Synthesis of propyl and 2-aminoethyl glycosides of α-D-galactosyl-(1 → 3′)-β-lactoside

Article abstract of DOI:10.1016/S0008-6215(01)00097-0

Propyl and 2-aminoethyl α-D-galactopyranosyl-(1 → 3′)-β-lactosides (1 and 2) were prepared from the corresponding perbenzylated trisaccharide allyl glycoside 6 which, in turn, was obtained by methyl triflate promoted α-galactosylation of benzylated allyl lactoside acceptor 4 with thiogalactoside 3. Transformation of the allyl moiety in compound 6 into 2-azidoethyl one was achieved by cleavage of the double bond followed by reduction into alcohol 9, subsequent mesylation, and mesylate → azide substitution. Alternatively trisaccharide 2 was synthesized using α-galactosylation of selectively benzoylated 2-azidoethyl lactoside 19 with 3 as the key step.

Full text of DOI:10.1016/S0008-6215(01)00097-0

www.elsevier.nl/locate/carres
Carbohydrate Research 332 (2001) 363–371
Synthesis of propyl and 2-aminoethyl glycosides of
a- -galactosyl-(1“3%)-b-lactoside
D
Olga N. Yudina, Andrei A. Sherman, Nikolay E. Nifantiev*
N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prospect 47,
119992 Moscow B-334, Russia
Received 12 December 2000; accepted 23 March 2001
Abstract
Propyl and 2-aminoethyl a-
D
-galactopyranosyl-(1“3%)-b-lactosides (1 and 2) were prepared from the correspond-
ing perbenzylated trisaccharide allyl glycoside 6 which, in turn, was obtained by methyl triflate promoted a-galacto-
sylation of benzylated allyl lactoside acceptor 4 with thiogalactoside 3. Transformation of the allyl moiety in
compound 6 into 2-azidoethyl one was achieved by cleavage of the double bond followed by reduction into alcohol
9, subsequent mesylation, and mesylate“azide substitution. Alternatively trisaccharide 2 was synthesized using
a-galactosylation of selectively benzoylated 2-azidoethyl lactoside 19 with 3 as the key step. © 2001 Elsevier Science
Ltd. All rights reserved.
Keywords: Gal(a1,3)Gal epitope; a-Galactosylation; Allyl glycoside; Ozonolysis; Xenotransplantation; iso-Globo trisaccharide
O(CH2)8CO2Me,8 OH,9,10 and ceramide11 have
been described earlier.
1. Introduction
The presence of anti a-
D
-Gal-(1“3)- -Gal
D
antibodies in human sera constitutes the main
obstacle for the xenotransplantation from pig
to man.1,2 In order to study the carbohydrate
specificity of these antibodies we have been
preparing various oligosaccharides, and neo-
glycoconjugates
and
glycodendrimers
thereof.3,4 In this paper we describe prepara-
tive synthesis of propyl (1, R=OPr) and 2-
aminoethyl (2, R=OCH2CH2NH2) glycosides
We anticipated, that appropriately pro-
tected trisaccharide allyl glycoside 6 was a
versatile precursor of both compounds 1 and
2: while the former is available from 3 by
hydrogenolysis, the latter can be obtained by
double bond splitting followed by introduc-
tion of amino function procedure.12,13 Such
conversion of allyl aglycon into 2-aminoethyl
one seems advantageous over the sequence
deallylation“glycosyl donor formation“
condensation with protected 2-aminoethanol,
because low yields and poor stereoselectivity is
of the trisaccharide a- -galactosyl-(1“3%)-b-
D
lactoside. Several chemical and enzymatic syn-
theses of the derivatives related to the
trisaccharides 1 and 2 but with R=OAll,5
SPh,5 N3,5 NHAc,6 NHC(O)(CH2)4NH2,7
* Corresponding author. Fax +7-095-1358784.
E-mail address: nen@ioc.ac.ru (N.E. Nifantiev).
0008-6215/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(01)00097-0

364
O.N. Yudina et al. / Carbohydrate Research 332 (2001) 363–371
often observed during glycosylation of such
simple alcohols with complex oligosaccharide
donors.14
The alternative route to 2 included a-galac-
tosylation of selectively protected 2-azidoethyl
lactoside 19. The choice of azido group as a
protected equivalent of amino one was dic-
tated by the possibility to use this lactose
block in the syntheses of longer oligasaccha-
ride chains of such type, for example pen-
one was achieved by ozonolysis of the double
bond followed by NaBH4 reduction into the
corresponding alcohol 9 in 95% yield. Alterna-
tively, catalytic osmylation followed by perio-
date oxidation and NaBH4 reduction afforded
9 in 81% yield. Subsequent mesylation (9“10,
97%), followed by displacement with NaN3 in
the presence of 18-crown-6 at room
temperature19 afforded protected 2-azidoethyl
derivative 11 in 89% yield.
However, the perbenzylated 2-azidoethyl
glycoside 11 failed to yield aminoethyl gly-
coside 2 when subjected to catalytic hy-
drogenolysis. Under both neutral and acidic
conditions the azido group hydrogenation oc-
curred within minutes, but debenzylation of
the amine thus formed could never be brought
to the completion. This might be due to the
known ability of amines to influence on benzyl
ether hydrogenolysis.20 Therefore, compound
11 was subjected to hydrogenolysis in the
presence of ditertbutyldicarbonate (Boc2O) to
give N-protected polyol 12 in 90% yield. Sub-
sequent deprotection with trifluoracetic acid
afforded the target 2-aminoethyl glycoside 2.
An alternative route to the target spacer-
armed glycoside 2 employed glycosylation of
2-azidoethyl hexa-O-benzoyl lactoside accep-
tor 19 with the direct precursor of amino
function already present. The benzoyl protec-
tions in 19 were chosen instead of benzyl ones
in order to simplify further deblocking and
improve stereoselectivity of a-galactosylation.
