shifts (l, ppm) and coupling constants (J, in
D
Hz) for solutions in CDCl3, unless otherwise stated.
b CD3OD.
c D2O.
(6).—Acetic anhydride (15 mL) was added at
0 °C to a solution of 2 (2.1 g, 15 mmol) in

F. Be´lot, J.-C. Jacquinet / Carbohydrate Research 325 (2000) 93–106
101
pyridine (20 mL), and the mixture was stirred
overnight at rt, then concentrated, and evapo-
rated with toluene (3×20 mL). Crystalliza-
tion of the residue from EtOAc–petroleum
ether gave 6 (2.45 g, 92%); mp 151–152 °C;
4-Methoxyphenyl 2-deoxy-3,6-di-O-pi6al-
oyl-2-trichloroacetamido-i- -glucopyranoside
(10a) and 4-methoxyphenyl 2-deoxy-4,6-di-O-
pi6aloyl-2-trichloroacetamido-i- -glucopyran-
D
D
oside (10b).—Pivaloyl chloride (2.0 mL, 15.6
mmol) was added dropwise at 0 °C to a solu-
tion of 9 (1.15 g, 2.6 mmol) in dry pyridine (80
mL), and the mixture was stirred for 5 h at rt,
then diluted with CH2Cl2 (100 mL), washed
with water, 5% aq HCl, satd aq NaHCO3, and
water, dried (MgSO4), and concentrated. The
residue was eluted from a column (100 g) of
silica gel to give first 10b (0.14 g, 9%); mp
199–200 °C (from EtOAc–hexanes); [h]D
1
[h]D −10° (c1, CHCl3); H NMR (CDCl3):
carbohydrate ring protons (see Table 2); 7.52–
7.25 (m, 5 H, Ph), 2.10, 2.03, 1.97 (3 s, 9 H,
Ac). Anal. Calcd for C20H22Cl3NO8S: C,
44.30; H, 4.08; N, 2.58. Found: C, 44.30; H,
4.08; N, 2.61.
4-Methoxyphenyl 3,4,6-tri-O-acetyl-2-de-
oxy-2-trichloroacetamido-i- -glucopyranoside
D
(8).—A mixture of 1,3,4,6-tetra-O-acetyl-2-
deoxy - 2 - trichloroacetamido - b - - glucopyr-
1
D
−2° (c1, CHCl3); H NMR (CDCl3): carbo-
anose (7) [12] (5.0 g, 10 mmol), 4-
hydrate ring protons (see Table 2); 6.85 (m, 4
H, Ph), 3.73 (s 3 H, OCH3), 2.98 (d, 1 H, J 5.0
Hz, HO-3), 1.25, 1.15 (2 s, 18 H, (CH3)3C).
Anal. Calcd for C25H34Cl3NO9: C, 50.13; H,
5.89; N, 2.34. Found: C, 50.23; H, 5.93; N,
2.34.
,
methoxyphenol (2.5 g, 20 mmol), and 4 A
powdered molecular sieves (2.0 g) in anhyd
CH2Cl2 (50 mL) was stirred for 1 h at rt under
dry Ar, then cooled to 0 °C. Triflic acid (0.19
mL, 2 mmol) was added, and the mixture was
stirred for 1.5 h at 0 °C and 1.5 h at rt. The
mixture was then neutralized with solid
NaHCO3, diluted with CH2Cl2 (100 mL),
washed with water, aq 2 M NaOH, and water,
dried (MgSO4), and concentrated. The residue
was eluted from a column (100 g) of silica gel
with 1:1 EtOAc–petroleum ether, and crystal-
lized from the same mixture of solvents to give
8 (4.9 g, 87%); mp 176–177 °C; [h]D −10°
Next eluted was 10a (1.38 g, 89%); mp
192–193 °C (from EtOAc–hexanes); [h]D
1
−23° (c1, CHCl3); H NMR (CDCl3): carbo-
hydrate ring protons (see Table 2); 6.82 (m, 4
H, Ph), 3.72 (s, 3 H, OCH3), 3.30 (d, 1 H, J
6.0 Hz, HO-4), 1.25, 1.10 (2 s, 18 H,
(CH3)3C). Anal. Calcd for C25H34Cl3NO9: C,
50.13; H, 5.89; N, 2.34. Found: C, 49.95; H,
5.81; N, 2.26.
