Rational design and synthesis of a 1,1-linked disaccharide that is 5 times as active as sialyl Lewis X in binding to E-selectin

Article abstract of DOI:10.1021/ja9611093

We describe here a rational design and synthesis of (3-O-carboxymethyl)-β-D-galactopyranosyl α-D-mannopyranoside which is 5 times as active as sialyl Lewis X in binding to E-selectin and also effective against P- and L-selectin. A new method for the 1,1-g

Full text of DOI:10.1021/ja9611093

J. Am. Chem. Soc. 1996, 118, 9265-9270
9265
Rational Design and Synthesis of a 1,1-Linked Disaccharide
That Is 5 Times as Active as Sialyl Lewis X in Binding to
E-Selectin
Kazumi Hiruma,† Tetsuya Kajimoto,† Gabriel Weitz-Schmidt,‡ Ian Ollmann,§ and
Chi-Huey Wong*,†,§
Contribution from the Frontier Research Program, The Institute of Physical and Chemical
Research (RIKEN), 2-1 Hirosawa, Wako-shi, Saitama, 351-01 Japan, and the Department of
Chemistry, The Scripps Research Institute, 10666 N. Torrey Pines Road,
La Jolla, California 92037
ReceiVed April 4, 1996X
Abstract: We describe here a rational design and synthesis of (3-O-carboxymethyl)-â-D-galactopyranosyl R-D-
mannopyranoside which is 5 times as active as sialyl Lewis X in binding to E-selectin and also effective against P-
and L-selectin. A new method for the 1,1-glycosidic bond formation Via coupling of protected trimethylsilyl â-D-
galactoside and R-mannosyl fluoride in the presence of BF3‚Et2O is described.
Sialyl Lewis X (SLex, 1) is a terminal tetrasaccharide found
at the nonreducing end of glycoconjugates expressed especially
on the surface of tumor cells and neutrophils. The interaction
between SLex on neutrophils and E- or P-selectin on the surface
of endothelial cells occurs at the early stage of inflammatory
response.1 This finding has led to the development of large-
scale synthesis2 of SLex as a potential therapeutic agent for the
treatment of such acute symptoms as repurfusion injury.3
Recently, however, many mimetics of SLex have been
reported4 as potential alternative anti-inflammatory agents
because of the high cost associated with the synthesis of SLex
and its weak activity, low stability, and poor oral activity. As
part of our interest in the development of oligosaccharide
mimetics,4b-d we have designed a novel disaccharide to mimic
the active conformation2,5 of SLex (see 2 in Figure 1). In this
designed structure, an R-mannosyl group was linked to the
anomeric â-OH group of galactose, resulting in the formation
of a 1,1-linked disaccharide with all OH groups expected to be
Figure 1. Structure of SLex showing the essential functional groups
for binding to E-selectin (O), P-selectin (b), and L-selectin (0) and
the designed mimetic 2.
in the same orientation and relative through-space distance as
that of the fucosyl and the galactosyl groups in the active
conformation of SLex. A carboxymethyl group was then
incorporated into the 3-OH group of the galactose residue. The
reason to use this flexible carboxymethyl group is based on the
observation that only the carboxyl group of sialic acid is essential
for binding5a and that the orientation of this negative charge in
the bound complex5c appears to be different from that in the
free form (Figure 2).2
A dihedral energy contour plot (Figure 3) indicates that the
bound conformation differs from the stable solution conforma-
tion by approximately 1.5 kcal/mol (Figure 4). This difference
suggests that it is plausible to design SLex mimetics with
constrained conformation to mimic the bound form of SLex or
with small energy barrier flexible conformation to improve the
binding affinity. Compound 2 was designed on the basis of
these considerations.
† The Institute of Physical and Chemical Research (RIKEN).
‡ Sandoz Pharma Preclinical Research.
§ The Scripps Research Institute.
X Abstract published in AdVance ACS Abstracts, September 1, 1996.
(1) Phillips, M. L.; Nudelman, E.; Gaeta, F. C. A.; Perez, M.; Singhal,
A. K.; Hakomori, S.; Paulson, J. C. Science 1990, 250, 1132. Lowe, J. B.;
Stoolman, L. M.; Nair, R. P.; Larsen, R. D.; Berhend, T. L.; Marks, R. M.
Cell 1990, 63, 475.
(2) Ichikawa, Y.; Dumas, D. P.; Shen, G.-J.; Garcia-Junceda, E.;
Williams, M. A. Bayer, R.; Ketcham, C.; Walker, L.; Paulson, J. C.; Wong,
C.-H. J. Am. Chem. Soc. 1992, 114, 9283 and references cited therein.
(3) Mulligan, M. S.; Paulson, J. C.; Frees, S. D.; Zheng, Z-L.; Lowe, J.
B.; Ward, P.A. Nature 1993, 364, 149; Murohara, T.; Margiotta, J.; Phillips,
L. M.; Paulson, J. C.; DeFrees, S.; Zalipsky, S.; Guo, L. S. S.; Lefer, A.
M. CardioVasc. Res. 1995, 30, 965.
(4) (a) Narasinga Rao, B. N.; Anderson, M. B.; Musser, J. H.; Gilbert,
J. H.; Schaefer, M. E.; Foxall, C.; Brandley, B. K. J. Biol. Chem. 1994,
269, 19663. (b) Uchiyama, T.; Vassilev, V. P.; Kajimoto, T.; Wong, W.;
Huang, H.; Lin, C.-C.; Wong, C.-H. J. Am. Chem. Soc. 1995, 117, 5395.
(c) Huang, H.; Wong, C.-H. J. Org. Chem. 1995, 63, 3100. (d) Wu, S.-H.;
Shimazaki, M.; Lin, C.-C.; Qiao, L.; Moree, W. J.; Weitz-Schmidt, G.;
Wong, C.-H. Angew. Chem., Int. Ed. Engl. 1996, 35, 88. (e) Kogan, T. P.;
Dupye, B.; Keller, K. M.; Scott, I. L.; Bui, H.; Market, B. V.; Beck, P. J.;
Voytus, J. A.; Revelle, B. M.; Scott, D. J. J. Med. Chem. 1995, 38, 4976.
Prodger, J. A.; Bamford, M. J.; Gore, P. M.; Holms, D. S.; Saez, V. J.;
Ward, P. Tetrahedron Lett. 1995, 36, 2339. (f) Bertozzi, C. R. Chem. Biol.
1995, 2, 703. (g) Dupre, B.; Bui, H.; Scott, I. L.; Market, R. V.; Keller, K.
M.; Beck, P.J.; Kogan, T. P. Bioorg. Med. Chem. Lett. 1996, 6, 569. (h)
Spevak, W.; Foxall, C.; Charych, D. H.; Dasgupta, F.; Nagy, J. O. J. Med.
Chem. 1996, 39, 1018.
Two methods were used to prepare the protected â-D-
galactopyranosyl R-D-mannopyranoside as a precursor to 2
(Table 1): one is â-D-galactosylation of 2,3,4,6-tetra-O-protected
(5) (a) For structure-function study, see: Brandley, B. K.; Kiso, M.;
Abbas, S.; Nikrad, P.; Srivastava, O.; Foxall, C.; Oda, Y.; Hasegawa, A.
Glycobiology 1993, 3, 633. Stahl, W.; Sprengard, U.; Kretzschmar, G.; Kunz,
H. Angew. Chem., Int. Ed. Engl. 1994, 33, 2096. Hemmerich, S.; Bertozzi,
C. R.; Leffler, H.; Rosen, S. D. Biochemistry 1994, 33, 4820. Chandraseka-
ran, E. V.; Jain, R. K.; Larsen, R. D.; Wlasichuk, K.; Matta, K. L.
