Synthesis of Lex-neoglycoconjugate to study carbohydrate-carbohydrate associations and its intramolecular interaction

Article abstract of DOI:10.1016/S0957-4166(02)00480-9

A straightforward synthetic strategy for the preparation of the Le^x neoglycoconjugate (11,11′-dithio bis[undecanyl-β-D-galactopyranosyl-(1→4)-α-L-fucopyranosyl- (1→3)-2-acetamido-2-deoxy-β-D-glucopyranoside]) and methyl Le^x glycoside

Full text of DOI:10.1016/S0957-4166(02)00480-9

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 13 (2002) 1879–1888
Synthesis of Lex-neoglycoconjugate to study
carbohydrate–carbohydrate associations and its intramolecular
interaction
Jesu´s M. de la Fuente and Soledad Penade´s*
Grupo de Carbohidrato, Instituto de Investigaciones Qu´ımicas, CSIC, Isla de la Cartuja, Ame´rico Vespucio s/n,
41092 Sevilla, Spain
Received 4 July 2002; accepted 14 August 2002
Abstract—A straightforward synthetic strategy for the preparation of the Lex neoglycoconjugate (11,11%-dithio bis[undecanyl-b-
D-
galactopyranosyl-(1“4)-a-
L
-fucopyranosyl-(1“3)-2-acetamido-2-deoxy-b-D
-glucopyranoside]) and methyl Lex glycoside starting
from the same trisaccharide donor is reported. This donor represents a very useful precursor for the construction of Lex
derivatives. The Lex neoglycoconjugate has allowed the preparation of polyvalent gold glyconanoparticles and self-assembled
1
monolayers on gold. H NMR of the Lex neoglycoconjugates suggests an intramolecular Lex–Lex cis-interaction in water, which
is destroyed by addition of methanol. © 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction
clarified owing to the difficulty of analysing weak
affinity interactions. The understanding and control of
interactions between carbohydrates face two main chal-
lenges. One has its origin in the low affinity that
characterizes these interactions. Nature overcomes this
problem by a polyvalent presentation of ligands and
receptors at the cell surface.8 The other problem arises
from the difficulty in obtaining chemically well-defined
glycoconjugates from natural sources. Attempts to
identify and quantify carbohydrate–carbohydrate inter-
actions in solution with monomeric ligands were unsuc-
cessful.9 Multivalent carbohydrate presentation using
liposomes,10,11 polymers12 and neoglycoproteins13 has
recently been used to obtain information on this inter-
action. Polyvalence seems to be mandatory to increase
the degree of this interaction.
The Lewis X (Lex) antigen is the terminal trisaccharide
moiety of numerous cell surface glycolipids and glyco-
proteins which are involved in selectin-mediated cell–
cell adhesion and recognition processes.1 In a mouse
model of pre-implantation embryo, differential expres-
sion of ‘stage-specific embryonic antigen 1’ (SSEA-1)
was observed at the 8–16 cell (morula) stage, which
correlates approximately in time with the onset of
compaction, and declines rapidly after compaction,
being restricted to the inner cell mass of the blastocyst.2
SSEA-1 was identified as Lewis X trisaccharide.3,4
Thus, the involvement of the Lex antigen in com-
paction, the first cell adhesion event of ontogenic devel-
opment, was proposed.5 Based on the observation that
a homotypic Lex–Lex interaction5 may play a crucial
role in morula compaction process, Hakomori et al.6
have advocated the concept of Ca2+-mediated carbohy-
drate–carbohydrate interaction as a new biological
mechanism for cell adhesion and recognition.7 Charac-
teristic features of this interaction are strong depen-
dency on divalent cations, high specificity and low
affinity. Although the existence of this interaction has
now been accepted, the mechanism has not yet been
Our laboratory is developing an integrated methodol-
ogy to obtain chemical tools for studying the Ca2+-
mediated carbohydrate self-interactions (Fig. 1). The
elusive nature of these interactions makes it necessary
to input data from different methodologies to obtain a
complete picture of the mechanisms involved. Our inte-
grated approach is based on self-assembled monolayers
(SAM), by which neoglycoconjugates of natural signifi-
cant oligosaccharides are attached to two- (2D) or
three- (3D) dimensional gold surfaces, creating highly
polyvalent arrays of carbohydrates with well-defined
chemical composition. The 2D self-assembled monolay-
* Corresponding author. Tel.: +34 954489561; fax: +34 954460565;
e-mail: penades@cica.es
0957-4166/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(02)00480-9

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J. M. de la Fuente, S. Penade´s / Tetrahedron: Asymmetry 13 (2002) 1879–1888
Figure 1. Lex-neoglycoconjugate 1 and methyl Lex glycoside 2 and their uses as polyvalent (SAMs) and monovalent analytes.
ers on gold is a strategy that has already been used by
different groups to study carbohydrate–protein interac-
tions.14,15 Our 3D polyvalent system is based on gold
nanoclusters functionalised with carbohydrate antigens
(glyconanoparticles, GNP).16,17 Following this strategy
we have demonstrated, by using transmission electron
microscopy (TEM), the selective ability of the Lex
determinant for self-recognition in calcium-containing
aqueous solutions.16 Well defined 2D-SAM of Lex
determinant have also been used to determine, by an
atomic force microscopy (AFM) study, the adhesion
forces between individual Lex molecules.18 Further-
more, the combination of SAMs of alkanothiolates on
gold presenting Lex epitopes as the substrate, gold
glyconanoparticles as the analyte and detection by sur-
face plasmon resonance (SPR) has allowed us to quan-
tify the kinetics of the putative Ca2+-mediated Lex–Lex
self-interaction.19
in Schemes 1 and 2. Both molecules have been obtained
from the trisaccharide intermediate 12 using the thio-
phenyl glycosylation method.29
For the preparation of 12 a previous successful strategy
for construction of Lex epitopes20,21—attachment of the
fucosyl residue to the 3-hydroxy group of the glu-
cosamine moiety followed by introduction of the galac-
tosyl residue to the 4-hydroxy group of the disaccharide
obtained in the first glycosylation reaction—was
envisaged.
