CHEM01200604012 Dibakar Goswami - Homi Bhabha National ...

for an additional 2 h, gradually brought to room temperature and treated successively with
water and EtOAc. The organic layer was separated and the aqueous layer extracted with
EtOAc. The combined organic extracts were washed with water and brine, and dried.
Removal of solvent in vacuo followed by column chromatography of the residue (silica
gel, 0-15% EtOAc/hexane) afforded of 69a or 69d.
23
69d : Yield: 0.56 g (93%); colourless thick oil; [α] D -12.3 (c 2.4, CHCl 3 ); IR: 3410, 1646,
979 cm -1 ; 1 H NMR: δ 1.1 (d, J = 6.8 Hz, 3H), 1.4-1.6 (m, 10H), 2.02 (m, 1H), 2.28-2.32
(m, 1H), 3.29 (dd, J = 4.6, 6.8 Hz, 1H), 3.70-3.77 (m, 1H), 3.98 (dd, J = 6.4, 8.0 Hz, 1H),
4.10-4.15 (m, 1H), 5.01-5.07 (m, 2H), 5.6-5.8 (m, 1H); 13 C NMR: δ 15.7, 23.7, 23.9, 25.0,
34.8, 36.0, 42.2, 66.1, 74.5, 76.2, 109.5, 115.2, 140.4. Anal. Calcd. for C 13 H 22 O 3 : C, 68.99;
H, 9.80%. Found: C, 69.23; H, 9.56%.
(3S,4R,5R)-4-Benzoyloxy-5,6-cyclohexylidenedioxy-3-methyl-1-hexene 71. To a well
stirred and cooled (0 o C) solution of 69c (1.1 g, 4.86 mmol) and Et 3 N (0.74 g, 7.3 mmol) in
CH 2 Cl 2 (25 mL) was added a solution BzCN (0.76 g, 5.83 mmol) in CH 2 Cl 2 (10 mL) in 40
min. After the completion of the reaction (cf. TLC, 2 h) the reaction mixture was poured
into water, the organic layer separated and the aqueous layer extracted with CHCl 3 (30
mL). The combined organic extracts were washed with water (30 mL) and brine (5 mL),
and dried. Solvent removal in vacuo followed by column chromatography (silica gel, 5-
24
15% EtOAc/hexane) of the residue gave 71. Yield: 1.52 g (95%); colourless oil; [α] D
+14.2 (c 1.47, CHCl 3 ); IR: 1722, 995, 920 cm -1 ; 1 H NMR: δ 1.07 (d, J = 7.0 Hz, 3H), 1.31-
1.43 (m, 8H), 1.58-1.67 (m, 2H), 2.65-2.75 (m, 1H) 3.83-3.90 (m, 1H), 3.95-4.03 (m, 1H),
4.20-4.26 (m, 1H), 5.06-5.18 (m, 2H), 5.26 (dd, J = 4.0 and 6.6 Hz, 1H), 5.77-5.87 (m,
1H), 7.38-7.54 (m, 3H), 7.99-8.04 (m, 2H). 13 C NMR (CDCl 3 ): δ 16.9, 23.8, 25.0, 34.9,
123