Biochemistry 1995, 34, 2925. DeFrees, S. A.; Gaeta, F. C. A.; Lin, Y. C.;
Ichikawa, Y.; Wong, C.-H. J. Am. Chem. Soc. 1993, 115, 7549. (b) Cooke,
R. M.; Hale, R. S.; Lister, S. G.; Shah, G.; Weir, M. P. Biochemistry 1994,
33, 10591. (c) Scheffler, K.; Ernst, B.; Katopodis, A.; Magnani, J. L.; Wang,
W. T.; Weisemann, R.; Peters, T. Angew. Chem., Int. Ed. Engl. 1995, 34,
1841.
S0002-7863(96)01109-2 CCC: $12.00 © 1996 American Chemical Society

9266 J. Am. Chem. Soc., Vol. 118, No. 39, 1996
Hiruma et al.
Figure 2. Three overlaid structures showing the bound conformation5c
(yellow) and the free conformation2 (white) of SLex determined by
NMR, and a stable conformation (green) of 2. A systematic grid search
about the glycosidic bonds was performed using the Amber parameter
set in Insight/Discover to determine likely stable conformers for 2. Five
low-energy conformations were detected, and the one consistent with
Figure 3. A dihedral energy contour plot showing the conformational
energies about the angles Φ and Ψ of the NeuAc-Gal glycosidic
linkage in SLex as determined by the Amber force field. The letters A,
B, C, and D denote conformations which were previously predicted
by the HSEA force field2 to be possible candidates for the solution
phase structure of SLex. Conformations A′ and B′ are local minima of
A and B, respectively, as determined by the MMS force field, and both
are consistent with the NMR analysis2 (A′ is about 1.4 kcal/mol more
stable than B′). The conformation of SLex when bound to E-selectin is
indicated in red.5c Stated energies are relative, with the global minimum
at {Φ ) -60°, Ψ ) 0°} as E ) 0.
NOE measurements in solution was used here (ΦMan ) 59.2°; ΦGal
174.3°).
)
D-mannose (entries 1-3) and the other is R-D-mannosylation
of 2,3,4,6-tetra-O-protected â-D-galactose (entry 4). Neighbor-
ing group participation is expected in the former reaction, and
anomeric effect is expected to assist in forming the R-glycosidic
bond in the latter reaction. 2,3,4,6-Tetra-O-acetyl-D-galactosyl
trichloroacetimidate (3)6 and 2,3,4,6-tetra-O-benzyl-D-mannopy-
ranosyl fluoride (4)6,7 were used initially as galactosyl and
mannosyl donors, respectively, in this investigation.
Figure 4. An energy diagram showing the conformation reorganization
pathway between the solution phase structure of SLex (A′) and the
structure of SLex when bound to E-selectin determined by constrained
computer minimization in Vacuo. It indicates a probable 5 kcal barrier
to the interconversion between the two forms.
To further investigate the stereoselectivity and yield in the
glycosylation reaction, we exploited the use of trimethylsilyl
glycosides as acceptors (entries 5-9) in reaction with R-man-
nosyl fluoride 4. It is interesting that only R-galactoside 12a
was obtained with the use of R-galactoside 16, and an R/â
mixture of galactoside was obtained with the use of an R/â
mixture of acceptor 17. Reaction of the trimethylsilyl â-ga-
lactoside 18 with 4 under various conditions, however, did not
give the desired â-isomer as the sole product, though a relatively
high â-selectivity was obtained at low temperature. Perhaps
some anomerization occurs during the activation. In any case,
compound 11b obtained in this reaction can be more easily
converted to 2 (Scheme 2).
As shown in Table 1, glycosylation between the galactosyl
donor 3 and mannosyl acceptors 5 and 6 in the presence of
TMSOTf or BF3‚Et2O afforded the unexpected R-D-mannosyl
R-mannoside 7 and/or fully protected R-D-mannopyranosyl-
(1f2)-D-galactopyranoses 8 and 9. Mannosylation of 2,3,4,6-
tetra-O-acetylgalactose (10) using 4 as mannosyl donor, acti-
vated with SnCl2-AgClO4,7 gave a mixture of 2,3,4,6-tetra-O-
acetyl-â-D-galactopyranosyl 2,3,4,6-tetra-O-benzyl R-D-manno-
pyranoside (11a) and 2,3,4,6-tetra-O-acetyl-R-D-galacto-
pyranosyl 2,3,4,6-tetra-O-benzyl-R-D-mannopyranoside (12a).
The disaccharide 11a with the desired configuration was
deacetylated and the exposed 3,4-hydroxy groups were protected
as acetonide followed by benzylation to afford 13. After
cleavage of the acetonide, the product 14 was reacted with di-
n-butyltin oxide and alkylated with methyl R-bromoacetate to
afford lactone 15. Hydrogenation on Pearlman’s catalyst
followed by saponification with sodium hydroxide yielded 2
(Scheme 1).
In a cell-free assay,8 compound 2 was found to be 5-fold
better than SLex as an inhibitor of E-selectin (IC50 ) 0.1 mM)
(Figure 5). The increase in activity for 2 compared to SLex is
perhaps due to the increase in the conformational stability as
there is only one glycosidic bond in 2, and the NOESY
experiment shows NOE’s between Man-H1 and Gal-H2, and
(6) Hall, L. D.; Manville, J. F.; Bhacca, N. S. Can. J. Chem. 1969, 47,
1. Schmidt, R. R. Angew. Chem., Int. Ed. Engl. 1986, 25, 212.
(7) Mukaiyama, T.; Murai, Y.; Shoda, S. Chem. Lett. 1981, 431.
(8) Weitz-Schmidt, G.; Stokmaier, D.; Scheel, G.; Nifantev, N. E.;
Tuzikov, A. B.; Bovin, N. V. Anal. Biochem., in press.

Design and Synthesis of a 1,1-Linked Disaccharide
J. Am. Chem. Soc., Vol. 118, No. 39, 1996 9267
Table 1. Formation of the 1,1-Glycosidic Linkage between D-Mannose and D-Galactosea
entry
1
acceptor
donor (amt, equiv) promoter (amt, equiv)
solvent
CH2Cl2
temp (°C)
-78 f 0
time (min)
product (yield, %)
5
3 (1.4)
TMSOTf (0.1)
60 + 120
7 (28)
8 (23)
2
3
4
5
6
10
3 (2.0)
3 (1.4)
4 (1.2)
BF3‚Et2O (3.0)
CH2Cl2
CH2Cl2
Et2O-CH2Cl2 (3:1) -20
-20
-20
75
50
150
8 (40)
9 (55)
TMSOTf (0.1)
SnCl2-AgClO4 (1.2)
12a (30)
11a (27)
12a (63)
12a (36)
11b (32)
12b (46)
11b (32)
12b (15)
11b (30)
12b (16)
11b (68)
5
6
16
4 (1.3)
4 (1.3)
TMSOTf (0.3)
TMSOTf (0.3)
CH2Cl2
CH2Cl2
-20
-20
45
30
17 (R:â ) 1:1.3)
7
8
9
18
18
18
4 (1.3)
4 (1.3)
4 (1.3)
TMSOTf (0.3)
BF3‚Et2O (0.3)
BF3‚Et2O (0.6)
CH2Cl2
CH2Cl2
CH2Cl2
-20 f -10
-20
60
30
-50 f -10 1230
a For the synthesis of 5, see: Koto, S.; Morishima, N.; Miyata, Y.; Zen, S. Bull. Chem. Soc. Jpn. 1976, 46, 2659. For 6 and 10, see: Klotz, W.;
Schmidt, R. R. J. Carbohydr. Chem. 1994, 13, 1093. For 7, see: Yoshimura, J.; Hara, K.; Sato, T.; Hashimoto, H. Chem. Lett. 1983, 319. For 16
and 17, see: Nashed, E. M.; Glaudemans, C. P. J. J. Org. Chem. 1989, 54, 6116.
Scheme 1a
a Key: (a) NaOMe in MeOH-CHCl3; (b) 2,2-dimethoxypropane,
CSA, then MeOH; (c) NaH/BnBr/DMF; (d) 70% aqueous AcOH; (e)
n-Bu2SnO/toluene; (f) BrCH2CO2Me, n-Bu4NI/toluene; (g) Pd(OH)2/
C-H2; (h) 0.25 N aqueous NaOH.
