Synthesis of chitotetraose and chitohexaose based on dimethylmaleoyl protection

Article abstract of DOI:10.1016/S0008-6215(01)00024-6

tert-Butyldimethylsilyl 3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-β-D-glucopyranoside was readily transformed into the disaccharide glycosyl donor, 3,4,6-tri-O-acetyl-2-deoxy-2-dimethylmaleimido-β-D-glucopyranosyl- (1→4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-α/β-D- glucopyranosyl trichloroacetimidate, and the disaccharide glycosyl acceptor, tert-butyldimethylsilyl 3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-β-D-glucopyranosyl- (1→4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-β-D- glucopyranoside. A TMSOTf-catalysed coupling of the acceptor with the donor afforded the respective tetrasaccharide derivative, which can be transformed to chitotetraose. tert-Butyldimethylsilyl 3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-4-O-phenoxyacetyl-β-D- glucopyranosyl-(1→4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido- β-D-glucopyranoside was converted into donor 3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-4-O-phenoxyacetyl-β-D- glucopyranosyl-(1→4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido- β-D-glucopyranosyl trichloroacetimidate. Its coupling with benzyl 3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-β-D-glucopyranosyl- (1→4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-β-D- glucopyranoside, followed by dephenoxyacetylation, gave benzyl 3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-β-D-glucopyranosyl- (1→4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-β-D- glucopyranosyl-(1→4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido- β-D-glucopyranosyl-(1→4)-3,6-di-O-benzyl-2-deoxy-2- dimethylmaleimido-β-D-glucopyranoside, whose glycosylation furnished, after replacement of the DMM-group by the acetyl moiety and subsequent deprotection, chitohexaose.

Full text of DOI:10.1016/S0008-6215(01)00024-6

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Carbohydrate Research 331 (2001) 129–142
Synthesis of chitotetraose and chitohexaose based on
dimethylmaleoyl protection
Mohamed R.E. Aly,1 El-Sayed I. Ibrahim,1 El Sayed H. El Ashry,*,2
Richard R. Schmidt
Fakulta¨t fu¨r Chemie, Uni6ersita¨t Konstanz, M 725, D-78457 Konstanz, Germany
Received 1 September 2000; accepted 16 January 2001
Abstract
tert-Butyldimethylsilyl 3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-b-
formed into the disaccharide glycosyl donor, 3,4,6-tri-O-acetyl-2-deoxy-2-dimethylmaleimido-b-
(1“4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-a/b- -glucopyranosyl trichloroacetimidate,
disaccharide glycosyl acceptor, tert-butyldimethylsilyl 3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-b-
nosyl-(1“4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-b- -glucopyranoside. A TMSOTf-catalysed coupling of
the acceptor with the donor afforded the respective tetrasaccharide derivative, which can be transformed to
chitotetraose. tert-Butyldimethylsilyl 3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-4-O-phenoxyacetyl-b- -glucopy-
ranosyl-(1“4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-b- -glucopyranoside was converted into donor 3,6-di-
O-benzyl-2-deoxy-2-dimethylmaleimido-4-O-phenoxyacetyl-b- -glucopyranosyl-(1“4)-3,6-di-O-benzyl-2-deoxy-2-
dimethylmaleimido-b- -glucopyranosyl trichloroacetimidate. Its coupling with benzyl 3,6-di-O-benzyl-2-deoxy-2-
dimethylmaleimido-b- -glucopyranosyl-(1“4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-b- -glucopyranoside,
followed by dephenoxyacetylation, gave benzyl 3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-b- -glucopyranosyl-
(1“4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-b- -glucopyranosyl-(1“4)-3,6-di-O-benzyl-2-deoxy-2-
dimethylmaleimido-b- -glucopyranosyl-(1“4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-b- -glucopyranoside,
D
-glucopyranoside was readily trans-
-glucopyranosyl-
and the
-glucopyra-
D
D
D
D
D
D
D
D
D
D
D
D
D
D
whose glycosylation furnished, after replacement of the DMM-group by the acetyl moiety and subsequent
deprotection, chitohexaose. © 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Chitotetraose; Chitohexaose; Chitooligomers; Glucosamine; Protective groups; Dimethylmaleoyl
1. Introduction
The b-(1–4) linked N-acetylglucosamine
moiety is a frequently occurring structural
* Corresponding author. Tel.: +20-3-5977665; fax: +20-
unit in various naturally and biologically im-
3-4271360.
portant oligosaccharides and their conjugates.
Chitin (1d) is a structural polysaccharide in
crab shells, and chitobiose (1a) is usually
found at the reducing end of N-glycan
residues of glycoproteins. Several biological
E-mail address: elashry@internetalex.com (E.S.H. El
Ashry).
1 Permanent address: Chemistry Department, Faculty of
Science, Suez Canal University, 41522 Ismailia, Egypt.
2 Permanent address: Chemistry Department, Faculty of
Science, Alexandria University, Alexandria, Egypt.
0008-6215/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(01)00024-6

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M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
functions are related to chitin oligomers.
Thus, they have been used as lysozyme sub-
strates,1–3 for biological studies on lectins,4–7
as antitumor agents8 and as immunopotentiat-
ing agents.9,10 Of these biologically active chi-
tooligosaccharides, chitotetraose (1b) has the
highest affinity among chitooligosaccharides
to bind to rat NKR-PL antigen, a carbohy-
drate-binding protein in rat natural killer
(NK) cells.11 On the other hand, chitohexaose
(1c) showed a remarkable antitumor activity
against Sarcoma 180 solid tumors in Bal b/c
mice; it is also an efficient elicitor of chitinase
(EC 3.2.1.14) activity in melon plants.12
Chemical and enzymatic hydrolysis of chitin
and chitosan are the commercial methods for
obtaining chitooligosaccharides,12–14 but these
procedures give low yields. Therefore, we re-
port herein the application of the dimethylma-
leoyl (DMM) group as an amino protective
group to the synthesis of chitotetraose (1b)
and chitohexaose (1c). Its ease of attachment
and subsequent cleavage, as well as its en-
hanced capability to form b linkages and its
compatibility with different protective group
manipulations made it a versatile amino pro-
tective group in glucosamine-containing
oligosaccharide synthesis.15–17 Our strategy is
based on using DMM-protected glucosamine
moieties as glycosyl donors and glycosyl ac-
ceptors for constructing these chitinoligomers.
2. Results and discussion
Synthesis of chitotetraose.—Glycosylation
of known tert-butyldimethylsilyl 3,6-di-O-
benzyl-2-dimethylmaleimido-b- -glucopyran-
D
oside (3)15 as a glycosyl acceptor with 4-O-
acetyl-3,6-di-O-benzyl-2-dimethylmaleimido-
a/b-
-glucopyranosyl trichloroactimidate (2)15
D
as glycosyl donor using trimethylsilyl trifl-
uoromethanesulfonate (TMSOTf) as a cata-
lyst in dichloromethane at room temperature
led to disaccharide derivative 4 in low yield.15
However, coupling of 3 with glycosyl donor 2
using TMSOTf as catalyst in acetonitrile as
solvent afforded the corresponding b-linked
1
disaccharide 4 in excellent yield (91%). Its H
NMR specrum (l 5.35, J1,2 8.4 Hz, H-1II)
supported the b anomeric linkage. Compound
4 was transformed into trichloroacetimidate 6
in high overall yield by 1-O-desilylation with
tetrabutylammonium fluoride (TBAF) and
acetic acid (AcOH) in dry tetrahydrofuran
(THF) (5) and subsequent reaction with
trichloroacetonitrile (TCA) in the presence of
1,8-diaza[5.4.0]bicycloundec-7-ene (DBU) as
base (Scheme 1).
Treatment of 3 with phenoxyacetyl chloride
in pyridine led to the 4-O-phenoxyacetyl
derivative 7. Ensuing 1-O-desilylation with
TBAF gave 8 which upon trichloroacetimida-
tion afforded glycosyl donor 9. TMSOTf-
catalysed glycosylation of acceptor 3 with 9 in
acetonitrile as solvent afforded the b linked
disaccharide 10 in good yield (71%). [1H
NMR: l 5.07 (J1,2 8.4 Hz, H-1II)]. Deacylation
of 10 with sodium methanolate in dry
methanol (Zemple´n conditions)18 led to 11, a
disaccharide glycosyl acceptor. Glycosylation
of 11 with the disaccharide donor 6 under
catalysis by TMSOTf afforded the desired b
linked tetrasaccharide 12 in 74% yield [1H
NMR: l 4.93 (J1,2 8.6 Hz, H-1III)] (Scheme 2).
Anomeric O-desilylation of 12 with TBAF
and acetic acid gave 13, which was trans-
formed into trichloroacetimidate 14. Coupling
of 14 as glycosyl donor with benzyl alcohol in
Scheme 1.

