Syntheses of β-D-GalpNAc4SO3-(1→4)-L-IdopA2SO3, a disaccharide fragment of dermatan sulfate, and of its methyl α-L-glycoside derivative

Article abstract of DOI:10.1016/S0008-6215(00)00234-2

The syntheses of sodium (sodium 2-acetamido-2-deoxy-4-O-sulfonato-β-D-galactopyranosyl)-(1→4)-(sodium 2-O-sulfonato-L-idopyran)uronate, a disaccharide fragment of dermatan sulfate, and of its methyl α-L-glycoside derivative are reported for the first time. The use of 4-O-acetyl-3,6-di-O-benzyl-2-deoxy-2-trichloroacetamido-1-O-trichloroaceti midoyl-α-D-galactopyranose, readily prepared from a D-gluco precursor, allowed the stereocontrolled and high yielding coupling with the low reactive 4-hydroxyl group of L-iduronic acid ester derivatives. Classical transformation of the disaccharide products into the target molecules was achieved in high yield. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0008-6215(00)00234-2

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Carbohydrate Research 329 (2000) 667–679
Note
Syntheses of b-
disaccharide fragment of dermatan sulfate, and of its
methyl a- -glycoside derivative
D
-GalpNAc4SO3-(1“4)- -IdopA2SO3, a
L
L
Nadine Barroca, 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 22 June 2000; accepted 31 July 2000
Abstract
The syntheses of sodium (sodium 2-acetamido-2-deoxy-4-O-sulfonato-b-
sulfonato- -idopyran)uronate, a disaccharide fragment of dermatan sulfate, and of its methyl a-
are reported for the first time. The use of 4-O-acetyl-3,6-di-O-benzyl-2-deoxy-2-trichloroacetamido-1-O-trichloroace-
timidoyl-a- -galactopyranose, readily prepared from a -gluco precursor, allowed the stereocontrolled and high
yielding coupling with the low reactive 4-hydroxyl group of -iduronic acid ester derivatives. Classical transformation
D
-galactopyranosyl)-(1“4)-(sodium 2-O-
L
L
-glycoside derivative
D
D
L
of the disaccharide products into the target molecules was achieved in high yield. © 2000 Elsevier Science Ltd. All
rights reserved.
Keywords: Glycosylation reactions; 2-Deoxy-2-trichloroacetamido-D-galacto derivatives; Dermatan sulfate disaccharides
species [4,5] were also isolated, and the adja-
cent -iduronic acid residues are sulfated or
1. Introduction
L
not at C-2. DeS binds to the serine protease
inhibitor heparin cofactor II (HC II), and
enhances its thrombin inhibitory potency [6].
This interaction is associated with disulfated
Dermatan sulfate (DeS) is a proteoglycan
ubiquitous in most mammalian tissues. It was
first isolated from pig skin [1], and is mainly
composed of disaccharide repeating units of
sequences, namely [4)-a-
L
-IdopA2SO3-(1“3)-
L
-iduronic acid and 2-acetamido-2-deoxy-
D
-
-
b- -GalpNAc4SO3-(1“]n, and the minimal
D
galactose, namely [4)-a- -IdopA-(1“4)-b-
L
D
requirement for the HC II binding site was
first postulated to be a trimeric sequence [7],
and more recently a tetrameric species [8]. In
oncology surgery, DeS prevents venous
thromboembolism more effectively than hep-
arin without increasing bleeding complications
[9]. It was also recently reported [10] that DeS
released during wound repair should be a
potent promoter of fibroblast growth factor-2
(FGF-2) function.
GalpNAc-(1“]n. Structural studies on DeS
showed different patterns of sulfation substi-
tutions depending on its origin [2]. The
D
-
galactosamine residues are mainly sulfated at
C-4, but 6-sulfated [3] as well as 4,6-disulfated
* Corresponding author. Tel.: +33-238-417072; fax: +33-
238-417281.
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(00)00234-2

668
N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
Several syntheses of DeS fragments have
lar Tischenko reaction of aldonic acid esters
[22]. However, for large scale preparations,
older procedures [23] starting from known
been reported, such as those of a monosul-
fated disaccharide [11,12], a disulfated disac-
charide [13], as well as those of
a
3-O-benzyl-1,2-O-isopropylidene-a- -gluco-
D
hexasaccharide [14,15] containing three disul-
fated sequences. For the syntheses of these
hexasaccharide species, the strategy was
edicted by the encountered difficulties [15] to
obtain an efficient b-interglycosidic linkage
furanose (3) [24] were still used [25]. We now
report on a slightly modified and expeditious
preparation of the tetrabenzoate 6, for which
efficiency and reproducibility was the main
feature.
between a
hydroxyl group of
Thus, -idose derivatives were used as inter-
mediates, and these residues were oxidized
into the corresponding -iduronic acid after
D
-galactosamine donor and the 4-
Treatment of 3 with pivaloyl chloride (1.5
equiv) in pyridine at 0 °C afforded the crys-
talline 6-O-pivaloyl derivative 4 in 85% yield,
isolated by simple crystallization. Some dipi-
valoylated species were present in the mother
liquors, but were easily recycled through
transesterification. Trifluoromethanesulfonyla-
tion of 4 with triflic anhydride (1.1 equiv) and
pyridine in 1,2-dichloroethane at −15 °C, fol-
lowed by treatment in situ with water [26] and
heating at 85 °C afforded a mixture of 5- and
L
-iduronic acid esters.
L
L
construction of the oligosaccharide backbone.
We now report for the first time on an
efficient and stereocontrolled elaboration of
this b-interglycosidic linkage through synthe-
ses of disaccharide 1 and its methyl a- -gly-
L
coside derivative 2, in which the methyl group
is suitable as a marker for NMR studies, using
6-O-pivaloyl- -ido intermediates, which were
L
an activated 2-deoxy-2-trichloroacetamido- -
D
directly transesterified with methanolic sodium
methoxide to provide the known crystalline
diol 5 in 72% overall yield (61% yield from 3).
The physical data for 5 are in agreement with
those reported [27]. The route described here,
galacto glycosyl donor readily prepared from
a
D
-gluco precursor. An improved expeditious
preparation of 3-O-benzyl- -ido derivatives is
also reported.
L
the overall yield for the
D
-gluco“ -ido trans-
L
formation, as well as the ease of isolation of
the intermediates, compare well with those
previously reported. Acid hydrolysis of 5, as
reported [23], afforded the intermediate 3-O-
benzyl- -idose, which was directly treated
L
with benzoyl chloride in pyridine to afford
nearly exclusively the b-benzoate 6 in 62%
overall yield, the anomeric configuration of
1
which was deduced from its H NMR spec-
trum (Table 1). Treatment of 6 with methyl
and benzyl alcohols, respectively, in
dichloromethane, and in the presence of
trimethylsilyl triflate gave the methyl (7) and
2. Results and discussion
benzyl (8) a- -glycosides in 90 and 70% yields,
L
The availability of
L
-ido synthons is a key
-iduronic acid con-
respectively. The physical data for 7 (not de-
scribed in Section 3) are in agreement with
those reported [28].
point for the synthesis of
L
taining oligosaccharides, and constant efforts
were achieved for their efficient preparation.
Recent syntheses mainly involved modifica-
Transformation of 7 and 8 into the
L
-
iduronyl acceptors 15 and 16 was then
achieved as follows (Scheme 1). Transesterifi-
cation of 7 and 8 gave the corresponding triol
derivatives, which were treated with 2-
tions at C-5 of -gluco precursors through, for
D
example, diastereoselective hydroboration of
exo-glucal derivatives [16–18], functionaliza-
4
tion of D -uronic acid species [19] or
D
-xylo-
methoxypropene and 10-
D
, -camphorsulfonic
L
dialdose derivatives [20], epimerization of
-glucurono-6,3-lactone [21], or intramolecu-
D
acid in N,N-dimethylformamide to give the

