1-propylsulfonylpiperazine

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirring ice-cold solution of tert-butyl 4-(propylsulfonyl)piperazine-1-carboxylate (2, 15.70 g, 53.69 mmol) in CH2Cl2 (200 mL) was slowly added trifluoroacetic acid (21.4 mL, 268.45 mmol). The mixture stirred at room temperature for 16 h under an atmosphere of N2. The mixture was washed with 2 N NaOH (3×50 mL), H2O (50 mL), brine (50 mL), dried (Na2SO4), filtered, and concentrated under reduced pressure to afford 1-(propylsulfonyl)piperazine (3) as a crystalline solid (10.30 g quantitative): 1H NMR (500 MHz, CDCl3) δ 7.91 (d, J=1.7 Hz, 1H), 7.48 (d, J=1.6 Hz, 1H), 7.21 (m, 1H), 7.14 (s, 1H), 7.09 (s, 1H), 3.96 (s, 3H), 3.75 (s, 3H). The mixture was washed with 2 N NaOH (3×50 mL), H2O (50 mL), brine (50 mL) dried (Na2SO4) filtered concentrated under reduced pressure