M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
131
(J2,NH 9.0 Hz, NH-2I)]. The small coupling
constant for H-1I [1H NMR: [l 4.67 (J1,2 4.7
4
Hz)]] may be attributed to a C1“1C4 inver-
sion of conformation at ring I. Deacetylation
of 16 with sodium methanolate in methanol
and subsequent hydrogenolytic O-debenzyla-
tion with palladium-on-carbon catalyst gave
the desired chitotetraose 1b in high overall
yield. For complete structural assignment, 1b
was peracetylated with acetic anhydride in
pyridine to afford the O-peracetyl derivative
17, which showed the desired signals [HMQC:
l 4.38, 4.42, 4,45 (3d, J 8–10 Hz, H-1II, H-1III,
H-1IV) and 6.10 (J1,2 3.6 Hz, H-1I)] (Scheme
3).
Synthesis of chitohexaose.—The synthesis
of chitohexaose (1c) could be readily achieved
from the available disaccharide precursors 6,
9, and 10. Thus, anomeric O-desilylation of 10
gave 18; ensuing transformation into
trichloroacetimidate 19 furnished the desired
disaccharide glycosyl donor 19 in high overall
yield (Scheme 4).
Scheme 2.
Reaction of 9 with benzyl alcohol in the
presence of TMSOTf as catalyst gave benzyl
glycoside 20 which was O-deacylated to afford
the glycosyl acceptor 21. Glycosylation of ac-
ceptor 21 with 9 as donor afforded chito-
bioside derivative 22 in good yield.
4-O-Deacylation of 22 yielded glycosyl accep-
tor 23. Similarly, coupling of 23 with glycosyl
donor 19 furnished chitotetraose derivative 24,
which on 4-O-deacylation afforded the desired
tetrasaccharide glycosyl acceptor 25 (Scheme
5).
Glycosylation of 25 with disaccharide donor
6 under standard conditions led to b-linked
hexasaccharide derivative 26 in reasonable
yield [1H NMR: l 4.96 (J1,2 8.2 Hz, H-1V)].
The six DMM-groups were removed in a one-
pot procedure by treatment with a sodium
hydroxide solution in a methanol–dioxane–
Scheme 3.
the presence of TMSOTf as catalyst led to
benzyl glycoside 15. Removal of the DMM
groups in 15 and N-acetylation was performed
in
a
one-pot reaction under standard
conditions15 to give 16 in 75% yield [HMQC:
l 4.71 (J2,NH 8.5 Hz, NH-2IV), 4.92 (J2,NH 9.7
Hz, NH-2III), 5.82 (J2,NH 9.8 Hz, NH-2II), 6.29
Scheme 4.

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M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
4.20 (d, J1,2 10.0 Hz, H-1VI), 4.12 (d, J1,2 8.8
Hz, H-1III)]; the small coupling constant for
H-1I was again due to conformational
changes. O-Deacetylation of 27, followed by
catalytic O-debenzylation, afforded the de-
sired chitohexaose (1c) (MALDIMS: m/z
1259.9 [M+Na]+) (Scheme 6).
In conclusion, the use of DMM-protected
glucosamine derived glycosyl donors and ac-
ceptors led to the efficient generation of chito-
biose building blocks which readily provided
chitotetraose, and chitohexaose intermediates,
thus permitting the synthesis of the target
molecules
3. Experimental
General methods.—Melting points are un-
corrected. Thin-layer chromatography (TLC)
was performed on plastic plates Silica Gel 60
F254 and on HPTLC plates NH2 F254 S (E.
Merck, layer thickness 0.2 mm). The detection
was achieved by treatment with a solution of
20 g ammonium molybdate and 0.4 g cerium-
(IV) sulfate in 400 mL of 10% H2SO4 or with
15% H2SO4, and heating at 150 °C. Flash
chromatography was carried out on silica gel
(Baker, 30–60 mm) and Lichroprep NH2 (E.
Merck, 40–63 mm). Medium-pressure liquid
chromatography (MPLC): LiChroprep Si 60
(E. Merck, 15–25 mm), detection by differen-
tial refractometer. Optical rotations were de-
Scheme 5.
water mixture, followed by addition of HCl in
the presence of ethanolamine to pH 5.15 Then
acetylation with acetic anhydride in pyridine
afforded hexasaccharide 27 in 74% yield
[HMQC: l 4.11 (NH-2V, NH-2VI), 5.19 (NH-
2III), 5.42 (NH-2IV), 5.82 (NH-2II), 6.35 (NH-
2I)]. The structure of 27 could be confirmed by
1
the H NMR data [l 4.61 (d, J1,2 5.0 Hz,
H-1I), 4.27 (d, J1,2 8.8 Hz, H-1II), 4.22 (d, J1,2
10.0 Hz, H-1V), 4.21 (d, J1,2 8.8 Hz, H-1IV),
Scheme 6.

M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
133
(positive-ion mode, DHB–THF matrix): m/z:
1001 Anal. Calcd for
[M+Na]+.
C50H64N2O16Si (977.11): C, 61.45; H, 6.60; N,
2.86. Found: C, 61.52; H, 6.67; N, 2.87.
3,4,6 - Tri - O - acetyl - 2 - deoxy - 2 - dimethyl-
termined at 21 °C with a Perkin–Elmer 241
MC polarimeter (1-dm cell). NMR spectra
were recorded with Bruker AC 250 and 600
DRX instruments, using tetramethylsilane as
1
an internal standard. The assignment of H
maleimido-i-
D
-glucopyranosyl-(1“4)-3,6-di-
NMR spectra were based on chemical shift
correlation (DQFCOSY) and rotating frame
nuclear Overhauser effect spectroscopy
O-benzyl-2-deoxy-2-dimethylmaleimido-h/i-
D-
glucopyranosyl trichloroacetimidate (6).—A
mixture of 4 (1.854 g, 1.89 mmol), AcOH
(0.126 g, 2.1 mmol, 0.12 mL) in dry THF (5
mL) was stirred in an ice–salt bath while
TBAF (0.549 g, 2.1 mmol, 2.1 mL) was added
dropwise. After 30 min at −5 °C the cooling
bath was removed, and the mixture was
stirred at rt overnight. The reaction mixture
was diluted with satd NaCl (25 mL) and ex-
tracted with CH2Cl2 (3×20 mL). The organic
layer was separated and dried with anhyd
MgSO4, and the solvent was evaporated in
vacuo. The residue was purified by flash chro-
matography (1:1 petroleum ether–EtOAc) to
yield 5 (1.579 g, 96%) as a white foam. TLC
(1:1 petroleum ether–EtOAc): Rf 0.16.
13
(ROESY). The assignment of C NMR spec-
tra were based on carbon–proton shift-corre-
lation heteronuclear multiple quantum
coherence (HMQC). MS spectra were
recorded with MALDI-Kompakt (Kratos)
and FAB with Finningen MAT 312/AMD.
Microanalyses were performed in the unit of
Microanalysis at the Fakulta¨t fu¨r Chemie,
Universita¨t Konstanz.
tert-Butyldimethylsilyl 3,4,6-tri-O-acetyl-2-
deoxy-2-dimethylmaleimido-i- -glucopyran-
D
osyl - (1“4) - 3,6 - di - O - benzyl - 2 - deoxy - 2-
dimethylmaleimido-i- -glucopyranoside (4).—
D
A solution of 2 (0.27 g, 0.484 mmol) and 3
(0.2 g, 0.343 mmol) in dry CH2Cl2 (1 mL) was
stirred under N2 at rt while TMSOTf (0.01 M
in CH2Cl2, 0.52 mL) was added dropwise (10
min). After 4 h the reaction mixture was neu-
tralized with Et3N, and the solvent was evapo-
rated in vacuo. The residue was purified by
flash chromatography (2.5:1 petroleum ether–
EtOAc) to yield 4 (0.305 g, 91%) as a white
foam. TLC (2.5:1 petroleum ether–EtOAc):
A mixture of 5 (1.579 g, 1.82 mmol),
CCl3CN (1.5 mL, 2.26 mmol) and DBU (0.05
mL, 0.33 mmol) in dry CH2Cl2 (6 mL) was
stirred at rt. After 7 h the reaction mixture
was concentrated in vacuo, and the residual
syrup was purified by flash chromatography
(1.5:1 EtOAc–petroleum ether, +1% Et3N)
to yield 6 (1.571 g, 85%) as a white foam in
the a/b ratio 1:1.5. TLC (1.5:1 petroleum
1
Rf 0.09; [h]D +14.4° (c 0.53, CHCl3); H
1
ether–EtOAc+1% Et3N): Rf 0.6; H NMR
NMR (600 MHz, CDCl3): l 7.37–7.12 (m, 10
H, 2 Ph), 5.59 (dd, 1 H, J2,3 10.4, J3,4 9.2 Hz,
H-3II), 5.35 (d, 1 H, J1,2 8.4 Hz, H-1II), 5.05–
5.02 (m, 2 H, H-1I, H-4II), 4.80, 4.41 (2 d, 2 H,
Jgem 12.7 Hz, CH2Ph), 4.60, 4.57 (2 d, 2 H,
Jgem 12.2 Hz, CH2Ph), 4.16 (dd,1 H, Jgem 12.2,
J5,6 4.4 Hz, H-6%II), 4.07–4.03 (m, 3 H, H-2II,
H-3I, H-4I), 3.89 (dd, 1 H, Jgem 12.2, J5,6 1.8
Hz, H-6II), 3.81 (m, 1 H, H-2I), 3.53–3.48 (m,
2 H, H-5II, H-6%I), 3.41 (dd, 1 H, Jgem 11.1, J5,6
3.7 Hz, H-6I), 3.35 (m, 1 H, H-5I), 1.97, 1.94,
1.88 (3 s, 9 H, 3 CH3CO), 1.75 (br.s, 12 H, 4
CH3), 0.67 [s, 9 H, SiC(CH3)3], −0.02 (s, 3 H,
SiCH3), −0.14 (s, 3 H, SiCH3). 13C NMR
(150.9 MHz, CDCl3): l 97.20 (C-1II), 93.60
(C-1I), 77.10 (C-3I, C-4I), 74.90 (C-5I), 74.20
(CH2Ph), 73.40 (CH2Ph), 71.70 (C-5II), 71.10
(C-3II), 69.10 (C-4II), 68.50 (C-6I), 62.00 (C-
6II), 57.90 (C-2I), 55.40 (C-2II). MALDIMS
(250 MHz, CDCl3): l 8.49 (s, 1 H, NH),
7.44–7.12 (m, 10 H, 2 Ph), 6.14 (d, 0.6 H, J1,2
8.7 Hz, H-1Ib), 6.13 (d, 0.4 H, J1,2 3.9 Hz,
H-1Ia), 5.60 (dd, 1 H, J2,3 10.6, J3,4 9.1 Hz,
H-3II), 5.36 (d, 1 H, J1,2 8.4 Hz, H-1II), 5.05
(dd, 1 H, J3,4=J4,5 9.1 Hz, H-4II), 4.86, 4.43 (2
d, 2 H, Jgem 12.7 Hz, CH2Ph), 4.62 (br.s, 2 H,
CH2Ph), 4.31–3.37 (m, 10 H), 1.99, 1.98, 1.96,
1.90, 1.74 (5 s, 21 H, 4 CH3, 3 CH3CO).
FABMS (positive-ion mode, NBOH–NaI ma-
trix): m/z 1030 [M+Na]+. Anal. Calcd for
C46H50Cl3N3O16 (1007.25): C, 54.84; H, 5.00;
N 4.17. Found: C, 54.97; H 5.00; N, 4.45.
tert-Butyldimethylsilyl 3,6-di-O-benzyl-2-de-
oxy-2-dimethylmaleimido-4-phenoxyacetyl-i-
D
-glucopyranoside (7).—A solution of 3 (4.21
g, 7.23 mmol) in Py (12 mL) was cooled in an
ice–salt bath, then phenoxyacetyl chloride
(3.705 g, 21.7 mmol, 3.0 mL) was added drop-