N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
669
corresponding 4,6-O-isopropylidene deriva-
tives, which were, in turn, benzoylated to give
9 and 10 in 75 and 63% yields, respectively.
Mild acid hydrolysis of 9 and 10 with aqueous
acetic acid, followed by tert-butyldimethylsily-
lation of the intermediate diols gave 11 and
12, both in 90% overall yield. Jones oxidation
of 11 and 12 in acetone, followed by esterifica-
tion of the intermediate acids with methyl
chloroformate and 4-dimethylaminopyridine
gave the uronic acid esters 13 and 14 in 65 and
62% yields, respectively. Desilylation of 13
and 14 with tetrabutylammonium fluoride in
dry tetrahydrofuran at 0 °C afforded the
target glycosyl acceptors 15 and 16 in 60 and
74% yields, respectively. In these reactions, no
b-elimination reaction caused by the basicity
of fluoride ion was observed, as was the case
in the
D
-glucuronic acid ester series [29]. The
-ido derivatives 8–16
1H NMR spectra of the
L
(Table 1) showed, with the exception of 11
and 12, long-range coupling constants (J1,3
Table 1
1H NMR data: carbohydrate ring protons for monosaccharide derivatives 4–6 and 8–16 a
Proton
4
5
6
8
9
10
11
12
13
14
15
16
H-1
J1,2
J1,3
5.93
3.8
6.00
3.8
6.54
1.8
5.13
1.0
0.5
4.92
2.2
0.5
5.14
2.0
0.7
4.96
3.1
5.13
3.1
5.09 5.32 5.09 5.24
2.2
1.0
2.6
1.0
1.2
0.8
1.2
0.8
H-2
J2,3
J2,4
4.61
ꢀ0
4.66
ꢀ0
5.53
3.0
1.0
5.26
3.0
0.5
5.24
4.2
0.5
5.33
4.0
0.7
5.12
3.3
1.0
5.22
5.2
5.11 5.18 5.28 5.31
2.5
0.8
2.7
0.9
2.4
1.2
2.5
1.2
H-3
J3,4
H-4
J4,5
H-5
J5,6a
J5,6b
H-6a
J6a,6b
H-6b
4.15
4.0
4.15
4.03
3.5
4.21
5.2
4.08
4.3
5.4
4.33
3.0
5.34
2.0
4.81
1.5
3.0
4.07
2.0
5.30
2.0
4.88
5.0
8.0
3.68
3.6
3.92
2.6
3.98
3.2
2.6
3.72
3.6
4.03
2.4
3.94
4.6
2.6
3.78
3.0
3.78
2.3
4.04
5.2
5.7
4.12
2.8
3.88
2.5
3.88
6.0
4.4
3.80 4.10 3.93 3.90
3.4 3.2 3.2 1.4
4.13 3.75 4.15 4.12
2.7 2.7 1.7 1.8
4.85 4.81 4.98 4.95
4.15
6.2
4.37
−12.3
4.25
3.64
4.65
4.63
4.11
4.05
3.89
3.92
−12.0
4.64
−12.0
4.43
−13.2
3.93
−12.4
3.86
−10.6
3.80
−10.7
3.80
3.64
a Chemical shifts (l, ppm) and coupling constants (J, in Hz) for solutions in CDCl3.
Scheme 1.

670
N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
Scheme 2.
Table 2
1H NMR data: carbohydrate ring protons for aminosugar derivatives 18–24 a
Proton
18
19
20
5.40
21
5.32
22
23
24
H-1
J1,2
5.49
8.4
5.51
8.4
5.36
8.5
6.50
3.5
5.01
9.7
8.4
8.4
H-2
J2,3
3.75
10.0
3.81
10.2
3.75
10.3
3.93
10.7
3.85
11.0
4.48
11.3
4.25
10.7
H-3
J3,4
4.46
9.0
4.44
8.8
4.18
8.4
4.24
3.3
4.29
3.5
3.86
3.0
3.61
3.1
H-4
J4,5
3.90
9.5
3.90
9.6
3.88
4.16
0.8
5.71
0.6
5.78
1.0
5.71
0.9
H-5
J5,6a
J5,6b
H-6a
J6a,6b
H-6b
NH
J2,NH
3.75
9.0
4.6
3.70
9.3
5.0
3.75
3.88
3.83
3.90
6.1
6.7
3.52
−9.6
3.59
4.25
5.7
7.7
3.58
−9.4
3.50
3.90
5.3
7.8
3.60
−9.3
3.49
3.90
3.94
3.83
−10.7
4.48
−10.4
3.82
3.88
7.00
7.0
3.83
6.95
7.0
7.00
7.0
7.00
7.0
6.88
7.2
6.37
7.8
6.53
8.2
a Chemical shifts (l, ppm) and coupling constants (J, in Hz) for solutions in CDCl3.
and J2,4) indicating a large predominance, if
not the only one, of C4 conformation for
fluoroacetic acid did not improve the yield of
this reaction. Inversion of configuration at C-4
was then achieved by treatment of 20 with
triflic anhydride and pyridine in dichloro-
methane at −15 °C, followed by nucleophilic
displacement of the intermediate triflate with
sodium nitrite in N,N-dimethylformamide
1
these intermediates.
Preparation of the
D
-galactosaminyl donor
23 from a -glucosamine precursor was stud-
D
ied next (Scheme 2). Transesterification of the
easily available 4-methoxyphenyl 3,4,6-tri-O-
acetyl-2-deoxy-2-trichloroacetamido-b-
D
-glu-
[33,29] to give the crystalline -galacto deriva-
D
copyranoside (17) [30] with methanolic
sodium methoxide, followed by acetalation
with benzaldehyde and trifluoroacetic acid
gave crystalline 18 in 65% yield. Protection at
O-3 was then achieved by treatment of 18 with
benzyl bromide and sodium hydride in N,N-
dimethylformamide to give crystalline 19 in
82% yield. No N-benzylation reaction was
observed under these conditions. Regioselec-
tive reductive cleavage of the benzylidene ace-
tal in 19 with triethylsilane and trifluoroacetic
acid [31] gave the crystalline 3,6-di-O-benzyl
derivative 20 in 69% yield. The use of boron
trifluoride-ethyl etherate [32] instead of tri-
tive 21 in 89% yield, the structure of which
was evident from its 1H NMR spectrum
(Table 2). Acetylation of 21 gave 22, which
was submitted to oxidative removal of the
anomeric 4-methoxyphenyl glycoside with
ceric ammonium nitrate, followed by
trichloroacetimidoylation with trichloroace-
tonitrile and 1,8-diazabicyclo[5,4,0]undec-7-
ene (DBU) to afford the target a-imidate 23 in
88% overall yield, the anomeric configuration
of which was deduced from its H NMR
spectrum (Table 2).
Condensation of 15 and 16 (1 equiv) with a
moderate excess of 23 (1.1–1.3 equiv), in
1

