A solution of 1.0 g (2.89 mmol) of 4-[2-(4-fluorophenyl)-4,4-dimethylcyclopenten-1yl)benzenesulfonamide (from Step 2) in 20 mL of dichloromethane was treated with 800 mg (80% peroxyacid, 3.7 mmol) of m-chloroperoxybenzoic acid (MCPBA). The reaction was stirred at ambient temperature for 3 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 15 mL of acetic acid and 2 mL of water was subsequently treated with 1.0 g (12.2 mmol) of sodium acetate and stirred at 80° C. for 15 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 sodiun bicarbonate, water, brine, dried (MgSO4), and reconcentrated in vacuo. Purification by silica gel chromatography gave 665 mg (67%) of 4-[4-(4-fluorophenyl)-1,1-dimethylcyclopenta-2,4-dien-3-yl]benzenesulfonamide as a colorless solid: mp 163.5°-164.5° C. (dec); NMR (CDCl3) d 1.33 (s, 6H), 4.83 (br s, 2H), 6.34 (d, J=2 Hz, 1H), 6.45 (d, J=2 Hz, 1H), 6.94 (t, J=9 Hz, 2H), 7.00-7.20 (m, 2H), 7.25 (d, J=8 Hz, 2H), 7.78 (d, J=8 Hz, 2H).
