CHEM01200604012 Dibakar Goswami - Homi Bhabha National ...

74.2, 74.4, 110.1, 116.7, 127.6, 129.8, 129.9, 133.4, 133.6, 135.4, 136.1. Anal. Calcd. for
C 31 H 44 O 4 Si: C, 73.18; H, 8.72%. Found: C, C, 72.95; H, 8.78%.
(4S,5S,6S,7R)-7,8-Cyclohexylidenedioxy-4,6-dihydroxy-5-methyloct-1-ene 132a. To a
cooled (0 o C) and stirred solution of 132 (0.163 g, 0.32 mmol) in THF (10 mL) was added
Bu 4 NF (0.56 mL, 0.56 mmol, 1 M in THF), and the mixture stirred for ~2 h (cf. TLC). It
was poured in water, extracted with EtOAc (15 mL). The organic extract was washed with
H 2 O (5 mL) and brine, and dried. Removal of solvent in vacuo followed by column
chromatography (silica gel, 0-10% EtOAc/hexane) of the residue furnished pure 132a.
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Yield: 0.068 g (78%); colourless oil; [α] D +15.2 (c 1.4, CHCl3 ); IR: 3437, 2933, 2858 cm -
1 ; 1 H NMR: δ 0.88 (d, J = 6.8 Hz, 3H), 1.28-1.61 (m, 10H), 2.09-2.21 (m, 2H), 2.31-2.50
(m, 1H), 3.09 (broad s, 2H), 3.71-4.03 (m, 4H), 4.18-4.25 (m, 1H), 5.09-5.16 (m, 2H),
5.72-6.03 (m, 1H); 13 C NMR: δ 12.6, 23.7, 23.9, 25.1, 34.8, 36.0, 38.7, 40.5, 64.3, 74.1,
74.5, 76.4, 109.6, 117.7, 134.9. Anal. Calcd. for C 15 H 26 O 4 : C, 66.64; H, 9.69%. Found: C,
66.45; H, 9.75%.
(4S,5S,6S,7R)-7,8-Cyclohexanedioxy-4,6-isopropylidenedioxy-5-methyloct-1-ene 132b.
A mixture of the diol 132a (0.050 g, 0.185 mmol), DMP (1 mL) and PPTS (cat.) was
stirred for 1 h. The mixture was treated with aqueous10% NaHCO 3 , and extracted with
Et 2 O (10 mL). The ether layer was washed with H 2 O and brine, dried, and concentrated in
vacuo to give a residue which was purified by column chromatography (silica gel, 0–10%
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EtOAc/hexane) to afford 132b. Yield: 0.048 g (84%); colourless oil; [α] D +23.4 (c 1.2,
CHCl 3 ); IR: 2935, 1107 cm -1 ; 1 H NMR: δ 0.95 (d, J = 6.6 Hz, 3H), 1.24-1.42 (m
overlapped with two s, 8H), 1.55-1.59 (m, 8H), 2.10-2.28 (m, 2H), 2.32-2.49 (m, 1H),
3.41-3.59 (m, 2H), 3.85-3.90 (m, 1H), 3.99-4.04 (m, 2H), 5.01-5.09 (m, 2H), 5.78-6.05 (m,
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