N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
671
(AIBN) to give the crystalline acetamides 27
and 28 in 76 and 83% yields, respectively.
Saponification of the ester groups in 27 and 28
with lithium hydroperoxide [36] in tetra-
hydrofuran, followed by methanolic sodium
hydroxide afforded the corresponding hy-
droxy acids, which were directly O-sulfonated
by treatment with the sulfur trioxide–
trimethylamine complex in N,N-dimethylfor-
mamide at 50 °C, followed by ion-exchange
chromatography (Na+ resin) to provide the
sodium salts 29 and 30 in 65 and 68% overall
yields, respectively. As previously reported
dichloromethane at −15 °C, in the presence
of trimethylsilyl triflate, afforded readily the
b-linked disaccharide derivatives 25 and 26,
1
both in 60% yield. The H NMR spectra for
25 and 26 (Table 3) are in agreement with the
expected structures. A major by-product was
identified as the N-trichloroacetyl glycoside
24,
a
rather unexpected species, since
trichloroacetamide released by the glycosyla-
tion reaction is known [34] to be a rather poor
nucleophile. However, an intramolecular rear-
rangement of the trichloroacetimidoyl group
should be excluded since the corresponding
2-trichloromethyl oxazoline (not described in
Section 3) reacted slowly with trichloroac-
etamide under the glycosylation reaction con-
ditions. The N-trichloroacetyl groups in 25
and 26 were readily transformed [35] into
N-acetyl groups by radical reduction with
tributyltin hydride and azobisisobutyronitrile
[37], 4-O-sulfonation of the
D
-galactosamine
moiety was troublesome, and required a large
excess of reagent and prolonged reaction time
1
to go to completion. Comparison of the H
NMR spectra, recorded in deuterated
methanol, of 29 and 30 (Table 3) and of their
non-sulfated hydroxy acid precursors (details
Table 3
1H NMR data: carbohydrate ring protons for disaccharide derivatives 25–30, 1 and 2 a
b
Proton
25
26
27
28
29
30 b
1 c
5.25, 5.12
2 c
4.84
H-1I
J1,2
4.97
1.2
5.18
1.2
5.00
1.1
5.20
1.2
5.03
1.2
5.30
1.2
1.0, 1.5
1.0
J1,3
0.8
5.08
2.0
0.9
5.18
1.8
0.8
5.07
2.0
0.9
5.14
1.8
0.8
4.94
1.6
0.8
4.94
1.6
1.0
4.07
3.6
H-2I
J2,3
4.25, 4.05
3.5
J2,4
0.9
4.06
3.1
4.25
1.7
4.83
4.85
8.4
3.48
10.8
4.02
3.3
5.50
0.8
0.8
4.09
3.0
4.30
1.9
4.88
4.89
8.2
3.49
10.5
4.02
3.1
5.50
0.9
0.9
3.98
3.1
4.17
1.5
4.83
4.89
8.4
3.78
10.7
4.32
3.1
5.45
0.7
0.8
4.02
3.0
4.24
1.9
4.86
4.94
8.2
3.20
10.2
4.34
2.8
5.44
0.9
0.6
4.06
2.6
4.15
2.0
4.53
4.46
8.2
4.01
10.5
3.51
3.0
4.83
0.8
0.6
4.10
2.5
4.21
2.0
4.56
4.49
8.2
4.04
10.3
3.60
3.2
4.86
0.8
0.6
4.19
3.2
3.93
2.3
4.32
4.55
8.0
3.79
10.5
3.70
3.0
4.58
0.6
H-3I
J3,4
4.27, 4.17
3.0
3.96, 3.95
2.2
4.52, 4.51
4.50, 4.47
8.0
3.83
10.5
3.72
3.0
H-4I
J4,5
H-5I
H-1II
J1,2
H-2II
J2,3
H-3II
J3,4
H-4II
J4,5
4.60, 4.58
0.6
H-5II
J5,6a
J5,6b
H-6aII
J6a,6b
H-6bII
NH
3.60
5.9
6.9
3.13
−9.1
3.08
3.64
6.0
6.9
3.19
−9.2
3.13
3.60
5.7
7.2
3.07
−9.1
3.04
3.65
6.0
7.0
3.10
−9.2
3.02
3.68
5.0
6.5
3.88
−9.8
3.75
3.70
4.7
6.5
3.73
3.73
3.93
3.78
3.74
3.78
3.73
−10.0
3.82
6.72
7.6
6.82
7.5
5.52
7.2
5.54
6.6
J2,NH
a Chemical shifts (l, ppm) and coupling constants (J, in Hz) for solutions in CDCl3, unless otherwise stated.
b CD3OD.
c D2O.

672
N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
in Section 3) showed the expected [38]
downfield shifts (ꢀ0.8 ppm) of the signals for
H-4II in sulfates 29 and 30, and downfield
shifts (ꢀ0.8 ppm) of the signals for H-2I in 29
and 30, in good agreement with those reported
higher molecular size, which is currently being
investigated in our group.
3. Experimental
[13,28] for 2-O-sulfonated
L
-iduronic acid
residues in DeS oligosaccharides. These chem-
ical shift differences indicate clearly that sul-
fonation occurred at O-2I and O-4II. Final
hydrogenation of 29 and 30 with PdꢀC in
aqueous methanol afforded the target
molecules 2 and 1 in 78 and 90% yields,
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–
1
Elmer 241 polarimeter. H and 13C NMR
spectra were recorded at 27 °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.
Low-resolution 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 Cen-
tral de Microanalyse du CNRS (Vernaison,
France).
1
respectively. The H (Table 3) and 13C NMR
data for 1 and 2 are in agreement with the
expected structures. The coupling constants
observed for the reducing methyl a- -
L
iduronate residue in 2 indicate a predomi-
1
nance of C4 conformation, as reported [28]
for a similar reducing moiety in a synthetic
heparan sulfate fragment.
In conclusion, expeditious preparations of
L
-idose and
D
-galactosamine derivatives from
D
-gluco precursors are reported. A stereocon-
trolled and good-yielding coupling reaction
with the low reactive 4-hydroxyl group of
L
-iduronic acid esters was achieved using the
glycosyl donor 23, exemplifying the efficiency
of activated 2-deoxy-2-trichloroacetamido-
galacto derivatives in syntheses of 1,2-trans-2-
amino-2-deoxy- -glycosides. The way is now
open for the construction of fragments of
3-O-Benzyl-1,2-O-isopropylidene-6-O-pi6al-
oyl-h- -glucofuranose (4).—Pivaloyl chloride
D
D
-
(10.1 mL, 82 mmol) was added at 0 °C to a
solution of 3-O-benzyl-1,2-O-isopropylidene-
D
a-
D
-glucofuranose (3) [24] (17.0 g, 55 mmol)
in anhyd pyridine (90 mL) and anhyd CH2Cl2