1
(c1, CHCl3); H NMR (CDCl3): carbohydrate
4-Methoxyphenyl 2-deoxy-2-trichloroace-
ring protons (see Table 2); 6.95–6.70 (m, 4 H,
Ph), 3.72 (s, 3 H, OCH3), 2.10, 2.05, 2.04 (3 s,
9 H, Ac). Anal. Calcd for C21H24Cl3NO10: C,
45.30; H, 4.34; N, 2.51. Found: C, 45.05; H,
4.35; N, 2.46.
tamido-i- -galactopyranoside (11).—Triflic
D
anhydride (0.24 mL, 1.4 mmol) was added
dropwise at −15 °C to a solution of 10a (0.6
g, 1 mmol) in dry 1,2-dichloroethane (10 mL)
and dry pyridine (0.4 mL), and the mixture
was stirred for 3 h at this temperature. Water
(1 mL) was then added, and the mixture was
stirred for 1.5 h at 85 °C, then cooled, diluted
with CH2Cl2 (50 mL), washed with water, cold
5% aq HCl, satd aq NaHCO3, and water,
dried (MgSO4), and concentrated. A solution
of the residue in 2:1 petroleum ether–EtOAc
was filtered through a pad (2×3 cm) of silica
gel, and concentrated to give a mixture of 4,6-
4-Methoxyphenyl 2-deoxy-2-trichloroacet-
amido-i- -glucopyranoside (9).—Methanolic
D
NaOMe (0.1 M, 10 mL) was added to a
solution of 8 (2.0 g, 3.6 mmol) in dry MeOH
(30 mL), and the mixture was stirred for 2 h at
rt, and was then deionized with Amberlite
IR-120 (H+) resin, filtered, and concentrated
to give 9 as a white solid (1.52 g, 98%); mp
197–198 °C (from MeOH); [h]D −5° (c1,
1
MeOH); H NMR ((CD3)2SO): carbohydrate
and 3,4-di-O-pivaloyl- -galacto analogues of
D
ring protons (see Table 2); 6.90 (m, 4 H, Ph),
5.15 (d, 1 H, OH), 5.12 (d, 1 H, OH), 4.61 (t,
1 H, J 6.0 Hz, HO-6), 3.63 (s, 3 H, OCH3).
Anal. Calcd for C15H18Cl3NO7: C, 41.83; H,
4.21; N, 3.25. Found: C, 42.08; H, 4.26; N,
3.27.
10a (572 mg, 95%) in a 12:1 ratio (integrated
1H NMR).
A solution of the above isolated intermedi-
ates in MeOH (10 mL) was treated overnight
at rt with methanolic NaOMe (1 M, 1 mL),

102
F. Be´lot, J.-C. Jacquinet / Carbohydrate Research 325 (2000) 93–106
then deionized with Amberlite IR-120 (H+)
resin, filtered, and concentrated to give 11 as a
white solid (406 mg, 94% from 10a); mp 176–
177 °C (from EtOAc–petroleum ether); [h]D
A mixture of the above isolated hemiacetal,
CCl3CN (1.3 mL, 13 mmol), and DBU (40
mL, 0.25 mmol) in anhyd CH2Cl2 (6 mL) was
stirred for 1 h at rt, then concentrated. The
residue was eluted from a column (50 g) of
silica gel with 2:1 petroleum ether–EtOAc
containing 0.1% of Et3N, and crystallized
from EtOAc–hexanes to give 14 (0.65 g, 61%
from 13); mp 140–141 °C; [h]D +113° (c1,
1
+7° (c1, MeOH); H NMR ((CD3)2SO): car-
bohydrate ring protons (see Table 2); 6.82 (m,
4 H, Ph), 4.82 (d, 1 H, J 6.0 Hz, OH), 4.71 (d,
1 H, J 4.0 Hz, OH), 4.68 (t, 1 H, J 5.0 Hz,
HO-6), 3.63 (s, 3 H, OCH3). Anal. Calcd for
C15H18Cl3NO7: C, 41.83; H, 4.21; N, 3.25.
Found: C, 41.75; H, 4.32; N, 3.17.
