Dichloromethane → tert-Butyl 4-(thiophene-2-sulfonyl)piperazine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

A 1 L round-bottomed flask was charged with tert-butyl piperazine-1-carboxylate (20.70 g, 111 mmol, Sigma-Aldrich, St. Louis, Mo.), 300 mL of CH2Cl2, and triethylamine (17.81 mL, 128 mmol). After cooling to 0° C., 2-thiophenesulfonyl chloride (21.31 g, 117 mmol, Sigma-Aldrich, St. Louis, Mo.) was added and the reaction was stirred at 0° C. for 30 min. The mixture was diluted with water (200 mL) and the layers were separated, dried (MgSO4) and concentrated to give tert-butyl 4-(thiophen-2-ylsulfonyl)piperazine-1-carboxylate (37.0 g) as a white solid. To this solid was added 300 mL of EtOAc, and 4 N HCl in dioxane (100 mL). The mixture was heated to 65° C. to give a clear solution. Over the course of 2 h, a white precipitate formed. The white precipitate was collected by filtration and dried under reduced pressure to give 4-(thiophen-2-ylsulfonyl)piperazine hydrochloride (26.0 g).

Provenance & Evidence