Such possibility was confirmed by model con-
densation of 3 and allyl hexa-O-benzoyl-lac-
toside 5.16 In contrast to a 9:1 a/b ratio
tasaccharide a-
D
-Gal-(1“3)-b-
D
-Gal-(1“4)-
-Glc,
b- -GlcNAc-(1“3)-b-
D
D
-Gal-(1“4)-b-
D
because azido group is orthogonal to nitrogen
protections of many aminosugar synthetic
blocks.
2. Results and discussion
The allyl glycoside 6 was obtained (Scheme
1) by methyl triflate (MeOTf) promoted glyco-
sylation with the known ethyl tetra-O-benzyl-
1-thio-b-
-galactoside 315 of the readily
D
available allyl hexa-O-benzyl-b-lactoside 4.16
Similar to the parent examples,17,18 the reac-
tion afforded 9:1 mixture of compound 6 and
its b anomer 8 in 90% combined yield. The a
configuration of Gal% residue in compound 6
was confirmed by the value of J1,2Gal coupling
constant 3.2 Hz together with highfield chemi-
cal shift of its C-1 carbon 95.98 ppm in com-
parison with that of b anomer 8 (J1,2Gal% 7.8
Hz, lC-1Gal% 102.55 ppm).
Catalytic hydrogenolysis of 6 afforded the
target propyl glycoside 1 in 88% yield. Con-
version of allyl aglycon of 6 into 2-azidoethyl
,
Scheme 1. Reagents and conditions: (i) MeOTf, MS-4A, Et2O, rt; (ii) O3, MeOH–CH2Cl2, then NaBH4 (95%); (iii) OsO4,
NMMO, acetone–water (87%); (iv) NaIO4, EtOH–MeOH–water; (v) NaBH4, MeOH–CH2Cl2 (93%, two steps); (vi) MsCl, Et3N,
CH2Cl2 (97%); (vii) NaN3, 18-crown-6, DMF, rt (89%); (viii) H2, Pd–C, Boc2O, EtOAc–EtOH (90%); (ix) CF3CO2H, rt (84%);
(x) H2, Pd–C, EtOAc–EtOH.

O.N. Yudina et al. / Carbohydrate Research 332 (2001) 363–371
365
Scheme 2. Reagents and conditions: (i) PhC(OEt)3, TsOH, benzene, 60 °C, then 80% aq AcOH (74%); (ii) Ac2O, Py (100%); (iii)
HBr, AcOH, CH2Cl2 (96%); (iv) ClCH2CH2OH, AgOTf, CH2Cl2 (98%); (v) NaN3, 18-crown-6, DMF, 70 °C (91%); (vi) MeOH,
,
HCl, CH2Cl2 (86%); (vii) MeOTf, MS-4A, Et2O, rt (79%); (viii) H2, Pd–C, Boc2O, EtOAc–EtOH (86%); (ix) CF3CO2H, CH2Cl2,
rt; (x) NH3, MeOH–water (99%).
obtained on glycosylation of 4 with 3, coupling
of3and5undertheabovementioned conditions
afforded a-linked trisaccharide 7 as the sole
product in 89% yield. The a configuration of the
Gal% residue in 7 was deduced from the value
aglycon of glycosyl acceptor resulted in substan-
tial change in the stereoselectivity of its glyco-
sylation. Trisaccharide 20 was then deprotected
by catalytic hydrogenolysis in the presence of
Boc2O to give 21, subsequent amine deblocking
in 21 with trifluoroacetic acid followed by
debenzoylation with ammonia in aqueous
methanol to afford the target spacer-armed
derivative 2.
In summary, we demonstrated that allyl
glycoside 6 can serve as a convenient precursor
of the corresponding spacer-armed derivative,
2-aminoethyl glycoside 2. The important feature
of the approach is that the conversion of allyl
glycosideinto2-azidoethylonedoesnotproceed
via glycosylation reaction and thus no control
of anomeric stereochemistry is required. Spacer-
armed trisaccharide 2 was also synthesized in
good yield employing coupling of donor 3 and
acceptor 19 as the key step. Conjugation of 2
with various carriers and biological activity
studies of the polymers thus obtained will be
published elsewhere.
1
of J1,2Gal% coupling constant 2.9 Hz in its H
NMR spectrum and from the chemical shift of
its C-1 carbon 94.71 ppm in the 13C NMR one.
In order to prepare lactoside acceptor 19, the
readily available diol 1321 was converted via
orthoester procedure,22 into heptabenzoate 14
in 74% yield (Scheme 2), which was then
3%-O-acetylated into 15 and then brominated to
give 16. Silver triflate (AgOTf) promoted con-
densation of glycosyl bromide 16 with 2-
chloroethanol afforded b-glycoside 17 in near
quantitative yield. Subsequent chlorine dis-
placement in 17 upon treatment with NaN3 gave
2-azidoethyl glycoside 18 in 91% yield. The
two-step procedure was used instead of direct
glycosylation of 2-azidoethanol due to its explo-
sive nature. Finally, HCl-catalyzed methanoly-
sis of the acetate ester23 in 18 afforded mono
hydroxy derivative 19 in 86% yield.
