Methyl 2-(piperazin-1-yl)benzo[d]thiazole-6-carboxylate (0.35 g, 1.26 mmol), Boc-L-2-thienylalanine (0.34 g, 1.26 mmol), diisopropylethylamine (0.88 ml, 5.06 mmol) and HBTU (0.62 g, 1.64 mmol) were dissolved in DMF (36 ml) and the resulting mixture stirred overnight. The resulting mixture was then diluted with ethyl acetate (78 ml), washed with 1N HCl (3×39 ml), washed with brine (39 ml), dried (MgSO4) and concentrated in vacuo. The resulting residue was chromatographed eluting with dichloromethane/methanol (97:3) to yield (S)-methyl 2-(4-(2-(tert-butoxycarbonylamino)-3-(thiophen-2-yl)propanoyl)piperazin-1-yl)benzo[d]thiazole-6-carboxylate.
