N-Methoxy-N-methyl-(2S)-(3,4-dichlorophenyl)-4-pentenamide → 3-(S)-(3,4-dichlorophenyl)-5-hexen-2-one

Participants

Reaction Steps

A solution of 319 mg (1.11 mmoL) of N-methoxy-N-methyl-2-(S)-(3,4-dichlorophenyl)-4-pentenamide (from Step 1 above) in 10 mL of dry tetrahydrofuran was cooled to -70° C. and treated with 1.0 mL (1.40 mmol) of methyllithium and stirred between -70° C to -40° C. After 3 hours, the reaction was quenched with 5 mL of water, and diluted with 10 mL of ethyl acetate. The layers were separated and the organic layer was washed with water (3×10 mL). The aqueous layers were extracted with 10 mL of ethyl acetate. The combined organic layers were washed with 10 mL of saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography on 44 g of silica gel using 1:3 v/v ethyl acetate/hexane as the eluant afforded 250 mg (93%) of the title compound as a clear oil. 1H NMR (400 MHz, CDCl3) δ 2.07 (s, 3H), 2.36 (pentet, 1H), 2.72 (pentet, 1H), 3.64 (t, 1H), 4.95-5.01 (m, 2H), 5.55-5.65 (m, 1H), 7.03 (dd, 1H), 7.30 (d, 1H), 7.39 (d, 1H).

Provenance & Evidence