In contrast to the stereospecific coupling of
3 and 5, MeOTf promoted glycosylation of 19
with 3 in Et2O gave 70% of a-linked 20 and 9%
of its b-isomer 22. Thus a small variation in the
3. Experimental
General methods.—The reagents were pur-
chased from Fluka and Merck, all of the

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O.N. Yudina et al. / Carbohydrate Research 332 (2001) 363–371
with water, 10% aq NaOH, water, 10% aq
H2SO4, water, dried and concentrated. Chro-
matography (benzene“9:1 benzene–EtOAc)
of the residue on a column of silica gel (150 g)
afforded (in order of elution) b-glycoside 8 (93
mg, 9%) and a-glycoside 6 (842 mg, 81%) as
colorless oils.
highest grade available. Molecular Sieves were
activated by heating (180 °C) under vacuum
(0.1 mmHg) for 5–8 h. Peroxide-free Et2O
was distilled from sodium benzophenone ketyl
,
under Ar and stored over MS-3A deperox/de-
hydrate (Fluka). CH2Cl2 was washed with
96% H2SO4, water, satd aq NaHCO3, dried
(MgSO4), distilled twice from P2O5 under Ar,
a-Glycoside 6: Rf 0.32 (9:1, benzene–
,
and stored over MS-4A. The catalyst used for
EtOAc); [h]D 39° (c 0.5, CHCl3); NMR
1
hydrogenolysis was 10% Pd–C, oxide form,
(Merck–Schuchardt). In glycosylation reac-
tions, Molecular Sieve Union Carbide Type
(CDCl3): H, l 3.28–3.62 (m, 9 H), 3.65–3.87
(m, 5 H), 3.91–4.05 (m, 3 H), 4.11–4.20 (m, 2
H), 4.23–4.59 (m, 12 H), 4.60–5.17 (m, 12 H),
5.22 (broaden d, 1 H, J 9.9 Hz, OCH2CHꢀ
CH2), 5.25 (d, 1 H, J1,2 3.2 Hz, H-1Gal%), 5.38
(broaden d, 1 H, J 17.8 Hz, OCH2CHꢀCH2),
5.99 (m, 1 H, OCH2CHꢀCH2), 7.09–7.42 (m,
50 H, arom); 13C, l 95.98 (C-1Gal%), 102.71
(C-1Glc), 102.97 (C-1Gal), 117.13 (OCH2CHꢀ
CH2), 134.22 (OCH2CHꢀCH2). Anal. Calcd
for C91H96O16: C, 75.60; H, 6.69. Found C,
75.45; H 6.73.
,
4A (Fluka) were used. Column chromatogra-
phy was performed on Silica gel 60 (Fluka,
70–230 mesh). TLC was performed on Silica
Gel 60 F254 (E. Merck, Darmstadt, Germany)
with detection by dipping the chromatograms
into 10% H3PO4 in EtOH followed by heating
at 180 °C. Amines were also visualized by
dipping the chromatograms into 0.017 M nin-
hydrin solution in (33:1) n-butanol–AcOH,
followed by heating. For TLC analysis of
deblocked oligosaccharides, solvent systems
1:2:1 n-butanol–n-propanol–0.1 M aq HCl
b-Glycoside 8: Rf 0.33 (9:1 benzene–
EtOAc); [h]D 5° (c 0.5, CHCl3); NMR
1
(CDCl3): H, l 3.30–3.91 (m, 14 H), 3.93–
(BPHCl),
1:1:1
MeCN–MeOH–water
4.58 (m, 17 H), 4.59 (d, 1 H, J1,2 7.8 Hz,
H-1Gal%), 4.61 (d, 1 H, J1,2 8 Hz, H-1Glc),
4.66 (d, 1 H, J1,2 7.6 Hz, H-1Gal), 4.68–5.17
(m, 10 H), 5.20 (broaden d, 1 H, J 10 Hz,
OCH2CHꢀCH2), 5.36 (broaden d, 1 H, J 16.9
Hz, OCH2CHꢀCH2), 6.02 (m, 1 H, OCH2CHꢀ
CH2), 7.09–7.42 (m, 50 H, arom); 13C, l
102.55 (C-1Glc), 103.81 (C-1Gal, C-1Gal%),
116.99 (OCH2CHꢀCH2), 134.09 (OCH2CHꢀ
CH2). Anal. Calcd for C91H96O16: C, 75.60; H,
6.69. Found C, 75.51; H 6.55.
(AMW), and their combination were used.
Optical rotation was measured with JASCO
DIP-360 digital polarimeter at 26–30 °C.
NMR spectra were recorded with Bruker
1
DRX-500 instrument (500 MHz for H and
13
125 MHz for C), assignments were aided by
1
COSY, TOCSY, APT, and H–13C correla-
tion spectroscopy. Mass spectra were recorded
using matrix assisted laser desorption ioniza-
tion (MALDI)-time of flight (TOF) on VI-
SION 2000 mass spectrometer.
Propyl h-
galactopyranosyl-(1“4)-i-
D
-galactopyranosyl-(1“3)-i-
D
-
Allyl 2,3,4,6-tetra-O-benzyl-h-
ranosyl-(1“3)-2,4,6-tri-O-benzyl-i-
topyranosyl-(1“4)-2,3,6-tri-O-benzyl-i-
glycopyranoside (6) and allyl 2,3,4,6-tetra-O-
benzyl - i - - galactopyranosyl - (1“3) - 2,4,6-
tri - O - benzyl - i - - galactopyranosyl - (1“4)-
2,3,6-tri-O-benzyl-i- -glycopyranoside (8).—
D
-galactopy-
-galac-
D
-glycopyranoside
D
(1).—To a solution of 6 (36 mg, 0.025 mmol)
in EtOAc (3 mL) and EtOH (6 mL) Pd–C (10
mg) was added, the mixture was degassed
under vacuum with stirring, refilled with H2,
and stirred for 2 days under H2 at rt. The
mixture was filtered through Celite, and the
pad was washed thoroughly with distilled wa-
ter. The filtrate and washings were concen-
trated and the residue was subjected to
gel-filtration (elution with 0.1 M aq AcOH) on
a column (Vo=180 mL) of TSK HW-40 S gel
to afford 1 (12 mg, 88%) as a foam: Rf 0.4
D
-
D
D
D
A solution of 3 (625 mg, 1.07 mmol) and 4
(660 mg, 0.72 mmol) in dry Et2O (25 mL) was
,
stirred with freshly activated MS-4A (1.5 g)
during 1 h under Ar, MeOTf (0.58 mL, 5.3
mmol) was added, and stirring was continued
for 20 h at rt. Et3N (3 mL) was added, the
reaction mixture was filtered through a pad of
Celite, diluted with CH2Cl2 (200 mL), washed
1
(BPHCl); [h]D 97° (c 0.5, water); H NMR
(D2O): the spectrum was identical to that of 2

O.N. Yudina et al. / Carbohydrate Research 332 (2001) 363–371
367
DMF (3 mL) for 3 days at rt. The mixture
was then diluted with EtOAc (100 ml), washed
with water and concentrated. Chromatogra-
phy (9:2 toluene–EtOAc) on a column of
silica gel (50 g) gave the expected azide 11
(229 mg, 89%, 70% overall from 6) as colorless
oil: Rf 0.61 in 5:1 toluene–EtOAc; [h]D 37° (c
(see below), except the absence of two-proton
signal at l 3.31 (CH2NH2), and the presence
of three-proton triplet at l 0.91 (OCH2CH2-
CH3) and two-proton multiplet at l 1.62
(OCH2CH2CH3); MALDI-TOF-MS: Calcd
for [C21H38O16+Na]+: 569.2. Found 569.6.
