“…Chromatography (4:1 petroleum ether-ethyl acetate) afforded 0.35 g (50%) of alcohol 7: Rf = 0.42 (2:1 petroleum ether-ethyl acetate); IR (film) v 3438,3025,2956,2925,2888,1700,1456,1369,1250,1106,1031 cm'1; JH NMR (CDC13) 8 0.92 (d, J = 6.1 Hz, 3 H), 1.59 (m, 1 H), 1.77 (m, 1 H), 2.25 (m, 2 H), 2.64 (m, 1 H), 2.92 (m, 1 H), 3.38 (s, 3 H), 3.53 (m, 2 H), 3.68 (m, 2 H), 4.06 (d, J = 3.9 Hz, 1 H), 4.75 (d, J = 7.1 Hz, 1 H), 4.84 (d, J = 7.1 Hz, 1 H), 4.89 (s, 1 H), 5.13 (d, J = 12.7 Hz, 1 H), 5.92 (m, 3 H); 13C NMR (CDCI3) 8 23.51,23.98,35.00,41.63,48.29,58.86, 67.27, 71.56, 80.03, 85.89, 96.67, 124.81, 126.46, 127.89, 134.13, 207.86; mass spectrum, m/e (%) (No M+) 297 (M + 1, 24), 222 (17.0), 221 (100.0), 220 (20), 207 (M -MEM, 14), 173 (38), 89 (43), 59 (44). ]-7-oxo-9a-methyl-ll-[(2-methoxyethoxy)methoxy]bicyclo [4.4.1]undeca-2,4-diene (8). To a solution of acetal 3 (1.3 g, 3.4 mmol) in acetone (5 mL) was added a 15% aqueous solution of trifluoroacetic acid (2.6 mL).…”