Scheme 2a
Figure 5. Inhibition of SLea-polymer binding to E-selectin: (b)
compound 2; (2) SLex tetrasaccharide. Each point is the mean ( SD
of three experiments.
Experimental Section
General Methods. Melting points were measured with a Yanaco
MP-S3 micro melting point apparatus and are uncorrected. Dried
solvents were used for all reactions. Solutions were evaporated under
diminished pressure at a bath temperature not exceeding 50 °C. Optical
rotations were measured in a 1.0 dm tube with a Horiba SEPA-200
polarimeter, using chloroform as solvent, unless stated otherwise. 1H
NMR (270 MHz) and 13C NMR (67.5 MHz) spectra were recorded
with a JEOL EX-270 spectrometer for solutions in CDCl3, unless stated
otherwise, using Me4Si as the internal standard. Some key compounds
were measured with JEOL 400 and 600 MHz spectrometers as
indicated. Column chromatography was performed on silica gel (Merck
a Key: (a) TMSNEt2/toluene; (b) DDQ, CH2Cl2/H2O (20:1); (c)
Ac2O/pyridine; (d) BF3‚Et2O (0.6 equiv), -50 to ∼-10 °C, 21 h; (e)
Kieselgel 60). Inhibition analysis was carried out according to the
NaOMe, MeOH-CHCl3, 95%; (f) Ag2O, Kl, BrCH2CO2Me, DMF; (g)
procedure described previously.8 Computer modeling was performed
(1) Pd(OH)2/C, MeOH, H2; (2) 0.25 M NaOH.
using the Insight/Discover program (Biosym, San Diego, CA) installed
in a Silicon Graphics 4D/35 computer. The conformational energy
between Man-H2 and Gal-H2. Another NOE was observed
between Man-H1 and Gal-H1, indicating the existence in
equilibrium of a different glycosidic conformation (2a) which
is perhaps influenced by the exoanomeric effect of Man-1-O.
Work is in progress to prepare a rigid structure to mimic 2 and
a multivalent SLex mimetic in order to further improve the
inhibition potency.
associated with the dihedral angles about the NeuAc-Gal glycosidic
linkage was evaluated by Insight/Discover using the Amber forcefield
in Vacuo. An energetic minimum was determined at 20° increments
about angles Φ and Ψ to generate a grid of 324 minimized conforma-
tions. To obtain the conformational energy at each point, a few ring
atoms within the galactose, N-acetylglucosamine, and fucose residues
were fixed and an energetic force was applied to constrain the two
dihedral angles of the neuraminic acid-galactose glycosidic linkage
to a set value. The molecule was minimized under these conditions
for 10 000 steps using a VA09A minimization algorithm to resolve
steric clashes. The pattern of energies so obtained revealed a series of
three local minima at Ψ = 0, Φ = {60, 180, 300). These were
consistent with the four structures previously predicted2 by the GESA
Note Added in Proof. Compound 2 is also effective against
P- and L-selectin, showing 77% and 71% inhibition, respec-
tively, with 3 mH 2, compared to 0% and 50% inhibition with
3 mH SLex.

9268 J. Am. Chem. Soc., Vol. 118, No. 39, 1996
Hiruma et al.
(HSEA) force field. (Conformations A and B determined by the HSEA
force field belong to the same well.) The bound conformation,5c which
is almost identical to conformation GESA-C,2 was within error limits
of the global minimum.
suitable temperature, this solution was kept for 30-60 min as shown
in Table 1 to complete the reaction. Triethylamine (0.5 mL) was added
to this solution. The mixture was poured into cold aqueous sodium
hydrogen carbonate and extracted with chloroform. The extract was
washed with water, dried over anhydrous sodium sulfate, and evapo-
rated. The residue was subjected to column chromatography on silica
gel to give â-D-galactopyranoside 11a or 11b and/or R-D-galacto-
pyranoside 12a or 12b. Reaction conditions and yields are shown in
Table 1.
Trimethylsilyl 2,4,6-Tri-O-benzyl-3-O-[(p-methoxyphenyl)methyl]-
â-D-galactopyranoside. 1H-NMR (CDCl3): δ 7.39-7.20 (m, 17H,
3Ph, MPh), 6.89-6.80 (m, 2H, MPh), 4.93, 4.60 (ABq, J ) 11.7 Hz,
PhCH2), 4.89, 4.76 (ABq, J ) 11.2 Hz, PhCH2), 4.67, 4.62 (ABq,
PhCH2), 4.60 (d, J1,2 ) 7.3 Hz, H-1), 4.44, 4.38 (ABq, J ) 11.6 Hz,
PhCH2), 3.84 (d, J3,4 ) 3.0 Hz, H-4), 3.80 (s, 3H, OMc), 3.74 (dd, J2,3
) 9.9 Hz, H-2), 3.60-3.51 (m, 3H, H-5,6a,6b), 3.47 (dd, H-3), 0.17
(s, 9H, SiCH3 × 3′).
2,3,4,6-Tetra-O-acetyl-â-D-galactopyranosyl
2,3,4,6-tetra-O-
benzyl-r-D-mannopyranoside (11a). To a solution of 2,3,4,6-tetra-
O-acetyl-D-galactopyranose (10) (610 mg, 1.75 mmol) and 2,3,4,6-tetra-
O-benzyl-D-mannopyranosyl fluoride (4) (1.14 g, 2.1 mmol, 1.2 equiv)
in dry ether (15 mL) and dichloromethane (5 mL) were added under
N2 at -20 °C silver perchlorate (AgCLO4) (435 mg, 2.1 mmol) and
stannous chloride (SnCL2) (398 mg, 2.1 mmol), and the mixture was
stirred for 150 min at the same temperature. The reaction mixture was
diluted with dichloromethane and filtered through Celite. The filtrate
was washed with aqueous sodium hydrogen carbonate and saturated
NaCl, and dried over anhydrous sodium sulfate, and then the solvent
was evaporated. The residue was subjected to column chromatography
on silica gel to give â-D-galactopyranoside 11a, R-D-galactopyranoside
12a, and the unreacted acceptor 10. The yields are shown in Table 1.
1H-NMR (CDCl3): δ 7.48-7.09 (m, 20H, 4Ph), 5.33 (d, J3′,4′ ) 3.3
Hz, H-4′), 5.09 (dd, J1′,2′ ) 7.6 Hz, J2′,3′ ) 10.6 Hz, H-2′), 4.98 (d, J1,2
) 2.3 Hz, H-1), 4.96 (dd, H-3′), 4.86, 4.48 (ABq, J ) 10.9 Hz, PhCH2),
4.77, 4.64 (ABq, J ) 12.5 Hz, PhCH2), 4.69, 4.62 (ABq, J ) 12.1 Hz,
PhCH2), 4.66 4.50 (ABq, J ) 11.9 Hz, PhCH2), 4.57 (d, H-1′), 4.09
(dd, J5′,6a′ ) 7.3 Hz, Jgem ) 11.2 Hz, H-6a′), 4.05 (brd, 2H, H-4, 5),
3.99 (dd, J5′,6b′ ) 6.1 Hz, H-6b′), 3.91 (dd, J2,3 ) 3.0 Hz, J3,4 ) 9.2
Hz, H-3), 3.85 (brt, H-5′), 3.78 (brdd, Jgem ) 10.6 Hz, H-6a), 3.65 (d,
H-6b), 3.61 (dd, H-2), 2.14, 1.97, 1.84 (each s, 12H, COCH3). 13C-
NMR (CDCl3): δ 170.21, 170.04, 169.06 (CdO), 138.42, 138.35,
138.22 (Ph), 128.41-127.49 (Ph), 100.56 (JC-H ) 159 Hz, C-1′), 100.43
(JC-H ) 159 Hz, C-1′), 100.43 (JC-H ) 173 Hz, C-1), 80.00 (C-3),
75.10, 73.39, 72.69 (PhCH2), 74.57 (C-4), 73.89 (C-2), 72.60 (C-5),
70.93 (C-5′), 70.77 (C-3′), 69.00 (C-2′), 68.73 (C-6), 66.79 (C-4′), 61.03
(C-6′), 20.63, 20.58, 20.54, 20.49 (COCH3). Anal. Calcd. for
Trimethylsilyl 3-O-Acetyl-2,4,6-tri-O-benzyl-â-D-galactopyrano-
side (18). To a stirred solution of 2,4,6-tri-O-benzyl-3-O-[(p-meth-
oxyphenyl)methyl]-D-galactopyranose (1.24 g, 2.12 mmol) in dry
toluene (4 mL) was added N-(trimethylsilyl)diethylamine (0.5 mL), and
the solvent was evaporated at 40 °C. This manipulation was repeated
three times until starting material disappeared on TLC, and then the
mixture was dried in Vacuo. To the residue dissolved in dichlo-
romethane (40 mL) were added water (2 mL) and DDQ (621 mg, 2.60
mmol). The resulting mixture was stirred vigorously at room temper-
ature for 1 h, poured into cold aqueous sodium hydrogen carbonate,
and extracted with dichloromethane. The extract was washed with
brine, dried over anhydrous sodium sulfate, and concentrated. The
residue was acetylated using Ac2O (2 mL) and pyridine (3 mL) and
purified on a column of silica gel with hexane-ethyl acetate (8:1) to
give silyl â-galactoside (917 mg, 75%) and â-acetate (113 mg, 10%).