2-Azidoethyl
galactopyranosyl - (1“3) - 2,4,6 - tri - O - benzyl-
i- -galactopyranosyl-(1“4)-2,3,6-tri-O-ben-
zyl-i- -glycopyranoside (11).—(a) To a solu-
2,3,4,6-tetra-O-benzyl-h- -
D
1
0.5, CHCl3); NMR (CDCl3): H, the spectrum
D
was identical to that of 3, except the disap-
pearance of three one-proton signals at l 5.99
(OCH2CHꢀCH2), 5.38 (OCH2CHꢀCH2), 5.22
(OCH2CHꢀCH2), and the presence of two
D
tion of N-methyl morpholine N-oxide (36 mg,
0.26 mmol) and 6 (322 mg, 0.22 mmol) in
acetone (5 mL) and water (1 mL) 0.02 M
solution of OsO4 in t-BuOH (0.5 mL) was
added, and the mixture was stirred for 20 h at
rt. H2S was then bubbled at 0 °C for 5 min,
the black precipitate was filtered off through
Celite, the pad was washed thoroughly with
acetone. Combined filtrate and washings were
concentrated and filtered through a short
column of silica gel with 2:3 toluene–acetone
as eluent to give 287 mg (87%) of the expected
diol as an oil: Rf 0.45 in 2:3 toluene–acetone.
It was dissolved in 17 mL of 12:4:1 EtOH–
MeOH–water mixture and treated with
NaIO4 (80 mg, 0.37 mmol) for 5 h at rt with
stirring. The reaction mixture was then diluted
with CH2Cl2 (100 mL), washed with water,
and concentrated to afford the expected alde-
hyde as an oil: Rf 0.28 in 4:1 toluene–EtOAc.
It was dissolved in CH2Cl2 (10 mL) and
MeOH (20 mL), and NaBH4 (76 mg, 2 mmol)
was added portionwise at 0 °C, and stirring
was continued 20 h. Satd aq NH4Cl (10 mL)
and CH2Cl2 (100 mL) were added, the reac-
tion mixture was washed with water, dried,
and concentrated to give crude alcohol 9 (261
mg, 93%, 81% from 6, Rf 0.3 in 4:1 toluene–
EtOAc), which was mesylated at 0 °C with
MsCl (0.07 mL, 0.6 mmol) and Et3N (1 mL)
in dry CH2Cl2 (5 mL) for 1 h. The reaction
mixture was then poured into satd aq
NaHCO3 (30 mL) and extracted with CH2Cl2
(3×50 mL), the combined extracts were
washed with water, dried and concentrated.
Chromatography (benzene“6:1 benzene–
EtOAc) on a column of silica gel (50 g) af-
forded the expected mesylate 10 (266 mg,
97%) as a colorless oil: Rf 0.57 in 5:1 toluene–
EtOAc. It was stirred with NaN3 (130 mg, 2
mmol) and 18-crown-6 (5 mg, 0.02 mmol) in
one-proton multiplets at
l
3.31–3.54
(CH2N3); 13C: the spectrum was identical to
that of 6, except the disappearance of the
signals at l 117.13 (OCH2CHꢀCH2) and
134.22 (OCH2CHꢀCH2) and the presence of
the signal at l 50.73 (CH2N3). Anal. Calcd for
C90H95O16N3: C, 73.30; H, 6.49; N, 2.85.
Found C, 73.48; H, 6.52; N, 2.76.
(b) Ozone was bubbled through a solution
of 6 (100 mg, 0.07 mmol) in dry MeOH (5
mL) and CH2Cl2 (2.5 mL) at −70 °C until
blue color persisted, the excess was then
purged out with Ar until decolorization, and
NaBH4 (53 mg, 1.4 mmol) was added with
stirring at the same temperature, and reaction
mixture was allowed to attain 0 °C in a Dewar
flask (ca. 2 h). Another portion of NaBH4 (27
mg, 0.7 mmol) was then added, the mixture
was stirred for 0.5 h at rt, and then processed
as described above to afford the crude alcohol
9 (96 mg, 95%), which was used for the prepa-
ration of 11 without further purification.
Allyl 2,3,4,6-tetra-O-benzyl-h-
ranosyl - (1“3) - 2,4,6 - tri - O - benzoyl - i -
galactopyranosyl-(1“4)-2,3,6-tri-O-benzoyl-
i-
D
-galactopy-
D
-
D
-glycopyranoside (7).—A solution of 3 (43
mg, 0.075 mmol) and 5 (50 mg, 0.049 mmol)
in dry Et2O (1 mL) was stirred with freshly
,
activated MS-4A (150 mg) during 1 h, MeOTf
(0.04 mL, 0.37 mmol) was added, and stirring
was continued for 20 h at rt. Et3N (0.4 mL)
was added, the reaction was filtered through a
pad of Celite, diluted with CH2Cl2 (50 mL),
washed with 10% aq H2SO4, water, satd aq
NaHCO3, water, dried and concentrated.