134
M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
(positive-ion mode, NBOH–NaI matrix): m/z
769 [M+Na]+ and m/z 919 [M+NaI]Na+.
Anal. Calcd for C36H35Cl3N2O9 (746.03): C,
57.95; H, 4.72; N, 3.75. Found: C, 58.04; H,
4.82; N, 3.74.
tert-Butyldimethylsilyl 3,6-di-O-benzyl-2-de-
oxy-2-dimethylmaleimido-4-O-phenoxyacetyl-
wise. After 2 h the reaction mixture was co-
evaporated with toluene in vacuo. The residue
was dissolved in CH2Cl2, and the solution was
then washed successively with HCl (3%, 50
mL), water (50 mL), and satd NaHCO3 (50
mL), and then dried with MgSO4. The solvent
was evaporated, and traces were removed by
coevaporation with toluene in vacuo. The
residue was purified by flash chromatography
(8:1, petroleum ether–EtOAc) to yield 7 (4.6
g, 88%) as a colorless oil. TLC (8:1 petroleum
ether–EtOAc): Rf 0.13; [h]D +17.3° (c 0.33,
CHCl3); 1H NMR (250 MHz, CDCl3): l
7.33–6.80 (m, 15 H, 3 Ph), 5.18 (d, 1 H, J1,2
8.1 Hz, H-1), 5.15 (dd, 1 H, J3,4 =J4,5 9.8 Hz,
H-4), 4.54–4.29 (2 d, 2 H, Jgem 12.1 Hz,
CH2Ph), 4.48–4.30 (m, 5 H, H-3, CH2Ph,
PhOCH2CO), 3.98 (dd, 1 H, J1,2 8.1, J2,3 10.9
Hz, H-2), 3.74–3.66, 3.57–3.55 (2 m, 3 H,
H-5, H-6, H-6%), 1.82 (br.s, 6 H, 2 CH3), 0.74
[s, 9 H, SiC(CH3)3], 0.05 (s, 3 H, SiCH3),
−0.05 (s, 3 H, SiCH3). MALDIMS (positive-
ion mode, DHB–THF matrix) m/z: 739 [M+
Na]+. Anal. Calcd for C40H49NO9Si (715.88):
C, 67.10; H, 6.89; N, 1.95. Found: C, 66.82;
H, 6.80; N, 1.71.
i-
D
-glucopyranosyl-(1“4)-3,6-di-O-benzyl-
-glucopyran-
2-deoxy-2-dimethylmaleimido-i-
D
oside (10).—A mixture of 9 (1.519 g, 2.036
mmol) and 3 (1.0 g, 1.716 mmol) in dry
MeCN (4 mL) was stirred under N2 at rt for
10 min while TMSOTf (0.01 M in MeCN,
2.03 mL) was added dropwise. After stirring
overnight the reaction mixture was neutralized
with triethylamine, the solvent was evapo-
rated, and the residue was dried in vacuo. The
residue was purified by flash chromatography
(6:1 petroleum ether–EtOAc) to yield 10
(1.425 g, 71%) as a white foam. TLC (3:1
petroleum ether–EtOAc): Rf 0.29; [h]D
+
1
30.4° (c 0.46, CHCl3); H NMR (600 MHz,
CDCl3): l 7.26–6.72 (m, 25 H, 5 Ph), 5.14
(dd, 1 H, J3,4 =J4,5 9.4 Hz, H-4II), 5.07 (d, 1
H, J1,2 8.4 Hz, H-1II), 4.97 (d, 1 H, J1,2 8.2 Hz,
H-1I), 4.74, 4.36 (2 d, 2 H, Jgem 12.6 Hz,
CH2Ph), 4.46, 4.18 (2 d, 2 H, Jgem 12.2 Hz,
CH2Ph), 4.34–4.24 (m, 5 H, H-3II, 2 CH2Ph),
4.27 (m, 2 H, PhOCH2), 4.00–3.93 (m, 3 H,
H-4I, H-2II, H-3I), 3.76 (dd, 1 H, J1,2 8.2, J2,3
10.2 Hz, H-2I), 3.47–3.44 (m, 1 H, H-5II),
3.43–3.40 (m, 2 H, H-6%I, H-6%II), 3.33 (dd, 1
H, Jgem 10.4, J5,6 4.4 Hz, H-6II), 3.26–3.25 (m,
2 H, H-5I, H-6I), 1.72–1.69 (br.m, 12 H, 4
CH3), 0.64 [s, 9 H, SiC(CH3)3], −0.09 (s, 3 H,
SiCH3), −0.20 (s, 3 H, SiCH3). 13C NMR
(150.9 MHz, CDCl3): l 97.30 (C-1II), 93.30
(C-1I), 77.00 (C-3II), 76.90 (C-3I), 76.30 (C-4I),
74.60 (C-5I), 74.20 (CH2Ph), 73.80 (CH2Ph),
73.60 (C-4II, CH2Ph), 72.80 (CH2Ph), 72.50
(C-5II), 69.60 (C-6II), 67.90 (C-6I), 65.20
(PhOCH2), 57.60 (C-2I), 55.90 (C-2II).
MALDIMS (positive-ion mode, DHB–THF
matrix): m/z 1191 [M+Na]+. Anal. Calcd for
C66H76N2O15Si (1165.37): C, 68.01; H, 6.57; N,
2.40. Found: C, 67.61; H, 6.57; N, 1.91.
3,6 - Di - O - benzyl - 2 - deoxy - 2 - dimethyl-
maleimido-4-phenoxyacetyl-h/i- -glucopyran-
D
osyl trichloroacetimidate (9).—A mixture of 7
(2.728 g, 3.81 mmol) and AcOH (0.26 g, 4.3
mmol) in dry THF (10 mL) was treated with
TBAF (1.0 M solution in THF, 4.29 mL, 4.29
mmol) and then worked up as described for
the synthesis of 5. The residue was purified by
flash chromatography (1.5:1 petroleum ether–
EtOAc) to yield 8 (1.824 g, 79%) as a white
foam. TLC (1.5:1 petroleum ether–EtOAc):
Rf 0.13.
A mixture of 8 (1.824 g, 3.02 mmol),
CCl3CN (2.0 mL, 1.2 mmol) and DBU (0.07
mL, 0.42 mmol) in dry CH2Cl2 (7 mL) was
stirred at rt for 2 h, then concentrated in
vacuo. The residue was purified by flash chro-
matography (1:1 petroleum ether–EtOAc+
1% Et3N) to yield 9 (1.954 g, 86%) as a yellow
foam in the a/b ratio 1:6. TLC (1:1 petroleum
ether–EtOAc+1% Et3N): Rf 0.58 (b-form)
tert-Butyldimethylsilyl 3,6-di-O-benzyl-2-de-
1
and Rf 0.69 (a-form); H NMR (250 MHz,
oxy-2-dimethylmaleimido-i- -glucopyranosyl-
D
CDCl3): l 8.61 (s, 0.14 H, NHa), 8.59 (s, 0.86
H, NHb), 7.33–6.78 (m, 15 H, 3 Ph), 6.26–
3.55 (m, 13 H), 1.78 (s, 6 H, 2 CH3). FABMS
(1“4)-3,6-di-O-benzyl-2-deoxy-2-dimethyl-
maleimido-i- -glucopyranoside (11).—A solu-
tion of 10 (1.425 g, 1.222 mmol) in MeOH
D

