238
portionwise during 1 h. The mixture was stirred for 5 h, and water (2 mL), treated with Ac2O (4 mL) for 17 h at 20°, and
CHCl3 (10 mL) and satd aq KBr (5 mL) were added. The finally concentrated. A solution of the product was subjected
mixture was stirred for 10 min, then filtered through Celite. to gel filtration on fracto-gel TSK HW-40(S) (25-40 mm, Vo
The organic layer was separated, washed with satd aq KBr and 50 ml), in 0.01 M acetic acid, to give amorphous 1 (7.5 mg,
NaHCO3, then filtered through cotton, and concentrated. The 80%), [α]D -88° (c 0.5, H2O). Lit. [22]: [α]D –90.2° (c 0.5,
residue was dissolved in chloroform (2 mL), treated with 90% H2O).1H and 13C NMR data are presented in Tables 2 and 3.
aq trifluoacetic acid (0.5 mL ), and, after being kept for 30 min
at r.t., the solution was concentrated, and toluene (3 × 5 mL)
was evaporated from the residue. A solution of the product in
Methyl O-(β-L-fucopyranosyl)-(1→2)-O-(β-D-galacto-
pyranosyl)-(1→4)-2-acetamido-2-deoxy-β-D-gluco-
pyranoside (2). Hydrolysis and saponification of the com-
pound 32 (35 mg, 0.027 mmol), followed by gel filtration as
chloroform (1 mL), pyridine 3 mL, and acetic anhydride (1 mL)
was kept for 3 h at r.t., and toluene (3 × 10 mL) was evaporated
described above, gave amorphous 2 (14 mg, 82%), [α]D 131°
from the residue. The mixture was subjected to catalytic
(c 0.5, H2O). The 1H and 13C NMR data are presented in Tables
hydrogenolysis in EtOH–EtOAc (1:2, 12 mL) with 10% Pd-C
2 and 3.
at 41 °C and atm. pressure for 20 h. The mixture was filtered,
Methyl O-(α-L-fucopyranosyl)-(1→2)-O-(β-D-galacto-
and the solvent was evaporated in vacuo. Column chromatog-
pyranosyl)-(1→4)-β-D-quinovopyranoside (3). Compound 29
raphy of the product gave amorphous 28 (80 mg, 26%), [α]D
(8.1 mg, 0.008 mmol) was debenzylated as described for the
–81° (c 0.8, CHCl3), Rf 0.24 (solvent B), and 32 (159 mg,
1
preparation of 1, O-deacylated by treatment with methanolic
0.1M MeONa as described for preparation of 19, and subjected
to gel filtration on fracto-gel TSK HW-40(S) (25-40 mm, Vo
50 mL), in water, to give amorphous 3 (3.5 mg, 93%), [α]D
–59° (c 0.2, H2O). The 1H and 13C NMR data are presented in
Tables 2 and 3.
53%), [α]D -122o (c 1, CHCl3), RF 0.15 (solvent B). The H
NMR data for 28 and 32 are presented in Table 1.
Methyl O-(2,3,4-tri-O-benzoyl-a-L-fucopyranosyl)-(1→2)-
O-(3-O-benzoyl-b-D-galactopyranosyl)-(1→4)-2,3-di-O-ben-
zyl-b-D-quinovopyranoside (29) and methyl O-(2,3,4-tri-O-
benzoyl-α-L-fucopyranosyl)-(1→2)-O-(3-O-benzoyl-β-
D-galactopyranosyl)-(1→4)-2,3-di-O-benzyl-6-deoxy-b-
D-glucopyranoside (33). Glycosylation of 23 (62 mg, 0.087
mmol) with 26 {prepared26 from tetra-O-benzoyl-L-
fucopyranose (101 mg, 0.174 mmol)} and treatment with
trifluoroacetic acid, as for the synthesis of 28 and 32, gave
amorphous 29 (24 mg, 26%), [α]D –81° (c 0.5, CHCl3), Rf 0.21
(solvent C), and 33 (48 mg, 52%) [α]D –100° (c 0.5, CHCl3),
Methyl O-(β-L-fucopyranosyl)-(1→2)-O-(β-D-galacto-
pyranosyl)-(1→4)-β-D-quinovopyranoside (4). Compound 33
(9 mg, 0.009 mmol) was deblocked, as described for the
preparation of 3, to give amorphous 4 (4 mg, 95%), [α]D –88°
(c 0.3, H2O). The 1H and 13C NMR data are presented in Tables 2
and 3.
