Hydrochloric Acid → Benzenesulfonamide

A solution of N,2-dimethylbenzenesulfonamide (3.70 g, 20.0 mmol) in dry tetrahydrofuran (75 ml) was cooled to -78° with stirring under nitrogen. n-Butyllithium in hexanes (1.6 M, 28 ml, 44 mmol) was added dropwise over 1/2 hour. After 2 hours at -78°, a solution of trimethyltin chloride (4.42 g, 22.0 mmol) in dry tetrahydrofuran (20 ml) was added dropwise. The reaction mixture was allowed to warm to 0° over 1 hour, and then 5% HCl (50 ml) was added dropwise at a rate to maintain an internal temperature less than 10°. After concentrating the reaction mixture in vacuo, the product was extracted into methylene chloride (3×100 ml), washed with water (2×200 ml), dried (MgSO4), filtered and concentrated. Purification by flash chromatography (SiO2, hexane/ethyl acetate, 8:2) gave N-methyl-2-[(trimethylstannyl)methyl)]benzenesulfonamide (3.4 g, 49%) as a white powder, m.p. 59° -60°.