To a solution of 1-[6-methyl-4-(trifluoromethyl)pyridin-2-yl]piperazine (280 mg, 1.1 mmol), (1S,3R)-3-[(tert-butoxycarbonyl)amino]-1-isopropylcyclopentanecarboxylic acid (460 mg, 1.7 mmol) in methylene chloride (30 mL) was added benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate (0.60 g, 1.4 mmol), and triethylamine (0.20 g, 2.0 mmol). After being stirred overnight, the reaction mixture was diluted with methylene chloride, washed with brine, dried over sodium sulfate, filtered and concentrated. The crude residue was purified by flash column chromatography to provide the desired product (200 mg, 35.1%). LCMS calculated for C25H37F3N4O3: (M+1) 499.3; found 499.2.
