GENERAL STEPS: A mixture of 4-fluorobenzenesulfonyl chloride (2.0 g, 10.3 mmol), dimethylamine (2.0 M in methanol, 11.0 mL, 22.0 mmol), and dichloromethane (11.0 mL) was stirred at 0 °C, followed by continued stirring at room temperature for 5 min. Dichloromethane (30 mL) was added to dilute the reaction mixture. The organic phase was washed sequentially with 1 M hydrochloric acid (30 mL) and saturated brine (30 mL), dried over anhydrous magnesium sulfate and filtered. The solvent was removed by concentration under reduced pressure to give 4-fluoro-N,N-dimethylbenzenesulfonamide as a white solid (2.12 g, quantitative yield). A mixture of 4-fluoro-N,N-dimethylbenzenesulfonamide (1.50 g, 7.39 mmol), sodium thiosulfate (2.08 g, 29.7 mmol), and N,N-dimethylformamide (9.0 mL) was placed in a sealed tube and the reaction was stirred for 16 h at 170 °C. The reaction was completed by cooling to room temperature. After completion of the reaction, it was cooled to room temperature and 1 M sodium hydroxide solution (40 mL) was added. The aqueous phase was washed with ether (2 x 40 mL) and subsequently acidified with 2M hydrochloric acid to pH < 2 and extracted with ether (3 x 40 mL). The organic phases were combined, dried over anhydrous magnesium sulfate and filtered. The solvent was removed by concentration under reduced pressure to afford 4-mercapto-N,N-dimethylbenzenesulfonamide as an orange oil (503 mg, 31% yield).1H NMR (500 MHz, CDCl3) δ 7.67-7.58 (m, 2H), 7.43-7.35 (m, 2H), 3.67 (s, 1H), 2.71 (s, 6H).