To this end,
D-glucosamine was transformed into the
known N-phthalimide (Phth) protected thiophenyl
(SPh) peracetylated derivative 3 (Scheme 1).30–32 In
order to block glycosylation at the 4- and 6-positions,
de-O-acetylation with MeONa–MeOH33 to give 4, fol-
lowed by 4,6-O-benzylidenation with benzaldehyde
dimethyl acetal34 were performed providing the desired
starting material 5 in good yield. For the fucosylation
of 5, a method described by Hindsgaul at al.35 was
chosen because of the simplicity of preparation of the
donor 6 and the unique chromatographic properties of
the reaction products, which permit facile separation of
the desired glycoside and recovery of the unreacted
We report herein the total synthesis of Lex neoglyco-
conjugate 1, the molecule used in our previous studies,
by an efficient and stereospecific route based on previ-
ously reported two-stage activation procedure for
oligosaccharide construction.20,21 The synthesis of the
trisaccharide Lex has represented some of the most
complex synthetic targets.22–27 The neoglycoconjugate 1
was synthesized with a linker ending in a thiol group, to
allow us to attach it to gold surfaces for the preparation
of polyvalent glyconanoparticles of Lex (3D-SAM),16,17
and self-assembled monolayers (2D-SAM).18,19 Self
assembled monolayers of alkanethiolates on gold are
structurally well-organized substrates that provide
excellent model surfaces for studies in biology.14,15,28
The methyl Lex glycoside 2 was also prepared as a
monovalent ligand.
acceptor on silica gel. Reaction of L-fucopyranose with
chlorotrimethylsilane (TMS-Cl) and triethylamine
(TEA) in N,N-dimethylformamide (DMF) gave 6.35
Reaction of 6 with iodotrimethylsilane (TMS-I) in
CH2Cl2 resulted in the quantitative formation of the
iodo-fucopyranoside that was not isolated. The pro-
tected disaccharide 7 was prepared by addition of 6 and
2,6-di-tert-butylpyridine to the iodo-fucopyranoside,
deprotection of the TMS groups using MeOH and
subsequent acetylation, obtaining a good yield (80%) in
four steps.
Deprotection of the benzylidene groups in 7 with
ethanethiol using BF3·Et2O as catalyst dramatically
accelerated the reaction to form 8. Selective benzoyl-
protection36 of the primary alcohol group with benzoyl
cyanide and a catalytic amount of triethylamine at
−40°C gave the desired 4-O-unprotected, 6-O-benzoyl-
protected disaccharide 9 in good yields (95%). The
galactosylation of 9 with the already described galacto-
2. Results and discussion
The chemical synthesis of 11,11%-dithio bis[undecanyl-b-
D
-galactopyranosyl-(1“4)-a- -fucopyranosyl-(1“3)-2-
L
acetamido-2-deoxy-b-
b- -galactopyranosyl-(1“4)-a-
2-acetamido-2-deoxy-b- -glucopyranoside 2 is shown
D
-glucopyranoside] 1 and methyl
D
L
-fucopyranosyl-(1“3)-
D

J. M. de la Fuente, S. Penade´s / Tetrahedron: Asymmetry 13 (2002) 1879–1888
1881
Scheme 1. Reagents and conditions: (a) MeOH/MeONa, quantitative; (b) benzylidene dimethyl acetal, PTSA cat.; CH3CN, 84%;
(c) ClTMS, TEA, DMF, 90%; (d) i. TMS-I, CH2Cl2; ii. 5, 2,6-di-tert-butylpyridine; iii. MeOH; iv. Ac2O, py, 80%, four steps; (e)
EtSH, BF3·Et2O cat., CH2Cl2, 83%; (f) BzCN, CH3CN, NEt3 cat., −40°C, 95%; (g) Cl3CCN, Cs2CO3, CH2Cl2, 95%; (h) 9,
TMSOTf (0.1 equiv.), Et2O:CH2Cl2 (5:1), 0°C, 80%.
Zemple´n conditions,39 the unprotected neoglycolipid-
Lex 1 and methyl Lex glycoside 2 were obtained in high
overall yields. The b-anomeric protons of both com-
syl donor 11,37 was carried out at 0°C using TMSOTf
(0.1 equiv.) as promoter, and ether:CH2Cl2 (5:1) as
solvent,20 thus affording the desired protected LeX-
trisaccharide building block 12 in 80% yield.
1
pounds could be assigned by H NMR spectroscopy,
thus confirming the configurations at the anomeric
centers.
Trisaccharide 12 is the donor in the synthesis of neogly-
coconjugate 1 as well as methyl glycoside 2. A standard
protocol for glycosylation in CH2Cl2 in the presence of
NIS and triflic acid at −60°C was used.29 As acceptor,
11-bromo undecanol and MeOH were chosen (Scheme
2) to obtain 13 and 14, respectively, in very good yields.
Replacement of the bromide group in 13 by the thio-
acetate group could be carried out with KSAc, and
(NBut)4I in butanone, yielding the corresponding neo-
glyconjugate 15 in quantitative yield.
Conjugates 1 and 2 are water and methanol soluble.
Neoglycolipid 1 was isolated as a disulfide derivative. A
significant fact is the difference between the H NMR
1
spectra of 1 in D2O and in CD3OD (Fig. 2). The
spectra of 1 in D2O (Fig. 2a) shows a broadening for all
signals similar to that observed in the spectrum of
Lex-glyconanoparticles (Fig. 2e). In the case of glyco-
nanoparticles, this line broadening can be attributed to
the slowly rotating macromolecules in solution. How-
ever, in the case of 1, an intramolecular cis-interaction
between the Lex molecules in water can be suggested as
being responsible for the broadening. The intramolecu-
lar nature of this interaction is supported by the persis-
Removal of the acyl and phthalimide groups in 14 and
15 by treatment with ethylendiamine in 2-buthanol at
90°C was quite straightforward.38 Peracetylation of the
deprotected trisaccharides afforded 16 and 17. Using

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J. M. de la Fuente, S. Penade´s / Tetrahedron: Asymmetry 13 (2002) 1879–1888
Scheme 2. Reagents and conditions: (a) 11-Bromo-undecanol, NIS, TfOH, CH2Cl2, −60°C, 80%; (b) NIS, TfOH, CH2Cl2; MeOH,
−60°C, 98%; (c) SAcK, NBu4I cat., butanone, 60°C quantitative; (d) i. ethylenediamine, 2-butanol; ii. Ac2O, py, 80–60%; (e)
MeOH, MeONa, 90%.
tence of the signal broadening even at highly diluted
water solution. Addition of increasing amounts of
CD3OD to the D2O solution of 1 abolished this self-
interaction. Some well-resolved signals appear already
in CD3OD/D2O (1:1) solution (Fig. 2b) and in 65%
CD3OD/D2O solution all signals are well-resolved in the
spectrum, indicating that hydrophobic interactions are
involved (Fig. 2c). The tendency of the Lex disulfide 1 to
interact intramolecularly in water cannot exclusively be
attributed to the hydrophobicity of the aliphatic chain,
but rather to specific interactions between carbohydrate
moieties. This is supported by the lack of broadening in
the carbohydrate signals of the corresponding lactose-
3. Experimental
3.1. General procedures
3.1.1. Materials and methods. TLC analysis was per-
formed on silica gel 60 F254 precoated on aluminium
plates (Merck) and the compounds were detected by
staining with sulphuric acid/ethanol (1/9, v/v) followed
by heating at over 200°C. Column chromatography was
carried out on silica gel 60 (0.2–0.5 mm; 0.2–0.063 mm;
0.040–0.015 mm; Merck). Optical rotations were deter-
mined with a Perkin–Elmer 341 polarimeter. 1H and 13
C
NMR spectra were acquired on Bruker DPX-300,
DRX-400 and DRX-500 spectrometers and chemical
shifts are given in ppm (l) relative to D2O. Elemental
analyses were performed with a Leco CHNS-932
apparatus, after drying analytical samples over phos-
phorous pentoxide for 24 h. Mass spectra were recorded
with a MALDI-TOF GSG System spectrometer. Sam-
ples of the products were dissolved in MeOH at mM
concentration and 2,5-dihidroxybenzoic acid was used
as matrix.