1
CHCl3); H NMR (CDCl3): carbohydrate ring
protons (see Table 2); 8.80 (s, 1 H, CꢀNH),
7.40 (m, 5 H, Ph), 5.57 (s, 1 H, PhCH), 4.10
(ABq, 2 H, COCH2Cl). Anal. Calcd for
C19H17Cl7N2O5: C, 36.02; H, 2.70; N, 4.42.
Found: C, 35.82; H, 2.81; N, 4.21.
4-Methoxyphenyl 4,6-O-benzylidene-2-de-
oxy - 2 - trichloroacetamido - i -
D
- galactopyr-
anoside (12).—Compound 11 (1.1 g, 2.5
mmol) was treated as described for the prepa-
ration of 3 to give 12 (1.12 g, 85%); mp
223–224 °C (from EtOH); [h]D −11° (c1,
4-Methoxyphenyl 3,4,6-tri-O-acetyl-2-de-
oxy-2-trichloroacetamido-i- -galactopyran-
D
oside (15).—A solution of 11 (988 mg, 2.29
mmol) in pyridine (10 mL) and Ac2O (5 mL)
was stirred overnight at rt, then concentrated,
evaporated with toluene (3×10 mL), and
crystallized from EtOAc–hexanes to give 15
(1.09 g, 85%); mp 145–146 °C; [h]D −10° (c1,
1
pyridine); H NMR ((CD3)2SO): carbohydrate
ring protons (see Table 2); 7.50–6.80 (m, 9 H,
Ph), 5.60 (s, 1 H, PhCH), 5.18 (d, 1 H, J 7.0
Hz, HO-3), 3.62 (s, 3 H, OCH3). Anal. Calcd
for C22H22Cl3NO7: C, 50.93; H, 4.27; N, 2.70.
Found: C, 51.12; H, 4.33; N, 2.77.
1
CHCl3); H NMR (CDCl3): carbohydrate ring
4-Methoxyphenyl
chloroacetyl-2-deoxy-2-trichloroacetamido-i-
-galactopyranoside (13).—Compound 12
4,6-O-benzylidene-3-O-
protons (see Table 2); 6.80 (m, 4 H, Ph), 3.73
(s, 3 H, OCH3), 2.15, 2.05, 2.01 (3 s, 9 H, Ac).
Anal. Calcd for C21H24Cl3NO10: C, 45.30; H,
4.34; N, 2.51. Found: C, 45.25; H, 4.26; N,
2.60.
D
(1.85 g, 3.5 mmol) was treated as described for
the preparation of 4. The residue was eluted
from a column (50 g) of silica gel with 1:1
EtOAc–petroleum ether to give amorphous
3,4,6-Tri-O-acetyl-2-deoxy-2-trichloroacet-
amido-1-O-trichloroacetimidoyl-h- -galacto-
D
1
13 (1.9 g, 90%); [h]D +14° (c1, CHCl3); H
pyranose (16).—Compound 15 (595 mg, 1
mmol) was treated as described for the prepa-
ration of 14. The residue was eluted from a
column (25 g) of silica gel with 2:1 petroleum
ether–EtOAc containing 0.1% of Et3N, and
crystallized from EtOAc–hexanes to give 16
(416 mg, 70%); mp 89–90 °C, lit. 91–92 °C
[14]; [h]D +80° (c1, CHCl3), lit. +81° [14];
13C NMR (CDCl3): l 171.29, 170.11, 169.82,
162.02, 159.90 (CꢀO, CꢀN), 94.20 (C-1), 91.67
(CCl3), 69.93, 69.28, 67.58, 66.71 (C-3, C-4,
C-5, C-6), 49.61 (C-2), 20.49, 20.47, 20.43
(COCH3).
NMR (CDCl3): carbohydrate ring protons
(see Table 2); 7.50–6.80 (m, 9 H, Ph), 5.54 (s,
1 H, PhCH), 4.07 (ABq, 2 H, COCH2Cl), 3.72
(s, 3 H, OCH3). Anal. Calcd for C24H23Cl4-
NO8: C, 48.43; H, 3.89; N, 2.35. Found: C,
48.21; H, 3.95; N, 2.41.
