CHEM01200604012 Dibakar Goswami - Homi Bhabha National ...

(m, 2H), 5.82-5.98 (m, 1H), 7.25-7.38 (m, 4H), 7.46-7.84 (m, 9H), 7.98-8.02 (m, 2H); 13 C
NMR: δ 17.4, 19.1, 37.7, 63.5, 72.1, 75.9, 116.6, 127.2, 127.5, 128.5, 129.3, 130.4, 133.5,
138.3, 171.2. Anal. Calcd. for C 30 H 36 O 4 Si: C, 73.73; H, 7.43%. Found: C, 73.61; H,
7.59%.
(3S,4S,5R)-(4-Benzoyloxy-3-methyl-5-(tert)-butyldiphenylsilyloxymethyl)
dihydro-
(3R,4S,5R)-(4-Benzoyloxy-3-methyl-5-(tert)-butyldiphenylsilyloxymethyl)
2(3H)-furanone 74c. Ozone was bubbled for 20 min through a solution of 73 (1 g, 2.03
mmol) and methanolic NaOH (1.5 mL, 2.5 M) in CH 2 Cl 2 (20 mL) at -78 o C. After stirring
the mixture for 3 h, it was diluted with CHCl 3 and water, and brought to room temperature.
The organic layer was separated and the aqueous layer extracted with CHCl 3 . The
combined organic extracts were washed with water and brine, and dried. Removal of
solvent in vacuo followed by chromatographic purification (silica gel, 5-15%
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CHCl 3 /MeOH) afforded 74c. Yield: 0.72 g (72%); colourless oil; [α] D +16.3 (c 0.884,
CHCl 3 ); IR: 1742, 1695 cm -1 ; 1 H NMR: δ 0.91 (d, J = 6.8 Hz, 3H), 1.14 (s, 9H), 3.40-
3.50 (m, 1H), 3.90-4.20 (m, 2H), 4.63-4.70 (m, 1H), 5.96 (dd, J = 13.7 and 2.4 Hz, 1H),
7.27-7.37 (m, 4H), 7.44-7.81 (m, 9H), 7.97-8.01 (m, 2H). Anal. Calcd. for C 29 H 32 O 5 Si: C,
71.28; H, 6.60%. Found, C, 71.37; H, 6.81%.
dihydro-
2(3H)-furanone 74b. colourless oil; [α] D
22
+21.1 (c 0.721, CHCl 3 ); IR: 1739, 1692 cm -1 ;
1 H NMR: δ 0.93 (d, J = 6.4 Hz, 3H), 1.17 (s, 9H), 2.92-2.98 (m, 1H), 3.78-3.88 (m, 2H),
4.61-4.67 (m, 1H), 5.84 (dd, J = 12.2 and 9.7 Hz, 1H), 7.29-7.37 (m, 4H), 7.48-7.75 (m,
9H), 7.95-8.02 (m, 2H). Anal. Calcd. for C 29 H 32 O 5 Si: C, 71.28; H, 6.60%. Found, C,
71.15; H, 6.62%.
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