1
disulfide neoglycoconjugate observed in the H NMR
spectrum in water (Fig. 2f).40 In this case the disulfide
bond adopts the usual trans conformation keeping the
lactose moieties in trans position.
In conclusion, we have shown that the thiophenyl trisac-
charide 12 is a very good precursor for the construction
of the Lex neoglycoconjugate and methyl Lex glycoside.
In addition, the tendency of Lex trisaccharide to self-
interact in a cis-intramolecular manner has been sug-
gested by NMR spectroscopy, supporting the capacity
of this antigen to establish homotypic carbohydrate–
carbohydrate interactions.
3.1.2. Titration with CD3OD. A D2O solution of 1 (21
mM) was prepared. CD3OD (1 mL) was added in
portions via microsyringe (5×20 mL, 2×50 mL, 8×100

J. M. de la Fuente, S. Penade´s / Tetrahedron: Asymmetry 13 (2002) 1879–1888
1883
Figure 2. 1H NMR spectra of: (a) 1 in D2O; (b) 1 in CD3OD/D2O (1:1); (c) 1 in 65% CD3OD/D2O; (d) 1 in CD3OD; (e)
glyconanoparticles of 1 in D2O; (f) lactose-neoglycoconjugate in D2O.
mL). The 1H NMR spectrum of each solution was
recorded, and the signal broadening was observed. The
temperature was kept constant at 298 1 K.
3.3. Phenyl 2-deoxy-2-phthalimide-1-thio-b-D-glucopy-
ranoside, 4
Compound 3 (6.51 g, 12.35 mmol, 1 equiv.) was added
to a solution of MeONa in MeOH (1N, 90 mL) and the
mixture was stirred at room temperature for 3 h. When
the reaction was complete (TLC, AcOEt:hexane, 1:1),
amberlite IR-120 (H+) was added until the medium was
neutral. The mixture was filtered and concentrated to
3.2. Phenyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-1-
thio-b-D-glucopyranoside, 3
1,3,4,6-Tetra-O-acetyl-2-deoxy-2-phthalimido-b-D-
1
give 4 as an amorphous solid (5.24 g, quantitative); H
glucopyranose30,31 (8.63 g, 18.1 mmol, 1 equiv.) was
dissolved in dry dichloromethane (80 mL), and to this
solution thiophenol (2.2 mL, 21.7 mmol, 1.2 equiv.)
and boron trifluoride etherate (11.5 mL, 90.5 mmol, 5
equiv.) were added. When the reaction was complete
(TLC, AcOEt:hexane, 1:1), the solution was washed
with saturated aqueous sodium hydrogencarbonate and
then with water before being dried with anhydrous
sodium sulfate. Removal of the solvent afforded a light
yellow syrup which crystallized on treatment with etha-
nol to afford 3 as a yellow solid (6.52 g, 69%); 1H
NMR (300 MHz, CDCl3): l 7.90–7.70 (m, 4H, NPhth),
7.50–7.20 (m, 5H, SPh), 5.82 (t, 1H, J=9.6 Hz), 5.74
(d, 1H, J=10.5 Hz, H-1), 5.16 (t, 1H, J=9.8 Hz), 4.37
(t, 1H, J=10.2 Hz), 4.31 (dd, 1H, J=12.0, 4.8 Hz),
4.23 (dd, 1H, J=12.3, 2.3 Hz), 4.00–3.90 (m, 1H, H-5),
2.13, 2.06, 1.84 (s, 9H, 3 OAc).
NMR (300 MHz, CD3OD): l 8.00–7.80 (m, 4H,
NPhth), 7.50–7.20 (m, 5H, SPh), 5.59 (d, 1H, J=10.5
Hz, H-1), 4.27 (dd, 1H, J=10.2, 8.1 Hz), 4.11 (t, 1H,
J=10.2 Hz), 3.94 (m, 1H), 3.76 (dd, 1H, J=11.7, 5.1
Hz), 3.50–3.30 (m, 2H).
3.4. Phenyl 4,5-benzyliden-2-deoxy-2-phthalimido-1-
thio-b-D-glucopyranoside, 5
Compound 4 (5.15 g, 12.84 mmol, 1 equiv.) was dis-
solved in acetonitrile (100 mL), and to this solution was
added benzaldehyde dimethyl acetal (3.86 mL, 25.69
mmol, 2 equiv.) and a catalytic amount of p-toluensul-
fonic acid. The reaction was kept under an argon
atmosphere and room temperature for 2 h. When the
reaction was complete (TLC, AcOEt:hexane, 1:1), tri-

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J. M. de la Fuente, S. Penade´s / Tetrahedron: Asymmetry 13 (2002) 1879–1888
ethylamine was added until neutral medium. The solu-
tion was concentrated and flash chromatography of the
residue (AcOEt:hexane, 1:2) gave 5 as a white solid
3.7. Phenyl 2,3,4-tri-O-acetyl-a-
2-deoxy-2-phthalimido-1-thio-b-
L
-fucopyranosyl-(1“3)-
D
-glucopyranoside, 8
1
(5.18 g, 86%); H NMR (300 MHz, CDCl3): l 8.00–
Compound 7 (1.49 g, 1.95 mmol, 1 equiv.) was dis-
solved in dry dichloromethane (100 mL). EtSH (0.8
mL, 10.5 mmol, 5 equiv.) and a catalytic amount of
BF3·Et2O were added. The solution was stirred at room
temperature. When the reaction was complete (TLC,
AcOEt:hexane, 1:1), the solution was washed with a
saturated aqueous sodium hydrogencarbonate solution
and then with water before being dried with anhydrous
sodium sulfate. The mixture was concentrated and flash
chromatography of the residue (AcOEt:hexane, 1:2)
7.70 (m, 4H, NPhth), 7.60–7.20 (m, 10H, SPh, CH-Ph),
5.72 (d, 1H, J=10.5 Hz, H-1b), 5.59 (s, 1H, CH-Ph),
4.67 (td, 1H, J=9.6, 3.1 Hz, H-2), 4.44 (dd, 1H,
J=10.2, 4.2 Hz), 4.36 (t, 1H, J=10.2 Hz), 3.86 (t, 1H,
J=9.9 Hz), 3.75 (td, 1H, J=9.4, 4.5 Hz), 3.64 (t, 1H,
J=9.0 Hz), 2.45 (d, 1H, J=3.0 Hz, OH); MALDI-
TOF: calcd for C27H23NO6S 489.1, found m/z 512.2
([M+Na]+), 528.9 ([M+K]+). Elemental analysis: found
C, 66.22; H, 4.99; N, 2.72; calcd for C27H23NO6S
(489.1) C, 66.26; H, 4.70; N, 2.86%.