M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
135
74%) as a white foam. TLC (1.75:1 petroleum
ether–EtOAc): Rf 0.13; [h]D −1.8° (c 0.6,
CHCl3); 1H NMR (600 MHz, CDCl3): l
7.22–6.97 (m, 30 H, 6 Ph), 5.53 (dd, 1 H, J2,3
10.3, J3, 4 9.2 Hz, H-3IV), 5.25 (d, 1 H, J1,2 8.4
Hz, H-1IV), 5.00 (dd, 1 H, J3,4=J4,5 9.2 Hz,
H-4IV), 4.96 (d, 1 H, J1,2 8.1 Hz, H-1I), 4.95 (d,
1 H, J1,2 8.7 Hz, H-1II), 4.93 (d, 1 H, J1,2 8.6
Hz, H-1III), 4.86–4.82 (m, 2 H, CH2Ph), 4.73
(d, 1 H, Jgem 13.0 Hz, CHHPh), 4.50–4.30 (m,
9 H, 4.5 CH2Ph), 4.11–4.10 (m, 2 H, H-6%IV,
H-4II), 4.00–3.88 (m, 6 H, H-4I, H-3I, H-3III,
H-4III, H-2IV, H-3II), 3.83–3.82 (m, 3 H, H-
2III, H-6IV, H-2II), 3.73 (dd, 1 H, J1,2 8.1 Hz,
H-2I), 3.49 (d, 1 H, Jgem 10.8 Hz, H-6%II),
3.40–3.37 (m, 2 H, H-6%I, H-6%III), 3.31 (m, 1
H, H-5IV), 3.24–3.22 (m, 2 H, H-5I, H-6I),
3.20 (dd, 1 H, H-6II), 3.08 (dd, 1 H, H-6III),
3.04–3.03 (m, 2 H, H-5III, H-5II), 1.95–1.51
(several s, 21 H, 8 CH3, 3 CH3CO), 0.64 [s, 9
H, SiC(CH3)3], 0.64 [s, 9 H, SiC(CH3)3], −
0.20 (s, 3 H, SiCH3). 13C NMR (150.9 MHz,
CDCl3): l 97.40 (C-1II, C-1III), 97.10 (C-1IV),
93.60 (C-1I), 78.00 (C-3III), 77.90 (C-3II), 77.50
(C-3I), 76.30 (C-4I), 76.10 (C-4III, C-4II), 75.00
(C-5I), 74.80 (C-5III, CH2Ph), 74.70, 74.50 (2
CH2Ph), 74.50 (C-5II), 73.20, 73.00, 72.80 (3
CH2Ph), 71.60 (C-5IV), 71.20 (C-3IV), 69.00
(C-4IV), 68.40 (C-6I), 67.70 (C-6II), 67.40 (C-
6III), 61.70 (C-6IV), 58.00 (C-2I), 56.70 (C-2III,
C-2II), 55.50 (C-2IV). MALDIMS (positive-ion
mode, DHB–THF matrix): m/z 1899 [M+
Na]+, m/z 1915 [M+K]+. Anal. Calcd for
C102H118N4O28Si (1876.07): C, 65.29; H, 6.33;
N, 2.98. Found: C, 64.68; H, 6.34; N, 2.53.
3,4,6 - Tri - O - acetyl - 2 - deoxy - 2 - dimethyl-
(11.7 mL) was stirred with NaOMe (0.195 M,
0.63 mL). After 75 min the reaction mixture
was neutralized with Amberlite IR120 resin
(H+-form) and filtered, and the solvent was
evaporated in vacuo. The residue was purified
by flash chromatography (3.5:1 petroleum
ether–EtOAc) to yield 11 (0.942 g, 74%) as a
white foam. TLC (3.5:1 petroleum ether–
EtOAc): Rf 0.12; [h]D −0.94° (c 0.53, CHCl3).
1H NMR (600 MHz, CDCl3): l 7.35–7.12 (m,
20 H, 4 Ph), 5.15 (d, 1 H, J1,2 8.4 Hz, H-1II),
5.05 (d, 1 H, J1,2 8.2 Hz, H-1I), 4.82 (d, 1 H,
Jgem 12.5 Hz, CHHPh), 4.59, 4.53 (2 d, 2 H,
Jgem 12.2 Hz, CH2Ph), 4.52–4.47 (m, 3 H, 1.5
CH2Ph), 4.79, 4.44 (2 d, 2 H, Jgem 12.5 Hz,
CH2Ph), 4.11 (dd, 1 H, J2,3 10.6, J3,4 8.6 Hz,
H-3II), 4.05–4.03 (m, 2 H, H-3I, H-4I), 3.92
(dd, 1 H, J1,2 8.4, J2,3 10.7 Hz, H-2II), 3.83 (dd,
1 H, J1,2 8.2, J2,3 10.3 Hz, H-2I), 3.75 (dd, 1 H,
J3,4 8.6, J4,5 9.2 Hz, H-4II), 3.67 (dd, 1 H, Jgem
10.0, J5,6% 4.4 Hz, H-6%II), 3.54–3.50 (m, 2 H,
H-6%I, H-6II), 3.42–3.33 (m, 3 H, H-5I, H-6I,
H-5II), 3.05 (s, 1 H, OH), 1.90–1.77 (br.m, 12
H, 4 CH3), 0.72 [s, 9 H, SiC(CH3)3], 0.01 (s, 3
13
H, SiCH3), −0.11 (s, 3 H, SiCH3). C NMR
(150.9 MHz, CDCl3): l 97.60 (C-1II), 93.70
(C-1I), 79.30 (C-3II), 77.20 (C-3I), 76.50 (C-4I),
75.60 (C-4II), 75.10 (C-5I), 74.70 (CH2Ph),
74.40 (2 CH2Ph), 73.20 (C-5II, CH2Ph), 71.40
(C-6II), 68.50 (C-6I), 58.10 (C-2I), 56.20 (C-2II).
MALDIMS (positive-ion mode, DHB–THF
matrix): m/z 1054 [M+Na]+. Anal. Calcd for
C58H70N2O13Si (1031.24): C, 67.54; H, 6.84; N,
2.71. Found: C, 67.24; H, 7.00; N, 2.78.
tert-Butyldimethylsilyl 3,4,6-tri-O-acetyl-2-
deoxy-2-dimethylmaleimido-i- -glucopyran-
D
maleimido-i-
O-benzyl-2-deoxy-2-dimethylmaleimido-i-
glucopyranosyl-(1“4) -3,6-di-O-benzyl-2-de-
oxy-2-dimethylmaleimido-i- -glucopyranosyl-
(1“4)-3,6-di-O-benzyl-2-deoxy-2-dimethyl-
maleimido - i - - glucopyranosyl trichloroacet-
D
-glucopyranosyl-(1“4)-3,6-di-
osyl - (1“4) - 3,6 - di - O - benzyl - 2 - deoxy - 2-
dimethylmaleimido - i - - glucopyranosyl - (1“
4)-3,6-di-O-benzyl-2-deoxy-2-dimethylmaleim-
ido - i - - glucopyranosyl - (1“4) - 3,6 - di-
O-benzyl-2-deoxy-2-dimethylmaleimido-i-
D
-
D
D
D
D-
D
glucopyranoside (12).—A mixture of 6 (0.764
g, 0.758 mmol) and 11 (0.613 g, 0.594 mmol)
in dry MeCN (2 mL) was stirred under N2 at
rt while TMSOTf (0.01 M in MeCN (0.76
mL) was added dropwise, and the mixture was
stirred overnight. The reaction mixture was
then neutralized with Et3N, and the solvent
was evaporated in vacuo. The residue was
purified by flash chromatography (1.75:1
petroleum ether–EtOAc) to yield 12 (0.828 g,
imidate (14).—A mixture of 12 (1.044 g, 0.556
mmol) and AcOH (0.042 g, 0.61 mmol, 0.035
mL) in dry THF (3 mL) was treated with
TBAF (1.0 M in THF, 0.56 mL, 0.56 mmol)
and then worked up as described for the syn-
thesis of 5. The residue was purified by flash
chromatography (1:1 petroleum ether–
EtOAc) to yield 13 (0.659 g, 67%) as a white
foam. TLC (1:1 petroleum ether–EtOAc): Rf
0.17.