4,6-O-Benzylidene-3-O-chloroacetyl-2-de-
oxy - 2 - trichloroacetamido - 1 - O - trichloroace-
timidoyl-h- -galactopyranose (14).—A mix-
D
ture of 13 (1.0 g, 1.68 mmol) and ceric ammo-
nium nitrate (7.0 g, 12.7 mmol) in 1:1.5:1
toluene–MeCN–water (52 mL) was vigor-
ously stirred for 1 h at rt. The mixture was
then diluted with EtOAc (150 mL), washed
with water, brine, and water, dried (MgSO4),
and concentrated. The residue was eluted
from a column (50 g) of silica gel with 1:1
EtOAc–petroleum ether to give the corre-
sponding free hemiacetal (0.65 g, 71%).
Methyl 4,6-O-benzylidene-3-O-chloroacetyl-
2-deoxy-2-trichloroacetamido-i- -galactopyr-
D
anoside (17).—A mixture of 4 (50 mg, 86
,
mmol), NIS (25 mg, 115 mmol), 3 A powdered
molecular sieves (50 mg), and anhyd MeOH
(35 mL, 0.86 mmol) in anhyd CH2Cl2 (1.5 mL)
was stirred for 1 h at rt under dry Ar, then

F. Be´lot, J.-C. Jacquinet / Carbohydrate Research 325 (2000) 93–106
103
for 1 h. Triethylamine (25 mL) was added, and
the mixture was filtered, and concentrated.
The residue was eluted from a column (10 g)
of silica gel with 6:1 toluene–EtOAc to give
first 21 (65 mg, 50%); mp 175–176 °C (from
cooled to 0 °C. A solution of Me3SiOTf in
toluene (1 M, 13 mL) was added, and the
mixture was stirred for 1 h at 0 °C. Triethyl-
amine (25 mL) was added, and the mixture
was filtered, and concentrated. The residue
was eluted from a column (5 g) of silica gel
with 1:1 EtOAc–petroleum ether, and crystal-
lized from the same mixture of solvents to give
17 (32 mg, 74%); mp 203–204 °C; [h]D +34°
1
EtOAc–hexanes); [h]D +18° (c1, CHCl3); H
NMR (CDCl3): carbohydrate ring protons
(see Table 3); 8.0–6.75 (m, 19 H, Ph), 5.25 (s,
1 H, PhCH), 3.97 (ABq, 2 H, COCH2Cl), 3.71
(s, 6 H, COOCH3, OCH3). Anal. Calcd for
C45H41Cl4NO16: C, 54.34; H, 4.25; N, 1.41.
Found: C, 54.04; H, 4.27; N, 1.30.
1
(c1, CHCl3); H NMR (CDCl3): carbohydrate
ring protons (see Table 2); 7.40 (m, 5 H, Ph),
5.51 (s, 1 H, PhCH), 4.02 (ABq, 2 H,
COCH2Cl), 3.52 (s, 3 H, OCH3). Anal. Calcd
for C18H19Cl4NO7: C, 42.97; H, 3.80; N, 2.78.
Found: C, 43.11; H, 4.02; N, 2.80.
Next eluted was 25 (25 mg, 15%); [h]D
1
+93° (c1, CHCl3); H NMR (CDCl3): carbo-
hydrate ring protons (see Table 3); 7.95–6.85
(m, 19 H, Ph), 5.53 (s, 1 H, PhCH), 4.05
(ABq, 2 H, COCH2Cl), 3.75 (s, 6 H,
COOCH3, OCH3). Anal. Calcd for C45H41-
Cl4NO16: C, 54.34; H, 4.25; N, 1.41. Found:
C, 54.12; N, 4.32; N, 1.29.
Methyl 3,4,6-tri-O-acetyl-2-deoxy-2-tri-
chloroacetamido - i -
D
- galactopyranoside (18).