1
gave 8 as a syrup (1.09 g, 83%); H NMR (300 MHz,
CDCl3): l 8.00–7.70 (m, 4H, NPhth), 7.50–7.10 (m, 5H,
SPh), 5.59 (d, 1H, J=9.6 Hz, H-1), 5.29 (d, 1H, J=1.8
Hz, H-4%), 5.20–5.00 (m, 3H, H-1%, H-2%, H-3%), 4.50 (m,
1H, H-5%), 4.50–4.30 (m, 3H, H-2), 3.99 (dd, 1H, J=
11.7, 2.55 Hz, H-6a), 3.87 (dd, 1H, J=11.9, 3.9 Hz,
H-6b), 3.80–3.50 (m, 2H, H-5), 2.12, 2.05, 1.89 (s, 9H,
3 OAc), 1.16 (d, 3H, J=6.6 Hz, H-6%); 13C NMR (75
MHz, CDCl3): l 170.8, 170.3, 170.0, 134.7, 132.9,
132.0, 129.4, 128.6, 124.6, 123.8, 97.9, 83.8, 82.7, 79.7,
71.4, 71.2, 67.8, 66.6, 63.0, 60.8, 54.1, 31.4, 21.0, 19.8,
16.3; MALDI-TOF: calcd for C32H35NO13S 673.1,
found m/z 695.9 ([M+Na]+), 712.2 ([M+K]+). Elemental
analysis: found C, 55.77; H, 5.25; N, 1.98%; calcd for
C32H35NO13S·1H2O (691.1) C, 55.56; H, 5.35; N,
1.98%.
3.5. Pertrimethylsilyl-fucose, 6
L
-Fucose (1 g, 6.09 mmol, 1 equiv.) and triethylamine
(4.4 mL, 31.55 mmol, 5.18 equiv.) were dissolved in dry
DMF (30 mL). Chloride trimethylsilyl (4 mL, 31.55
mmol, 5.18 equiv.) was added at 0°C, and the reaction
was stirred at room temperature for 4 h (TLC,
AcOEt:hexane, 1:1). The solution was diluted with pen-
tane (100 mL), and extracted with cooled water (3×30
mL). The organic layer was dried (anhydrous sodium
sulfate), filtered and concentrated to give 6 as a colour-
less syrup (2.48 g, 90%).
3.6. Phenyl 2,3,4-tri-O-acetyl-a-L-fucopyranosyl-(1“3)-
4,5-benzylidene-2-deoxy-2-phthalimido-1-thio-b-D-
glucopyranoside, 7
To a solution of 6 (0.65 g, 1.45 mmol, 3 equiv.) in dry
dichloromethane (10 mL), ITMS (0.21 mL, 1.45 mmol,
3 equiv.) was added at room temperature and stirred
for 20 min. A solution of 5 (0.26 g, 0.53 mmol, 1.1
equiv.) and 2,6-di-tert-butylpyridine (0.33 mL, 1.45
mmol, 3 equiv.) in dry dichloromethane (15 mL) was
added and the resulting mixture was stirred at room
temperature. When the reaction was complete (TLC,
AcOEt:hexane, 1:1), methanol (30 mL) was added, and
the solution was stirred for 30 min. The mixture was
neutralized with triethylamine, and concentrated to give
a syrup. Acetic anhydride (0.8 mL) and pyridine (1.6
mL) were added under cooling to the residue. The
mixture was stirred at room temperature and then
poured into ice-water. The emulsion was extracted with
AcOEt (3×20 mL). The extract was dried and concen-
trated. The reaction was followed by TLC
(AcOEt:hexane, 2:1, 3 elution). Flash chromatography
of the residue (AcOEt:hexane, 1:4) gave 7 as an amor-
3.8. Phenyl 2,3,4-tri-O-acetyl-a-L-fucopyranosyl-(1“3)-
6-O-benzoyl-2-deoxy-2-phthalimide-1-thio-b-D-glucopy-
ranoside, 9
Compound 8 (1.13 g, 1.68 mmol, 1 equiv.) was dis-
solved in dry acetonitrile (75 mL) under an argon
atmosphere at −40°C. Benzoyl cyanide (0.22 mL, 1.85
mmol, 1.1 equiv.) and a catalytic amount of triethyl-
amine were added. The reaction was stirred at −40°C.
The reaction was monitored by TLC (AcOEt:hexane,
1:1). Methanol was added three times to remove gener-
ated HCN and the mixture was concentrated. Flash
chromatography of the residue (AcOEt:hexane, 1:2)
1
gave 9 as an white solid (1.24 g, 95%); H NMR (300
MHz, CDCl3): l 8.15–7.00 (m, 14H, SPh, Bz, NPhth),
5.55 (d, 1H, J=10.2 Hz, H-1), 5.27 (bs, 1H, H-4%), 5.16
(dd, 1H, J=10.5, 3.0 Hz, H-3%), 5.10–5.00 (m, 2H, H-1%,
H-2%), 4.80–4.60 (m, 2H, H-6), 4.50 (m, 1H, H-5%),
4.43–4.30 (m, 2H, H-3, H-2), 4.25 (s, 1H, OH), 3.90–
3.80 (m, 1H, H-5), 3.70–3.50 (m, 1H, H-4), 2.09, 2.04,
1.87 (s, 9H, 3 OAc), 1.11 (d, 3H, J=6.6 Hz, H-6%); 13C
NMR (75 MHz, CDCl3): l 170.8, 170.3, 170.0, 167.1,
134.8, 133.7, 133.1, 132.1, 130.3, 130.2, 129.2, 128.9,
128.4, 124.5, 97.8, 83.8, 82.1, 71.2, 70.9, 67.9, 67.8, 66.5,
64.3, 54.1, 31.4, 21.0, 19.9, 16.1; MALDI-TOF: calcd
for C39H39NO14S 777.1, found m/z 800.4 ([M+Na]+),
817.0 ([M+K]+). Elemental analysis: found C, 58.95; H,
5.39; N, 1.83; calcd for C39H39NO14S·1H2O (795.1) C,
58.86; H, 5.16; N, 1.76%.
1
phous solid (0.32 g, 80% for four steps); H NMR (300
MHz, CDCl3): l 7.90–7.70 (m, 4H, NPhth), 7.50–7.10
(m, 10H, SPh, CH-Ph), 5.57 (s, 1H, CH-Ph), 5.57 (d,
1H, J=10.5 Hz, H-1), 5.24 (dd, 1H, J=10.8, 2.7 Hz),
5.01 (d, 1H, J=2.7 Hz), 4.90–4.70 (m, 3H), 4.50–4.40
(m, 2H), 4.33 (m, 1H, H-5%), 3.90–3.70 (m, 3H), 2.01,
2.00, 1.92 (s, 9H, 3 OAc), 0.49 (d, 3H, J=6.3 Hz, H-6%);
MALDI-TOF: calcd for C39H39NO13S 761.1, found m/z
784.4 ([M+Na]+), 800.7 ([M+K]+). Elemental analysis:
found C, 59.19; H, 5.14; N, 1.98; calcd for
C39H39NO13S·2H2O (797.1) C, 58.72; H, 5.40; N,
1.76%.