136
M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
(m, 2 H, H-6I, H-5IV), 3.27 (m, 1 H, H-5I),
A mixture of 13 (0.659 g, 0.374 mmol),
3.22 (dd, 1 H, Jgem 11.1, J5,6 3.1 Hz, H-6III),
3.11 (dd, 1 H, Jgem 11.2, J5,6 3.2 Hz, H-6II),
3.07 (m, 1 H, H-5III), 2.98 (m, 1 H, H-5II),
1.99–1.60 (m, 33 H, 8 CH3, 3 CH3CO). 13C
NMR (150.9 MHz, CDCl3): l 171.91–169.43
(8 CO, 3 CH3CO), 138.49–136.47, 128.26–
126.69 (7 Ph-C), 97.24 (C-1I), 96.99 (C-1III),
96.86 (C-1II), 96.73 (C-1IV), 77.50 (C-3III),
77.60 (C-3II), 77.10 (C-3I), 75.70 (C-4III), 75.60
(C-4II), 75.50 (C-4I), 74.71 (CH2Ph), 74.50 (C-
5I), 74.30 (C-5II, CH2Ph), 74.20 (CH2Ph),
74.00 (C-5III), 72.74 (CH2Ph), 72.49 (CH2Ph),
72.39 (CH2Ph), 71.22 (C-5IV), 70.80 (C-3IV),
70.37 (CH2Ph), 68.63 (C-4IV), 68.10 (C-6I),
67.30 (C-6III), 67.08 (C-6II), 61.37 (C-6IV),
56.39 (C-2II), 56.31 (C-2III), 55.42 (C-2I), 55.12
(C-2IV), 20.57, 20.51 (3 CH3CO), 8.84, 8.43 (8
CH3). MALDIMS (positive-ion mode, DHB–
THF matrix): m/z 1872 [M+Na]+, m/z
1887.3 [M+K]+. C103H110N4O28 (1851.94).
Benzyl 2-acetamido-3,4,6-tri-O-acetyl-2-de-
CCl3CN (0.5 mL, 4.986 mmol) and DBU
(0.05 mL, 0.33 mmol) in dry CH2Cl2 (6 mL)
was stirred at rt. After 8 h the rection mixture
was concentrated in vacuo, and the residual
syrup was purified by flash chromatography
(1:1 petroleum ether–EtOAc+1% Et3N) to
yield 14 (0.634 g, 88%) as a yellow foam. TLC
(1.5:1 petroleum ether–EtOAc+1% Et3N): Rf
1
0.67; [h]D +16.7° (c 0.4, CHCl3); H NMR
(250 MHz, CDCl3): l 8.44 (s, 1 H, NH),
7.37–6.96 (m, 30 H, 6 Ph),. 6.10 (d, 1 H, J1,2
7.9 Hz, H-1I), 5.58 (dd, 1 H, J2,3 10.3, J3,4 9.3
Hz, H-3IV), 5.28 (d, 1 H, J1,2 8.3 Hz, H-1IV),
5.08–2.65 (m, 37 H), 1.66–2.03 (several s, 33
H, 8 CH3, 3 CH3CO). Anal. Calcd for
C98H104Cl3N5O28 (1906.22): C, 61.74; H, 5.49;
N 3.67. Found: C, 62.45; H, 5.74; N, 3.32.
Benzyl 3,4,6-tri-O-acetyl-2-deoxy-2-dimethyl-
maleimido - i -
3,6 - di - O - benzyl - 2 - deoxy - 2 - dimethylmale-
imido-i- -glucopyranosyl-(1“4)-3,6-di-O-
benzyl-2-deoxy-2-dimethylmaleimido-i- -glu-
copyranosyl-(1“4)-3,6-di-O-benzyl-2-deoxy-
2 - dimethylmaleimido - i - - glucopyranoside
D
- glucopyranosyl - (1“4)-
D
oxy-i-
3,6-di-O-benzyl-2-deoxy-i-
(1“4)-2-acetamido-3,6-di-O-benzyl-2-deoxy-
i- -glucopyranosyl-(1“4)-2-acetamido-3,6-
di - O - benzyl - 2 - deoxy - i - - glucopyranoside
D
-glucopyranosyl-(1“4)-2-acetamido-
D
D
-glucopyranosyl-
D
D
(15).—A mixture of 14 (0.151 g, 0.079 mmol)
and benzyl alcohol (0.015 g, 0.138 mmol, 15.0
mL) in dry MeCN (1 mL) was stirred under N2
at rt while TMSOTf (0.01 M in MeCN, 0.09
mL) was added dropwise. After 2 h the reac-
tion mixture was neutralized with Et3N, and
the solvent was evaporated in vacuo. The
residue was purified by flash chromatography
(1.5:1 petroleum ether–EtOAc) to yield 15
(0.109 g, 75%) as an amorphous mass. TLC
(1.5:1 petroleum ether–EtOAc): Rf 0.14; [h]D
D
(16).—A mixture of 15 (0.109 g, 0.059 mmol)
and NaOH (0.6 g, 15.0 mmol) in 5:2:1
MeOH–dioxane–water (8 mL) was stirred at
rt overnight. The mixture was neutralized with
2 N HCl, and the pH was adjusted to pH 5
with N HCl in the presence of ethanolamine
(0.02 g, 0.332 mmol, 0.02 mL). After 1 day the
solution was neutralized with ethanolamine
and evaporated, and the residue was thor-
oughly dried in vacuo. The residue was treated
with Py 2:1 Ac2O (15 mL) and stirred
overnight. The reaction mixture was worked
up as described for the synthesis of 7. The
residue was purified by flash chromatography
(2:1 toluene–acetone), and the fractions of
partially deprotected products were collected
and treated again similarly as described before
to yield 16 (0.078 g, 75%) as an amorphous
mass. TLC (1:1 toluene–acetone): Rf 0.34;
1
+2.6° (c 0.6, CHCl3); H NMR (600 MHz,
CDCl3): l 7.26–7.00 (m, 35 H, 7 Ph), 5.57
(dd, 1 H, J2,3 10.7, J3,4 9.0 Hz, H-3IV), 5.29 (d,
1 H, J1,2 8.4 Hz, H-1IV), 5.04 (dd, 1 H, J3,4=
J4,5 9.0 Hz, H-4IV), 5.00 (d, 1 H, J1,2 8.5 Hz,
H-1III), 4.95 (d, 1 H, J1,2 8.4 Hz, H-1II),. 4.89
(d, 1 H, Jgem 12.9 Hz, CHHPh), 4.87 (d, 1 H,
Jgem 12.5 Hz, CHHPh), 4.80 (d, 1 H, J1,2 8.3
Hz, H-1I), 4.75 (d, 1 H, Jgem 13.0 Hz,
CHHPh), 4.69 (d, 1 H, Jgem 12.4 Hz, CHHPh),
4.54–4.34 (m, 10 H, 5 CH2Ph), 4.14–3.85 (m,
12 H, H-2I, H-2II, H-2III, H-2IV, H-3I, H-3II,
H-3III, H-4I, H-4II,, H-4III, H-6IV, H-6%IV),
3.52–3.51 (m, 2 H, H-6%I, H-6%III), 3.42 (dd, 1
H, Jgem 11.2, J5,6%B.1.0 Hz, H-6%II), 3.35–3.32
1
[h]D −11.5° (c 0.2, CHCl3); H NMR (600
MHz, CDCl3): l 7.40–7.25 (m, 35 H, 7 Ph),
6.29 (br.d, 1 H, J2,NH 9.0 Hz, NH-2I), 5.82
(br.d, 1 H, J2,NH 9.8 Hz, NH-2II), 5.04 (dd, 1
H, J3,4 =J4,5 9.7 Hz, H-4IV), 4.92 (br.d, NH-
2III), 4.88–4.70 (m, 9 H, 7 CHHPh, NH-2IV,

M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
137
H-3IV), 4.67 (d, 1 H, J1,2 4.7 Hz, H-1I), 4.63–
4.47 (m, 6 H, 6 CHHPh), 4.36 (d, 1 H, Jgem
11.8 Hz, CHHPh), 4.30 (d, 1 H, J1,2 7.4 Hz,
H-1II), 4.29 (d, 1 H, J1,2 8.3 Hz, H-1IV), 4.26
(m, 1 H, H-2I), 4.21 (dd, 1 H, Jgem 12.4, J5,6%
4.5. Hz, H-6%IV), 4.12–3.92 (m, 8 H, H-1III
H-2II, H-2III, H-2IV, H-4I, H-4II, H-4III,, H-
6IV), 3.83–3.74 (m, H-3I, 4 H, H-5I, H-6I,
H-6%I), 3.64–3.56 (m, 3 H, H–6II, H-6%II, H-
6%III), 3.49–3.44 (m, 4 H, H-3II, H-5IV, H-5II,
H-6III), 3.26 (dd, 1 H, J2,3 =J3,4 7.8 Hz, H-
3III), 3.22 (m, 1 H, H-5III), 2.04, 2.03, 1.97,
1.80, 1.78, 1.76, 1.67 (7 s, 21 H, 7 CH3CO).
13C NMR (150.9 MHz, CDCl3): l 170.89–
169.27 (7 CH3CO), 138.61–137.54, 128.95–
127.50 (7 CꢀPh), 100.47 (C-1II), 100.00
(C-1IV), 99.78 (C-1III), 99.53 (C-1I), 79.74 (C-
3II), 79.43 (C-3III), 78.28 (C-3I), 75.80 (C-4III),
75.08–72.03 (6 CH2Ph, C-3IV, C-5I, C-4II, C-
5III, C-4I, C-5II), 71.46 (C-5IV), 70.15(CH2Ph),
69.94 (C-6I), 69.94 (C-6II), 68.26 (C-4IV), 68.09
(C-6III), 61.71 (C-6IV), 53.97 (C-2III, C-2IV),
53.32 (C-2II), 51.10 (C-2I), 29.67, 23.28, 23.21,
20.60 (7 CH3CO). MALDIMS (positive-ion
mode, DHB–THF matrix): m/z 1612.3 [M+
Na]+; m/z 1628.5 [M+K]+. Anal. Calcd for
C87H102N4O24 (1587.71): C, 65.80; H, 6.47; N,
3.52. Found: C, 65.26; H, 6.43; N, 3.13.
amido-3,6-di-O-acetyl-2-deoxy-i-
D
-glucopyran-
osyl-(1“4)-2-acetamido-3,6-di-O-acetyl-2-
deoxy - i -
D
- glucopyranosyl - (1“4) - 2 - acet-
-glucopyran-
amido-3,6-di-O-acetyl-2-deoxy-h-
D
oside (17).—A mixture of 1b (22.0 mg, 26.4
mmol), Py (8 mL) and Ac2O (4 mL) was
stirred at rt. After 3 days the reaction mixture
was worked up as described for the synthesis
of 7. The residue was purified by flash chro-
matography (3:1 acetone–toluene) to yield 17
(0.018 g, 54%). TLC (3:1 acetone–toluene): Rf
1
0.13; H NMR (600 MHz, CDCl3): l 6.24
(br.t, 1 H, NH), 6.10 (d, 1 H, J1,2 3.6 Hz,
H-1Ih), 5.96 (br.d, 1 H, NH), 5.59 (br.d, 1 H,
NH), 5.35–5.02, 4.45–3.25 (2 m, 27 H), 2.19–
1.93 (several s, 42 H, 14 CH3CO).
C52H76N4O31 (1253.16).
3,6 - Di - O - benzyl - 2 - deoxy - 2 - dimethyl-
maleimido-4-O-phenoxyacetyl-i- -glucopyra-
D
nosyl - (1“4) - 3,6 - di - O - benzyl - 2 - deoxy - 2-
dimethylmaleimido - i - - glucopyranosyl tri-
D
chloroacetimidate (19).—A mixture of 10 (1.74
g, 1.493 mmol) and AcOH (0.105 g, 1.748
mmol, 0.1 mL) in dry THF (5 mL) was
treated with TBAF (1.0 M solution in THF,
1.6 mL, 1.6 mmol) and then worked up as
described for the synthesis of 5. The residue
was purified by flash chromatography (1:1
petroleum ether–EtOAc) to yield 18 (1.364 g,
86%) as a white foam. TLC (1:1 petroleum
ether–EtOAc): Rf 0.24.
2-Acetamido-2-deoxy-i-
(1“4) - 2 - acetamido - 2 - deoxy - i -
pyranosyl-(1“4)-2-acetamido-2-deoxy-i-
glucopyranosyl-(1“4)-2-acetamido-2-deoxy-
-glucopyranose (1b).—A solution of 16 (36.0
D
-glucopyranosyl-
D
- gluco-
A mixture of 18 (1.688 g, 1.605 mmol),
CCl3CN (2.448 g, 16.9 mmol, 1.7 mL) and
DBU (0.1 mL, 0.66 mmol) in dry CH2Cl2 (8
mL) was stirred at rt for 2 h then concentrated
in vacuo. The residue was purified by flash
chromatography (1:1 petroleum ether–
EtOAc, +1% Et3N) to yield 19 (1.618 g, 82%)
as a yellow foam in the a/b ratio 1:9. TLC (1:1
petroleum ether–EtOAc, +1% Et3N): Rf
D-
D
mg, 22.0 mmol) in dry MeOH (6.85 mL) was
treated with NaOMe (0.195 M, 0.45 mL) and
then worked up as described for the synthesis
of 11. The residue was dissolved in 1:1:1
MeOH–AcOH–dioxane (3 mL) and then hy-
drogenated in the presence of Pd/C (10% Pd,
0.02 g). After 3 days the reaction mixture was
filtered through Celite, washed with (1:1
MeOH–water) and evaporated in vacuo. The
residue was purified by flash chromatography
NH2-phase (3:1 EtOH–water) to yield 1b
(0.018 g, quant). TLC (3:1 EtOH–water): Rf
0.65. MALDIMS (positive-ion mode, DHB–
water matrix): m/z 851.7 [M+Na]+.
C32H54N4O21 (830.78).
1
0.66; H NMR (250 MHz, CDCl3): l 8.50 (s,
0.1 H, NHa), 8.48 (s, 0.9 H, NHb), 7.37–6.79
(m, 25 H, 5 Ph), 6.14 (d, 0.1 H, J1,2 2.3 Hz,
H-1Ia), 6.12 (d, 0.9 H, J1,2 8.3 Hz, H-1Ib), 5.22
(dd, 1 H, J3,4 =J4,5 9.4 Hz, H-4II), 5.14 (d, 1
H, J1,2 8.3 Hz, H-1II), 4.84 (d, 1 H, Jgem 12.7
Hz, CHHPh), 4.57–3.35 (m, 20 H), 1.95–1.73
(m, 12 H, 4 CH3). FABMS (positive-ion
mode, NBOH–NaI matrix): 1216 [M+Na]+;
m/z 1218 [M+Na+2]+. Anal. Calcd for
C62H62Cl3N3O15 (1195.51): C, 62.28; H, 5.22;
N, 3.51. Found: C, 62.17; H, 5.26; N, 3.16.
Acetyl 2-acetamido-3,4,6-tri-O-acetyl-2-de-
oxy - i -
D
- glucopyranosyl - (1“4) - 2 - acet-

