B.D. Johnston, B.M. Pinto/Carbohydrate Research 310 (1998) 17±25
21
1H, J5,6 4.5, J6a,6b 9.9 Hz, H-6a), 4.24 (d, 1H, H-10),
9.5 Hz, H-40), 5.37 (dd, 1H, J1 ,2 4.3, J2 ,3 3.1 Hz,
H-20), 5.28 (dd, 1H, H-30), 5.25 (dd, 1H, J4,5 9.7 Hz,
H-4), 4.89 (d, 1H, J1,2 1.6 Hz, H-1), 4.33 (dd, 1H,
0
0
0
4.13 (dd, 1H, J5 ,6b 4.1 Hz, H-6b0), 3.99 (t, 1H, J4,5
9.6 Hz, H-4), 3.93 (ddd, 1H, J5,6b 9.9 Hz, H-5), 3.81
(t, 1H, H-6b), 3.75 (dd, 1H, H-2), 3.67 (ddd, 1H,
H-50), 3.41 (s, 3H, OCH3), 2.18, 2.09(2), 2.06, 2.02
(5 COCH3); 13C NMR: ꢂ 170.27, 170.16, 169.79,
169.51, 169.30 (5 COCH3), 137.2, 128.97, 128.15,
126.17 (Ph), 102.84 (C-1), 101.92 (PhCH), 77.70
(C-4), 71.73 (C-20), 70.09 (C-30), 69.54, 69.41 (C-3,
C-40), 68.74 (C-6), 64.00 (C-5), 61.86 (C-60), 55.12
0
0
J5 ,6a 6.0, J6a ,6b 11.9 Hz, H-6a0), 4.25 (d, 1H, H-
10), 4.20 (dd, 1H, J5,6a 4.7, J6a,6b 12.3 Hz, H-6a),
4.13 (dd, 1H, J5,6 2.5 Hz, H-6b), 4.12 (dd, 1H,
0
0
0
0
J5 ,6b 4.5 Hz, H-6b0), 3.92 (ddd, 1H, H-5), 3.63
(ddd, 1H, H-50), 3.62 (dd, 1H, H-2), 3.41 (s, 3H,
OCH3), 2.17, 2.12, 2.08, 2.07, 2.05, 2.04, 2.01 (7s,
each 3H, COCH3); 13C NMR: ꢂ 170.49, 170.31,
169.91, 169.71, 169.47, 169.31(2C), (7 COCH3),
101.57 (C-1), 71.53 (C-20), 70.41 (C-3), 69.84 (C-30),
69.42 (C-40), 68.51 (C-5), 67.17 (C-4), 62.26 (C-6),
61.84 (C-60), 55.35 (OCH3), 50.83 (C-10), 50.19 (C-
2), 40.51 (C-50), 20.96, 20.79(2C), 20.65(3C), 20.58,
(7 COCH3) Anal. Calcd for C27H38O16S2: C, 47.50;
H, 5.61. Found: C, 47.71 ; H, 5.68.
Methyl 2-S-(5-thio-a-d-mannopyranosyl)-2-thio-
a-d-mannopyranoside (1).ÐTo a solution of dis-
accharide 13 (122 mg, 0.179 mmol) in anhyd
MeOH was added a 1 M solution of NaOMe in
MeOH (1.0 mL), and the mixture was kept at room
temperature for 1.5 h. The solution was neutralized
with Rexyn 101 H+ ion-exchange resin, ®ltered
and concentrated to a syrup. Anhydrous toluene
(20 mL) was added and removed in vacuo to give 1
(65 mg, 94%) as a colorless glass: [ꢀ]d +218ꢁ (c
0
0
(OCH3), 51.66 (C-10, JC1 ,H1 153 Hz), 51.30 (C-2),
40.59 (C-50), 20.80, 20.74, 20.49 (COCH3). Anal.
Calcd for C30H38O14S2: C, 52.47; H, 5.58. Found:
C, 52.40; H, 5.55.