1H-NMR (CDCl3): δ 7.42-7.18 (m, 15H, 3Ph), 4.87 (d, J2,3 ) 10.4
Hz, J3,4 ) 3.1 Hz, H-3), 4.85, 4.64 (ABq, J ) 11.8 Hz, PhCH2), 4.66
(d, J1,2 ) 7.3 Hz, H-1), 4.59, 4.50 (ABq, J ) 11.4 Hz, PhCH2), 4.50,
4.42 (ABq, J ) 11.2 Hz, PhCH2), 3.93 (d, H-4), 3.71 (dd, H-2), 3.66
(t, H-5), 3.61-3.54 (m, 2H, H-6a,6b), 1.88 (s, 3H, COCH3), 0.19 (s,
9H, SiCH3 × 3).
C48H54O15: C, 66.20; H, 6.25. Found: C, 65.89; H, 6.26. [R]24
+38.8° (c ) 1.0, CHCl3).
)
D
2,3,4,6-Tetra-O-acetyl-r-D-galactopyranosyl 2,3,4,6-Tetra-O-
benzyl-r-D-mannopyranoside (12a). 1H-NMR (CDCl3): δ 7.48-7.08
(m, 20H, 4Ph), 5.40 (brs, H-4′, 5.32 (d, J1′,2′ ) 2.6 Hz, H-1′), 5.22 (dd,
J2′,3′ ) 10.9 Hz, H-2′), 5.18 (dd, J3′,4′ ) 2.3 Hz, H-3′), 5.06 (d, J1,2
)
3,4-O-Isopropylidene-â-D-galactopyranosyl
2,3,4,6-Tetra-O-
2.0 Hz, H-1), 4.88, 4.52 (ABq, J ) 10.9 Hz, PhCH2), 4.76, 4.66 (ABq,
J ) 12.5 Hz, PhCH2), 4.74, 4.62 (ABq, J ) 11.7 Hz, PhCH2), 4.60,
benzyl-r-D-mannopyranoside. To a solution of 11a (239 mg, 0.34
mmol) in dry methanol (3 mL) and chloroform (0.5 mL) was added
powdered sodium methoxide (2 spoons by microspatel), and the mixture
was stirred at room temperature for 1.5 h. The mixture was neutralized
with 1 M HCl and extracted with chloroform. The extract was washed
with water and dried over anhydrous sodium sulfate, and the solvent
was evaporated. The residue was dissolved in 2,2-dimethoxypropane
(1 mL) and treated with a catalytic amount of DL-camphorsulfonic acid.
The resulting mixture was stirred at room temperature for 1 h, and
then the solvent wasevaporated. The residue was dissolved in methanol
(3 mL), stirred for 5 min, and neutralized with triethylamine, the solvent
was evaporated, and the residue purified on a column of silica gel with
hexane-ethyl acetate (1:1) to give isopropylidene galactoside (109 mg,
43%) and unreacted â-D-galactopyranosyl 2,3,4,6-tetra-O-benzyl-R-D-
mannopyranoside (119 mg, 50%). 1H-NMR (CDCl3): δ 7.42-7.02
(m, 20H, 4Ph), 5.17 (d, J1,2 ) 1.7 Hz, H-1), 4.83, 4.40 (ABq, J ) 10.9
Hz, PhCH2), 4.75, 4.68 (ABq, J ) 12.2 Hz, PhCH2), 4.66, 4.61 (ABq,
J ) 11.9 Hz, PhCH2), 4.64, 4.48 (ABq, J ) 12.9 Hz, PhCH2), 4.36 (d,
J1′,2′ ) 8.6 Hz, H-1′), 4.15 (t, H-5′), 4.07 (s, H-4′), 4.05 (m, H-3′),
3.92 (d, J2,3 ) 3.0 Hz, J3,4 ) 9.2 Hz, H-3), 3.97-3.82 (m, 2H, H-5,
OH-6′), 3.75 (t, H-2), 3.73-3.60 (m, 2H, H-6a,6a′), 3.69 (t, H-4), 3.56
(ddd, H-2′), 3.47 (dd, J5′,6b′ ) 8.3 Hz, Jgem ) 9.9 Hz, H-6b′), 3.40 (dd,
J5,6b ) 2.3 Hz, Jgem ) 10.6 Hz, H-6b), 2.72 (d, J2′,OH ) 3.3 Hz, OH-
2′), 1.52, 1.33 (each s, 3H × 2, CCH3). 13C-NMR (CDCl3): δ 138.29,
137.99, 137.39 (Ph), 128.37-127.64 (Ph), 110.42 (CMe3), 102.09
(C-1′), 98.29 (C-1), 79.62 (C-3), 79.05 (C-3′), 75.31 (C-4), 75.08, 73.16,
72.74, 72.38 (PhCH2), 74.93 (C-5), 74.56 (C-2), 73.77 (C-4′), 73.10
(C-2′), 72.38 (C-5′), 69.65 (C-6), 62.43 (C-6′), 28.20, 26.29 (CMe2).
4.50 (ABq, J ) 12.2 Hz, PhCH2), 4.03 (dd, J5′,6a′ ) 6.9 Hz, Jgem
)
10.9 Hz, H-6a′), 3.97-3.87 (m, H-6b′), 3.93 (t, J3,4 ) 9.6 Hz, H-4),
3.87 (dd, J2,3 ) 3.0 Hz, H-3), 3.85 (t, H-5′), 3.76-3.60 (m, 3H, H-5,
6a, 6b), 3.53 (dd, H-2), 2.14, 2.04, 1.99, 1.98 (each s, 12H, COCH3).
13C-NMR (CDCl3): δ 170.21, 170.10 (CdO), 138.33, 138.20, 137.84
(Ph), 128.43-127.49 (Ph), 94.20 (JC-H ) 173 Hz, C-1), 92.26 (JC-H
) 179 Hz, C-1′), 89.10 (C-3), 75.10, 73.44, 72.89, 72.76 (PhCH2),
74.93 (C-2), 74.63 (C-4), 73.11 (C-5), 69.02 (C-6), 67.66 (C-4′), 67.39
(C-3′), 66.94 (C-2′), 66.60 (C-5′), 61.46 (C-6′), 20.61 (COCH3). Anal.
Calcd for C48H54O15: C, 66.20; H, 6.25. Found: C, 65.97; H, 6.25.
[R]26 ) +106.3° (c ) 1.0, CHCl3).