Chromatography (benzene“10:1 benzene–
EtOAc) of the residue on a column of silica
gel (50 g) afforded a single product, a-gly-
coside 7 (67 mg, 89%) as white foam: Rf 0.36

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O.N. Yudina et al. / Carbohydrate Research 332 (2001) 363–371
ene–MeOH); [h]D 42° (c 1, CHCl3); NMR
(data for a anomer, CDCl3): H, l 4.05 (dd, 1
in 9:1 toluene–EtOAc; [h]D 25° (c 1, CHCl3);
NMR (CDCl3): H, see Table 1 for carbohy-
1
1
H, J2,3 9, J3,4 1 Hz, H-3Gal), 4.89 (d, 1 H, J1,2
7.9 Hz, H-1Gal), 5.43 (dd, 1 H, H-2Gal), 5.55
(broaden s, 1 H, H-4Gal), 5.67 (dd, 1 H, J1,2
3.5, J2,3 10.3 Hz, H-2Glc), 6.22 (t, 1 H, J2,3=
J3,4 7.6 Hz, H-3Glc), 6.83 (d, 1 H, H-1Glc),
7.12–7.72 (m, 21 H, arom), 7.89–8.13 (m, 14
H, arom); 13C, l 61.42, 62.01 (C-6Glc, C-
6Gal), 89.79 (C-1Glc), 100.71 (C-1Gal). Anal.
Calcd for C61H50O18: C, 68.41; H, 4.70. Found
C, 68.70; H, 4.70.
drate ring protons; l 4.07 (dd, 1 H, Jgem 12,
Jvic 5 Hz, OCH2CHꢀCH2), 4.22, 4.25, 4.27 (3
d, 3 H, PhCH2), 4.29 (dd, 1 H, Jvic 3 Hz,
OCH2CHꢀCH2), 4.37, 4.38, 4.41, 4.42 (4 d, 4
H, PhCH2), 4.67 (d, 1 H, PhCH2), 5.10
(broaden d, 1 H, J 9.7 Hz, OCH2CHꢀCH2),
5.18 (broaden d,
1
H,
J
17.2 Hz,
OCH2CHꢀCH2), 5.79 (m, 1 H, OCH2CHꢀ
CH2), 6.99–7.72 (m, 38 H, arom), 7.87–8.12
(m, 12 H, ortho-protons of Bz); 13C, l 61.50,
62, 57 (C-6Glc, C-6Gal), 94.71 (C-1Gal%),
99.67, 101.13 (C-1Gal, C-1Glc), 117.74
(OCH2CHꢀCH2). Anal. Calcd for C91H84O22:
C, 71.45; H, 5.54. Found C, 71.42; H, 5.68.
2-Chloroethyl 3-O-acetyl-2,4,6-tri-O-ben-
zoyl - i -
tetra-O-benzoyl-i-
D
- galactopyranosyl - (1“4) - 2,3,6-
-glycopyranoside (17).—
D
The heptabenzoate 14 (2.79 g, 2.6 mmol) was
acetylated with Ac2O (2.35 mL, 20 mmol) in
Py (8 mL) (20 h, rt), MeOH was added, the
mixture was coevaporated with toluene, dried
in vacuo to give compound 15 (2.89 g, 100%)
as white foam: Rf 0.58 in 10:1, toluene–
MeOH. To a solution of monoacetate 15 (2.78
g, 2.5 mmol) in dry CH2Cl2 (4 ml) a solution
of HBr in AcOH (33% w/v, 6 mL) was added
at 0 °C. The reaction mixture was kept 1 h at
rt, and then poured into crushed ice and ex-
tracted rapidly with CH2Cl2 (3×70 mL). The
organic phase was then immediately washed
with cold satd aq NaHCO3, dried (MgSO4),
and concentrated to give bromide 16 (2.57 g,
96%) as white foam: Rf 0.64 in 10:1 toluene–
2,4,6-Tri-O-benzoyl-i-
(1“4)-1,2,3,6-tetra-O-benzoyl-h,i-
pyranose (14).—A solution of 13 (3.54 g, 3.67
mmol, ca. 1.3:1 a/b mixture according to H
D
-galactopyranosyl-
-glyco-
D
1
NMR), triethylorthobenzoate (3.5 mL) and
TsOH (35 mg) in dry benzene (20 mL) and
CH2Cl2 (4 mL) was heated at 60 °C for 2 days
in tightly closed flask, then 80% aq AcOH (25
mL) was added, and the biphasic mixture was
stirred vigorously for 3 h at rt. The reaction
mixture was diluted with CH2Cl2 (200 mL),
washed with water, satd aq NaHCO3, dried
and concentrated. Chromatography (tolu-
ene“3:2 toluene–EtOAc) on a column of
silica gel (250 g) afforded heptabenzoate 14
(2.9 g, 74%) as white foam which was ca. 5:1
a/b mixture (1H NMR): Rf 0.42 (10:1 tolu-
1
MeOH; NMR (CDCl3): H, see Table 1 for
carbohydrate ring protons; l 1.82 (s, 3 H,
Table 1
1
Chemical shifts (l, ppm) and coupling constants (J, Hz) for carbohydrate ring protons in H NMR spectra of compounds 2, 7,
16, 17, 19 in the solvent specified
Compound
(solvent)
Residue
H-1
(J1,2
H-2
(J2,3
H-3
(J3,4
H-4
(J4,5
H-5
(J5,6a
H-6a
(J6a,6b
H-6b
(J6b,5)
)
)
)
)
)
)
2 (D2O)
Glc
Gal
Gal%
Glc
Gal
Gal%
Glc
Gal
Glc
Gal
Glc
Gal
4.58 (8)
3.43 (8.3)
3.71
3.72
3.73
3.66 (\1)
3.77
4.2 (12.5)
3.85
3.78
4.58 (11.7)
3.21 (8)
3.79 (11.6)
4.59
3.82
4.65 (12.2)
3.78
4.66 (12)
3.49
3.88 (5)
3.82
4.56 (7.8)
5.18 (3.8)
4.77 (8)