,
—A mixture of 16 (238 mg, 0.4 mmol), 3 A
powdered molecular sieves (200 mg), and an-
hyd MeOH (0.16 mL, 4 mmol) in anhyd
CH2Cl2 (3 mL) was stirred for 1 h at rt under
dry Ar. A solution of Me3SiOTf in toluene (1
M, 58 mL) was added, and the mixture was
stirred for 1 h at rt. Triethylamine (0.1 mL)
was added, and the mixture was filtered, and
concentrated. The residue was eluted from a
column (10 g) of silica gel with 5:4 petroleum
ether–EtOAc to give 18 (175 mg, 94%); mp
122–123 °C (from EtOAc–hexanes); [h]D
Methyl
chloroacetamido-i-
(4-methoxyphenyl 2,3-di-O-benzoyl-i-
(3,4,6-tri-O-acetyl-2-deoxy-2-tri-
-galactopyranosyl)-(1“4)-
-glu-
D
D
copyranosid)uronate (22).—A mixture of 6
(408 mg, 0.75 mmol) and 20 (340 mg, 0.65
mmol) was treated as described for the prepa-
ration of 21. The residue was eluted from a
column (40 g) of silica gel with 6:1 toluene–
EtOAc to give 22 (470 mg, 77%); mp 128–
129 °C (from EtOAc–hexanes); [h]D −10°
1
+16° (c1, CHCl3); H NMR (CDCl3): carbo-
1
hydrate ring protons (see Table 2); 3.49 (s, 3
H, OCH3), 2.15, 2.01, 1.95 (3 s, 9 H, Ac).
Anal. Calcd for C15H20Cl3NO9: C, 38.77; H,
4.34; N, 3.01. Found: C, 38.63; H, 4.31; N,
3.05.
(c1, CHCl3); H NMR (CDCl3): carbohydrate
ring protons (see Table 3); 8.0–6.82 (m, 14 H,
Ph), 3.72, 3.71 (2 s, 6 H, COOCH3, OCH3),
1.98, 1.95, 1.92 (3 s, 9 H, Ac). Anal. Calcd for
C42H42Cl3NO18: C, 52.81; H, 4.43; N, 1.43.
Found: C, 52.64; H, 4.49; N, 1.53.
Methyl (4,6 - O - benzylidene - 3 - O - chloro-
acetyl - 2 - deoxy - 2 - trichloroacetamido - i -
D-
Methyl (3,4,6-tri-O-acetyl-2-deoxy-2-tri-
galactopyranosyl) - (1“4) - (4-methoxyphenyl
2,3-di-O-benzoyl-i- -glucopyranosid)uronate
chloroacetamido-i-
D
-galactopyranosyl)-(1“4)-
D
(methyl 2,3 - di - O - benzoyl - i -
D
- glucopyran-
(21) and methyl (4,6-O-benzylidene-3-O-
chloroacetyl-2-deoxy-2-trichloroacetamido-h-
osid)uronate (23).—A mixture of 6 (0.4 g, 0.74
mmol) and methyl (methyl 2,3-di-O-benzoyl-
b- -glucopyranosid)uronate (19) [9] (276 mg,
D
-galactopyranosyl)-(1“4)-(4-methoxyphenyl
D
2,3-di-O-benzoyl-i- -glucopyranosid)uronate
D
0.64 mmol) was treated as described for the
preparation of 21. The residue was eluted
from a column (50 g) of silica gel with 3:1
toluene–EtOAc to give 23 (421 mg, 76%); mp
120–121 °C (from EtOAc–hexanes); [h]D
(25).—A mixture of 4 (76 mg, 0.13 mmol),
methyl (4-methoxyphenyl 2,3-di-O-benzoyl-b-
D
-glucopyranosid)uronate (20) [10] (69 mg,
,
0.13 mmol), NIS (40 mg), and 4 A powdered
molecular sieves (100 mg) in anhyd CH2Cl2
(1.5 mL) was stirred for 1 h at rt under dry
Ar. A solution of Me3SiOTf in toluene (1 M,
16 mL) was added, and the mixture was stirred
1
−5° (c1, CHCl3); H NMR (CDCl3): carbo-
hydrate ring protons (see Table 3); 8.0–7.10
(m, 10 H, Ph), 3.80 (s, 3 H, COOCH3), 3.49 (s,
3 H, OCH3), 2.10, 2.07, 2.05 (3 s, 9 H, Ac).

104
F. Be´lot, J.-C. Jacquinet / Carbohydrate Research 325 (2000) 93–106
i-
of 24 (0.2 g, 0.24 mmol), methyl 2,3,4-tri-O-
benzoyl-1-O-trichloroacetimidoyl-a- -gluco-
D
-glucopyranosid)uronate (29).—A mixture
Anal. Calcd for C36H38Cl3NO17: C, 50.10; H,
4.41; N, 1.62. Found: C, 50.00; H, 4.54; N,
1.49.