D
3-O-Acetyl-2,4,6-tri-O-benzyl-â-D-galactopyranosyl 2,3,4,6-Tetra-
O-benzyl-r-D-mannopyranoside (11b). 1H-NMR (CDCl3): δ 7.42-
7.07 (m, 35H, 7Ph), 5.14 (d, J1,2 ) 1.3 Hz, H-1), 4.89 (ABq, 1H, J )
10.2 Hz, PhCH2), 4.85 (dd, J2′,3′ ) 10.9 Hz, J3′,4′ ) 3.6 Hz, H-3′), 4.68-
4.43 (m, 10H, PhCH2), 4.53 (d, J1′,2′ ) 7.6 Hz, H-1′), 4.39 (ABq, 1H,
J ) 12.2 Hz, PhCH2), 4.35, 4.30 (ABq, J ) 12.5 Hz, PhCH2), 4.11
(brd, H-5), 4.03 (t, H-4), 3.97-3.89 (m, 2H, H-2,3), 3.76-3.51 (m,
6H, H-6a,6b,2′,4′,5′,6a′), 3.47 (dd, J5′,6b′ ) 6.1 Hz, Jgem ) 9.1 Hz, H-6b′),
1.84 (s, 3H, COCH3). 13C-NMR (CDCl3): δ 170.21 (CdO), 138.74,
138.53, 137.26, 138.11, 137.74, (Ph), 128.34-127.31 (Ph), 102.97 (JC-H
) 161 Hz, C-1′), 99.68 (JC-H ) 179 Hz, C-1), 79.57 (C-3), 75.01 (C-
2′ or C-5′), 74.90, 74.77, 73.23, 73.11, 72.49 (PhCH2), 74.72 (C-4),
74.29 (C-4′), 74.28 (C-3), 72.36 (C-5), 68.92 (C-6), 67.75 (C-6′), 20.76
(COCH3).
General Method of Glycosylation for the Synthesis of Unsym-
metrical 1,1-Linked Disaccharides Using Trimethylsilyl Galactoside
in the Presence of a Lewis Acid. Silylated galactoside 16, 17, or 18
(0.11 mmol) and mannosyl donor 4 (0.14 mmol, 1.3 equiv) were
dissolved in dichloromethane (1 mL). After the addition of TMSOTf
or BF3‚OEt (0.04 mmol, 0.3 equiv) in dichloromethane (0.1 mL) at a
FAB MS for C43H51O11: calcd 743.3431, found 743.3431. [R]24
+54.9° (c ) 1.5, CHCl3).
)
D
2,6-di-O-benzyl-3,4-O-isopropylidene-â-D-galactopyranosyl 2,3,4,6-
Tetra-O-benzyl-r-D-mannopyranoside (13). To a suspension of NaH
(60% oil dispersion, 67 mg, 1.68 mmol) rinsed with hexane two times

Design and Synthesis of a 1,1-Linked Disaccharide
J. Am. Chem. Soc., Vol. 118, No. 39, 1996 9269
in DMF (0.5 mL) was added dropwise 3,4-O-isopropylidene-â-D-
galactopyranosyl 2,3,4,6-tetra-O-benzyl-R-D-mannopyranoside (415 mg,
0.56 mmol) in DMF (2.5 mL), and the mixture was stirred at room
temperature overnight (17 h). The reaction mixture was added to benzyl
bromide (0.2 mL, 1.68 mmol), stirred at room temperature for 1 h and
at 70 °C for 1 h, and then poured into cold water and extracted with
ether. The extract was washed with brine, dried over anhydrous sodium
sulfate, and concentrated. The residue was purified on a column of
silica gel with hexane-ethyl acetate (5:1) to give 13 (326 mg, 63%).
1H-NMR (CDCl3): δ 7.41-7.10 (m, 30H, 6Ph), 5.17 (d, J1,2 ) 1.3
Hz, H-1), 4.88, 4.50 (ABq, J ) 10.9 Hz, PhCH2), 4.68, 4.59 (ABq, J
) 11.8 Hz, PhCH2), 4.66 (s, 2H, PhCH2), 4.58, 4.32 (ABq, J ) 12.4
Hz, PhCH2), 4.48 (s, 2H, PhCH2), 4.43 (d, J1′,2′ ) 8.3 Hz, H-1′), 4.17-
4.06 (m, 4H, H-4,5,3′,4′), 3.96-3.87 (m, 1H, H-3), 3.91 (br t, H-5′),
3.75 (dd, J2,3 ) 3.0 Hz, H-2), 3.73-3.57 (m, 4H, H-6,6′), 3.77-3.37
(m, 1H, H-2′), 1.38, 1.32 (each s, 3H × 2, CCH3). 13C-NMR
(CDCl3): δ 138.81, 138.56, 138.51, 138.15, 138.10 (Ph), 128.27-
127.38 (Ph), 109.87 (CMe2), 101.47 (C-1′), 99.41 (C-1), 79.77 (C-3),
79.64 (C-2′), 79.25 (C-3′), 74.84, 73.33, 73.12, 72.33, 72.27 (PhCH2),
74.59 (C-4), 74.45 (C-2), 73.59 (C-4′), 72.44 (C-5), 72.50 (C-5′), 69.15,
68.63 (C-6,6′), 27.87, 26.31 (CMe2). Anal. Calcd for C67H62O11: C,
2.10, 2.04, 1.96, 1.94 (each s, 12H, COCH3). 13C-NMR (CDCl3): δ
170.43, 170.19, 170.15, 170.06 (CdO), 138.58, 138.20, 138.15, 138.04
(Ph), 128.43-127.39 (Ph), 95.08, 89.51 (C-1,1′), 79.30 (C-3′), 74.84,
73.33, 72.29, 71.90 (PhCH2), 74.38, 73.89, 72.22, 68.95, 68.16, 67.61,
67.51 (C-2,3,4,5,2′,4′,5′), 69.42, 61.44 (C-6,6′), 20.94, 20.65, 20.33
(COCH3).
O-(2,3,4,6-Tetra-O-acetyl-r-D-mannopyranosyl)-(1f2)-1,3,4,6-
tetra-O-acetyl-r-D-galactopyranose (9). 1H-NMR (CDCl3): δ 5.92
(d, J1,2 ) 5.0 Hz, H-1), 5.40 (brt, J4,5 ) 2.3 Hz, H-4), 5.33 (dd, J2′,3′
)
3.3 Hz, J3′,4′ ) 9.9 Hz, H-3′), 5.26 (t, H-4′), 5.26 (d, J1′,2′ ) 2.0 Hz,
H-1′), 5.13 (br t, H-2′), 5.02 (dd, J2,3 ) 6.8 Hz, J3,4 ) 3.5 Hz, H-3),
4.32 (dd, H-2), 4.29-4.02 (m, 6H, H-5,6,5′,6′), 2.17, 2.12, 2.11, 2.10,
2.07, 2.05, 2.00 (each s, 24H, COCH3). 13C-NMR (CDCl3): δ 170.49,
170.44, 170.01, 169.94, 169.86, 169.76, 169.70 (CdO), 98.11 (C-1),
91.56 (C-1′), 73.14 (C-2), 71.12 (C-3), 69.76 (C-2′), 69.13, 69.00 (C-
5, 5′), 68.79 (C-3′), 65.97 (C-4′), 65.57 (C-4), 62.52, 61.39 (C-6, 6′),
20.81, 20.70, 20.61, 20.49 (COCH3).
