To a solution of 112 mg (0.53 mmol) of 5-chloro-6-fluoro-1H-indole-7-carboxylic acid and 169 mg of TBTU (0.53 mmol) in 6 ml DMF, were added 0.45 ml (2.63 mmol) of N,N-diisopropylethyl amine. After stirring for 5 min at rt, 200 mg (0.57 mmol) of (4-tert-butyl-benzyl)-[2-(3-fluoro-5-trifluoromethyl-phenyl)-ethyl]-amine in 2 ml DMF were added. After stirring for 21 h at rt, the reaction mixture was diluted with 80 ml water and extracted with EtOAc (2×). The combined organic phases were washed with water and brine, dried with magnesium sulfate, filtered and concentrated in vacuo. The residue was purified by column chromatography (40 g silica gel; DCM/heptane 9:1) to give 158 mg off-white solid (48%). MS (EI) 548.2 (M)+.