J. M. de la Fuente, S. Penade´s / Tetrahedron: Asymmetry 13 (2002) 1879–1888
1885
3.9. 2,3,4,6-Tetra-O-acetyl-
D
-galactopyranose, 10
134.5, 133.6, 132.8, 129.7, 128.0, 123.8, 100.7, 95.4,
84.1, 77.4, 75.5, 72.4, 71.4, 71.2, 71.1, 70.7, 68.9, 68.1,
67.6, 66.7, 64.4, 62.3, 60.7, 60.4, 55.4, 20.8, 20.8, 20.6,
20.5, 20.5, 15.9; MALDI-TOF: calcd for C53H57NO23S
1106.1, found m/z 1107.1 ([M+H]+). Elemental analysis:
found C, 54.24; H, 5.01; N, 1.25; calcd for C53H57NO23-
S·3H2O (1160.1) C, 53.94; H, 5.34; N, 1.19%.
D
-Galactose pentaacetate (5 g, 12.8 mmol, 1 equiv.) was
dissolved in DMF (50 mL). Hydrazine acetate (1.42 g,
15.4 mmol, 1.2 equiv.) was added, and was stirred at
50°C for 45 min. The reaction was monitored by TLC
(hexane:EtOAc, 1:1). The mixture was diluted with
ethyl acetate (50 mL) and washed with brine. The
organic layer was dried over anhydride sodium sulfate,
filtered and concentrated to give 10 as a white solid (4
3.12. 11-Bromo-undecyl 2,3,4,6-tetra-O-acetyl-b-
galactopyranosyl-(1“4)-(2,3,4-tri-O-acetyl-a-
fucopyranosyl)-(1“3)-6-O-benzoyl-2-deoxy-2-
phthalimido-1-thio-b- -glucopyranoside, 13
D-
L
-
1
g, 90%); H NMR (300 MHz, CDCl3): l 5.50–5.30 (m,
3H), 5.20–5.00 (m, 2H), 4.69 (d, 0.4H, J=6.6 Hz,
H-1b), 4.43 (m, 1H, H-4a), 4.10–4.00 (m, 3H, H-5a),
4.00–3.90 (m, 0.4H, H-5b), 3.00–2.70 (m, 1H), 2.11,
2.06, 2.01, 1.96 (s, 12H, 4 OAc).
D
To a solution of 12 (50 mg, 0.045 mmol, 1 equiv.), and
11-bromo-undecanol (20 mL, 0.09 mmol, 2 equiv.) in
,
dry dichloromethane (5 mL) 4 A molecular sieves (50
mg) was added and the mixture was stirred at room
temperature for 1 h and then cooled to −60°C. NIS (41
mg, 0.18 mmol, 4 equiv.) and TfOH (4.5 mL, 0.045
mmol, 1 equiv.) were added to the reaction mixture and
the stirring was continued at −60°C. The course of the
reaction was monitored by TLC (AcOEt:hexane, 1:2).
The solution was neutralized with triethylamine and a
white precipitate appeared. The precipitate was filtered
off and washed with dichloromethane. The filtrate and
washings were combined, and the solution was washed
with Na2S2O3 (1 M) and water, dried (anhydrous
sodium sulfate) and concentrated. Flash chromatogra-
phy of the residue (AcOEt:hexane, 1:3) gave 13 as an
3.10. Trichloroacetimidate 2,3,4,6-tetra-O-acetyl-D-
galactopyranoside, 11
Compound 10 (9.52 g, 27.4 mmol, 1 equiv.) was dis-
solved in dry dichloromethane (100 mL) under an
argon atmosphere and treated with Cl3CCN (27.5 mL,
274 mmol, 10 equiv.) and cesium carbonate (9.82 g,
30.14 mmol, 1.1 equiv.) and the mixture was stirred at
room temperature. When the reaction was complete
(TLC, AcOEt:hexane, 1:1) the mixture was filtered over
Celite, and was concentrated to give 11 as an amor-
phous solid (12.82 g, 95%); 1H NMR (300 MHz,
CDCl3): l 8.50 (s, 1H, NH), 6.69 (d, 1H, J=3.3 Hz,
H-1a), 5.77 (dd, 1H, J=3, 1.2 Hz, H-4), 5.63 (dd, 1H,
J=9.3, 3.0 Hz), 4.79 (t, 1H, J=6.0 Hz), 4.60–4.40 (m,
2H), 3.46 (m, 1H), 2.79, 2.67, 2.67, 2.66 (s, 12H, 4
OAc).
1
amorphous solid (44 mg, 80%); H NMR (300 MHz,
CDCl3): l 8.10–8.00 (m, 2H, Bz), 7.85–7.68 (m, 4H,
NPhth), 7.65–7.50 (m, 3H, Bz), 5.40–5.30 (m, 2H,
H-4%), 5.20–4.85 (m, 7H, H-1, H-1%, H-5%), 4.80–4.75 (m,
2H), 4.67 (d, 1H, J=8.1 Hz, H-1¦), 4.55 (m, 1H), 4.36
(dd, 1H, J=12.3 Hz, H-2), 4.30–4.20 (m, 2H), 4.12–
4.00 (m, 1H), 3.80–3.68 (m, 3H, CHO), 3.39 (t, 1H,
J=6.9 Hz, CHBr), 3.29 (m, 1H, CHO), 3.17 (t, 1H,
J=6.9 Hz, CHBr), 2.16, 2.11, 2.08, 2.05, 2.04, 1.95,
1.91 (s, 21H, 7 OAc), 1.50–1.70 (m, 21H, CH2CH2,
H-6%).
3.11. Phenyl 2,3,4,6-tetra-O-acetyl-b-
D
-galactopyran-
osyl-(1“4)-(2,3,4-tri-O-acetyl-a-
L-fucopyranosyl)-
(1“3)-6-O-benzoyl-2-deoxy-2-phthalimido-1-thio-b-D-
glucopyranoside, 12
A mixture of 9 (3.47 g, 4.47 mmol, 1 equiv.) and 11
(6.61 g, 13.41 mmol, 3 equiv.) was dissolved in
ether:dichloromethane (5:1 v/v, 120 mL) at 0°C.
TMSOTf (0.08 mL, 0.45 mmol, 0.1 equiv.) was added
and the mixture was stirred at 0°C. The reaction was
monitored by TLC (AcOEt:hexane, 1:2, 3 elutions).