3-O-acetyl-2,4,6-tri-O-benzyl-r-D-galactopyranosyl) 2,3,4,6-Tetra-
O-benzyl-r-D-mannopyranoside (12b). 1H-NMR (CDCl3): δ 7.42-
7.09 (m, 35H, 7Ph), 5.29 (d, J1′,2′ ) 3.6 Hz, H-1′), 5.14 (d, J1,2 ) 1.7
Hz, H-1), 5.09 (dd, J2′,3′ ) 10.7 Hz, J3′,4′ ) 3.2 Hz, H-3′), 4.86,4.48
(ABq, 1H, J ) 10.9 Hz, PhCH2), 4.68, 4.61 (ABq, J ) 11.2 Hz,
PhCH2), 4.48, 4.40 (ABq, J ) 12.0 Hz, PhCH2), 4.56, 4.45 (ABq, J )
11.6 Hz, PhCH2), 4.69-4.45 (m, 6H, PhCH2), 4.07-3.93 (m, 5H,
H-3,4,5,2′,4′), 3.79 (br t, H-5′), 3.64-3.58 (m, 2H, H-6), 3.56 (br s,
H-2), 3.50 (dd, J5′,6a′ ) 7.3 Hz, Jgem ) 9.1 Hz, H-6b′), 3.39 (dd, J5′,6b′
) 6.9 Hz, H-6b′), 1.96 (s, 3H, COCH3). 13C-NMR (CDCl3): δ 170.49
(CdO), 138.69, 138.44, 138.35, 138.13, 138.06, 138.02, 137.83 (Ph),
128.41-127.37 (Ph), 93.84, 92.99 (C-1,1′), 79.55 (C-3), 75.33, 75.17,
74.86, 73.48, 73.33, 72.76, 72.49, 72.40 (PhCH2), 74.81, 72.81, 72.54,
72.36, 69.29, 69.17, 68.39 (C-6,6′), 20.97 (COCH3).
74,165; H, 6.77. Found: C, 73.80; H, 6.87. [R]26 ) +43.8° (c )
D
1.1, CHCl3).
2,6-Di-O-benzyl-â-D-galactopyranosyl 2,3,4,6-Tetra-O-benzyl-r-
D-mannopyranoside (14). A solution of 13 (240 mg, 0.26 mmol) in
acetic acid (5 mL) and water (1.3 mL) was stirred at 60 °C for 3 h,
and then the solvent was evaporated. The residue was purified on a
column of silica gel with hexane-ethyl acetate (1:2) to give 14 (201
mg, 88%). 1H-NMR (CDCl3): δ 7.44-7.11 (m, 30H, 6Ph), 5.14 (d,
J1,2 ) 1.7 Hz, H-1), 4.90, 4.51 (ABq, J ) 10.9 Hz, PhCH2), 4.67, 4.55
(ABq, J ) 12.9 Hz, PhCH2), 4.66, 4.56 (ABq, J ) 11.5 Hz, PhCH2),
4.58, 4.38 (ABq, J ) 12.2 Hz, PhCH2), 4.48 (d, J1′,2′ ) 7.9 Hz, H-1′)
4.46 (s, 2H, PhCH2), 4.27-4.09 (m, 1H, H-5), 4.06 (t, J3,4 ) J4,5 ) 8.9
Hz, H-4), 3.99 (t, J3′,4′ ) J4′,OH ) 3.0 Hz, H-4′), 3.94 (dd, J2,3 ) 3.0
Hz, H-3), 3.71 (dd, J5,6a ) 3.5 Hz, Jgem ) 10.8 Hz, H-6a), 3.72-3.51
(m, 5H, H-6a,3′,5′,6′), 3.66 (m, H-2), 3.44 (dd, J2′,3′ ) 9.2 Hz, H-2′),
2.69 (d, 4′-OH), 3.40 (d, J3′,OH ) 5.3 Hz, 3′-OH). 13C-NMR (CDCl3):
δ 138.74, 138.47, 138.19, 138.11, 137.63 (Ph), 128.55-127.37 (Ph),
102.89 (C-1′), 99.7 (C-1), 79.50 (C-3), 79.37 (C-2′), 74.90, 74.68, 73.50,
73.17, 72.51, 72.42 (PhCH2), 74.90 (C-2), 74.79 (C-4), 73.33, 72.51
(C-5,5′), 73.08 (C-3′), 69.13, 68.93 (C-6,6′), 68.93 (C-4′). FAB MS
Allyl 3-O-[(p-methoxyphenyl)methyl]-r-D-galactopyranoside. Al-
lyl R-D-galactopyranoside9 (4.64 g, 21 mmol) was refluxed overnight
in dry methanol (100 mL) with dibutyltin oxide (5.75 g, 23 mmol) in
a Dean-Stark apparatus. After methanol was removed, the residue was
dried in Vacuo, dissolved in dry toluene (200 mL), and stirred with
n-Bu4NI (8.5 g, 23 mmol) and p-methoxybenzyl chloride (6.0 mL, 11.1
mmol) at 80 °C for 3 h. The solvent was evaporated, and the residue
was purified by chromatography (hexane:ethyl acetate ) 3:1) to give
allyl 3-O-[(p-methoxyphenyl)methyl]-R-D-galactopyranoside (5.0 g,
70%). [R]25 ) +127.4° (c 1.0, CHCl3). Mp: 62-63.5 °C (from
D
for C54H59O11: calcd 883.4057, found 883.4058. [R]24 ) +40.2° (c
EtOAc). 1H-NMR (CDCl3): δ 7.30 (d, 2H, J ) 8.58 Hz, Ph), 7.97 (d,
2H, Ph), 5.93 (dddd, J ) 17.3 Hz, 5.8 Hz), 5.30 (dq, 1H, J ) 1.65 Hz,
dCH2-trans), 5.22 (dq, 1H, dCH2-cis), 5.02 (d, J1,2 ) 4.0 Hz, H-1),
4.70, 4.64 (ABq, J ) 11.4 Hz, PhCH2), 4.22 (ddt, 1H, Jgem ) 12.9 Hz,
OCH2), 4.20-3.76 (m, 4H, H-5, 6a,6b, OCH2), 4.07 (br d, H-4), 3.98
(dd, J2,3 ) 9.6 Hz, H-2), 3.81 (s, 3H, OMe), 3.65 (dd, J3,4 ) 3.5 Hz,
H-3), 2.6-1.8 (br, 3H, 3OH). 13C-NMR (CDCl3): δ 159.51 (CMe),
134.00 (HCd), 129.79, 129.52 (Ph), 118.06 (dCH2), 114.03 (CHCOMe),
97.77 (C-1), 77.93, 69.53, 68.70, 68.43, 68.36, 63.06 (OCH2), 71.95
(PhCH2), 55.29 (OMe). Anal. Calcd for C17H24O7: C, 59.99; H, 7.11.
Found: C, 59.74; H, 6.93.
D
) 1.25, CHCl3).
