A mixture of 4.92 mmol rac-2-benzenesulfonyl-2-methyl-3-trifluoromethyl-oxirane and 5.41 mmol 4-thiocarbamoyl-piperazine-1-carboxylic acid tert-butyl ester (prepared from tert-butyl 1-piperazinecarboxylate, 1,1′-thiocarbonyldiimidazole and ammonia according to the procedure of J. Med. Chem. 1998, 41, 5037–5054) in 15 ml N,N-dimethylformamide was heated at 100° C. for 4.5 h. The reaction mixture was then concentrated in vacuo and the residue purified by chromatography (SiO2, ethyl acetate/heptane) to afford the title compound as a yellow crystalline solid (yield 30%). MS (m/e): 352.3 (M+H+, 100%).