D
Methyl (4,6-O-benzylidene-2-deoxy-2-tri-
pyranuronate (28) [9] (0.23 g, 0.36 mmol), and
chloroacetamido-i-
D
-galactopyranosyl)-(1“4)-
,
4 A powdered molecular sieves (0.2 g) in
(methyl 2,3 - di - O - benzoyl - i -
D
- glucopyran-
anhyd toluene (10 mL) was stirred for 45 min
at rt under dry Ar. A solution of Me3SiOTf in
toluene (1 M, 0.11 mL) was added, and the
mixture was stirred for 2 h. Triethylamine
(0.25 mL) was added, and the mixture was
filtered, and concentrated. The residue was
eluted from a column (25 g) of silica gel with
5:1 toluene–EtOAc containing 0.2% of Et3N
to give 29 (274 mg, 85%); mp 215–216 °C
(from EtOAc–petroleum ether); [h]D +14°
osid)uronate (24).—A solution of AcCl (0.2
mL) in anhyd MeOH (5 mL) was added to a
solution of 23 (422 mg, 0.5 mmol) in anhyd
CH2Cl2 (5 mL), and the mixture was stirred
for 24 h at rt, then deionized with Dowex
1X2-400 (OH−) resin, filtered, concentrated,
and dried, to give the corresponding triol (360
mg).
The crude residue was treated as described
for the preparation of 3. The residue was
eluted from a column (50 g) of silica gel with
1:1“3:1 EtOAc–petroleum ether to give 24
(327 mg, 79%); mp 191–192 °C (from
1
(c1, CHCl3); H NMR (CDCl3): carbohydrate
ring protons (see Table 4); 7.95–7.10 (m, 30
H, Ph), 5.32 (s, 1 H, PhCH), 3.80, 3.60 (2 s, 6
H, COOCH3), 3.45 (s, 3 H, OCH3). Anal.
Calcd for C65H58Cl3NO23: C, 58.81; H, 4.40;
N, 1.05. Found: C, 58.75; H, 4.38; N, 1.10.
1
EtOAc–hexanes); [h]D −12° (c1, CHCl3); H
NMR (CDCl3): carbohydrate ring protons
(see Table 3); 8.10–7.0 (m, 15 H, Ph), 5.27 (s,
1 H, PhCH), 3.85 (s, 3 H, COOCH3), 3.50 (s,
3 H, OCH3), 2.64 (d, 1 H, J 10.0 Hz, HO-3II).
Anal. Calcd for C37H35Cl3NO14: C, 53.93; H,
4.28; N, 1.70. Found: C, 53.97; H, 4.37; N,
1.56.
Methyl (methyl 2,3,4-tri-O-benzoyl-i-
copyranosyluronate)-(1“3)-(2-acetamido-4,6-
O-benzylidene-2-deoxy-i- -galactopyranosyl)-
(1“4)-(methyl 2,3-di-O-benzoyl-i- -gluco-
D-glu-
D
D
pyranosid)uronate (30).—A mixture of 29 (1.0
g, 0.75 mmol), Bu3SnH (1.2 mL, 3.4 mmol),
and AIBN (100 mg) in dry benzene (40 mL)
and N,N-dimethylacetamide (2 mL) was
stirred for 1 h at rt under a stream of dry Ar,
then heated for 2 h at 80 °C, cooled, and
concentrated. The residue was stirred with
petroleum ether (20 mL) for 1 h at 0 °C, and
the precipitate was filtered off, washed with
petroleum ether, and crystallized from
EtOAc–petroleum ether to give 30 (775 mg,
82%); mp 220–221 °C; [h]D +14° (c1,
2-Trichloromethyl-4,5-dihydro-(4,6-O-ben-
zylidene-1,2-dideoxy-3-O-tert-butyldimethyl-
silyl-h- -galactopyranoso)[2,1-d]-1,3-oxazole
D
(27).—A mixture of 5 (50 mg, 80 mmol), NIS
,
(37 mg, 0.16 mmol), and 4 A powdered molec-
ular sieves (50 mg) in anhyd CH2Cl2 (1.5 mL)
was stirred for 1 h at rt under dry Ar. A
solution of Me3SiOTf in toluene (1 M, 25 mL)
was added, and the mixture was stirred for 10
min. Triethylamine (30 mL) was added, and
the mixture was filtered, and concentrated.
