A mixture of 3-(4-bromobutyl)-4-thiazolidinone (4.00 g), 1-(2-benzothiazolyl)piperazine (4.05 g), K2CO3 (7.01 g), NaI (250 mg) and acetonitrile (160 mL) was heated at 93° (bath temperature) under nitrogen. After 19 h, TLC analysis (silica gel, 5% methanol/methylene chloride) showed the absence of starting bromide and the presence of a major product, Rf =0.26. The reaction mixture was cooled to room temperature, ethyl acetate (100 mL) was added, and the mixture filtered. The filtrate was concentrated in vacuo to a solid which was redissolved in ethyl acetate causing a white solid to precipitate. The mixture was filtered again and the filtrate concentrated in vacuo to 6.43 g of an off-white solid. Chromatography of the crude product by HPLC (Waters Prep 500, 1 silica gel column, 5% methanol/methylene chloride) yielded 5.44 g of an off-white solid. A sample of the solid (3.08 g) was recrystallized from methylene chloride (15 mL)/hexanes (85 mL) yielding 2.28 g of a crystalline solid, mp 111°-112° C.