0
0
The slower-eluting ꢁ-isomer 12 (258 mg, 46%)
was isolated as a colorless syrup which slowly crys-
tallized on standing: mp 109±112 ꢁC; [ꢀ]d 34.8ꢁ (c
1.15, CHCl3); 1H NMR: ꢂ 7.5±7.3 (m, 5H, Ph), 5.70
(dd, 1H, J1 2 1.9, J2 ,3 2.9 Hz, H-20), 5.52 (s, 1H,
0
0
0
0
PhCH), 5.43 (dd, 1H, J2,3 4.7, J3,4 10.3 Hz, H-3),
0
0
0
0
0
5.39 (t, 1H, J3 ,4 =J4 ,5 =10.3 Hz, H-4 ), 4.89 (d,
1H, J1,2 1.2 Hz, H-1), 4.83 (dd, 1H, H-30), 4.22 (dd,
1H, J5,6a 4.6, J6a,6b 10.2 Hz, H-6a), 4.18 (dd, 1H,
J5 ,6a 4.4, J6a ,6b 11.8 Hz, H-6a0), 4.14 (dd, 1H,
0
0
0
0
J5 ,6b 6.3 Hz, H-6b0), 4.06 (d, 1H, H-10), 3.89 (ddd,
1H, J4,5 9.7, J5,6b 10.3 Hz, H-5), 3.76 (t, 1H, H-6b),
3.73 (dd, 1H, H-4), 3.67 (dd, 1H, H-2), 3.41 (s, 3H,
OCH3), 3.27 (ddd, 1H, H-50), 2.22, 2.17, 2.08, 2.03
1.98 (5 COCH3); 13C NMR: ꢂ 170.31(2C), 170.11,
169.78, 169.62, (5 COCH3), 137.19, 129.06, 128.21,
126.21 (Ph), 102.72 (C-1), 101.96 (PhCH), 77.11
(C-4), 73.30 (C-30), 71.85 (C-20), 68.91 (C-3), 68.73
(C-6), 68.55 (C-40), 64.04 (C-5), 62.04 (C-60), 55.14
0
0
1
0.87, H2O); H NMR (D2O): ꢂ 4.99 (d, 1H, J1,2
1.2 Hz, H-1), 4.29 (d, 1H, J1 ,2 3.6 Hz, H-10), 4.25
0
0
(dd, 1H, J2 ,3 2.9 Hz, H-20), 4.13 (dd, 1H, J2,3 4.7,
0
0
0
0
0
0
J3,4 9.7 Hz, H-3), 3.94 (dd, 1H, J5 ,6a 3.3, J6a ,6b
12.0 Hz, H-6a0), 3.82 (dd, 1H, J5,6a 2.2, J6a,6b
12.0 Hz, H-6a), 3.78 (dd, 1H, J5 ,6b 7.1 Hz, H-6b0),
0
0
(OCH3), 52.48 (C-2), 50.10 (C-10, JC1 ,H1 146 Hz),
44.91 (C-50), 21.29, 20.95, 20.71, 20.55, 20.44 (5
COCH3). Anal. Calcd for C30H38O14S2: C, 52.47;
H, 5.58. Found: C, 52.21; H, 5.53.
3.76 (dd, 1H, J2 ,3 2.8, J4 ,5 9.9 Hz, H-40), 3.69 (dd,
0
0
0
0
0
0
0
0
1H, J5,6 5.8 Hz, H-6b), 3.67 (dd, 1H, J3 ,4 9.5 Hz,
H-30), 3.58 (ddd, 1H, H-5), 3.49 (t, 1H, J4,5 9.7 Hz,
H-4), 3.46 (dd, 1H, H-2), 3.36 (s, 3H, OCH3), 3.25
(ddd, 1H, H-50); 13C NMR (D2O): ꢂ 104.53 (C-1),
75.41 (C-5), 74.97 (C-20), 74.73 (C-30), 72.59 (C-40),
72.21 (C-3), 70.68 (C-4), 63.39 (C-6), 62.94 (C-60),
57.70 (C-10), 57.52 (OCH3), 55.94 (C-2), 47.72 (C-
50) Anal. Calcd for C13H24O9S2: C, 40.20; H, 6.23.
Found: C, 40.31; H, 6.21.
Methyl 3,4,6-tri-O-acetyl-2-S-(2,3,4,6-tetra-O-
acetyl-5-thio-a-d-mannopyranosyl)-2-thio-a-d-manno-
pyranoside (13).ÐA solution of the disaccharide 11
(167 mg, 0.243 mmol) in 80% aq HOAc (10 mL)
was stirred at room temperature for 2 h and at
ꢁ
45 C for 5 h. The solvent and benzaldehyde were
removed in vacuo and the residue was acetylated
by treatment with Ac2O (1.5 mL) and 4-dimethyla-
minopyridine (0.020 g) in pyridine (4 mL) at room
temperature for 4 h. Volatile material was removed
in vacuo and the residue was puri®ed by column
chromatography (2:3 hexanes±EtOAc,) to yield 13
(152 mg, 92%) as an amorphous solid: [ꢀ]d
+131.7ꢁ (c 1.04, CHCl3); 1H NMR: ꢂ 5.51 (dd, 1H,
Methyl 3-O-benzoyl-4,6-O-benzylidene-2-O-(2,3,
4,6-tetra-O-acetyl-5-thio-a-d-mannopyranosyl)-a-
d-mannopyranoside (14) and 3,4,6-Tri-O-Acetyl-
1,2-(methyl 3-O-benzoyl-4,6-O-benzylidene-a-d-
mannopyranos-2-yl)-5-thio-b-d-mannopyranose Orth-
oacetate (17).ÐCrude trichloroacetimidate
5
(prepared from 5-thio-ꢀ-d-mannopyranose pen-
taacetate (408 mg, 1.00 mmol)) and methyl 3-O-
benzoyl-4,6-O-benzylidene-ꢀ-d-mannopyranoside
0
0
0
J2,3 4.5, J3,4 9.5 Hz, H-3), 5.43 (t, 1H, J3 ,4 =J4 ,5 =
0