N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
673
(45 mL), and the mixture was allowed to
attain rt within 3.5 h, then was cooled to 0 °C.
Methanol (20 mL) was added, and the mix-
ture was diluted with CH2Cl2 (50 mL), washed
with water, satd aq NaHCO3, and water,
dried (MgSO4) and concentrated. The residue
was crystallized from EtOAc–petroleum ether
to give 4 (18.47 g, 85%); mp 100–101 °C;
mmol) in dioxane (130 mL), and the mixture
was stirred for 5 h at 80 °C, then cooled,
deionized with Dowex 1X2-400 [OH−] resin,
filtered, and concentrated.
Benzoyl chloride (14 mL, 121 mmol) was
added at 0 °C to a solution of the residue in
anhyd CH2Cl2 (40 mL) and anhyd pyridine
(32 mL), and the mixture was stirred for 5 h at
rt, then cooled to 0 °C. Methanol (20 mL) was
added, and the mixture was diluted with
CH2Cl2 (50 mL), washed with water, satd aq
NaHCO3 and water, dried (MgSO4) and con-
centrated. The residue was eluted from a
column (200 g) of silica gel with 4:1 petroleum
ether–EtOAc to give 6 as a white foam (8.36
1
[h]D−32° (c 1, CHCl3); H NMR (CDCl3):
carbohydrate ring protons (see Table 1); 7.30
(m, 5 H, Ph), 4.65 (ABq, 2 H, CH2Ph), 1.47,
1.32 (2 s, 6 H, (CH3)2C), 1.21 (s, 9 H,
(CH3)3C); ISMS: m/z 417, [M+Na]+, 412,
[M+NH4]+, 395, [M+H]+. Anal. Calcd for
C21H30O7: C, 63.94; H, 7.66. Found: C, 63.81;
H, 7.53.
1
g, 62% from 5); [h]D −27° (c 1, CHCl3); H
3-O-Benzyl-1,2-O-isopropylidene-i-
L
-ido-
NMR (CDCl3): carbohydrate ring protons
(see Table 1); 8.10–7.10 (m, 25 H, Ph), 4.90 (s,
2 H, CH2Ph); ISMS: m/z 709, [M+Na]+,
704, [M+NH4]+, 687, [M+H]+. Anal. Calcd
for C41H34O10: C, 71.71; H, 4.99. Found: C,
71.79; H, 4.98.
furanose (5).—Triflic anhydride (5 mL, 30.5
mmol) was added dropwise at −15 °C to a
solution of 4 (11.13 g, 28.2 mmol) in anhyd
1,2-dichloroethane (140 mL) and anhyd pyri-
dine (11.4 mL), and the mixture was stirred
for 2 h at this temperature. Water (14 mL)
was added, and the mixture was stirred for 30
min at 85 °C, then cooled, diluted with
CH2Cl2 (75 mL), washed with water, cold 5%
aq HCl, satd aq NaHCO3, and water, dried
(MgSO4) and concentrated. The residue was
eluted from a column (100 g) of silica gel with
6:1“4:1 petroleum ether–EtOAc to give a
Benzyl 2,4,6-tri-O-benzoyl-3-O-benzyl-h- -
L
idopyranoside (8).—A mixture of 6 (8.39 g,
12.2 mmol), benzyl alcohol (1.9 mL, 18.4
,
mmol), and 4 A powdered molecular sieves (5
g) in anhyd CH2Cl2 (40 mL) was stirred for 1
h at rt under dry Ar, then cooled to 0 °C.
Trimethylsilyl triflate (2.3 mL, 12.2 mmol) was
added, and the mixture was stirred for 3 h at
0 °C. Triethylamine (5.5 mL) was added, and
the mixture was filtered, and concentrated.
The residue was eluted from a column (200 g)
of silica gel with 4:1 petroleum ether–EtOAc
containing 0.2% of Et3N, and crystallized
from the same mixture of solvents to give 8
(5.7 g, 70%); mp 113–114 °C; [h]D−5° (c 1,
mixture of 5- and 6-O-pivaloyl- -ido deriva-
L
tives (10.04 g, 90%).
A solution of the above intermediates in
MeOH (100 mL) was treated overnight at rt
with methanolic MeONa (1 M, 3 mL), then it
was deionized with Amberlite IR-120 [H+]
resin, filtered, and concentrated. The residue
was eluted from a column (100 g) of silica gel
with 5:2 AcOEt–CH2Cl2, and crystallized
from EtOAc–petroleum ether to afford 5
(6.31 g, 72% from 4); mp 84 °C, lit. 86–87 °C
[27]; [h]D−58° (c 1, CHCl3), lit. −61° [27];
1H NMR (CDCl3): carbohydrate ring protons
(see Table 1); 7.40 (m, 5 H, Ph), 4.60 (ABq, 2
H, CH2Ph), 3.05 (d, 1 H, J 2.5 Hz, HO-5),
2.12 (dd, 1 H, J 5.6 and 6.7 Hz, HO-6), 1.49,
1.34 (2 s, 6 H, (CH3)2C); ISMS: m/z 333,
[M+Na]+, 328, [M+NH4]+.
1
CHCl3); H NMR (CDCl3): carbohydrate ring
protons (see Table 1); 8.20–7.10 (m, 25 H,
Ph), 4.83, 4.70 (2 ABq, 4 H, CH2Ph); ISMS:
m/z 695, [M+Na]+, 690, [M+NH4]+, 565,
[M−OCH2Ph]+. Anal. Calcd for C41H36O9:
C, 73.20; H, 5.39. Found: C, 73.18; H, 5.24.
Methyl 2-O-benzoyl-3-O-benzyl-4,6-O-iso-
propylidene-h- -idopyranoside (9).—A solu-
L
tion of 7 (4.13 g, 7 mmol) in MeOH (20 mL)
was treated for 4 h at rt with methanolic
MeONa (1 M, 0.5 mL), then it was deionized
with Amberlite IR-120 [H+] resin, filtered and
concentrated to give the corresponding triol as
an oil (2.47 g, quantitative).
1,2,4,6-Tetra-O-benzoyl-3-O-benzyl-i- -
L
idopyranose (6).—Sulfuric acid (0.1 M, 220
mL) was added to a solution of 5 (6.5 g, 22

674
N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
min at 80 °C, then cooled, concentrated, evap-
orated with water (2×10 mL) and toluene
(2×10 mL).
A mixture of the above isolated triol, 2-
methoxypropene (1.4 mL, 14 mmol), and 10-
-camphorsulfonic acid (0.28 g) in dry
D,L
A mixture of the residue, imidazole (5.1 g,
75 mmol), and tert-butyldimethylsilyl chloride
(5.7 g, 37 mmol) in dry DMF (20 mL) was
stirred for 18 h at 50 °C, then cooled, diluted
with EtOAc (100 mL), washed with water, 5%
aq HCl and water, dried (MgSO4) and con-
centrated. The residue was eluted from a
column (50 g) of silica gel with 14:1 petroleum
ether–EtOAc to give 11 as an oil (2.55 g,
90%); [h]D−22° (c 1, CHCl3); 1H NMR
(CDCl3): carbohydrate ring protons (see Table
1); 8.10–7.10 (m, 10 H, Ph), 4.75 (ABq, 2 H,
CH2Ph), 3.45 (s, 3 H, OCH3), 0.93, 0.76 (2 s,
18 H, (CH3)3C), 0.11, 0.09,−0.08,−0.25 (4 s,
12 H, CH3Si); ISMS: m/z 639, [M+Na]+,
634, [M+NH4]+, 585, [M−OCH3]+. Anal.
Calcd for C33H52O7Si2: C, 64.24; H, 8.65.
Found: C, 64.08; H, 8.81.
DMF (28 mL) was stirred for 3 h at 0 °C.
Triethylamine (0.5 mL) was added, and the
mixture was diluted with EtOAc (200 mL),
washed with water, satd aq NaHCO3 and
water, dried (MgSO4) and concentrated. The
residue was eluted from a column (100 g) of
silica gel with 3:1 petroleum ether–EtOAc to
give the corresponding 4,6-O-isopropylidene
derivative (1.98 g, 87%).
Benzoyl chloride (0.84 mL, 7.2 mmol) was
added at 0 °C to a solution of the above
isolated alcohol in anhyd pyridine (20 mL),
and the mixture was stirred for 30 min at rt,
then cooled to 0 °C. Methanol (5 mL) was
added, and the mixture was diluted with
CH2Cl2 (100 mL), washed with water, satd aq
NaHCO3, and water, dried, and concentrated.
The residue was eluted from a column (50 g)
of silica gel with 3:1 petroleum ether–EtOAc
containing 0.2% of Et3N, and crystallized
from the same mixture of solvents to give 9
(2.25 g, 75% from 7); mp 110–111 °C; [h]D−
Benzyl
2-O-benzoyl-3-O-benzyl-4,6-di-O-
-idopyranoside (12).
tert-butyldimethylsilyl-h-
L
—Compound 10 (3.04 g, 6 mmol) was treated
as described for the preparation of 11 to give
oily 12 (3.74, 90%); [h]D −40° (c 1, CHCl3);
1H NMR (CDCl3): carbohydrate ring protons
(see Table 1); 8.10–7.20 (m, 15 H, Ph), 4.76,
4.70 (2 ABq, 4 H, CH2Ph), 0.90, 0.78 (2 s, 18
H, (CH3)3C), 0.09, 0.05, −0.03, −0.16 (4 s,
12 H, CH3Si); ISMS: m/z 716, [M+Na]+,
711, [M+NH4]+, 586, [M−OCH2Ph]+.
Anal. Calcd for C39H56O7Si2: C, 67.59; H,
8.14. Found: C, 67.60; H, 7.98.
1
29° (c 1, CHCl3); H NMR (CDCl3): carbohy-
drate ring protons (see Table 1); 8.10–7.30 (m,
10 H, Ph), 4.74 (ABq, 2 H, CH2Ph), 3.44 (s, 3
H, OCH3), 1.47, 1.42 (2 s, 6 H, (CH3)2C);
ISMS: m/z 451, [M+Na]+, 429, [M+H]+,
397, [M−OCH3]+. Anal. Calcd for C24H28O7:
C, 67.28; H, 6.59. Found: C, 67.12; H, 6.39.
Benzyl 2-O-benzoyl-3-O-benzyl-4,6-O-iso-
propylidene-h-
L
-idopyranoside
(10).—Com-
pound 8 (5.63 g, 8.4 mmol) was transesterified,
acetalated, and benzoylated as described for
the preparation of 9. The residue was eluted
from a column (150 g) of silica gel with 5:1
petroleum ether–EtOAc containing 0.2% of
Et3N to afford amorphous 10 (2.53 g, 63%);
Methyl (methyl 2-O-benzoyl-3-O-benzyl-4-
O - tert - butyldimethylsilyl - h - - idopyranosid)-
L
uronate (13).—A solution of chromium triox-
ide (1.34 g) in H2SO4 (18 M, 1.15 mL) and
water (2.85 mL) was added dropwise at 0 °C
to a solution of 11 (2.79 g, 4.5 mmol) in
acetone (100 mL) until thin-layer chromatog-
raphy (TLC) (15:1 CH2Cl2–MeOH) indicated
complete disappearance of the starting mate-
rial. The mixture was then poured into ice-
cold water, and extracted with EtOAc
(2×100 mL). The organic extracts were
washed with water, dried (MgSO4), and con-
centrated. The residue was eluted from a
column (80 g) of silica gel with 15:1 CH2Cl2–
MeOH to give the corresponding acid as an
oil (1.91 g).
1
[h]D−51° (c 1, CHCl3); H NMR (CDCl3):
carbohydrate ring protons (see Table 1); 8.10–
7.20 (m, 15 H, Ph), 4.75, 4.70 (2 ABq, 4 H,
CH2Ph), 1.45, 1.42 (2 s, 6 H, (CH3)2C); ISMS:
m/z 527, [M+Na]+, 522, [M+NH4]+, 397,
[M−OCH2Ph]+. Anal. Calcd for C30H32O7:
C, 71.41; H, 6.39. Found: C, 71.31; H, 6.51.
Methyl 2-O-benzoyl-3-O-benzyl-4,6-di-O-
tert-butyldimethylsilyl-h- -idopyranoside (11).
L
—A solution of 9 (1.97 g, 4.6 mmol) in AcOH
(20 mL) and water (10 mL) was stirred for 15