More donor 11 solution in ether (6.61 g, 13.41 mmol, 3
equiv.) was added when this disappeared in the reac-
tion. Triethylamine was added, the mixture was concen-
trated. Flash chromatography of the residue
(AcOEt:hexane, 1:4) gave 12 as an amorphous solid
(3.96 g, 80%); [h]2D3 −25.3 (c=1, CH2Cl2); 1H NMR
(500 MHz, CDCl3): l 8.03–8.01 (m, 2H, Bz), 7.83–7.75
(m, 4H, NPhth), 7.62–7.49 (m, 3H, Bz), 7.27–6.98 (m,
5H, SPh), 5.44 (d, 1H, J=10.5 Hz, H-1), 5.34 (m, 2H),
5.10 (m, 2H, H-2¦), 4.93 (m, 4H, H-6a, H-5%, H-1%), 4.81
(dd, 1H, J=11.0, 4.0 Hz.), 4.76 (t, 1H, J=9.5 Hz, H-3),
4.62 (d, 1H, J=8 Hz, H-1¦), 4.53 (m, 1H), 4.34 (m, 2H,
H-2, H-6b), 4.25 (m, 1H), 3.99 (t, 1H, J=9.5 Hz, H-4),
3.84 (m, 1H, H-5), 3.77 (t, 1H, J=7.0 Hz), 2.14, 2.08,
2.05, 2.04, 2.03, 2.01, 1.93 (s, 21H, 7 OAc), 1.18 (d, 3H,
J=6.5 Hz, H-6%); 13C NMR (125 MHz, CDCl3): l
170.7, 170.6, 170.5, 170.4, 169.9, 169.7, 169.0, 165.7,
3.13. Methyl 2,3,4,6-tetra-O-acetyl-b-
D
-galactopyran-
osyl-(1“4)-(2,3,4-tri-O-acetyl-a-
L-fucopyranosyl)-
(1“3)-6-O-benzoyl-2-deoxy-2-phthalimido-b-D-gluco-
pyranoside, 14
A solution of 12 (0.5 g, 0.45 mmol, 1 equiv.) in
methanol (1.5 mL, 45 mmol, 100 equiv.) and dry
dichloromethane (20 mL) was cooled to −60°C. To the
reaction mixture NIS (0.31 g, 1.35 mmol, 3 equiv.) and
TfOH (45 mL, 0.45 mmol, 1 equiv.) were added and
stirring was continued at −60°C. When the reaction was
finished (TLC, AcOEt:hexane, 2:1), the solution was
neutralized with triethylamine. The solution was
washed with Na2S2O3 (1 M) and water, dried (anhy-
drous sodium sulfate) and concentrated. Flash chro-
matography of the residue (AcOEt:hexane, 1:1) gave 14
1
as an amorphous solid (0.46 g, quantitative); H NMR
(300 MHz, CDCl3): l 8.10–8.00 (m, 2H, Bz), 7.90–7.70
(m, 4H, NPhth), 7.70–7.40 (m, 3H, Bz), 5.35 (m, 2H),
5.20–5.08 (m, 2H), 5.01–4.95 (m, 3H, H-1), 4.90 (dd,
2H, J=9.9, 3.6 Hz), 4.83–4.72 (m, 2H), 4.67 (d, 1H,
J=8.4 Hz, H-1¦), 4.55 (m, 1H), 4.36 (dd, 1H, J=12.2,

1886
J. M. de la Fuente, S. Penade´s / Tetrahedron: Asymmetry 13 (2002) 1879–1888
3.7 Hz), 4.29–4.22 (m, 2H), 4.05 (m, 1H), 3.81–3.74 (m,
2H, H-5), 3.33 (s, 3H, OCH3), 2.17, 2.12, 2.08, 2.05,
2.05, 2.03, 1.95 (s, 21H, 7 OAc), 1.21 (d, 3H, J=6.3 Hz,
H-6%).
4.26 (dd, 1H, J=11.5, 7.5 Hz, H-6¦a), 4.09 (m, 2H,
H-6a, H-3), 3.85 (t, 1H, J=7.0 Hz, H-5¦), 3.79 (t, 1H,
J=8.5 Hz, H-4), 3.74 (m, 1H, CHO), 3.64 (m, 1H,
H-2), 3.52 (m, 1H, H-5), 3.38 (m, 1H, CHO), 2.65 (t,
2H, J=7.0 Hz, CH2S), 2.17, 2.12, 2.11, 2.08, 2.05, 2.04,
1.95, 1.94, 1.94 (s, 27H, 9 Ac), 1.67–1.22 (m, 18H,
CH2CH2), 1.19 (d, 3H, J=6.5 Hz, H-6%); 13C NMR
(125 MHz, CDCl3): l 170.8, 170.6, 170.5, 170.4, 170.3,
170.0, 169.8, 169.2, 100.5, 100.0, 95.3, 74.6, 73.2, 72.8,
71.4, 71.1, 70.9, 69.6, 69.0, 68.4, 68.1, 66.7, 64.3, 62.1,
60.8, 56.1, 39.2, 29.7, 29.6, 29.6, 29.5, 29.4, 29.2, 29.2,
28.5, 25.9, 23.4, 21.0, 20.9, 20.8, 20.7, 20.6, 20.6, 20.5,
15.9; MALDI-TOF: calcd for C94H144N2O46S2 2100.1,
found m/z 2123.1 ([M+Na]+), 2138.2 ([M+K]+).
3.14. 11-Thioacetyl-undecyl 2,3,4,6-tetra-O-acetyl-b-
galactopyranosyl-(1“4)-(2,3,4-tri-O-acetyl-a-
fucopyranosyl)-(1“3)-6-O-benzoyl-2-deoxy-2-
phthalimido-1-thio-b- -glucopyranoside, 15
D-
L
-
D
Compound 13 (0.04 g, 0.036 mmol, 1 equiv.), SAcK
(0.01 g, 0.108 mmol, 3 equiv.) and a catalytic amount
of NBu4I were dissolved in butanone (5 mL), and
stirred for 3 h at 60°C. When the reaction was complete
(TLC, AcOEt:hexane, 1:1) the emulsion was extracted
with AcOEt (3×20 mL) and the extract washed with
water (20 mL). The extract was dried and concentrated.
