Trifluoroacetic acid → 1-(Naphthalene-2-sulfonyl)-piperazine

Participants

Reaction Steps

A solution of N-tert-butyoxycarbonylpiperazine (2a) (1.86 g) in DCM (100 mL) and N,N-di-2-propyl-ethylamine (2 mL) was cooled in ice-water as a solution of 2-naphthalenesulfonylchloride (2.27 g) in DCM (50 mL) was added drop-wise. After addition, the cooling was removed and the reaction stirred overnight. The solvent was evaporated and the residue partitioned between water and ethyl acetate. The organic phase was sequentially washed with 0.5 N hydrochloric acid, water, saturated aqueous sodium bicarbonate and brine. After drying, the solvent was evaporated to provide a white solid. The white solid was dissolved in DCM (35 mL) and treated with trifluoroacetic acid (15 mL). After one hour, the solvent was evaporated, the residue suspended in water and the solution made basic with 1 N sodium hydroxide. The mixture was extracted with ethyl acetate. The extracts were washed with water, dried, and the solvent evaporated to give a white solid (2.7 g).

Provenance & Evidence