4.65 (7.9)
5.08 (2.9)
6.73 (4)
4.89 (7.9)
4.80 (7.8)
4.86 (7.9)
4.91 (8.1)
4.89 (8.3)
3.82 (2.7)
3.97 (3.1)
5.79 (9.5)
3.98 (3.2)
3.46 (2.5)
6.15 (9.1)
5.21 (3.5)
5.83 (9.6)
5.22 (3.4)
5.79 (9.5)
3.99 (2)
4.22 (0)
4.05 (0)
4.18 (9.5)
5.64 (0)
3.21 (0)
4.36 (9.1)
5.61 (0)
4.28 (9.6)
5.63 (0)
4.21 (9.5)
5.51 (0)
3.90 (10.3)
5.50 (9.5)
5.63 (10.1)
3.85 (10.1)
5.26 (9.1)
5.59 (9.4)
5.48 (9.6)
5.57 (10.4)
5.51 (9.5)
5.38 (9.9)
4.22 (6.1)
3.84 (0)
3.65 (6.2)
3.52 (4.3)
3.83
4.40
3.85 (1)
3.84
3.78 (6.1)
4.50 (4.8)
3.13 (6.2)
3.43 (4.3)
4.59
3.72
4.49 (4.4)
3.78
7 (CDCl3)
16 (CDCl3)
17 (CDCl3)
19 (CDCl3)
3.88 (1.6)
3.68
4.58 (4.7)
3.49

O.N. Yudina et al. / Carbohydrate Research 332 (2001) 363–371
369
Table 2
Chemical shifts (l, ppm) for carbohydrate ring carbons in 13C NMR spectra of compounds 2 and 17 in the solvent specified
Compound (solvent)
Residue
C-1
C-2
C-3
C-4
C-5
C-6
2 (D2O)
Glc
Gal
Gal%
103.19
104.07
96.66
73.90
70.77
69.41
75.49
78.43
70.50
79.71
66.04
70.36
75.95
76.27
72.04
61.21
62.22
62.16
17 (CDCl3)
Glc
Gal
101.17
100.96
71.57
69.69
72.75
70.99
75.91
67.37
73.08
71.29
62.21
60.99
OAc), 7.08–7.65 (m, 18 H, arom), 7.93–8.15
(m, 12 H, arom); 13C, l 20.44 (CH3CO), 60.87,
61.39 (C-6Glc, C-6Gal), 86.62 (C-1Glc),
101.04 (C-1Gal). A solution of the bromide 16
(2.5 g, 2.3 mmol) and freshly distilled 2-
chloroethanol (3.9 mL, 58.3 mmol) in dry
CH2Cl2 (20 mL) was stirred under Ar with
matography (toluene“15:1 toluene–acetone)
of the residue on a column of silica gel (200 g)
afforded 18 (2.13 g, 91%) as white foam: Rf
0.52 in 9:1 toluene–acetone; [h]D 23° (c 1,
1
CHCl3); NMR (CDCl3): H, the spectrum was
identical to that of 17, except the disappear-
ance of two-proton signal at l 3.51 (CH2Cl)
and the presence of two one-proton multiplets
,
freshly activated MS-4A (2 g) for 1 h, then
13
cooled to 0 °C and powdered AgOTf (1.2 g,
4.7 mmol) was added. After stirring for 2 h at
0 °C the reaction was quenched by addition of
Et3N (5 mL), filtered through Celite, diluted
with CH2Cl2 (200 mL), washed with satd aq
NaHCO3, 3 M aq Na2S2O3, water, dried and
concentrated. Chromatography (toluene“6:1
toluene–acetone) of the residue on a column
of silica gel (250 g) afforded 17 (2.46 g, 98%)
as white foam: Rf 0.28 in 40:1 toluene–MeOH
(double elution); [h]D 20° (c 1, CHCl3); NMR
at l 3.23 and 3.34 (CH2N3); C, the spectrum
was identical to that of 17, except the disap-
pearance of the signal at l 42.04 (CH2Cl) and
the presence of the signal at l 50.42 (CH2N3).
Anal. Calcd for C58H51O18N3: C, 64.62; H,
4.77; N, 3.89. Found C, 64.62; H, 4.89; N,
3.71.
2-Azidoethyl 2,4,6-tri-O-benzoyl-i-
topyranosyl-(1“4)-2,3,6-tetra-O-benzoyl-i-
-glycopyranoside (19).—The reagent was
D
-galac-
D
prepared by dropwise addition, at 0 °C, of
acetyl chloride (2 mL, 28 mmol) to anhydrous
MeOH (20 mL). After 10 min, the reagent was
added to a solution of compound 18 (2.29 g,
2.14 mmol) in dry CH2Cl2 (10 mL). After 5 h
at rt the reaction mixture was poured into
ice-cold water and extracted with CH2Cl2 (200
mL). The organic phase was then washed with
satd aq NaHCO3 and water, dried, and con-
centrated. Chromatography (toluene“6:1 tol-
uene–acetone) of the residue on a column of
silica gel (200 g) afforded 19 (1.88 g, 86%) as
white foam: Rf 0.33 in 9:1 toluene–acetone;
1
(CDCl3): H, see Table 1 for carbohydrate
ring protons; l 1.8 (s, 3 H, OAc), 3.51 (m, 2
H, CH2Cl), 3.75 (m, OCH2CH2Cl), 4.02 (m,
1 H, OCH2CH2Cl), 7.09–7.69 (m, 18 H,
arom), 7.91–8.12 (m, 12 H, arom); 13C, see
Table 2 for carbohydrate ring carbons; l
20.33 (CH3CO), 42.04 (CH2Cl), 69.81
(OCH2CH2Cl), 164.61, 165.13, 165.20, 165.31,
165.40, 165.69 (6 PhCO), 169.94 (CH3CO).
