Ammonia → Cyclopentaneethanesulfonamide

A solution of 2-(cyclopentyl)ethanesulfonyl chloride (14.1 g, 71.4 mmol) in dry tetrahydrofuran (40 ml) was saturated with gaseous ammonia at 0° C. The resulting solution was stirred at room temperature under nitrogen for 2 hours and then concentrated under vacuum. The residue was dissolved in ethyl acetate (50 ml) and water (50 ml) and the aqueous phase was then acidified to pH 2 with 2.0 M aqueous hydrochloric acid. The organic phase was separated and then washed with water (2×30 ml), dried (sodium sulfate) and concentrated under vacuum. Purification of the residue by chromatography on silica (500 g) using 65/35 pentane/ethyl acetate as eluant gave the title compound as an off-white solid (6.48 g), Rf 0.7 (pentane/ethyl acetate 1:1).