N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
675
l 170.04, 165.01 (CꢁO), 137.47–127.89 (aro-
matic C), 100.07 (C-1), 74.27 (C-5), 72.07
(CH2Ph), 68.05, 67.57, 67.50 (C-2,3,4), 56.48
(OCH3), 52.53 (COOCH3); ISMS: m/z 439,
[M+Na]+, 417, [M+H]+, 385, [M−
OCH3]+. Anal. Calcd for C22H24O8: C, 63.45;
H, 5.81. Found: C, 63.35; H, 5.89.
Methyl chloroformate (0.32 mL, 4.1 mmol)
was added at 0 °C to a solution of the above
isolated acid, Et3N (0.62 mL, 4.5 mmol), and
4-dimethylaminopyridine (46 mg, 0.4 mmol)
in anhyd CH2Cl2 (50 mL), and the mixture
was stirred for 90 min at 0 °C, then for 2 h at
rt. The mixture was poured into ice-cold wa-
ter, extracted with EtOAc (2×100 mL),
washed with water, satd aq NH4Cl and water,
dried (MgSO4) and concentrated. The residue
was eluted from a column (80 g) of silica gel
with 5:1 petroleum ether–EtOAc to give 13 as
a white foam (1.55 g, 65% from 11); [h]D−41°
(c 1, CHCl3); 1H NMR (CDCl3): carbohydrate
ring protons (see Table 1); 8.15–7.30 (m, 10
H, Ph), 4.88 (ABq, 2 H, CH2Ph), 3.79 (s, 3 H,
COOCH3), 3.50 (s, 3 H, OCH3), 0.69 (s, 9 H,
(CH3)3C), −0.13, −0.37 (2 s, 6 H, CH3Si);
ISMS: m/z 553, [M+Na]+, 531, [M+H]+,
499, [M−OCH3]+. Anal. Calcd for
C28H38O8Si: C, 63.37; H, 7.22. Found: C,
63.13; H, 7.34.
Methyl (benzyl 2-O-benzoyl-3-O-benzyl-h-
L
-idopyranosid)uronate (16).—Compound 14
(1.29 g, 2.1 mmol) was treated as described for
the preparation of 15. The residue was eluted
from a column (80 g) of silica gel with 5:1
petroleum ether–EtOAc to afford syrupy 16
1
(0.77 g; 74%); [h]D−36° (c 1, CHCl3); H
NMR (CDCl3): carbohydrate ring protons
(see Table 1); 8.0–7.20 (m, 15 H, Ph), 4.77,
4.75 (2 ABq, 4 H, CH2Ph), 3.82 (s, 3 H,
COOCH3), 2.80 (d, 1 H, J 11.7 Hz, HO-4);
13C (CDCl3): l 169.99, 165.05 (CꢁO), 137.55–
127.77 (aromatic C), 98.27 (C-1), 74.46 (C-5),
72.07, 70.28 (CH2Ph), 68.29, 67.94, 67.39 (C-
2,3,4), 52.52 (COOCH3); ISMS: m/z 515,
[M+Na]+, 385, [M−OCH2Ph]+. Anal.
Calcd for C28H28O8: C, 68.28; H, 5.12. Found:
C, 68.12; H, 5.25.
Methyl (benzyl 2-O-benzoyl-3-O-benzyl-4-
O - tert - butyldimethylsilyl - h - - idopyranosid)-
L
uronate (14).—Compound 12 (3.2 g, 4.6
mmol) was oxidized and esterified as described
for the preparation of 13 to give 14 (1.73 g,
4-Methoxyphenyl 4,6-O-benzylidene-2-de-
oxy-2-trichloroacetamido-i- -glucopyranoside
D
1
62% from 12); [h]D−73° (c 1, CHCl3); H
(18).—A suspension of 4-methoxyphenyl
3,4,6-tri-O-acetyl-2-deoxy-2-trichloroaceta-
NMR (CDCl3): carbohydrate ring protons
(see Table 1); 8.0–7.20 (m, 15 H, Ph), 4.82,
4.77 (2 ABq, 4 H, CH2Ph), 3.77 (s, 3 H,
COOCH3), 0.60 (s, 9 H, (CH3)3C), −0.10,
−0.30 (2 s, 6 H, CH3Si); ISMS: m/z 629,
[M+Na]+, 607, [M+H]+, 499, [M−
OCH2Ph]+. Anal. Calcd for C34H42O8Si: C,
67.08; H, 6.95. Found: C, 67.10; H, 6.78.
Methyl (methyl 2-O-benzoyl-3-O-benzyl-h-
mido-b- -glucopyranoside (17) [30] (32.0 g,
D
57.4 mmol) in MeOH (150 mL) was treated
for 2 h at rt with methanolic MeONa (1 M, 3
mL). The solution was then deionized with
Amberlite IR-120 [H+] resin, filtered and con-
centrated to give the corresponding triol as a
white powder (24.65 g).
Trifluoroacetic acid (9 mL) was added to a
suspension of the above isolated triol in ben-
zaldehyde (200 mL), and the mixture was
stirred for 3 h at rt. Triethylamine (15 mL),
then Et2O (500 mL) were added, and the
mixture was stirred for 15 min at 0 °C. The
solids were filtered off, and washed with Et2O
to give 18 as a white powder (19.2 g, 65%); mp
222–223 °C (from MeOH); [h]D +1° (c 1,
MeOH); 1H NMR (CDCl3): carbohydrate ring
protons (see Table 2); 7.50–6.80 (m, 9 H, Ph),
5.66 (s, 1 H, PhCH), 3.85 (s, 3 H, OCH3), 2.85
(d, 1 H, J 2.9 Hz, HO-3); ISMS: m/z 541,
[M+Na]+, 519, [M+H]+, 395, [M−
OC6H4OCH3]+ for 35Cl. Anal. Calcd for
L
-idopyranosid)uronate (15).—A mixture of 13
(2.62 g, 4.9 mmol) and Bu4NF (2.58 g, 9.9
mmol) in anhyd THF (30 mL) was stirred for
20 min at 0 °C, then it was diluted with cooled
(0 °C) EtOAc (100 mL), washed with satd aq
NH4Cl, and water, dried (MgSO4) and con-
centrated. The residue was eluted from a
column (50 g) of silica gel with 5:2 petroleum
ether–EtOAc to give syrupy 15 (1.24 g, 60%);
1
[h]D−19° (c 1, CHCl3); H NMR (CDCl3):
carbohydrate ring protons (see Table 1); 8.0–
7.20 (m, 10 H, Ph), 4.84 (ABq, 2 H, CH2Ph),
3.91 (s, 3 H, COOCH3), 3.52 (s, 3 H, OCH3),
13
2.85 (d, 1 H, J 11.5 Hz, HO-4); C (CDCl3):