Anal. Calcd for C58H51O18Cl: C, 65.02; H,
4.79; Cl, 3.31. Found C, 65.08; H, 4.78; Cl,
3.30.
1
2-Azidoethyl
zoyl - i - - galactopyranosyl - (1“4) - 2,3,6-
tetra-O-benzoyl-i- -glycopyranoside (18).—A
3-O-acetyl-2,4,6-tri-O-ben-
[h]D 5° (c 1, CHCl3); NMR (CDCl3): H, see
D
Table 1 for carbohydrate ring protons; l 2.9
(broaden s, 1 H, OH), 3.28 (m, 1 H, CH2N3),
3.38 (m, 1 H, CH2N3), 3.67 (m, 1 H,
OCH2CH2N3), 3.99 (m, OCH2CH2N3), 7.12–
7.73 (m, 18 H, arom), 7.88–8.09 (m, 12 H,
arom); 13C, l 50.53 (CH2N3), 61.56, 62.51
(C-6Glc, C-6Gal), 100.56, 101.09 (C-1Glc, C-
1Gal). Anal. Calcd for C56H49O17N3: C, 64.92;
D
mixture of 17 (2.33 g, 2.17 mmol), NaN3 (1.4
g, 21.7 mmol) and 18-crown-6 (0.058 g, 0.22
mmol) in amine-free, dry DMF (10 mL) was
heated, with stirring for 24 h at 70 °C, then
diluted with EtOAc (200 mL), washed with
water, dried (MgSO4) and concentrated. Chro-

370
O.N. Yudina et al. / Carbohydrate Research 332 (2001) 363–371
2-(tert-Butoxycarbonylamino)ethyl
galactopyranosyl-(1“3)-2,4,6-tri-O-benzoyl-
i- -galactopyranosyl-(1“4)-2,3,6-tri-O-ben-
zoyl-i- -glycopyranoside (21).—To a solu-
tion of 20 (0.87 g, 0.56 mmol) and Boc2O (0.3
g, 1.4 mmol) in EtOAc (16 mL) and EtOH (48
mL) was added Pd–C (50 mg), the mixture
was degassed under vacuum with stirring,
refilled with hydrogen, and stirred for 20 h
under H2 at rt. At this point, TLC (9:1, tolu-
ene–acetone) indicated the presence of one
h- -
D
H, 4.77; N, 4.06. Found C, 65.13; H, 4.73; N,
4.02.
D
2-Azidoethyl
galactopyranosyl-(1“3)-2,4,6-tri-O-benzoyl-
i- -galactopyranosyl-(1“4)-2,3,6-tri-O-ben-
zoyl-i- -glycopyranoside (20) and 2-azi-
doethyl 2,3,4,6-tetra-O-benzyl-i- -galactopy-
ranosyl-(1“3)-2,4,6-tri-O-benzoyl-i- -galac-
topyranosyl-(1“4)-2,3,6-tri-O-benzoyl-i-
2,3,4,6-tetra-O-benzyl-h- -
D
D
D
D
D
D
D
-
glycopyranoside (22).—A solution of 3 (0.42
g, 0.72 mmol) and 19 (0.5 g, 0.48 mmol) in dry
Et2O (10 mL) was stirred with freshly acti-
major
amino)ethyl 2,3,4,6-tetra-O-benzyl-a-
topyranosyl-(1“3)-2,4,6-tri-O-benzoyl-b-
galactopyranosyl-(1“4)-2,3,6-tri-O-benzoyl-
b- -glycopyranoside (Rf 0.43). New 50 mg
product,
2-(tert-butoxycarbonyl-
,
vated MS-4A (1.5 g) during 1 h, MeOTf (0.4
D
-galac-
mL, 3.6 mmol) was added, and stirring was
continued for 2 h at rt. Et3N (2 mL) was
added, the reaction mixture was filtered
through a pad of Celite, diluted with CH2Cl2
(100 mL), washed with 10% aq H2SO4, water,
satd aq NaHCO3, water, dried and concen-
trated. Chromatography (toluene“25:1 tolu-
ene–acetone) of the residue on a column of
silica gel (150 g) afforded (in order of elution)
a-glycoside 20 (526 mg, 70%) and b-glycoside
22 (67 mg, 9%) as white foams.
D
-
D
portions of Pd–C were added every 24 h, and
after stirring for 3 days at rt the reaction
mixture was filtered through Celite, the pad
was washed thoroughly with linear gradient
from EtOAc to EtOH, and the filtrate and
washings were concentrated. Chromatography
(CH2Cl2“10:1 CH2Cl2–MeOH) of the
residue on a column of silica gel (100 g)
afforded 21 (0.62 g, 86%) as white foam: Rf
0.14 in 30:1 CH2Cl2–MeOH; [h]D 35° (c 1,
a-Glycoside 20: Rf 0.27 (20:1, toluene–ace-
tone); [h]D 35° (c 1, CHCl3); NMR (CDCl3):
1H, the spectrum was identical to that of 7,
except the absence of the signals of allyl moi-
1
CHCl3); NMR (CDCl3–CD3OD, 10:1): H, l
1.25 (s, 9 H, t-Bu), 4.08 (dd, 1 H, J2,3 10.1, J3,4
2.9 Hz, H-3Gal), 4.12 (t, 1 H, J3,4=J4,5 9.5
Hz, H-4Glc), 4.53 (m, 2 H, H-6aGlc, H-
6bGlc), 4.67(d, 1 H, J1,2 8 Hz, H-1Glc), 4.71
(d, 1 H, J1,2 8.1 Hz, H-1Gal), 5.08 (d, 1 H, J1,2
3.7 Hz, H-1Gal%), 5.41 (m, 2 H, H-2Gal, H-
2Glc), 5.61 (d, 1 H, H-4Gal), 5.74 (t, 1 H,
J2,3=J3,4 9.5 Hz), 7.11–7.73 (m, 18 H, arom),
7.91–8.12 (m, 12 H, arom); 13C, l 28.16 (t-
Bu), 40.14 (CH2NHBoc), 60.84, 62.29 (C-
6Glc, C-6Gal, C-6Gal%), 96.95 (C-1Gal%),
100.88, 101.23 (C-1Glc, C-1Gal). Anal. Calcd
for C67H69O24N: C, 63.25; H, 5.47; N, 1.1.
