To a solution of 540 mg (3.53 mmol) of 3,5-difluorophenylacetonitrile in 8 mL of THF a solution of 1.41 mL (3.53 mmol) of butyllithium (2.5M solution in hexanes) was added and it was stirred for 30 minutes at −78° C. Then a solution of 985 mg (3.21 mmol) of 1-[bis(4-chlorophenyl)methyl]azetidin-3-one (1) in THF was added and it was stirred for 3 h at −78° C. Then 510 mg (4.17 mmol) of 4-dimethylaminopyridine, 840 uL(4.82 mmol) of N,N-diisopropylethylamine and 558 uL (7.06 mmol) of methanesulfonyl chloride was added and it was stirred at −78° C. to rt overnight. The solution was poured into 80 mL of ether and washed with 10 mL of aq NaHCO3. The organic layer was dried over Na2SO4 and concentrated. The residue was purified by silica gel chromatography with hexanes/ethyl acetate=9:1 to afford the title compound; 1NMR(CDCl3) δ 3.84 (m, 2H), 4.25 (m, 2H), 4.54 (s, 1H), 6.76 (m, 1H), 6.78 (m, 2H), 7.33 (m, 3H), 7.38 (m, 2H); Mass Spectrum: m/e=430 (M+1 35Cl, 35Cl) and 432 (M+1 35Cl, 37Cl).
