[CH2:1]([S:3][C:4]1[CH:9]=[C:8]([Cl:10])[CH:7]=[C:6]([Cl:11])[CH:5]=1)[CH3:2].C([Li])CCC.CN(C)[CH:19]=[O:20]>O1CCCC1>[Cl:10][C:8]1[CH:9]=[C:4]([S:3][CH2:1][CH3:2])[CH:5]=[C:6]([Cl:11])[C:7]=1[CH:19]=[O:20]A solution of 3,5-dichlorophenyl ethyl sulfide (1.0 g, 4.8 mmol) in tetrahydrofuran (4 mL) was cooled to −78° C. A solution of n-butyllithium (4.5 mL, 1.6 M in hexane) was added dropwise and the mixture was stirred at −78° C. for 45 minutes. N,N-dimethylformamide (4.47 mL, 57.7 mmol) was added and the mixture was stirred at −78° C. for 1 hour. The mixture was stirred at room temperature for 2 hours. The mixture was quenched with ice water and extracted three times with ethyl acetate. The combined extracts were dried with sodium sulfate, filtered and concentrated. The residue was purified by chromatography on silica gel to give the desired product (1.1 g, 97%). 1H NMR (CDCl3) δ 10.40 (s, 1H), 7.20 (s, 2H), 3.00 (m, 2H), 1.4 (m, 3H). LC/MS: 235 (M+H)+.
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