3,4-O-(2-Carbonylethylene)-2,6-di-O-benzyl-â-D-galacto-
pyranosyl 2,3,4,6,-Tetra-O-benzyl-r-D-mannopyranoside (15). Diol
14 (76 mg, 0.09 mmol) was refluxed in dry toluene (3 mL) with
dibutyltin oxide (23 mg, 0.09 mmol) in a Dean-Stark apparatus for 1
h. The solvent was evaporated, and the residue was dried in Vacuo,
dissolved in dry toluene (3 mL), and then refluxed with n-Bu4NI (32
mg, 0.09 mmol) and a large excess amount of methyl 2-bromo acetate
(0.3 mL) for 1 h. The concentrated residue was purified by chroma-
tography (hexane:ethyl acetate ) 2:1) to give 15 (64 mg, 80%). 1H-
NMR (CDCl3): δ 7.41-7.11 (m, 30H, 6Ph), 5.14 (d, J1,2 ) 1.7 Hz,
H-1), 4.90, 4.51 (ABq, J ) 10.9 Hz, PhCH2), 4.72, 4.64 (ABq, J )
11.5 Hz, PhCH2), 4.70, 4.60 (ABq, J ) 11.9 Hz, PhCH2), 4.70 (d, J3′,4′
) 4.0 Hz, H-4′), 4.57, 4.47 (ABq, J ) 11.7 Hz, PhCH2), 4.57, 4.38
(ABq, J ) 12.0 Hz, PhCH2), 4.52 (d, J1′,2′ ) 7.6 Hz, H-1′), 4.46, 4.37
(ABq, J ) 12.2 Hz, PhCH2), 4.16, 3.63 (ABq, J ) 18.1 Hz, OCH2),
Allyl 2,4,6-Tri-O-benzyl-3-O-[(p-methoxyphenyl)methyl]-r-D-ga-
lactopyranoside. To a suspension of NaH (55% oil dispersion, 980
mg, 22.45 mmol) rinsed with hexane two times in DMF (3 mL) was
added dropwise allyl 3-O-[(p-methoxyphenyl)methyl]-R-D-galacto-
pyranoside (1.7 g, 4.99 mmol) in DMF (8 mL), and the mixture was
stirred at room temperature for 4 h. The reaction mixture was added
to benzyl chloride (2.6 mL, 22.45 mmol), stirred at room temperature
overnight, poured into cold water, and extracted with ether. The extract
was washed with brine, dried over anhydrous sodium sulfate, and
concentrated. The residue was purified on a column of silica gel with
hexane-ethyl acetate (10:1) to give allyl 2,4,6-tri-O-benzyl-3-O-[(p-
methoxyphenyl)methyl]-R-D-galactopyranoside (2.21 g, 73%). 1H-
NMR (CDCl3): δ 7.42-7.18 (m, 17H, Ph), 6.87 (d, 2H, J ) 8.9 Hz,
Ph), 5.93 (dddd, J ) 17.3 Hz, J ) 10.2 Hz, J ) 5.8 Hz, CHd), 5.29
(dq, 1H, J ) 1.65 Hz, dCH2-trans), 5.18 (dq, 1H, dCH2-cis) 4.94,
4.66 (ABq, J ) 11.5 Hz, PhCH2), 4.87 (d, J1,2 ) 3.3 Hz, H-1), 4.81,
4.66 (ABq, J ) 12.2 Hz, PhCH2), 4.77, 4.56 (ABq, J ) 11.6 Hz,
4.07-4.02 (m, 2H, H-4,5), 3.97-3.89 (m, 1H, H-3), 3.86 (dd, J2′,3′
)
9.9 Hz, H-3′), 3.78-3.55 (m, 6H, H-2,6,5′,6′), 3.48 (dd, H-2′). 13C-
NMR (CDCl3): δ 166.59 (CdO), 138.58, 138.45, 138.38, 138.00,
137.61, 137.32 (Ph), 128.50-127.39 (Ph), 102.75 (C-1′), 100.02 (C-
1), 79.55 (C-3), 74.92, 74.68, 73.48, 73.16, 72.58 (PhCH2), 74.72 (C-
2,4), 73.73 (C-4′), 72.87 (C-2′), 72.57 (C-5), 71.97 (C-3′), 71.81 (C-
5′), 68.86, 66.45 (C-6,6′), 60.20 (OCH2). [R]24 ) +35.2° (c ) 1.2,
D
CHCl3).
O-2,3,4,6-tetra-O-benzyl-r-D-mannopyranosyl)-(1f2)-1,3,4,6-
tetra-O-acetyl-r-D-galactopyranose (8). 1H-NMR (CDCl3): δ 7.49-
7.04 (m, 20H, 4Ph), 6.44 (d, J1,2 ) 3.3 Hz, H-1), 5.44 (d, J3,4 ) 3.1
Hz, H-4), 5.18 (dd, J2,3 ) 10.7 Hz, H-3), 5.08 (d, J1′,2′ ) 1.7 Hz, H-1′),
4.93-4.40 (m, 8H, PhCH2), 4.33 (dd, H-2), 4.07 (d, 2H, J5,6 ) 6.9 Hz,
H-6), 3.91-3.59 (m, 6H, H-5,3′,4,5′,6′), 3.55 (dd, J2′,3′ ) 3.0 Hz, H-2′),
PhCH2), 4.47, 4.39 (ABq, J ) 11.9 Hz, PhCH2), 4.15 (ddt, 1H, Jgem
)
(9) Lee, R. T.; Lee, Y. C. Carbohydr. Res. 1974, 37, 193.

9270 J. Am. Chem. Soc., Vol. 118, No. 39, 1996
Hiruma et al.
12.9 Hz, OCH2), 4.08-3.91 (m, 4H, H-2, 3, 4, 5, OCH2), 3.81 (s, 3H,
OMe), 3.51 (d, J5,6 ) 6.6 Hz, H-6). 13C-NMR (CDCl3): δ 159.07
(CMe), 138.72, 138.65, 138.02, 131.02, 129.09 (3Ph), 134.00 (HCd),
128.34-127.48 (Ph), 117.86 (dCH2), 113.73 (CHCOMe), 96.32 (C-
1), 78.87, 77.21, 76.43, 75.22, 74.68, 73.41, 73.32, 72.92, 69.38, 69.04,
68.21, 55.24 (OMe).
2.04, 1.96, 1.94 (each s, 12H, COCH3). 13C-NMR: δ 170.43, 170.19,
170.15, 170.06 (CdO), 138.58, 138.20, 138.15, 138.04 (Ph), 128.43-
127.39 (Ph), 95.08, 89.51 (C-1,1′), 79.30 (C-3′), 74.84, 73.33, 72.29,
71.90 (PhCH2), 74.38, 73.89, 72.22, 68.95, 68.16, 67.61, 67.51 (C-
2,3,4,5,2′,4′,5′), 69.42, 61.44 (C-6,6′), 20.94, 20.65, 20.33 (COCH3).
2,4,6-Tri-O-benzyl-â-D-galactopyranosyl 2,3,4,6-Tetra-O-benzyl-
r-D-mannopyranoside. To a solution of 11b (100 mg, 0.10 mmol)
in dry methanol (3 mL) and chloroform (0.5 mL) was added powdered
sodium methoxide (2 spoons by microspatel), and the mixture was
stirred at room temperature for 1 h. The mixture was neutralized with
1 M HCl and extracted with chloroform. The extract was washed with
water and dried over anhydrous sodium sulfate, the solvent was
evaporated, and the residue was purified on a column of silica gel with
hexane-ethyl acetate (3:1) to give the title compound (91 mg, 95%).
1H-NMR: δ 7.43-7.08 (m, 35H, 7Ph), 5.14 (br s, H-1), 4.89 (ABq,
1H, J ) 10.9 Hz, PhCH2), 4.71 (ABq, 1H, J ) 11.6 Hz, PhCH2), 4.75-
4.30 (m, 12H, PhCH2), 4.46 (d, J1′,2′ ) 7.6 Hz, H-1′), 4.12 (br d, H-5),
4.04 (t, J3,4 ) 9.0 Hz, H-4), 3.93 (dd, J2,3 ) 2.8 Hz, H-3), 3.84 (d, J3′,4′
) 3.3 Hz, H-4′), 3.73 (dd, J5,6b ) 3.8 Hz, Jgem ) 11.0 Hz, H-6), 3.67-
3.47 (m, 6H, H-2,6,3′,5′6′), 3.46 (dd, J2′,3′ ) 9.6 Hz, H-2′), 2.11 (d,
J3′,OH ) 5.6 Hz, OH-3′). 13C-NMR: δ 138.72, 138.51, 138.33, 138.26,
138.13, 137.74 (Ph), 128.46-127.31 (Ph), 102.98 (C-1′), 99.64 (C-1),
79.89, 79.53, 75.49, 74.90, 74.81, 73.91, 73.48 (C-2,3,4,5,2′,3′,4′,5′),
75.06, 74.90, 74.68, 73.26, 73.10, 72.47, 72.35, (PhCH2), 68.89, 68.11
(C-6,6′).
