A solution of 500 mg (1.46 mmol) of 5-(4-fluorophenyl)-6-[4-(methylsulfonyl)phenyl]spiro[2.4]hept-5-ene (from Step 11) in 7 mL of dichloromethane was treated with 480 mg (55% peroxyacid, 1.53 mmol) of m-chloroperoxybenzoic acid (MCPBA). The reaction was stirred at ambient temperature for 2.5 hours, washed with aqueous saturated sodium bisulfite, dried (MgSO4), and concentrated in vacuo to give a mixture of desired expoxide intermediate and m-chlorobenzoic acid; this crude mixture in 10 mL of acetic acid and 1 mL of water was subsequently treated with 500 mg (6.1 mmol) of sodium acetate and stirred at 80° C. for 10 hours. The reaction mixture was cooled to ambient temperature and concentrated in .vacuo. The residue was partitioned between water and ethyl acetate; the organic phase was washed with aqueous saturated sodium bicarbonate, water, brine, dried (MgSO4), and reconcentrated in vacuo. Purification by silica gel chromatography gave 317 mg (64%) of 5-(4-fluorophenyl)-6-[4-(methylsulfonyl)phenyl]spiro[2.4]hepta-4,6-diene as a colorless solid: mp 119°-128° C. (dec); NMR (CDCl3) δ 1.81 (s, 4H), 3.06 (s, 3H), 6.22 (d, J=2 Hz, 1H), 6.36 d, J=2 Hz, 1H), 6.95 (t, J=8 Hz, 2H), 7.02-7.18 (m, 2H), 7.33 (d, J=8 Hz, 2H), 7.80 (d, J=8 Hz, 2H). MS (FAB) m/e (rel intensity) 347 (100) (M+Li). HRMS. Calc'd for C20H17FO2S: 340.0933. Found: 340.0952. Anal. Calc'd for C20H17FO2S: C, 69.29; H, 4.97; F, 5.45. Found: C, 69.21; H, 5.23; F, 5.81.