Flash chromatography of the residue (AcOEt:hexane,
1:2) gave 15 as an amorphous solid (46 mg, quantita-
3.16. Methyl (2,3,4,6-tetra-O-acetyl-b-
D
-galactopyran-
osyl)-(1“4)-(2,3,4-tri-O-acetyl-a-
L-fucopyranosyl)-
(1“3)-6-O-acetyl-2-acetamido-2-deoxy-b-D-gluco-
pyranoside, 17
1
tive); [h]2D3 −16.6 (c=1, CH2Cl2); H NMR (300 MHz,
CDCl3): l 8.10–8.00 (m, 2H, Bz), 7.90–7.70 (m, 4H,
NPhth), 7.70–7.50 (m, 3H, Bz), 5.40–5.30 (m, 2H),
5.21–5.09 (m, 2H), 5.05 (d, 1H, J=8.7 Hz, H-1), 5.02–
4.93 (m, 3H, H-1%), 4.88 (dd, 1H, J=10.5, 3.6 Hz),
4.83–4.74 (m, 2H), 4.66 (d, 1H, J=8.1 Hz, H-1¦), 4.57
(dd, 1H, J=11.4, 6.6 Hz), 4.36 (dd, 1H, J=12.3, 3.9
Hz), 4.34 (m, 2H), 4.09 (t, 1H, J=9.3 Hz), 3.80–3.70
(m, 3H, H-5, CHO), 3.28 (m, 1H, CHO), 2.85 (t, 2H,
J=7.2 Hz, CH2S), 2.32, 2.18, 2.12, 2.09, 2.07, 2.05,
1.96, 1.92 (s, 24H, 8 OAc), 1.60–0.70 (m, 21H,
CH2CH2, H-6%); 13C NMR (75 MHz, CDCl3): l 179.9,
171.2, 170.9, 170.8, 170.4, 170.2, 169.5, 166.1, 152.5,
134.8, 134.0, 131.9, 130.8, 130.1, 129.8, 129.2, 123.9,
100.9, 98.6, 95.6, 75.7, 73.5, 71.8, 71.7, 71.5, 70.3, 70.1,
69.3, 68.6, 68.2, 67.1, 64.6, 62.6, 61.1, 56.8, 31.3, 31.1,
29.9, 29.7, 29.5, 29.4, 26.8, 21.2, 21.1, 16.1; MALDI-
TOF: calcd for C60H77NO25S 1243.1, found m/z 1266.2
([M+Na]+), 1281.6 ([M+K]+). Elemental analysis: found
C, 56.48; H, 6.08; N, 1.12; calcd for C60H77NO25-
S·1H2O (1261.1) C, 57.10; H, 6.26; N, 1.11%.
Compound 14 (0.46 g, 0.44 mmol, 1 equiv.) was dis-
solved in 2-buthanol (20 mL). Ethylenediamine (8.8
mL, 132 mmol, 300 equiv.) was added. The reaction
was stirred for 18 h at 90°C. When the reaction was
complete (TLC, MeOH), the solvent was removed.
Methanol was added three times to remove the excess
ethylenediamine and the mixture was concentrated. A
mixture of acetic anhydride (15 mL) and dry pyridine
(30 mL) was added under cooling. The mixture was
kept for 24 h at room temperature. The solvent was
removed, and the product was purified by silica gel
1
column (AcOEt) to give 17 (0.23 g, 60%); H NMR
(500 MHz, CDCl3): l 5.66 (d, 1H, J=9.0 Hz, NH),
5.39 (m, 2H, H-1%), 5.33 (d, 1H, J=3 Hz, H-4%), 5.18
(dd, 1H, J=11.0, 3.0 Hz, H-3%), 5.08 (t, 1H, J=9.0 Hz),
4.99 (m, 2H, H-2%, H-5¦), 4.70 (m, 1H, H-5%), 4.57 (dd,
1H, J=12.0, 3.5 Hz, H.6b), 4.51 (d, 1H, J=6.5 Hz,
H-1), 4.45 (d, 1H, J=8.0 Hz, H-1¦), 4.41 (m, 1H, H-4¦),
4.25 (dd, 1H, J=11.0, 7.5 Hz, H-2¦), 4.19 (dd, 1H,
J=11.5, 5.0 Hz, H-6a), 4.09 (t, 1H, J=7.5 Hz, H-3),
3.86 (t, 1H, J=7.0 Hz, H-3¦), 3.82 (t, 1H, J=7.5 Hz,
H-4), 3.77 (m, 1H, H-2), 3.59 (m, 1H, H-5), 3.40 (s, 3H,
OCH3), 2.17, 2.12, 2.11, 2.07, 2.05, 1.97, 1.96, 1.94 (s,
24H, 8 OAc), 1.63 (s, 3H, NHAc), 1.18 (d, 3H, J=6.5
Hz, H-6%); 13C NMR (125 MHz, CDCl3): l 206.9,
171.0, 170.7, 170.6, 170.4, 170.0, 169.9, 169.4, 137.9,
129.0, 128.2, 125.3, 101.0, 100.4, 94.9, 74.3, 72.7, 72.5,
71.3, 71.1, 70.8, 68.9, 68.2, 68.0, 66.7, 64.4, 62.4, 60.8,
56.6, 23.4, 21.5, 20.9, 20.9, 20.8, 20.7, 20.6, 20.5, 15.9;
MALDI-TOF: calcd for C37H53NO23 879.0, found m/z
902.4 ([M+Na]+), 918.8 ([M+K]+). Elemental analysis:
found C, 49.76; H, 5.98; N, 1.81; calcd for
C37H53NO23·1H2O (897) C, 49.50; H, 6.13; N, 1.56%.
3.15. 11,11%-Dithio bis[undecyl(2,3,4,6-tetra-O-acetyl-b-
D
-galactopyranosyl)-(1“4)-(2,3,4-tri-O-acetyl-a-L-
fucopyranosyl)-(1“3)-(6-O-acetyl-2-acetamido-2-
deoxy-b- -glucopyranoside], 16
D
Compound 15 (0.44 g, 0.35 mmol, 1 equiv.) was dis-
solved in 2-buthanol (60 mL). Ethilendiamine (10.5 mL,
156 mmol, 300 equiv.) was added. The reaction was
stirred for 18 h at 90°C. When the reaction was com-
plete (TLC, MeOH), the solvent was removed.
