General procedure for the synthesis of 4-amino-N-phenethylbenzenesulfonamide from 4-nitro-N-phenethylbenzenesulfonamide: Concentrated hydrochloric acid (10-15 mL) was slowly added to a mixture of ethanol (10 mL) containing 4-nitro-N-phenethylbenzenesulfonamide or its analog (13a-q, 1.4 mmol, 1 equiv.) and tin particles (2-2.5 equiv.). The reaction mixture was refluxed for 3.5-6 hours. The progress of the reaction was monitored by thin layer chromatography (TLC) until the feedstock completely disappeared. Upon completion of the reaction, the mixture was cooled to room temperature. Subsequently, 30% or 5 M aqueous sodium hydroxide solution was slowly added to the mixture until the reaction mixture became alkaline. The mixture was extracted with ethyl acetate (EA) or dichloromethane (DCM) and the organic layer was dried with anhydrous sodium sulfate (Na2SO4). The solvent was removed by evaporation under reduced pressure. If necessary, the product was purified by column chromatography. Using 13j (0.37 g, 1.2 mmol) as raw material, 4-amino-N-phenylethylbenzenesulfonamide (14j) was obtained as a yellow solid (0.39 g, 100% yield), which was ready to be used without further purification, according to the above described General Procedure B. The 1H NMR (DMSO-d6) data were as follows: δ 2.64 (2H, t, J = 7.7 Hz), δ 2.85 (2H, dt, J = 7.7, 5.8 Hz), 5.92 (2H, s), 6.60 (2H, d, J = 8.6 Hz), 7.12 (2H, d, J = 8.2 Hz), 7.20 (1H, t, J = 6.3 Hz), 7.26 (2H, t, J = 7.6 Hz), 7.40 (2H, d, J = 8.6 Hz).