138
M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
Method A. A mixture of 9 (1.38 g, 1.849
Benzyl 3,6-di-O-benzyl-2-deoxy-2-dimethyl-
maleimido-4-O-phenoxyacetyl-i- -glucopyra-
mmol) and 21 (0.765 g, 1.371 mmol) in dry
MeCN (5 mL) was stirred under N2 at rt while
TMSOTf (0.01 M in MeCN, 1.8 mL) was
added dropwise. After 2 h the reaction mix-
ture was neutralized with Et3N, the solvent
was evaporated, and the residue was dried in
vacuo. The residue was purified by flash chro-
matography (3:1 petroleum ether–EtOAc) to
yield 22 (1.025 g, 65%) as a white foam. TLC
(3:1 petroleum ether–EtOAc): Rf 0.12; [h]D
D
noside (20).—A mixture of 9 (0.719 g, 0.963
mmol) and benzyl alcohol (0.125 g, 1.155
mmol, 0.12 mL) in dry MeCN (2 mL) was
stirred at rt while TMSOTf (0.01 M in MeCN,
1.1 mL) was added dropwise. After 6 h the
reaction mixture was neutralized with Et3N,
and the solvent was evaporated in vacuo. The
residue was purified by flash chromatography
(3:1 petroleum ether–EtOAc) to yield 20 (0.66
g, quant) as a colorless oil. TLC (4:1
petroleum ether–EtOAc): Rf 0.11; [h]D −4.0°
1
−38.0° (c 0.4, CHCl3); H NMR (600 MHz,
CDCl3): l 7.28–6.79 (m, 30 H, 6 Ph). 5.21
(dd, 1 H, J3,4 =J4,5 9.4 Hz, H-4II), 5.12 (d, 1
H, J1,2 8.4 Hz, H-1II), 4.86 (d, 1 H, J1,2 8.5 Hz,
H-1I), 4.72 (d, 1 H, Jgem 12.2 Hz, CHHPh),
4.59–4.52 (m, 3 H, 1.5 CH2Ph), 4.41–4.31 (m,
7 H, PhOCH2, 2.5 CH2Ph), 4.31 (dd, 1 H, J2,3
10.6, J3,4 9.4 Hz, H-3II), 4.06 (dd, 1 H, J3,4 =
J4,5 9.4 Hz, H-4I), 4.02 (dd, 1 H, J1,2 8.4, J2,3
10.6 Hz, H-2II), 4.00 (dd, 1 H, J2,3 10.6, J3,4 9.4
Hz, H-3I), 3.94 (dd, 1 H, J1,2 8.8, J2,3 10.6 Hz,
H-2I), 3.56 (dd, 1 H, Jgem 10.6, J5,6%B1.0 Hz,
H-6%I), 3.48–3.45 (m, 2 H, H-5II, H-6%II), 3.40–
3.37 (m, 2 H, H-6I, H-6II), 3.33 (m, 1 H, H-5I),
1.71–1.85 (br.m, 12 H, 4 CH3). 13C NMR
(150.9 MHz, CDCl3): l 167.84 (4 CO), 157.62
(PhOCH2CO), 139.00–136.60, 129.53–114.57
(6 Ph-C), 97.38 (C-1I), 97.11 (C-1II), 77.10
(C-3II), 77.00 (C-3I), 76.02 (C-4I), 74.60 (C-5I),
74.45–72.87 (C-4II, 4 CH2Ph), 72.54 (C-5II),
70.41 (CH2Ph), 69.62 (C-6II), 68.10 (C-6I),
65.22 (PhOCH2), 55.90 (C-2II), 55.40 (C-2I),
8.53 (4 CH3). MALDIMS (positive-ion mode,
DHB–THF matrix): m/z 1164.7 [M+Na]+.
Anal. Calcd for C67H68N2O15 (1141.23): C,
70.50; H, 6.00; N, 2.45. Found: C, 70.45; H,
5.96; N, 2.16.
1
(c 0.6, CHCl3); H NMR (250 MHz, CDCl3):
l 7.35–6.79 (m, 20 H, 4 Ph), 5.21 (dd, 1 H,
J3,4 =J4,5 9.3 Hz, H-4), 4.98 (d, 1 H, J1,2 8.5
Hz, H-1), 4.79 (d, 1 H, Jgem 12.3 Hz,
CHHPh), 4.08 (dd, 1 H, J1,2 8.5, J2,3 10.7 Hz,
H-2), 4.54–4.22, 3.72–3.58 (2 m, 13 H, H-5,
H-6, H-6%, H-3, 3.5 CH2Ph, CH2OPh), 1.75
(br.s, 6 H, 2 CH3). MALDIMS (positive-ion
mode, DHB–THF matrix): m/z 716 [M+
Na]+; m/z 732 [M+K]+. Anal. Calcd for
C41H41NO9 (691.74): C, 71.18; H, 5.97; N,
2.02. Found: C, 70.66; H, 6.07; N, 1.81.
Benzyl 3,6-di-O-benzyl-2-deoxy-2-dimethyl-
maleimido-i- -glucopyranoside (21).—A solu-
D
tion of 20 (0.674 g, 0.974 mmol) in MeOH
(9.2 mL) was treated with NaOMe (0.195 M,
0.49 mL) and worked up as described for the
synthesis of 11. The residue was purified by
flash chromatography (3:1 petroleum ether–
EtOAc) to yield 21 (0.456 g, 83%) as a color-
less oil. TLC (3:1 petroleum ether–EtOAc): Rf
1
0.13; [a]D −7.0° (c 0.4, CHCl3); H NMR
(250 MHz, CDCl3): l 7.40–7.09 (m, 15 H, 3
Ph), 5.00 (d, 1 H, J1,2 8.2 Hz, H-1),. 4.79, 4.73
(2 d, 1 H, Jgem 12.4 Hz, CH2Ph), 4.65, 4.58 (2
d, 2 H, Jgem 12.0 Hz, CH2Ph), 4.48, 4.45 (2 d,
2 H, Jgem 12.3 Hz, CH2Ph), 4.12–3.54 (m, 6 H,
H-2, H-3, H-4, H-5, H-6, H-6%), 2.83 (d, 1 H,
J4,OH 2.2 Hz, OH), 1.77 (br.s, 6 H, 2 CH3).
MALDIMS (positive-ion mode, DHB–THF
matrix): m/z 582 [M+Na]+. Anal. Calcd for
C33H35NO7 (557.61): C, 71.07; H, 6.32; N,
2.51. Found: C, 70.81; H, 6.40; N, 2.33.
Method B. A mixture of 19 (0.36 g, 0.301
mmol) and benzyl alcohol (0.032 g, 0.301
mmol) in dry MeCN (2 mL) was stirred under
N2 at rt for 10 min while TMSOTf (0.01 M in
MeCN, 0.3 mL) was added dropwise. After 2
h the reaction mixture was neutralized with
Et3N, and the solvent was evaporated in
vacuo. The residue was purified as previously
described to yield 22 (0.273 g, 81%).
Benzyl 3,6-di-O-benzyl-2-deoxy-2-dimethyl-
Benzyl 3,6-di-O-benzyl-2-deoxy-2-dimethyl-
maleimido-4-O-phenoxyacetyl-i-
osyl - (1“4) - 3,6 - di - O - benzyl - 2 - deoxy - 2-
dimethylmaleimido-i- -glucopyranoside (22)
D
-glucopyran-
maleimido-i-
O-benzyl-2-deoxy-2-dimethylmaleimido-i-
glucopyranoside (23).—A solution of 22 (1.025
D
-glucopyranosyl-(1“4)-3,6-di-
D
-
D

