1-(4-Chlorophenyl)pyrrolidine-3-carboxylic acid → 1-[1-(4-Chlorophenyl)-pyrrolidin-3-yl]-pent-4-en-1-one

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Reaction Steps

A solution of 1-(4-chlorophenyl)-pyrrolidine-3-carboxylic acid and methoxy-methyl amide (1.1 g, 4.1 mmol) in tetrahydrofuran (20 mL) was cooled to 0° C. while maintaining the solution under an at mosphere of nitrogen. To the cold solution was added a THF solution of 4-butenylmagnesium bromide (0.5M in THF, 16.4 mL, 8.2 mmol) in a dropwise manner. After stirring for 1 hour the bath was removed and stirring was continued overnight. The resulting solution was poured into water, acidified to pH 3-4 with 1 N hydrochloric acid and extracted with ethyl acetate (3×). The combined organic phase was washed with saturated aqueous sodium chloride, dried over anhydrous magnesium sulfate, filtered and concentrated. Purification of the crude by flash column chromatography (silica gel, 0-25% ethyl acetate in heptane) gave the title compound as a colorless oil (940 mg, 87%); 1H NMR (CDCl3, 300 MHz) δ 7.15 (d, J=9 Hz, 2H), 6.46 (d, J=9 Hz, 2H), 5.81 (m, 1H), 5.12 (m, 2H), 3.54 (m, 2H), 3.26-3.39 (m, 3H), 2.62 (m, 2H), 2.36 (m, 2H) and 2.12-2.26 (m, 2H).

Provenance & Evidence