676
N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
Calcd for C29H30Cl3NO7: C, 57.11; H, 4.79; N,
2.30. Found: C, 56.86; H, 4.83; N, 2.11.
4-Methoxyphenyl 3,6-di-O-benzyl-2-deoxy-
C22H22Cl3NO7: C, 50.93; H, 4.27; N, 2.70.
Found: C, 50.88; H, 4.41; N, 2.68.
4-Methoxyphenyl 3-O-benzyl-4,6-O-benzyli-
2 - trichloroacetamido - i -
D
- galactopyranoside
dene-2-deoxy-2-trichloroacetamido-i- -gluco-
D
(21).—Triflic anhydride (1.9 mL, 11.6 mmol)
was added dropwise at −15 °C under dry Ar
to a solution of 20 (4.55 g, 7.5 mmol) in anhyd
CH2Cl2 (70 mL) and anhyd pyridine (4.2 mL),
and the mixture was stirred for 2 h at this
temperature. Crushed ice (5 g) was then
added, and the mixture was diluted with
CH2Cl2 (100 mL), washed with water, brine
and water, dried (MgSO4), concentrated and
evaporated twice with toluene.
pyranoside (19).—Sodium hydride (60% in
mineral oil, 3.0 g, 74 mmol) was added por-
tionwise at 0 °C to a solution of 18 (19.17 g,
37 mmol) in dry DMF (150 mL), and the
mixture was stirred for 30 min at this temper-
ature. Benzyl bromide (5.8 mL, 49 mmol) was
then added, and the mixture was stirred for 30
min at 0 °C and for 90 min at rt. Methanol
(10 mL) was cautiously added, and the mix-
ture was diluted with EtOAc (1 L), washed
twice with water, dried (MgSO4) and concen-
trated. The solid residue was recrystallized
from MeOH to give 19 (18.37 g, 82%); mp
Sodium nitrite (5.17 g, 75 mmol) was added
at rt to a solution of the residue in dry DMF
(90 mL), and the mixture was stirred for 1 h at
rt, then was poured into ice-cold water and
extracted with EtOAc (2×100 mL). The com-
bined extracts were washed with water, 5% aq
HCl and water, dried (MgSO4) and concen-
trated. The residue was crystallized from
EtOAc–petroleum ether to afford 21 (4.06 g,
89%); mp 142–143 °C; [h]D+6.5° (c 1,
1
261–262 °C; [h]D+4° (c 1, CHCl3); H NMR
(CDCl3): carbohydrate ring protons (see Table
2); 7.50–6.80 (m, 14 H, Ph), 5.70 (s, 1 H,
PhCH), 4.91 (ABq, 2 H, CH2Ph), 3.84 (s, 1 H,
OCH3); ISMS: m/z 631, [M+Na]+, 609,
[M+H]+, 485, [M-OC6H4OCH3]+ for 35Cl.
Anal. Calcd for C29H28Cl3NO7: C, 57.11; H,
4.63; N, 2.30. Found: C, 57.14; H, 4.64; N,
2.37.
1
CHCl3); H NMR (CDCl3): carbohydrate ring
protons (see Table 2); 7.50–6.70 (m, 14 H,
Ph), 4.64, 4.57 (2 ABq, 4 H, CH2Ph), 3.75 (s,
3 H, OCH3); ISMS: m/z 634, [M+Na]+, 488,
4-Methoxyphenyl 3,6-di-O-benzyl-2-deoxy-
2 - trichloroacetamido - i -
D
- glucopyranoside
35
[M−OC6H4OCH3]+ for Cl. Anal. Calcd for
(20).—A mixture of 19 (6.42 g, 10.5 mmol), 4
C29H30Cl3NO7: C, 57.11; H, 4.79; N, 2.30.
Found: C, 56.91; H, 4.81; N, 2.36.
,
A powdered molecular sieves (5 g), and tri-
ethylsilane (8.5 mL, 53 mmol) in anhyd
CH2Cl2 (80 mL) was stirred for 1 h at rt under
dry Ar, then cooled to 0 °C. Trifluoroacetic
acid (4.1 mL, 53 mmol) was added, and the
mixture was stirred for 1 h at 0 °C and 1 h at
rt. Triethylamine (15 mL) was added, and the
mixture was filtered and concentrated. A solu-
tion of the residue in EtOAc (250 mL) was
washed with water, satd aq NaHCO3 and
water, dried (MgSO4) and concentrated. The
residue was eluted from a column (100 g) of
silica gel with 20:1 CH2Cl2–EtOAc and crys-
tallized from EtOAc–petroleum ether to af-
ford 20 (4.43 g, 69%); mp 141–142 °C;
4-Methoxyphenyl 4-O-acetyl-3,6-di-O-ben-
zyl-2-deoxy-2-trichloroacetamido-i- -galac-
D
topyranoside (22).—Conventional acetylation
(Ac2O in pyridine) of 21 (6.69 g, 10.9 mmol)
followed by concentration of the mixture and
crystallization of the residue from EtOAc–
petroleum ether gave 22 (6.09 g, 85%); mp
144–145 °C; [h]D +13° (c 1, CHCl3); 1H
NMR (CDCl3): carbohydrate ring protons
(see Table 2); 7.40–6.70 (m, 14 H, Ph), 4.58,
4.53 (2 ABq, 4 H, CH2Ph), 3.75 (s, 3 H,
OCH3), 2.10 (s, 3 H, Ac); ISMS: m/z 671,
[M+NH4]+, 530, [M−OC6H4OCH3]+ for
35Cl. Anal. Calcd for C31H32Cl3NO8: C, 57.02;
H, 4.94; N, 2.15. Found: C, 57.03; H, 4.98; N,
2.26.
1
[h]D−15° (c 1, CHCl3); H NMR (CDCl3):
carbohydrate ring protons (see Table 2); 7.50–
6.80 (m, 14 H, Ph), 4.88, 4.67 (2 ABq, 4 H,
CH2Ph), 3.83 (s, 3 H, OCH3), 2.82 (d, 1 H, J
2.6 Hz, HO-4); ISMS: m/z 632, [M+Na]+,
4.88, [M−OC6H4OCH3]+ for 35Cl. Anal.
4-O-Acetyl-3,6-di-O-benzyl-2-deoxy-2-
trichloroacetamido-1-O-trichloroacetimidoyl-h-
D
-galactopyranose (23).—A mixture of 22
(2.20 g, 3.4 mmol) and ceric ammonium ni-