M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
139
petroleum ether–EtOAc) to yield 24 (0.225 g,
41%) as a white foam. TLC (2.5:1 petroleum
ether–EtOAc): Rf 0.09; [h]D +33.8° (c 0.13,
CHCl3); 1H NMR (600 MHz, CDCl3): l
7.26–6.77 (m, 50 H, 10 Ph), 5.18 (m, 1 H,
H-4IV), 5.08 (d, 1 H, J1,2 8.4 Hz, H-1IV),
4.97–2.98 (several signals, 46 H), 1.88–1.64
(m, 24 H, 8 CH3). MALDIMS (positive-ion
mode, DHB–THF matrix): m/z 2063.6 [M+
Na]+. Anal. Calcd for C119H112N4O27
(2040.19): C, 70.05; H, 6.02; N, 2.74. Found:
C, 70.13; H, 6.39; N, 2.53.
g, 0.898 mmol) in dry 6:2.5 MeOH–THF (8.5
mL) was treated with NaOMe (0.195 M, 0.46
mL) and then worked up as described for the
synthesis of 11. The residue was purified by
flash chromatography (3:1 petroleum ether–
EtOAc) to yield 23 (0.742 g, 82%) as a white
foam. TLC (3:1 petroleum ether–EtOAc): Rf
1
0.08; [h]D +4.5° (c 0.4, CHCl3); H NMR
(600 MHz, CDCl3): l 7.29–7.07 (m, 25 H, 5
Ph), 5.12 (d, 1 H, J1,2 8.4 Hz, H-1II), 4.85 (d,
1 H, J1,2 8.3 Hz, H-1I), 4.80, 4.48 (2 d, 2 H,
Jgem 12.3 Hz, CH2Ph), 4.76, 3.38 (2 d, 2 H,
Jgem 12.6 Hz, CH2Ph), 4.72, 4.40 (2 d, 2 H,
Jgem 12.4 Hz, CH2Ph), 4.58–4.54 (q, 2 H,
CH2Ph), 4.47 (br.s, 2 H, CH2Ph), 4.10–4.05
(m, 2 H, H-4I, H-3II), 3.99 (dd, 1 H, J2,3 10.6,
J3,4 8.4 Hz, H-3I), 3.95–3.90 (m, 2 H, H-2II,
H-2I), 3.73 (dd, 1 H, J3,4=J4,5 9.0 Hz, H-4II),
3.66 (dd, 1 H, Jgem 10.0, J5,6% 4.3 Hz, H-6%II),
3.58 (dd, 1 H, Jgem 11.0, J5,6% 1.5 Hz, H-6%I),
3.51 (dd, 1 H, Jgem 10.0, J5,6 6.1 Hz, H-6II),
3.42 (dd, 1 H, Jgem 11.0, J5,6 4.0 Hz, H-6I),
3.34–3.30 (m, 2 H, H-5I, H-5II), 3.00 (br.s, 1
H, OH), 1.89–1.70 (m, 12 H, 4 CH3). 13C
NMR (150.9 MHz, CDCl3): l 139.10–136.63,
128.51–126.88 (5 Ph), 97.34 (C-1I), 97.02 (C-
1II), 78.92 (C-3II), 77.00 (C-3I), 75.62 (C-4I),
75.21 (C-4II), 74.72 (C-5I), 74.32 (CH2Ph),
74.12 (CH2Ph), 73.70 (CH2Ph), 72.87 (C-5II),
72.79 (CH2Ph), 71.01 (C-6II), 70.42 (CH2Ph),
68.26 (C-6I), 55.86 (C-2II), 55.44 (C-2I), 8.52 (4
CH3). MALDIMS (positive-ion mode, DHB–
THF matrix): m/z 1033 [M+Na]+. Anal.
Calcd for C59H62N2O13 (1007.92): C, 70.30; H,
6.20; N, 2.77. Found: C, 69.94; H, 6.37; N,
2.18.
Benzyl 3,6-di-O-benzyl-2-deoxy-2-dimethyl-
maleimido-i-
O-benzyl-2-deoxy-2-dimethylmaleimido-i-
glucopyranosyl-(1“4)-3,6-di-O-benzyl-2-de-
oxy-2-dimethylmaleimido-i- -glucopyranosyl-
(1“4)-3,6-di-O-benzyl-2-deoxy-2-dimeth-
ylmaleimido-i- -glucopyranoside (25).—A
D
-glucopyranosyl-(1“4)-3,6-di-
D
-
D
D
solution of 24 (1.003 g, 0.491 mmol) in dry 2:1
MeOH–THF (6.9 mL) was treated with
NaOMe (0.195 M, 0.39 mL) and then worked
up as described for the synthesis of 11. The
residue was purified by flash chromatography
(1.75:1 petroleum ether–EtOAc) to yield 25
(0.834 g, 89%) as a white foam. TLC (1.75:1
petroleum ether–EtOAc): Rf 0.18; [h]D
+
1
34.6° (c 0.26, CHCl3); H NMR (600 MHz,
CDCl3): l 7.26–6.97 (m, 45 H, 9 Ph), 5.06 (d,
1 H, J1,2 8.3 Hz, H-1IV), 4.97 (d, 1 H, J1,2 8.3
Hz, H-1III), 4.95 (d, 1 H, J1,2 8.5 Hz, H-1II),
4.87 (d, 1 H, Jgem 13.0 Hz, 1 H, CHHPh),
4.82–4.78 (m, 3 H, H-1I, 2 CHHPh), 4.75 (d,
1 H, Jgem 13.0 Hz, CHHPh), 4.69 (d, 1 H, Jgem
12.4 Hz, CHHPh), 4.50–4.33 (m, 13 H, 6.5
CH2Ph), 4.09–4.06 (m, 2 H, H-3IV, H-4III),
4.01–3.84 (m, 9 H, H-2I, H-2II, H-2III, H-2IV,
H-3I, H-3II, H-3III, H-4I, H-4II), 3.70 (br.t, 1
H, H-4IV), 3.61 (dd, 1 H, J5,6% 3.9 Hz, H-6%IV),
3.51–3.47 (m, 2 H, H-6%I, H-6%III), 3.44–3.41
(m, 2 H, H-6%II, H-6IV), 3.32 (dd, 1 H, Jgem
11.0, J5,6 3.5 Hz, H-6I), 3.27–3.28 (m, 2 H,
H-5I, H-5IV), 3.17 (br.d, 1 H, H-6III), 3.10
(br.d, 1 H, H-6II), 3.03 (m, 1 H, H-5III), 2.99
(m, 1 H, H-5II), 1.88–1.56 (m, 24 H, 8 CH3).
13C NMR (150.9 MHz, CDCl3): l 97.90 (C-
1I), 97.70 (C-1III), 97.60 (C-1IV), 97.50 (C-1II),
79.50 (C-3IV), 78.20 (C-3I), 77.80 (C-3II, C-
3III), 76.30 (C-4II), 76.20 (C-4I), 76.00 (C-4III,
C-4IV), 75.20–73.30 (8 CH2Ph, C-5III, C-5II,
C-5I), 73.00 (C-5IV), 71.80 (C-6IV), 71.20
Benzyl 3,6-di-O-benzyl-2-deoxy-2-dimethyl-
maleimido-4-O-phenoxyacetyl-i- -glucopyran-
D
osyl - (1“4) - 3,6 - di - O - benzyl - 2 - deoxy - 2-
dimethylmaleimido-i- -glucopyranosyl-(1“4)-
3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-
i- -glucopyranosyl-(1“4)-3,6-di-O-benzyl-
2-deoxy-2-dimethylmaleimido-i- -glucopyran-
D
D
D
oside (24).—A mixture of 19 (0.38 g, 0.317
mmol) and 23 (0.27 g, 0.267 mmol) in dry
MeCN (2 mL) was stirred under N2 at rt while
TMSOTf (0.01 M in MeCN, 0.31 mL) was
added dropwise. After 3 h the reaction mix-
ture was neutralized with Et3N, and the sol-
vent was evaporated in vacuo. The residue
was purified by flash chromatography (2.5:1