Methyl O-(α-L-fucopyranosyl)-(1→2)-O-(β-D-galactopy-
ranosyl)-(1→4)-β-D-xylopyranoside (5). Compound 30 (29 mg,
0.027 mmol) was deblocked, as described for the preparation
of 3, to give amorphous 5 (12 mg, 94%), [α]D –3° (c 1, H2O).
The obtained value of optical rotation for 5 varied from that
reported previously in ref 6 [–90.2° (c 0.5, H2O)]; nevertheless
the NMR data for 5 (Tables 2 and 3) coincide well with that
reported in ref 6.
1
RF 0.17 (solvent C). The H NMR data for 28 and 33 are
presented in Table 1.
Methyl O-(2,3,4-tri-O-benzoyl-α-L-fucopyranosyl)-
(1→2)-O-(3-O-benzoyl-β-D-galactopyranosyl)-(1→4)-2,3-
di-O-benzyl-β-D-xylopyranoside (30) and methyl O-(2,3,4-tri-
O-benzoyl-α-L-fucopyranosyl)-(1→2)-O-(3-O-benzoyl-β-D-
galactopyranosyl)-(1→4)-2,3-di-O-benzyl-b-D-xylopyran-
oside (34). Glycosylation of 24 (29 mg, 0.041 mmol) with 26
{prepared26 from tetra-O-benzoyl-L-fucopyranose (48 mg,
0.082 mmol)} and treatment with trifluoroacetic acid, as for
the synthesis of 28 and 32, gave amorphous 30 (7 mg, 16%),
[α]D –102° (c 1, CHCl3), RF 0.25 (solvent C), and 34 (23.5 mg,
54%) [α]D –78° (c 2, CHCl3), Rf 0.2 (solvent C). The 1H NMR
data for 30 and 34 are presented in Table 1.
Methyl O-(β-L-fucopyranosyl)-(1→2)-O-(β-D-galactopy-
ranosyl)-(1→4)-β-D-xylopyranoside (6). Compound 34 (36 mg,
0.034 mmol) was deblocked, as described for the preparation
of 3, to give amorphous 6 (15 mg, 96%), [α]D –52° (c 1, H2O).
The 1H and 13C NMR data are presented in Tables 2 and 3.
Methyl 4-O-(β-D-galactopyranosyl)-β-D-glucopyranoside
(8). Compound 17 (21.5 mg, 0.031 mmol) was deblocked, as
described for the preparation of 3, to give amorphous 8 (10
mg, 94%), [α]D –5° (c 0.5, H2O). The 1H and 13C NMR data are
presented in Tables 2 and 3.
Preparation of Non-substituted Oligosaccharide Methyl
Glycosides 1–6, 8, and 9
Methyl-O-(α-L-fucopyranosyl)-(1→2)-O-(β-D-galacto-
pyranosyl)-(1→4)-2-acetamido-2-deoxy-β-D-glucopyran-
oside (1). Compound 28 (20 mg, 0.015 mmol) was subjected
to catalytic hydrogenolysis in EtOH–AcOH (1:2, 12 mL) with
Pd-C as catalyst at 40 °C and atm. pressure for 20 h. The
mixture was filtered and filtrate was concentrated. Solution of
Methyl 4-O-(β-D-galactopyranosyl)-β-D-xylopyranoside
(9). Compound 18 (22 mg, 0.032 mmol) was deblocked, as
described for the preparation of 3, to give amorphous 9 (10 mg,
1
95%), [α]D –30° (c 0.5, H2O). The H and 13C NMR data are
presented in Tables 2 and 3.
the residue in aq 96% EtOH (10 mL) and 99% hydrazine Acknowledgment. We acknowledge support from NATO
hydrate (2 mL) was boiled under reflux for 10 h. The mixture (Collaborative Research Grant HTECH. CRG931145). The
was concentrated, and water (3 × 3 mL) was distilled from the authors would like to thank Bent O. Petersen for valuable
residue, which then was dissolved in MeOH (10 mL) and assistance in recording and assigning the NMR spectra.
Israel Journal of Chemistry
40
2000