N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
677
91.85 (CCl3), 81.79 (C-1), 75.33, 74.38 (C-4,5),
73.93, 71.09 (CH2Ph), 67.22, 64.75 (C-3,6),
52.30 (C-2), 20.96 (COCH3). Anal. Calcd for
C26H26Cl6N2O7: C, 45.17; H, 3.79; N, 4.15.
Found: C, 45.01; H, 3.92; N, 4.21.
trate (9.2 g, 16.8 mmol) in 1:1.5:1 toluene–
MeCN–water (56 mL) was vigorously stirred
for 15 min at rt, then was diluted with EtOAc
(100 mL), washed with water, dried (MgSO4)
and concentrated. The residue was eluted
from a column (80 g) of silica gel with 4:1
petroleum ether–EtOAc to give the corre-
sponding free hemiacetal (1.67 g).
Next eluted was 25, isolated as a white
foam (580 mg, 60%); [h]D −11.5° (c 1,
1
CHCl3); H NMR (CDCl3): carbohydrate ring
A mixture of the above isolated hemiacetal,
CCl3CN (3 mL, 30 mmol) and DBU (0.11
mL, 0.74 mmol) in anhyd CH2Cl2 (40 mL)
was stirred for 1 h at 0 °C, then concentrated.
The residue was eluted from a column (80 g)
of silica gel with 4:1 petroleum ether–EtOAc
containing 0.2% of Et3N to give 23 as a white
foam (1.94 g, 88% from 22); [h]D+78° (c 1,
protons (see Table 3); 8.10–7.20 (m, 20 H,
Ph), 4.74, 4.73, 4.40 (3 ABq, 6 H, CH2Ph),
3.82 (s, 3 H, COOCH3), 3.48 (s, 3 H, OCH3),
1.62 (s, 3 H, Ac); ISMS: m/z 963, [M+NH4]+
, 946, [M+H]+ for 35Cl. Anal. Calcd for
C46H48Cl3NO14: C, 58.45; H, 5.12; N, 1.48.
Found: C, 58.33; H, 5.23; N, 1.45.
Methyl (4-O-acetyl-3,6-di-O-benzyl-2-de-
1
CHCl3); H NMR (CDCl3): carbohydrate ring
oxy-2-trichloroacetamido-i- -galactopyran-
D
protons (see Table 2); 8.65 (s, 1 H, CꢁNH),
7.30 (m, 10 H, Ph), 4.59, 4.50 (2 ABq, 4 H,
CH2Ph), 2.10 (s, 3 H, Ac); 13C (CDCl3): l
170.16, 162.01 (CꢁO), 160.04 (CꢁN), 137.37–
128.07 (aromatic C), 94.64 (C-1), 92.11, 90.79
(CCl3), 73.80, 70.71 (CH2Ph), 71.62, 70.77
(C-4,5), 67.35, 65.15 (C-6,3), 50.75 (C-2),
20.84 (COCH3); ISMS: m/z 714, [M+Na]+,
osyl)-(1“4)-(benzyl 2-O-benzoyl-3-O-benzyl-
h- -idopyranosid)uronate (26).—A mixture of
L
alcohol 16 (774 mg, 1.6 mmol) and imidate 23
(1.17 g, 1.7 mmol) was treated as described for
the preparation of 25 to give 26 as a white
foam (960 mg, 60%); [h]D−27° (c 1, CHCl3);
1H NMR (CDCl3): carbohydrate ring protons
(see Table 3); 8.10–7.20 (m, 25 H, Ph), 4.73,
4.72, 4.44, 4.42 (4 ABq, 8 H, CH2Ph), 3.80 (s,
3 H, COOCH3), 1.60 (s, 3 H, Ac); ISMS: m/z
1039, [M+NH4]+ for 35Cl. Anal. Calcd for
C52H52Cl3NO14: C, 61.15; H, 5.13; N, 1.38.
Found: C, 61.05; H, 5.21; N, 1.41.
35
530, [M−CCl3CONH]+ for Cl. Anal. Calcd
for C26H26Cl6N2O7: C, 45.17; H, 3.79; N, 4.05.
Found: C, 44.94, H, 3.74; N, 4.24.
Methyl (4-O-acetyl-3,6-di-O-benzyl-2-de-
oxy-2-trichloroacetamido-i- -galactopyran-
D
osyl)-(1“4)-(methyl 2-O-benzoyl-3-O-benzyl-
h- -idopyranosid)uronate (25).—A mixture of
Methyl (2-acetamido-4-O-acetyl-3,6-di-O-
L
benzyl-2-deoxy-i-
D
-galactopyranosyl)-(1“4)-
-idopyra-
alcohol 15 (427 mg, 1 mmol), imidate 23 (900
(methyl 2-O-benzoyl-3-O-benzyl-h-
L
,
mg, 1.3 mmol) and 4 A powdered molecular
nosid)uronate (27).—A mixture of 25 (2.07 g,
2.2 mmol), Bu3SnH (3.2 mL, 12 mmol) and
AIBN (100 mg) in dry benzene (30 mL) was
stirred for 30 min at rt under a stream of dry
Ar, then heated for 1 h at 80 °C, cooled and
concentrated. The residue was stirred with
petroleum ether (40 mL), the crystalline mate-
rial was filtered off and washed with
petroleum ether to give 27 (1.41 g, 76%); mp
sieves (0.5 g) in anhyd CH2Cl2 (7 mL) was
stirred for 1 h at rt under dry Ar, then cooled
to −15 °C. A solution of Me3SiOTf in tolu-
ene (1 M, 0.76 mL) was added and the mix-
ture was stirred for 10 min at −15 °C.
Triethylamine (0.11 mL) was added and the
mixture was filtered and concentrated. The
residue was eluted from a column (75 g) of
silica gel with 2:1 petroleum ether–EtOAc
containing 0.2% of Et3N to give first amor-
phous 24 (276 mg, 31% from 23); [h]D+11.5°
(c 1, CHCl3); 1H NMR (CDCl3): carbohydrate
ring protons (see Table 2); 7.88 (d, 1 H, JNH,1
8.8 Hz, NHCOCCl3), 7.30 (m, 10 H, Ph), 4.59,
4.51 (2 ABq, 4 H, CH2Ph), 2.10 (s, 3 H, Ac);
13C (CDCl3): l 170.18 (CꢁO), 164.14, 162.73
(COCCl3), 137.38–128.22 (aromatic C), 92.49,
1
88–89 °C; [h]D−9° (c 1, CHCl3); H NMR
(CDCl3): carbohydrate ring protons (see Table
3); 8.10–7.20 (m, 20 H, Ph), 4.73, 4.51, 4.30 (3
ABq, 6 H, CH2Ph), 3.81 (s, 3 H, COOCH3),
3.47 (s, 3 H, OCH3), 1.96, 1.62 (2 s, 6 H, Ac);
ISMS: m/z 864, [M+Na]+, 842, [M+H]+.
Anal. Calcd for C46H51NO14: C, 65.62; H,
6.10; N, 1.66. Found: C, 65.42; H, 6.20; N,
1.74.