Methanol was added three times and each time the
mixture was re-concentrated. A mixture of acetic anhy-
dride (20 mL) and dry pyridine (40 mL) was added with
cooling. The mixture was kept for 24 h at room temper-
ature. The solvent was removed, and the product was
purified by silica gel column (AcOEt) to give 16 as a
3.17. 11,11%-Dithio bis[undecyl b-galactopyranosyl-
(1“4)-a-
L-fucopyranosyl-(1“3)-2-acetamido-2-deoxy-
b- -glucopyranoside], 1
D
1
white solid (0.44 g, 80%); H NMR (500 MHz, CDCl3):
l 5.51 (d, 1H, J=8.5 Hz, NH), 5.40 (m, 2H, H-1%,
H-4¦), 5.35 (d, 1H, J=3.0 Hz, H-4%), 5.18 (dd, 1H,
J=11.0, 3.5 Hz, H-3%), 5.07 (dd, 1H, J=10.5, 8.5 Hz,
H-2¦), 4.97 (m, 2H, H-2%, H-3¦), 4.84 (m, 1H, H-5%),
4.58 (m, 2H, H-1, H-6b), 4.46 (m, 2H, H-1¦, H-6b¦),
Compound 16 (0.44 g, 0.21 mmol, 1 equiv.) was added
to a solution of MeONa in MeOH (0.1 N, 20 mL) and
it was stirred at room temperature for 12 h. When the
reaction was finished (TLC, MeOH), amberlite IR-120
(H+) was added until neutral medium. The mixture was

J. M. de la Fuente, S. Penade´s / Tetrahedron: Asymmetry 13 (2002) 1879–1888
1887
filtered and concentrated to give 1 as an amorphous
solid (0.27 g, 91%); [h]2D3 −65.4 (c=1, MeOH); 1H
NMR (500 MHz, CD3OD): l 5.00 (d, 1H, J=4.0 Hz,
H-1%), 4.80 (m, 1H, H-5%), 4.42 (m, 2H, H-1, H-1¦),
4.00–3.80 (m, 7H), 3.80–3.67 (m, 3H), 3.67–3.55 (m,
2H), 3.50–3.35 (m, 5H), 2.65 (t, 2H, J=7.2 Hz,
CH2S), 1.93 (s, 3H, NHAc), 1.70–1.20 (m, 18H,
CH2CH2), 1.15 (d, 3H, J=6.5 Hz, H-6%); 13C NMR
(75 MHz, CD3OD): l 173.7, 103.8, 102.4, 100.4, 77.4,
76.6, 75.2, 74.9, 73.7, 72.8, 71.2, 70.7, 69.9, 67.7, 62.8,
61.4, 57.5, 39.8, 30.8, 30.7, 30.5, 30.3, 30.2, 29.4, 27.2,
5. Eggens, I.; Fenderson, B.; Toyokuni, T.; Dean, B.;
Stroud, M.; Hakomori, S.-I. J. Biol. Chem. 1989, 264,
9476–9484.
6. Hakomori, S.-I. Pure Appl. Chem. 1991, 63, 473–482.
7. Rojo, J.; Morales, J. C.; Penade´s, S. Top. Curr. Chem.
2002, 218, 45–92.
8. Mammen, M.; Choi, S.-K.; Whitesides, G. M. Angew.
Chem., Int. Ed. 1998, 37, 2754–2794.
9. Wormald, M. R.; Edge, C. J.; Dwek, R. A. Biochem.
Biophys. Res. Commun. 1991, 180, 1214–1221.
10. Eggens, I.; Fenderson, B.; Toyokuni, T.; Dean, B.;
Stroud, M.; Hakomori, S.-I. J. Biol. Chem. 1989, 264,
9476–9484.
11. Geyer, A.; Gege, C.; Schmidt, R. R. Angew. Chem., Int.
Ed. 1999, 38, 1466–1469.
12. Matsuura, K.; Kitakouji, H.; Sawada, N.; Ishida, H.;
Kiso, M.; Kitajima, K.; Kobajashi, K. J. Am. Chem.
Soc. 2000, 122, 7406–7407.
24.2,
23.1,
16.6;
MALDI-TOF:
calcd
for
C62H112N2O30S2 1428.2, found m/z 1451.6 ([M+Na]+),
1467.3 ([M+K]+), 1305.3 ([M−Fuc+Na]+). Elemental
analysis: found C, 50.11; H, 7.68; N, 2.02; calcd for
C62H112N2O30S2·3H2O (1482.2) C, 50.20; H, 7.96; N,
1.89%.
13. Haseley, S. R.; Vermeer, H. J.; Kamerling, J. P.;
Vliegenhart, J. F. G. Proc. Natl. Sci. USA 2001, 96,
9419–9429.
3.18. Methyl b-
D
-galactopyranosyl-(1“4)-a-
L
-fucopy-
ranosyl-(1“3)-2-acetamido-2-deoxy-b-
D-gluco-
pyranoside, 2
14. Mrksich, M. Chem. Soc. Rev. 2000, 29, 267–273.
15. Horan, N.; Yan, L.; Hiroyuki, I.; Whitesides, G. M.;
Kahne, D. Proc. Natl. Acad. Sci. USA 1999, 96, 11782–
11786.
16. de la Fuente, J. M.; Barrientos, A. G.; Rojas, T. C.;
Rojo, J.; Can˜ada, J.; Ferna´ndez, A.; Penade´s, S. Angew.
Chem., Int. Ed. 2001, 40, 3052–3055.
17. Rojas, T. C.; de la Fuente, J. M.; Barrientos, A. G.;
Penade´s, S.; Ponsonnet, L.; Ferna´ndez, A. Adv. Mater.
2002, 14, 585–588.
18. Tromas, C.; Rojo, J.; de la Fuente, J. M.; Barrientos, A.
G.; Garc´ıa, R.; Penade´s, S. Angew. Chem., Int. Ed. 2001,
40, 3052–3055.
19. Herna´iz, M. J.; de la Fuente, J. M.; Barrientos, A. G.;
Penade´s, S. Angew. Chem., Int. Ed. 2002, 41, 1554–1557.
20. Toepfer, A.; Schmidt, R. R. Tetrahedron Lett. 1992, 36,
5161–5164.
21. Dekany, G.; Wright, K.; Toth, I. J. Carbohydr. Chem.
1997, 16, 983–999.
Compound 17 (0.21 g, 0.24 mmol, 1 equiv.) was added
to a solution of MeONa in MeOH (0.1N, 20 mL) and
the mixture was stirred at room temperature for 12 h.
When the reaction was complete (TLC MeOH),
amberlite IR-120 (H+) was added until neutral
medium. The mixture was filtered and concentrated to
give 2 as an amorphous solid (0.12 g, 92%); [h]2D3 −74.5
1
(c=1, MeOH); H NMR (500 MHz, D2O): l 5.03 (d,
1H, J=3.5 Hz, H-1%), 4.76 (m, 1H, H-5%), 4.40 (d, 1H
J=7.5 Hz, H-1), 4.38 (d, 1H, J=8.0 Hz, H-1¦), 3.94
(m, 1H), 3.90–3.75 (m, 6H), 3.72 (m, 1H), 3.70–3.58
(m, 4H), 3.57 (d, 1H, J=3.5 Hz), 3.53 (m, 2H), 3.43
(s, 3H, OCH3), 1.95 (s, 3H, NHAc), 1.10 (d, 3H,
J=7.0 Hz, H-6%); 13C NMR (75 MHz, CD3OD): l
173.9, 103.9, 103.2, 100.4, 77.4, 76.7, 76.6, 75.2, 74.9,
73.7, 72.7, 71.2, 70.0, 67.7, 62.8, 61.3, 57.3, 57.0, 23.0,
16.6; MALDI-TOF: calcd for C21H37NO15 543.0,
found 565.9 ([M+Na]+), 581.9 ([M+K]+). Elemental
analysis: found C, 44.82; H, 6.83; N, 2.35; calcd for
C21H37NO15·H2O (561) C, 44.92; H, 6.95; N, 2.50%.
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Acknowledgements
This work was supported by the DGICYT (PB96-
0820), J.M.F. thanks the MEC for a predoctoral
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