Found C, 63.23; H, 5.72; N, 1.15.
ety at
l
4.07 (OCH2CHꢀCH2), 4.29
(OCH2CHꢀCH2), 5.10 (OCH2CHꢀCH2), 5.18
(OCH2CHꢀCH2), 5.79 (OCH2CHꢀCH2), and
the presence of one-proton multiplets at 3.24
(CH2N3), 3.37 (CH2N3), 3.65 (OCH2CH2N3),
3.95 (OCH2CH2N3); 13C, l 50.39 (CH2N3),
61.32, 62.23 (C-6Glc, C-6Gal), 94.49 (C-
1Gal%), 101.00 (C-1Gal, C-1Glc). Anal. Calcd
C90H83O22N3: C, 69.35; H, 5.37; N, 2.69;
Found C, 69.08; H, 5.40; N, 2.37.
b-Glycoside 22: Rf 0.25 (20:1, toluene–ace-
tone); [h]D 8° (c 1, CHCl3); NMR (CDCl3):
1H, l 4.69 (d, 1 H, J1,2 7.9 Hz, H-1Gal%) 4.73
(d, 1 H, J1,2 7.8 Hz, H-1Gal), 4.75 (d, 1 H, J1,2
8.2 Hz, H-1Glc), 4.81 (d, 1 H, J 12 Hz,
PhCH2), 5.50 (t, 1 H, H-2Glc), 5.61–5.77 (m,
3 H, H-2Gal, H-4Gal, H-3Glc), 6.91–7.69 (m,
38 H, arom), 7.78–8.21 (m, 12 H, ortho-pro-
2-Aminoethyl h-
D
-galactopyranosyl-(1“3)-
-glycopyran-
i-
D
-galactopyranosyl-(1“4)-i-
D
oside (2).—(a) To a solution of 21 (0.55 g,
0.43 mmol) in CH2Cl2 (10 mL) CF3CO2H (5
mL) was added. After 1 h at rt the reaction
mixture was coevaporated with toluene (5×
10 mL) and dried in vacuo. The residue was
dissolved in MeOH (30 mL), concd aq NH3
(ca 25%, 30 mL) was added, and the reaction
mixture was heated in tightly closed flask at
13
tons of Bz); C, l 50.4 (CH2N3), 61.99, 62.39
(C-6Glc, C-6Gal), 100.82, 101.00, 103.96 (C-
1Gal, C-1Glc, C-1Gal%). Anal. Calcd
C90H83O22N3: C, 69.35; H, 5.37; N, 2.69;
Found C, 69.14; H, 5.53; N; 2.39.

O.N. Yudina et al. / Carbohydrate Research 332 (2001) 363–371
371
tion for Basic Research (Projects No. 00-03-
32815a and 99-03-33047a).
50 °C for 24 h, then concentrated, dried in
vacuo, dissolved in water, filtered, and con-
centrated. Gel-filtration (elution with water)
of the residue on a column (2.5×100 cm) of
Sephadex G-10 gel (Vo=180 mL) followed by
rechromatography (elution with 0.1 M aq
AcOH) of mixed fractions on a column of
TSK HW-40S gel (1.5×100 cm, Vo =60 mL)
afforded 2 (0.23 g, 99%) as amorphous mass:
Rf 0.3 (3:2, BPHCl–AMW); [h]D 47° (c 1,
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1
water); NMR (D2O): H, see Table 1 for
carbohydrate ring protons; l 3.31 (t, 2 H, J 5
Hz, CH2NH2), 3.98 (m, OCH2CH2NH2), 4.18
13
(m, 1 H, OCH2CH2NH2); C, see Table 2 for
carbohydrate
ring
carbons;
l
40.63
(CH2NH2), 67.03 (OCH2CH2NH2); MALDI-
TOF-MS: Calcd for [C20H37O16N+Na+H]+
: 571.2. Found 571.4.
(b) Compound 6 (0.21 g, 0.14 mmol) was
subjected to hydrogenolysis in EtOAc (3 mL)
and EtOH (9 mL) in the presence of Boc2O
(0.15 g, 0.7 mmol) as described for 20. After
the completion of the reaction, the mixture
was filtered through Celite, and the pad was
washed thoroughly with MeOH. The filtrate
and washings were concentrated, the residue
was dissolved in water (20 mL), washed with
EtOAc (2×10 mL), and then lyophilized to
afford 12 (75 mg, 90%): Rf 0.5 (BPHCl). Com-
pound 12 thus obtained (7 mg, 0.01 mmol)
was dissolved in CF3CO2H (0.5 mL) and, after
0.5 h at rt, concentrated and dried in vacuo.
After treatment with Amberlyst A-26 anion
exchange resin (OH− form) in water, the
residue was purified by gel-filtration as above
to afford 2 (5 mg, 84%), which was identical
in all respect to the material, prepared by
deprotection of 21.
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1988, 174, 239–251.
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The authors are grateful to Dr L.O.
Kononov (N.D. Zelinsky Institute of Organic
Chemistry, Moscow) for valuable discussion
concerning allyl glycoside functionalization.
The work was supported by Russian Founda-