678
N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
Methyl (2-acetamido-4-O-acetyl-3,6-di-O-
benzyl-2-deoxy-i- -galactopyranosyl)-(1“4)-
(benzyl 2-O-benzoyl-3-O-benzyl-h- -idopyra-
[Na+] with 9:5:1 CH2Cl2–MeOH–water to
D
give amorphous 29 (590 mg, 65%); [h]D −6°
1
L
(c 1, MeOH); H NMR (CD3OD): carbohy-
nosid)uronate (28).—Compound 26 (825 mg,
0.81 mmol) was treated as described for the
preparation of 27 to afford 28 (617 mg, 83%);
drate ring protons (see Table 3); 7.30 (m, 15
H, Ph), 4.65–4.35 (m, 6 H, CH2Ph), 3.37 (s, 3
H, OCH3), 1.99 (s, 3 H, NAc). Anal. Calcd for
C36H40NNa2O18S2: C, 47.63; H, 4.44; N, 1.54.
Found: C, 47.35; H, 4.71; N, 1.44.
1
mp 83–84 °C; [h]D−25° (c 1, CHCl3); H
NMR (CDCl3): carbohydrate ring protons
(see Table 3); 8.10–7.20 (m, 25 H, Ph), 4.88–
4.28 (m, 8 H, CH2Ph), 3.77 (s, 3 H,
COOCH3), 2.0, 1.59 (2 s, 6 H, Ac); ISMS: m/z
941, [M+Na]+, 811, [M−OCH2Ph]+. Anal.
Calcd for C52H55NO14: C, 68.03; H, 6.04; N,
1.53. Found: C, 67.93; H, 6.04; N, 1.63.
Sodium (sodium 2-acetamido-3,6-di-O-ben-
zyl-2-deoxy-4-O-sulfonato-i- -galactopyran-
D
osyl)-(1“4)-(sodium benzyl 3-O-benzyl-2-O-
sulfonato-h- -idopyranosid)uronate (30).—
L
Compound 28 (571 mg, 0.62 mmol) was
treated as described for the preparation of 29
to afford the corresponding hydroxy acid (387
Sodium (sodium 2-acetamido-3,6-di-O-ben-
1
zyl-2-deoxy-4-O-sulfonato-i-
D
-galactopyran-
mg, 82%); H NMR (CD3OD): l 7.30 (m, 20
osyl)-(1“4)-(sodium methyl 3-O-benzyl-2-O-
sulfonato-h- -idopyranosid)uronate (29).—A
H, Ph), 5.18 (br s, 1 H, H-1I), 4.80–4.40 (m, 8
H, CH2Ph), 4.50 (d, 1 H, J1,2 8.0 Hz, H-1II),
4.47 (d, 1 H, J4,5 2.2 Hz, H-5I), 4.14 (m, 2 H,
H-2I,4I), 4.12 (dd, 1 H, J2,3 10.6 Hz, H-2II),
3.99 (dd, 1 H, J3,4 3.0, J4,5 0.5 Hz, H-4II), 3.78
(m, 1 H, H-3I), 3.63 (m, 3 H, H-5I,6aI,6bI),
3.50 (dd, 1 H, H-3II), 2.10 (s, 3 H, NAc);
ISMS: m/z 781, [M+Na]+, 759, [M+H]+.
The above isolated hydroxy acid (197 mg,
0.26 mmol) was O-sulfonated as described for
the preparation of 29 to give amorphous 30
L
solution of 27 (1.32 g, 1.6 mmol) in THF (30
mL) was treated at 0 °C with 30% H2O2 (3.9
mL) and LiOH (1 M, 7.8 mL) and the mixture
was stirred for 1 h at 0 °C and for 15 h at rt,
then cooled to 0 °C. Methanol (14 mL) and
NaOH (4 M, 2.4 mL) were added and the
mixture was stirred for 5 h at rt, then was
diluted with water (50 mL) and treated with
Amberlite IR-120 [H+] resin to pH 3.5 (pH
meter control), filtered and concentrated. The
residue was eluted from a column (80 g) of
silica gel with 15:1“9:1 CH2Cl2–MeOH to
give the corresponding hydroxy acid (1.06 g,
1
(174 mg, 68%); [h]D −10° (c 1, MeOH); H
NMR (CD3OD): carbohydrate ring protons
(see Table 3); 7.30 (m, 20 H, Ph), 4.95–4.40
(m, 8 H, CH2Ph), 2.0 (s, 3 H, NAc). Anal.
Calcd for C42H44NNa3O18S2: C, 51.27; H,4.51;
N, 1.42. Found: C, 51.02; H, 4.72; N, 1.31.
Sodium (sodium 2-acetamido-2-deoxy-4-O-
1
90%); H NMR (CD3OD): l 7.30 (m, 15 H,
Ph), 4.82 (br s, 1 H, H-1I), 4.73–4.43 (m, 6 H,
CH2Ph), 4.48 (d, 1 H, J4,5 1.7 Hz, H-5I), 4.41
(d, 1 H, J1,2 8.2 Hz, H-1II), 4.10 (m, 2 H,
H-2I,4I), 4.06 (dd, 1 H, J2,3 10.5 Hz, H-2II),
4.02 (m, 2 H, H-3I,4II), 3.61 (m, 3 H, H-
5II,6aII,6bII), 3.46 (dd, 1 H, J3,4 3.0 Hz, H-3II),
3.37 (s, 3 H, OCH3), 2.06 (s, 3 H, NAc);
ISMS: m/z 704, [M+Na]+, 699, [M+NH4]+,
682, [M+H]+.
sulfonato - i -
D
- galactopyranosyl) - (1“4)-
-idopyran)uronate (1).
(sodium 2-O-sulfonato-
L
—A solution of 30 (245 mg, 0.25 mmol) in 1:1
MeOH–water (8 mL) was hydrogenated in
the presence of 10% PdꢀC (100 mg) for 48 h at
rt. The mixture was filtered through a pad of
Celite and freeze-dried to give 1 (140 mg,
1
A mixture of the above isolated hydroxy
acid and sulfur trioxide–trimethylamine com-
plex (1.74 g, 12.5 mmol) was stirred for 2 days
at 50 °C. More reagent (1.74 g, 12.5 mmol)
was then added and the mixture was stirred
for further 2 days at 50 °C, then cooled.
Methanol (4 mL) was then added and the
mixture was concentrated. The residue was
eluted twice from columns (40 g) of silica gel
with 6:1“4:1 CH2Cl2–MeOH, then from a
column (1.5×20 cm) of Sephadex SP C25
90%); [h]D −2.5° (c 1, equilibrium, water); H
NMR (D2O, internal H2O, lH 4.754): carbo-
hydrate ring protons (see Table 3); 2.0, 1.99 (2
s, 3 H, NAc);13C (D2O, internal acetone, lC
30.45): l 175.39, 175.29 (CꢁO), 103.13, 101.77
(C-1II), 92.78, 91.90 (C-1I), 78.39, 77.60 (C-4I),
75.81 (C-2I, C-4II), 74.48 (C-5I), 70.10, 68.70,
67.70 (C-3I, C-3II, C-5II), 60.97 (C-6II), 52.78
(C-2II), 22.71 (COCH3). Anal. Calcd for
C14H20NNa3O18S2: C, 26.98; H, 3.23; N, 2.25.
Found: C, 26.69; H, 3.51; N, 2.10.

N. Barroca, J.-C. Jacquinet / Carbohydrate Research 329 (2000) 667–679
679
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Sodium (sodium 2-acetamido-2-deoxy-4-O-
sulfonato - i - - galactopyranosyl) - (1“4)-
(sodium methyl 2-O-sulfonato-h- -idopyra-
D
L
nosid)uronate (2).—Compound 29 (306 mg,
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−14° (c 1, water); H NMR (D2O, internal
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