In an argon gas stream and at −78° C., n-butyl lithium (a 1.57M hexane solution, 0.294 ml, 0.461 mmol) was added to a solution of 2-[5-(t-butyldimethylsilyloxy)-1-[(4-chlorophenyl)sulfonyl]pentyl]-1,4-difluorobenzene (205 mg, 0.419 mmol) in tetrahydrofuran (4 ml). The mixture was stirred at room temperature for 1 hour. After cooling to −78° C., iodomethane (0.339 ml, 0.545 mmol) was added dropwise to the reaction mixture and the mixture was stirred at room temperature for 4 hours. Water was added to the reaction mixture, followed by extraction with diethyl ether. The extracts were combined, washed successively with water and brine, dried over MgSO4, and then concentrated. The residue thus obtained was purified by medium-pressure chromatography on a silica gel column (6% ethyl acetate-hexane), whereby the title compound (168 mg, 80%) was obtained as a colorless oil.