3-O-(carboxymethyl)-2,4,6-tri-O-benzyl-â-D-galactopyranosyl
2,3,4,6-Tri-O-benzyl-r-D-mannopyranoside (16). To a stirred mixture
of the above compound (29 mg, 0.03 mmol), silver oxide (121 mg,
0.53 mmol), and potassium iodide (42 mg, 0.26 mmol) in DMF (1
mL) was added BrCH2COOMe (87 mg, 0.57 mmol), and the mixture
was stirred at room temperature for 3.7 days. The reaction mixture
was diluted with ether and water and then passed through Celite. The
organic layer was washed with brine, dried over anhydrous sodium
sulfate, and concentrated in Vacuo. The residue was purified on a
column of silica gel with hexane-ethyl acetate (3:1) to give 16 (13
mg, 43%). 1H-NMR (CDCl3): δ 7.41-7.12 (m, 35H, Ph), 5.13 (d,
J1,2 ) 1.3 Hz, H-1), 4.93, 4.66 (ABq, J ) 11.7 Hz, PhCH2), 4.87, 4.48
(ABq, J ) 10.9 Hz, PhCH2), 4.69-4.48 (m, 6H, PhCH2), 4.57, 4.34
(ABq, J ) 12.2 Hz, PhCH2), 4.44 (d, J1′,2′ ) 7.9 Hz, H-1′), 4.29, 4.22
(ABq, J ) 16.5 Hz, OCH2), 4.28 (s, 2H, PhCH2), 4.11 (brd, H-5), 4.05
(t, J ) 9.2 Hz, H-4), 4.05 (d, J3′,4′ ) 3.6 Hz, H-4′), 3.93 (dd, J2,3 ) 3.1
Hz, H-3), 3.66-3.80 (m, 5H, H-6a,2′, OMe), 3.63 (dd, H-2), 3.62-
3.42 (m, 4H, H-6b,5′,6′), 3.39 (dd, J2′,3′ ) 9.6 Hz, J3,4 ) 3.0 Hz, H-3′).
13C-NMR: δ 171.12 (CdO), 138.85, 138.67, 138.56, 138.44, 138.24,
137.92 (Ph), 128.45-127.30 (Ph), 102.98 (C-1′), 99.66 (C-1), 83.49
(C-3′), 79.89 (C-2′), 79.61 (C-3), 75.13 (C-2), 74.77 (C-4), 74.22 (C-
4′), 73.62 (C-5′), 72.54 (C-5), 74.93, 74.83, 74.57, 73.24, 73.10, 72.33
(PhCH2), 69.13 (OCH2), 68.77, 68.56 (C-6,6′).
2,4,6-Tri-O-benzyl-3-O-[(p-methoxyphenyl)methyl]-D-galacto-
pyranose. To a solution of allyl 2,4,6-tri-O-benzyl-3-O-[(p-methoxy-
phenyl)methyl]-R-D-galactopyranoside (1.99 g, 3.25 mmol) in dimethyl
sulfoxide (25 mL) was added t-BuOK (912 mg, 8.13 mmol), and the
mixture was stirred at 130 °C for 10 min. The mixture was poured
into cold water and extracted with ether. The extract was washed with
brine, dried over anhydrous sodium sulfate, and concentrated in Vacuo.
The residue was dissolved in acetone (16 mL), added to 1 M HCl (2
mL) and water (2 mL), and then refluxed for 30 min. After acetone
was removed, the concentrated mixture was dissolved in chloroform
and washed with water, and then the solvent was evaporated. The
residue was purified on a column of silica gel with hexane-ethyl acetate
(5:2) to give 2,4,6-tri-O-benzyl-3-O-[(p-methoxyphenyl)methyl]-D-
galactopyranose (1.66 g, 89%). 1H-NMR (CDCl3): δ 7.42-7.16 (m,
17H, Ph), 6.92-6.79 (m, 2H, Ph), 5.27 (dd, J1,2 ) 3.3 Hz, J1,OH ) 2.3
Hz, H-1R), 4.94, 4.92, 4.90,, 4.83, 4.80, 4.71, 4.69, 4.66 (each ABq, J
) 11-12 Hz, PhCH2), 4.63 (d, J1,2 ) 7.6 Hz, H-1â), 4.58, 4.57 (each
ABq, J ) 11.6 Hz, PhCH2), 4.47, 4.39 (ABq, J ) 11.9 Hz, PhCH2),
4.14 (br t, J5,6 ) 6.6 Hz, H-5), 4.01 (dd, J2,3 ) 9.7 Hz, H-2R), 3.91
(dd, J3,4 ) 2.3 Hz, H-3R), 3.94-3.78 (m, 2-3H), 3.81, 3.80 (each s,
3H × 2, OMe), 3.73 (dd, J2,3 ) 9.6 Hz, H-2â), 3.63-3.45 (m, 4-5H,
H-6), 3.47 (d, Jgem ) 9.4 Hz, H-6), 3.24-3.13 (br, OHâ), 2.98-2.92
(br, OHR); mp 81-82 °C (from ether-ethyl acetate). Anal. Calcd
For C35H38O7: C, 73.66; H, 6.71. Found: C, 73.29, H, 6.65.
3-O-(Carboxymethyl)-â-D-galactopyranosyl R-D-Mannopyrano-
side (2). Lactone 15 (36 mg, 0.04 mmol) was dissolved in methanol
(1.5 mL), and then a catalytic amount of 20% Pd(OII)2 on carbon was
added. To the reaction mixture was supplied hydrogen through a
balloon. After the reaction was complete in 4 h, the mixture was filtered
and concentrated in Vacuo and then dissolved in 0.25 N aqueous NaOH
(0.5 mL). After 10 min, the reaction mixture was neutralized and
purified by Sephadex LH-20 chromatography (H2O) and lyophilized
to give 2 (14 mg, 89%). 1H-NMR (25 °C, HDO 4.80 ppm, 600
MHz): δ 5.178 (d, J1,2 ) 1.70 Hz, H-1), 4.638 (d, J1′,2′ ) 8.12 Hz,
H-1′), 1.115 (d, J3′,4′ ) 3.13 Hz, H-4′), 4.103 (s, OCH2), 3.61 (dd, J2,3
) 3.10 Hz, H-2), 3.974 (ddd, J4,5 ) 10.04 Hz, J5,6a ) 2.42 Hz, J5,6b
)
6.54 Hz, H-5), 3.904 (dd, J3,4 ) 9.83 Hz, H-3), 3.900 (d, Jgem ) 12.18
Hz, H-6a), 3.807 (dd, J5′,6′a ) 8.11 Hz, Jgem ) 11.53 Hz, H-6′a), 3.764
(dd, H-6b), 3.753 (dd, J5′,6′b ) 5.13 Hz, H-6′b), 3.724 (t, H-5′), 3.708
(dd, J2′,3′ ) 9.83 Hz, H-2′), 3.688 (t, H-4), 3.535 (dd, H-3′). 13C-NMR
(dioxane, 67.4 ppm, 100 MHz): δ 170.32 (CdO), 103.48 (C-1′), 102.30
(C-1), 82.69 (C-3′), 76.04 (C-5′), 74.31 (C-5), 71.05 (C-3), 70.56, 70.53
(C-2, 2′), 69.19 (OCH2), 67.52 (C-4), 66.02 (C-4′), 61.92, 61.76 (C-6,
6′). [R]24D ) +43.6° (c ) 0.22, MeOH:H2O ) 1:1). When galacosyl
imidate 3 instead of 4 was used as a glycosyl donor in the same reaction,
a migration was observed.
Acknowledgment. This research was supported by the
Science and Technology Agency of the Japanese Government.
We thank Drs. J. Uzawa and H. Koshino and Mr. T. Chijimatsu
for NMR analysis, Ms. M. Yoshida and her colleagues for
elemental analysis, and Professors Y. Nagai and T. Ogawa for
their assistance.
1,3,4,6-Tetra-O-acetyl-2-O-(2,3,4,6-tetra-O-benzyl-r-D-manno-
pyranosyl)-r-D-galactopyranose (8). 1H-NMR: δ 7.49-7.04 (m,
20H, 4Ph), 6.44 (d, J1,2 ) 3.3 Hz, H-1), 5.44 (d, J3,4 ) 3.1 Hz, H-4),
5.18 (dd, J2,3 ) 10.7 Hz, H-3), 5.08 (d, J1′,2′ ) 1.7 Hz, H-1′), 4.93-
4.40 (m, 8H, PhCH2), 4.33 (dd, H-2), 4.07 (d, 2H, J5,6 ) 6.9 Hz, H-6),
3.91, 3.59 (m, 6H, H-5,3′,4′,5′,6′), 3.55 (dd, J2′,3′ ) 3.0 Hz, H-2′), 2.10,
JA9611093