E. V. E6tushenko / Carbohydrate Research 316 (1999) 187–200
197
NMR: l 102.0 (C-1), 80.9 (C-3), 66.8 (C-4),
65.9 (C-2), 63.1 (C-5), 57.3 (MeO-3), 55.8
(MeO-1).
room temperature. After 2 h, the mixtures
were evaporated to dryness under reduced
pressure, the residues were acetylated with
acetic anhydride and pyridine, the products
were isolated in the usual manner and chloro-
form solutions were used for GC.
Methyl 2,3-di-O-methyl-i- -rhamnopyran-
L
oside (18). From 16 (0.2 g); syrup, 0.15 g
(65%); Rf 0.60 (solvent a); [h]2D0+94,3° (c 0.8);
13C NMR: l 102.4 (C-1), 82.9 (C-3), 76.8
(C-2), 72.2 (C-5), 72.0 (C-4), 61.6 (MeO-2),
57.6 (MeO-1), 57.4 (MeO-3), 17.4 (C-6).
Methyl 3-O-methyl-h- -rhamnopyranoside
L
(14). Typical procedure for the preparation of
2, 5, 7, 14, 18, 21 and 24.—To a solution of 12
(1 g, 5.6 mmol) and SbCl3 (0.1 mmol) in
1,4-dioxane (10 mL), diazomethane in CH2Cl2
[6] ꢀ0.5 M (40 mL, 20 mmol) was added
slowly at room temperature until a yellow
color persisted. The solution was kept for 2 h
at room temperature and was evaporated to
dryness under vacuum. The residue was chro-
matographed on a column (30×1.5 cm) of
silica gel with gradient of MeOH in CHCl3.
Syrup, 0.58 g (54%); Rf 0.44 (solvent a); [h]D20
−60.3° (c 0.6), lit. −61° (c 1.3, CHCl3) [3];
13C NMR: l 101.6 (C-1), 80.5 (C-3), 71.6
(C-4), 69.2 (C-5), 66.5 (C-2), 56.9 (MeO-3),
55.4 (MeO-1), 17.4 (C-6).
Methyl 2-O-methyl-i- -rhamnopyranoside
L
(17). To a solution of 16 (0.2 g, 1.1 mmol) and
H3BO3 (0.04 mmol) in 1,4-dioxane (2 mL)
diazomethane in CH2Cl2 (5 mL, 2.5 mmol)
was added slowly at room temperature. The
solution was kept for 2 h at room tempera-
ture. Isolation was carried out as for 14; 0.16
g (74%); Rf 0.33, (solvent a); mp 141–142 °C
(from EtOAc–hexane); [h]2D0+111.9° (c 0.4);
13C NMR: l 102.4 (C-1), 81.0 (C-2), 73.7
(C-5), 73.1 (C-3), 72.9 (C-4), 62.0 (MeO-2),
57.5 (MeO-1), 17.3 (C-6).
Methyl 2-O-methyl-i- -xylopyranoside (4).
D
To a solution of 3 (0.2 g, 1.2 mmol) and CeCl3
(0.04 mmol) in MeOH (4 mL), diazomethane
in CH2Cl2 (10 mL, 5 mmol) was added slowly
at room temperature. The solution was kept
for 2 h at room temperature. Isolation was
carried out as for 14; 0.11 g (51%); Rf 0.40
(solvent a); mp 111–112 °C (from EtOAc–
hexane), lit. 110–111.5 °C [30]; [h]2D0 −69.8°
(c 0.9), lit. −69° (c 1.0, CHCl3) [30]; 13C
NMR: l 104.5 (C-1), 83.3 (C-2), 75.9 (C-3),
69.9 (C-4), 65.7 (C-5), 60.7 (MeO-2), 57.7
(MeO-1).
Methyl 3-O-methyl-h- -fucopyranoside (21).
L
From 19 (1.0 g); 0.65 g (60%); Rf 0.38 (solvent
a); mp 96–97 °C (from EtOAc–hexane), lit.
96–97 °C [5]; [h]D20 −142.5° (c 0.4), lit. −
13
135.8° (c 0.62, MeOH) [5]; C NMR: l 100.1
(C-1), 79.6 (C-3), 68.1 (C-4), 67.6 (C-2), 67.0
(C-5), 56.6 (MeO-3), 55.8 (MeO-1), 16.1 (C-6).
Methyl 3-O-methyl-i- -arabinopyranoside
L
(7). From 6 (1.0 g); 0.46 g (42%); Rf 0.36
(solvent a); mp 57–58 °C (from EtOAc–hex-
13
ane); [h]2D0+199.7° (c 1.5); C NMR: l 100.4
(C-1), 78.8 (C-3), 67.8 (C-2), 65.5 (C-4), 63.1
(C-5), 56.7 (MeO-3), 55.8 (MeO-1).
Methyl 3-O-methyl-h- -glucopyranoside (33).
D
Typical procedure for the preparation of
27, 30, 33, 35, 37, 41, 43, 45, 49, 54 and 61.—
To a solution of 31 (1.0 g, 5.2 mmol) and
SbCl3 (0.1 mmol) in MeOH (10 mL), dia-
zomethane in CH2Cl2 (40 mL, 20 mmol) was
added slowly at room temperature. The solu-
tion was kept for 2 h at room temperature.
Isolation was carried out as for 14; syrup, 0.7
g (65%); Rf 0.30 (solvent b); [h]2D0+158.4° (c
1.7), lit. +164° (c 0.86, water) [34]; 13C NMR:
l 99.9 (C-1), 83.7 (C-3), 72.3 (C-5), 71.5 (C-2),
69.7 (C-4), 61.2 (C-6), 60.6 (MeO-3), 55.7
(MeO-1).
Methyl 3-O-methyl-h- -xylopyranoside (2).
D
From 1 (1.0 g); syrup, 0.64 g (59%); Rf 0.36
13
(solvent a); [h]2D0+117.6° (c 1.2); C NMR: l
100.3 (C-1), 83.8 (C-3), 71.6 (C-2), 69.6 (C-4),
61.8 (C-5), 60.7 (MeO-3), 55.8 (MeO-1).
Methyl 3-O-methyl-i- -xylopyranoside (5).
D
From 3 (1.0 g); 0.47 g (43%); Rf 0.42 (solvent
a); mp 107–108 °C (from EtOAc–hexane), lit.
106–107 °C [30]; [h]2D0 −71.2° (c 0.6), lit. −
74° (c 1.0, CHCl3) [30]; 13C NMR: l 104.7
(C-1), 85.9 (C-3), 73.0 (C-2), 69.4 (C-4), 65.7
(C-5), 60.5 (MeO-3), 57.7 (MeO-1).
Methyl
3-O-methyl-h-
D-lyxopyranoside
Methyl
2,3-di-O-methyl-h- -glucopyran-
D
(24). From 23 (1.0 g); syrup, 0.49 g (45%); Rf
oside (35). From 32 (0.5 g); 0.42g (79%); Rf
0.53 (solvent b); mp 83–84 °C (from EtOAc–
0.35 (solvent a); [h]2D0+46.4° (c 2.4); 13C