The residue was eluted from a column (5 g) of
silica gel with 6:1 petroleum ether–EtOAc
containing 0.5% of Et3N to give unstable 27
1
CHCl3); H NMR (CDCl3): carbohydrate ring
protons (see Table 4); 7.93–7.18 (m, 30 H,
Ph), 5.27 (s, 1 H, PhCH), 3.75, 3.56 (2 s, 6 H,
COOCH3), 3.45 (s, 3 H, OCH3), 1.70 (s, 3 H,
NAc); ISMS: m/z 1225, [M+H]+. Anal.
Calcd for C65H61NO23: C, 63.77; H, 5.02; N,
1.14. Found: C, 63.88; H, 4.95; N, 1.10.
1
(14 mg, 34%); [h]D +50° (c1, CHCl3); H
NMR (CDCl3): carbohydrate ring protons
(see Table 2); 7.40 (m, 5 H, Ph), 5.59 (s, 1 H,
PhCH), 0.95 (s, 9 H, (CH3)3C), 0.15 (s, 6 H,
(CH3)2Si). No satisfactory elemental analysis
could be obtained for this unstable derivative.
Methyl (methyl 2,3,4-tri-O-benzoyl-i-
copyranosyluronate) - (1“3) - (2 - acetamido - 2-
deoxy-i- -galactopyranosyl)-(1“4)-(methyl
2,3-di-O-benzoyl-i- -glucopyranosid)uronate
D-glu-
D
Methyl (methyl 2,3,4-tri-O-benzoyl-i-
copyranosyluronate) - (1“3) - (4,6 - O - benzyli-
dene-2-deoxy-2-trichloroacetamido-i- -galac-
topyranosyl)-(1“4)-(methyl 2,3-di-O-benzoyl-
D-glu-
D
(31).—A mixture of 30 (0.17 g, 0.14 mmol)
and AcOH (5 mL) was stirred at 100 °C.
D

F. Be´lot, J.-C. Jacquinet / Carbohydrate Research 325 (2000) 93–106
105
C-4I, C-4III, C-5I, C-5III, C-3II, C-4II, C-5II),
68.70 (C-6II), 58.21, 54.49, 54.38 (COOCH3,
OCH3), 52.98 (C-2II), 23.40 (COCH3). Anal.
Calcd for C58H52NNaO26S·H2O: C, 55.64; H,
4.35; N, 1.12. Found: C, 55.32; H, 4.61; N,
1.05.
Water (2 mL) was then added dropwise, and
the mixture was stirred for 30 min at 100 °C,
cooled, concentrated, evaporated with water
(3×10 mL), and toluene (2×10 mL). The
residue was eluted from a column (15 g) of
silica gel with 1:1 CH2Cl2 –EtOAc to give 31
(126 mg, 80%); mp 188–189 °C (from
Sodium (sodium i-
nate)-(1“3)-(sodium 2-acetamido-2-deoxy-6-
O - sulfonato - i - - galactopyranosyl) - (1“4)-
(methyl i- -glucopyranosid)uronate (1).—A
D
-glucopyranosyluro-
1
EtOAc–hexanes); [h]D +12° (c1, CHCl3); H
D
NMR (CDCl3): carbohydrate ring protons
(see Table 4); 7.95–7.20 (m, 25 H, Ph), 3.71,
3.58 (2 s, 6 H, COOCH3), 3.45 (s, 3 H,
OCH3), 2.55 (d, 1 H, J 3.0 Hz, HO-4II), 1.90
(1 H, HO-6II), 1.33 (s, 3 H, NAc); 13C
(CDCl3): l 172.37, 167.84, 167.08, 165.65,
165.54, 165.22, 165.18, 164.72 (CꢀO), 133.61–
128.36 (aromatic C), 102.11, 101.51, 98.56 (C-
1I, C-1II, C-1III), 78.05, 77.56, 76.54, 75.61,
74.18, 72.80, 72.35, 71.81, 71.42, 71.26, 69.84
(C-2I, C-2III, C-3I, C-3III, C-4I, C-4III, C-5I,
C-5III, C-3II, C-4II, C-5II), 61.96 (C-6II), 57.38,
54.62 (2 COOCH3, OCH3), 52.99 (C-2II),
22.95 (COCH3); ISMS: m/z 1137, [M+H]+.