140
M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
C-5IV, C-5I, 10 CH2Ph), 71.60 (C-5VI), 71.20
(C-3VI), 70.70 (CH2Ph), 69.00 (C-4VI), 68.50
(C-6I), 67.70 (C-6V), 67.50 (C-6II, C-6III, C-
6IV), 61.80 (C-6VI), 56.70 (C-2II, C-2III, C-2IV,
C-2V), 55.80 (C-2I), 55.50 (C-2VI). MALDIMS
(positive-ion mode, DHB–THF matrix): m/z
(CH2Ph), 68.70 (C-6I), 68.00 (C-6III), 67.70
(C-6II), 56.90–56.00 (C-2I, C-2III, C-2II, C-2IV).
MALDIMS (positive-ion mode, DHB–THF
matrix): m/z 1928.9 [M+Na]+. Anal. Calcd
for C111H116N4O25 (1906.06): C, 69.94; H, 6.13;
N, 2.93. Found: C, 69.81; H, 6.26; N, 2.74.
Benzyl 3,4,6-tri-O-acetyl-2-deoxy-2-dimethyl-
2773.6
[M+Na]+.
Anal.
Calcd
for
maleimido - i -
3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-
i- -glucopyranosyl-(1“4)-3,6-di-O-benzyl-2-
deoxy-2-dimethylmaleimido-i- -glucopyran-
osyl - (1“4) - 3,6 - di - O - benzyl - 2 - deoxy - 2-
dimethylmaleimido-i- -glucopyranosyl-(1“4)-
3,6-di-O-benzyl-2-deoxy-2-dimethylmaleimido-
i- -glucopyranosyl-(1“4)-3,6-di-O-benzyl-
2-deoxy-2-dimethylmaleimido-i- -glucopyran-
D
- glucopyranosyl - (1“4)-
C115H164N6O40 (2750.91): C, 67.67; H, 6.00; N,
3.05. Found: C, 67.21; H, 5.95; N, 2.5
D
Benzyl 2-acetamido-3,4,6-tri-O-acetyl-2-de-
D
oxy-i-
3,6-di-O-benzyl-2-deoxy-i-
(1“4)-2-acetamido-3,6-di-O-benzyl-2-deoxy-
i- -glucopyranosyl-(1“4)-2-acetamido-3,6-
di-O-benzyl-2-deoxy-i- -glucopyranosyl-(1
“4)-2-acetamido-3,6-di-O-benzyl-2-deoxy-
i- -glucopyranosyl-(1“4)-2-acetamido-3,6-
di - O - benzyl - 2 - deoxy - i - - glucopyranoside
D
-glucopyranosyl-(1“4)-2-acetamido-
D
-glucopyranosyl-
D
D
D
D
D
oside (26).—A mixture of 6 (0.52 g, 0.516
mmol) and 25 (0.834 g, 0.437 mmol) in dry
MeCN (3 mL) was stirred under N2 at rt while
TMSOTf (0.01 M in MeCN, 0.51 mL) was
added dropwise. After 3 h the reaction mix-
ture was neutralized with Et3N, and the sol-
vent was evaporated in vacuo. The residue
was purified by flash chromatography (1.25:1
petroleum ether–EtOAc) to yield 26 (0.638 g,
53%) as a white foam. TLC (1.25:1 petroleum
ether–EtOAc): Rf 0.12; [h]D +6.9° (c 0.13,
CHCl3); 1H NMR (600 MHz, CDCl3): l
7.26–7.02 (m, 55 H, 11 Ph), 5.57 (dd, 1 H, J2,3
10.3, J3,4 9.3 Hz, H-3VI), 5.28(d, 1 H, J1,2 8.4
Hz, H-1VI), 5.03 (dd, 1 H, J3,4 =J4,5 9.3 Hz,
H-4VI), 4.96 (d, 1 H, J1,2 8.2 Hz, H-1V), 4.93–
4.79 (m, 8 H, 2 CH2Ph, H-1I, H-1II, H-1III,
H-1IV), 4.72 (d, 1 H, Jgem 12.9 Hz, CHHPh),
4.67 (d, 1 H, Jgem 12.6 Hz, CHHPh), 4.51–
4.29 (m, 16 H, 8 CH2Ph), 4.14–4.12 (m, 2 H,
H-6%VI, H-4V), 4.02–3.87 (m, 11 H, H-2I, H-
2VI, H-3I, H-3II, H-3III, H-3IV, H-3V, H-4I,
H-4II, H-4III, H-4IV), 3.87-3.81 (m, 5 H, H-2II,
H-2III, H-2IV, H-2V, H-6VI), 3.51–3.49 (m, 2 H,
H-6%I, H-6%V), 3.41–3.39 (m, 3 H, H-6%II, H-
6%III, H-6%IV), 3.38–3.31 (m, 2 H, H-6I, H-5VI),
3.26 (m, 1 H, H-5I), 3.20 (m, 1 H, H-6V),
3.08–3.03 (m, 4 H, H-5V, H-6II, H-6III, H-6IV),
2.97–2.95 (m, 3 H, H-5II, H-5III, H-5IV), 1.97–
D
D
(27).—A mixture of 26 (0.535 g, 0.194 mmol)
and NaOH (1.5 g, 37.5 mmol) in 5:2:1
MeOH–dioxane–water (8 mL) was stirred at
rt overnight. The reaction mixture was neu-
tralized with 2 N HCl, extracted with CH2Cl2
(2×20 mL), and the solvent was evaporated
in vacuo. The crude product was redissolved
in 5:2:1 MeOH–dioxane–water (8 mL),
treated with ethanolamine (0.082 g, 1.35
mmol, 0.08 mL), and the pH was adjusted and
kept at pH 5 by addition of N HCl. After 1
day the reaction mixture was neutralized with
ethanolamine, the solvent was evaporated,
and the residue was dried well in vacuo. The
residue was treated with 2:1 pyr/Ac2O (15
mL), stirred for 20 h and then worked up as
described for 7. The residue was purified by
flash chromatography (1.5:1 toluene–ace-
tone), and the fractions of partially depro-
tected products were collected and treated
again as described before to yield 27 (0.328 g,
74%) as an amorphous mass. TLC (1.5:1 tolu-
ene–acetone): Rf 0.1; [h]D −22.6° (c 0.53,
CHCl3); 1H NMR (600 MHz, CDCl3): l
7.34–7.19 (m, 35 H, 11 Ph), 6.35 (br s, 1 H,
NH-2I), 5.82 (br.s, 1 H, NH-2II), 5.42 (br.s, 1
H, NH-2IV), 5.19 (br.s, 1 H, NH-2III), 5.11
(br.d, 2 H, NH-2V, NH-2VI), 4.98 (dd, 1 H,
J3,4=J4,5 9.9 Hz, H-4VI), 4.84–4.65 (m, 12 H,
H-3VI, 5.5 CH2Ph), 4.61 (d, 1 H, J1,2 5.0 Hz,
H-1I), 4.60–4.31 (m, 11 H, 5.5 CH2Ph), 4.27
(d, 1 H, J1,2 8.8 Hz, H-1II), 4.24 (m, 1 H,
13
1.63 (m, 45 H, 12 CH3, 3 CH3CO). C NMR
(150.9 MHz, CDCl3): l 97.60 (C-1I), 97.30
(C-1II, C-1III, C-1IV, C-1V), 97.10 (C-1VI), 78.00
(C-3II, C-3III, C-3IV), 77.90 (C-3V), 77.50 (C-
3I), 76.10 (C-4V), 76.00 (C-4I), 75.90 (C-4II,
C-4III, C-4IV), 75.00–72.80 (C-5V, C-5II, C-5III,

M.R.E. Aly et al. / Carbohydrate Research 331 (2001) 129–142
141
H-2I), 4.22 (d, 1 H, J1,2 10.0 Hz, H-1V), 4.21
(d, 1 H, J1,2 8.8 Hz, H-1IV), 4.20 (d, 1 H, J1,2
10.0 Hz, H-1VI), 4.16 (dd, 1 H, Jgem 12.6, J5,6%
4.4 Hz, H-6%VI), 4.12 (d, 1 H, J1,2 8.8 Hz,
H-1III), 4.05–3.91 (m, 10 H,, H-2II, H-2III,
H-2IV, H-2V, H-2VI,H-4I, H-4II, H-4IV, H-4V,
H-6VI), 3.85–3.71 (m, 4 H, H-5I, H-6I, H-6%I,
H-3I), 3.84 (dd, 1 H, J3,4 =J4,5 7.0 Hz, H-4III),
3.59–3.44 (m, 10 H, H-3II, H-5II, H-6III, H-
6%III, H-6V, H-6%V, H-6IV, H-6%IV, H-6II, H-6%II),
3.38–3.25 (m, 7 H, H-5III, H-5V, H-5IV, H-3V,
H-3III, H-3IV, H-5VI), 2.02, 2.00, 1.95, 1.94,
1.74, 1.73, 1.72, 1.69 (8 s, 27 H, 9 CH3CO).
13C NMR (150.9 MHz, CDCl3): l 170.86–
170.06 (9 CH3CO), 138.90–137.62, 128.62–
127.45 (11 Ph-C), 100.50 (C-1II), 100.30
(C-1IV), 100.10 (C-1VI), 99.77 (C-1III, C-1V),
99.50 (C-1I), 80.20 (C-3IV), 80.00 (C-3III),
79.57 (C-3V), 79.60 (C-3II), 78.20 (C-3I), 75.40
(C-4III), 75.30 (C-4II), 75.00 (C-5II), 74.80 (C-
5IV, C-4V, C-4IV), 74.30 (C-5III, C-5V), 74.28
(C-4I), 74.02 (C-5I), 73.70–72.62 (9 CH2Ph),
72.60 (C-3VI), 71.43 (CH2Ph), 71.30 (C-5VI),
69.90 (C-6I, CH2Ph), 69.10 (C-6II), 68.87 (C-
6III, C-6IV), 68.40 (C-6V), 68.25 (C-4VI), 61.67
(C-6VI), 54.05–53.95 (C-2III, C-2IV, C-2V, C-
2VI), 53.38 (C-2II),. 50.78 (C-2I), 23.28, 23.17,
20.58 (9 CH3CO). MALDIMS (positive-ion
mode, DHB–THF matrix): m/z 2375.4 [M+
K]+. Anal. Calcd for C131H154N6O41·H2O
(2356.59): C, 66.76; H, 6.58; N, 3.56. Found:
C, 66.49; H, 6.64; N, 2.85.
yield 1c (0.014 g, 70%). TLC (1.5:1 EtOH–
water): Rf 0.72. MALDIMS (positive-ion
mode, DHB–water matrix): m/z 1259.9 [M+
Na]+. C48H80N6O31·(1237.17).
Acknowledgements
This work was supported by the European
Community (Grant No. FAIR-CT97-3142),
the Bundesministerium fu¨r Bildung und
Forschung (Grant No. 0311 229), and the
Fonds der Chemischen Industrie. M.R.E.A. is
grateful for a stipend from the Egyptian Gov-
ernment. The continued grant for E.S.H. El
Ashry from the Alexander von Humbolt
Stiftung is highly appreciated. The help of Dr
Armin Geyer in structural assignment is grate-
fully acknowledged
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