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9.8, 3.4, H-5a), 4.14–4.10 (3H, m, COCH2Cl, H-2b), 3.96–3.91 (2H, m, H-3a, H-6aa), 3.89–3.84 (2H,
m, H-3b, H-4b), 3.79–3.74 (3H, m, H-4a, H-5b, H-6ba), 3.67 (1H, dd, 10.8, 4.3, H-6ab), 3.61 (1H, dd,
10.7, 1.5, H-6bb), 2.66–2.53 (2H, m, SCH2CH3), 2.44 (1H, d, 2.4, 2-OHb), 1.26 (3H, t, J 7.4, SCH2CH3);
δC (150 MHz, CDCl3) 166.6 (COCH2Cl), [138.4, 138.3, 138.2, 137.8, 137.4 (Ar-C ipso)], [128.5, 128.3,
128.2, 128.0, 127.9, 127.8, 127.7, 127.6, 127.5 (Ar-C)], 99.2 (C-1b), 81.7 (C-1a), 79.9 (C-3b), 78.5 (C-3a),
75.1 (PhCH2-A), 75.0 (PhCH2-B), 74.3 (C-4a), 74.2 (C-4b), 73.4 (PhCH2-E), 72.3 (C-2a), 72.0 (PhCH2-
C), 71.8 (PhCH2-D), 71.6 (C-5a), 71.1 (C-5b), 68.8 (C-6b), 68.2 (C-2b), 65.7 (C-6a), 40.8 (COCH2Cl),
25.5 (SCH2CH3), 14.9 (SCH2CH3); (found (+ESI): M++Na, 935.3152. C51H57ClO11SNa requires: M,
935.3208); (found: C, 66.9%; H, 6.4%. C51H57ClO11S requires: C, 67.06%; H, 6.29%).
4.21. Synthesis of (20S,30S) ethyl 3,4-di-O-benzyl-2-O-chloroacetyl-6-O-(3,4,6-tri-O-benzyl-2-O-(6-O-
tert-butyldimethylsilyl-3-O,4-O-[20,30-dimethoxybutan-20,30-diyl]-2-O-(2,3,4,6-tetra-O-benzyl-α-D-
mannopyranosyl)-α-D-mannopyranosyl)-α-D-mannopyranosyl)-1-thio-α-D-mannopyranoside 31
To a mixture of AgOTf (74 mg, 0.28 mmol), 4 Å MS (0.50 g) and Cp2HfCl2 (55 mg, 0.14 mmol) was
added a solution of 24 (50 mg, 55 µmol) in toluene (0.6 ml) via syringe. The resulting suspension was
stirred for 10 min before a solution of 22 (67 mg, 72 µmol) in dichloromethane (0.6 ml) was added via
syringe. Stirring was maintained for a further 45 min before the reaction mixture was sonicated briefly.
Stirring was maintained for a further 1.25 h and then filtered through Celite®. The filter-cake was washed
with chloroform (50 ml) and the combined filtrates washed with aqueous sodium bicarbonate solution (50
ml). The aqueous portion was extracted with chloroform (50 ml) and the combined organic extracts dried
(MgSO4), filtered and concentrated in vacuo to give a yellow oil. Purification by flash chromatography on
silica gel (eluent: petrol:ether 2:1→1:1) gave the tetramannopyranoside 31 (73 mg, 73%) as a foam; δH
(600 MHz, CDCl3) 7.45–7.44 (2H, m, Ar-H), 7.32–7.12 (42H, m, Ar-H), 7.03 (1H, t, J 7.4, Ar-H), 5.55
(1H, s, H-1d), 5.49 (1H, s, H-2a), 5.25 (1H, s, H-1a), 5.21 (1H, s, H-1c), 4.88–4.86 (3H, m, H-1b, PhCH2-
A), 4.82 (1H, d, J 10.9, PhCHaHb-B), 4.78 (1H, d, J 12.4, PhCHaHb-C), 4.69–4.59 (5H, m, PhCHaHb-
D, PhCHaHb-C, PhCHaHb-E, PhCHaHb-F, PhCHaHb-G), 4.55–4.46 (8H, m, PhCHaHb-B, PhCHaHb-D,
PhCHaHb-E, PhCHaHb-G, PhCH2-H, PhCH2-I), 4.32 (1H, d, J 12.2, PhCHaHb-F), 4.20 (1H, s, H-2c),
4.19–4.16 (1H, m, H-5a), 4.15 (1H, s, H-2b), 4.12–4.06 (5H, m, H-4c, H-4d, H-3c, COCH2Cl), 4.01 (1H,
s, H-2d), 3.95–3.78 (7H, m, H-6ac, H-6bc, H-6aa, H-3a, H-3d, H-4b, H-3b), 3.76–3.59 (7H, m, H-5c, H-
6ba, H-4a, H-5d, H-6ad, H-6ab, H-5b), 3.55–3.50 (2H, m, H-6bb, H-6bd), 3.27 (3H, s, OCH3 BDA), 3.11
(3H, s, OCH3 BDA), 2.61–2.48 (2H, m, SCH2CH3), 1.28 (3H, s, CH3 BDA), 1.27 (3H, s, CH3 BDA),
1.21 (3H, t, J 7.4, SCH2CH3), 0.86 (9H, s, SiC(CH3)3), 0.06 (3H, s, SiCH3), 0.05 (3H, s, SiCH3); δC
(150 MHz, CDCl3) 166.7 (COCH2Cl), [138.9, 138.8, 138.5, 138.3, 138.2, 138.0, 137.3 (Ar-C ipso)],
[128.5, 128.4, 128.3 (×3), 128.2 (×2), 128.1, 128.0 (×2), 127.9, 127.8, 127.7 (×2), 127.5, 127.4 (×3),
127.3 (×2) (Ar-C)], 100.7 (C-1c), [99.6, 99.4 (BDA acetal C)], 98.9 (C-1b), 98.4 (C-1d), 81.5 (C-1a), 80.1
(C-3d), 79.9 (C-3b), 78.7 (C-3a), 74.9 (PhCH2-A, PhCH2-B), 74.6 (C-4b, C-4d), 74.5 (C-2d), 74.4 (C-4a),
73.6 (C-2c), 73.3 (PhCH2-F), [72.5, 72.4 (C-2b, C-5c)], 72.2 (C-2a), 72.0 (C-5d/5b), 72.0 (PhCH2-C), 71.9
(C-5d/5b), [71.9, 71.8, 71.6 (PhCH2-D, PhCH2-E, PhCH2-H, PhCH2-I)], 71.1 (C-5a), 69.0 (C-6b), 68.9
(C-3c), 68.8 (C-6d), 66.1 (C-6a), 62.8 (C-4c), 61.6 (C-6c), [48.0, 47.7 (OCH3 BDA)], 40.8 (COCH2Cl),
25.9 (SiC(CH3)3), 25.2 (SCH2CH3), 18.3 (SiC(CH3)3), [18.0, 17.8 (CH3 BDA)], 14.8 (SCH2CH3), [–4.7,
–5.4 (Si(CH3)2]; (found (+ESI): M++Na, 1847.7812. C103H125ClO23SSiNa requires: M, 1847.7682).