Anal. Calcd for C58H59NO23·2 H2O: C, 59.33;
H, 5.40; N, 1.19. Found: C, 59.21; H, 5.33; N,
1.18.
D
solution of 32 (267 mg, 0.22 mmol) in 7:3
THF–water (10 mL) was treated at −5 °C
with 30% H2O2 (1.1 mL) and LiOH (1 M, 2.2
mL), and the mixture was stirred for 2 h at
this temperature and 16 h at rt, then cooled to
0 °C. Methanol (8 mL) and NaOH (4 M, 1.4
mL) were added, and the mixture was stirred
for 8 h at rt, then diluted with water (3 mL),
and treated with Amberlite IR-120 (H+) resin
to pH 3 (pH meter control), filtered, and
concentrated. The residue was stirred for 1 h
at 0 °C with abs EtOH (10 mL), and the solids
were filtered off and washed with cold abs
EtOH. The residue was eluted from a column
(12 g) of silica gel with 4:3:3 EtOAc–MeOH–
water, then taken up in water (5 mL). The pH
of the solution was brought to 6.5 with diluted
NaOH (pH meter control), and the solution
was filtered, and freeze-dried to give 1 as an
amorphous hygroscopic powder (130 mg,
Methyl (methyl 2,3,4-tri-O-benzoyl-i-
copyranosyluronate)-(1“3)-(sodium 2-acet-
amido-2-deoxy-6-O-sulfonato-i- -galactopyr-
anosyl)-(1“4)-(methyl 2,3-di-O-benzoyl-i-
D-glu-
D
D
-
glucopyranosid)uronate (32).—A mixture of 31
(0.25 g, 0.22 mmol) and sulfur trioxide–
trimethylamine complex (91 mg, 0.66 mmol)
in anhyd DMF (9 mL) was stirred for 4 h at
50 °C under dry Ar, then cooled. Methanol
(0.25 mL) was then added, and the mixture
was concentrated. The residue was eluted
from a column (20 g) of silica gel with 8:1
CH2Cl2 –MeOH, then from a column (1.5×
20 cm) of Sephadex SP C25 (Na+) with 9:5:1
CH2Cl2 –MeOH–water to give 32 (196 mg,
72%); mp 196–198 °C (from CHCl3–
1
81%); [h]D −17° (c1, H2O); H NMR (D2O,
internal H2O): carbohydrate ring protons (see
Table 4); 3.43 (s, 3 H, OCH3), 1.98 (s 3 H,
NAc); 13C (D2O, internal acetone): l 176.01,
175.32, 174.85 (CꢀO), 104.45 (C-1III), 103.65
(C-1II) 101.72 (C-1I), 81.70 (C-4I), 80.29 (C-
3II), 76.95, 76.45 (C-5I, C-5III), 75.65 (C-3III),
74.45 (C-5II), 73.06 (C-3I), 72.97, 72.87 (C-2I,
C-2III), 67.89, 67.70 (C-4II, C-6II), 57.60
(OCH3), 51.23 (C-2II), 22.88 (COCH3). Anal.
Calcd for C21H30NNa3O21S: C, 34.29; H, 4.12;
N, 1.90. Found: C, 33.91; H, 4.32; N, 1.79.
1
petroleum ether); [h]D −3° (c1, MeOH); H
NMR (CD3OD): carbohydrate ring protons
(see Table 4); 8.0–7.15 (m, 25 H, Ph), 3.89,
3.62 (2 s, 6 H, COOCH3), 3.41 (s, 3 H,
OCH3), 1.32 (s, 3 H, NAc); 13C (CD3OD): l
174.14, 170.46, 170.36, 168.13, 167.56, 167.40,
167.34, 167.23 (CꢀO), 135.49–130.20 (aro-
matic C), 103.88, 103.57, 103.28 (C-1I, C-1II,
C-1III), 82.65, 78.19, 76.36, 74.94, 74.62, 74.46,
74.02, 73.68, 72.14 (C-2I, C-2III, C-3I, C-3III,
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