To a solution of 3-[1-(ethylsulfonyl)-4-piperidinyl]-5-(3-formylphenyl)-1H-indole-7-carboxamide (44 mg, 0.1 mmol) in dichloromethane (2 mL) and methanol (1 mL) was added 2-methyl-1-butanamine (52 mg, 0.6 mmol) and 1 drop of acetic acid. This mixture was stirred for 2 h then sodium tetrahydridoborate (22.8 mg, 0.6 mmol) was added. The resulting mixture was stirred for 1 h. It was then concentrated and again dissolved in dimethyl sulfoxide (3 mL). It was then purified by Gilson Preparatory HPLC to give 28.4 mg of the title compound (55.6%).
