CHEM01200604012 Dibakar Goswami - Homi Bhabha National ...

subsequent isolation afforded rotameric mixtures of 139 after purification by column
chromatography (silica gel, 0-10% Et 2 O/hexane). Yield: 0.189 g (94%); light yellow oil;
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[α] D +10.9 (c 1.41, CHCl3 ); IR: 1741 cm -1 ; 1 H NMR: δ 1.06-1.16 (merged s and d, J = 6.8
Hz, 12H), 1.27-1.39 (m, 6H), 1.44-1.56 (m, 4H), 1.88-2.08 (m, 1H), 2.18-2.32 (m, 2H),
3.76-3.86 (m, 1H), 3.89-3.99 (m, 1H), 4.12-4.30 (m, 2H), 4.79-4.99 (m, 2H), 5.22-5.28 and
5.44-5.52 (two m, 1H), 5.57-5.75 (m, 1H), 7.25-7.48 (m, 9H), 7.62-7.77 (m, 5H), 7.89-8.05
(m, 1H); 13 C NMR: δ 10.6, 11.2, 19.5, 23.7, 23.8, 25.1, 27.1, 34.7, 34.9, 35.7, 36.1, 36.8,
40.1, 40.5, 64.0, 67.8, 73.5, 73.9, 75.1, 75.3, 75.5, 77.8, 109.4, 109.6, 117.0, 118.0, 127.4,
127.5, 128.3, 129.1, 129.4, 129.6, 129.7, 129.8, 130.2, 132.1, 132.9, 133.8, 133.9, 134.1,
135.8, 136.0, 136.1, 165.4, 165.5. Anal. Calcd. for C 38 H 48 O 5 Si : C, 74.47; H, 7.89%.
Found: C, 74.55; H, 7.76%.
(2R,3R,4S,5S)-3-(tert)-Butyldiphenylsilyloxy-4-methyl-5-benzoyloxyoct-1-ene-1,2-diol
140. A mixture of 139 (0.150 g, 0.244 mmol) and aqueous 80% TFA (10 mL) was stirred
for 3 h at 0 °C. The mixture was diluted with water (15 mL) and extracted with CHCl 3 (30
mL), the organic layer separated and the aqueous layer extracted with CHCl 3 (10 mL). The
combined organic extracts were washed successively with aqueous 2% NaHCO 3 , H 2 O and
brine, and dried. Solvent removal in vacuo followed by column chromatography of the
residue (silica gel, 0-40% EtOAc/hexane) furnished pure 140. Yield: 0.118 g (91%);
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colourless oil; [α] D +4.0 (c 1.34, CHCl3 ); IR: 3438, 1721 cm -1 ; 1 H NMR: δ 1.09 (s, 9H),
1.16 (d, J = 7.2 Hz, 3H), 1.60 (broad s, 2H), 2.12-2.28 (m, 2H), 2.32-2.51 (m, 1H), 3.25-
3.39 (m, 1H), 3.54-3.75 (m, 3H), 4.96-5.07 (m, 2H), 5.32-5.39 (m, 1H), 5.55-5.71 (m, 1H),
7.12-7.41 (m, 8H), 7.45-7.58 (m, 5H), 7.80-7.84 (m, 2H); 13 C NMR: δ 10.2, 19.5, 27.1,
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