To a solution of 3-[1-(ethylsulfonyl)-4-piperidinyl]-5-(5-formyl-3-thienyl)-1H-indole-7-carboxamide (600 mg, 1.35 mmol) in dimethyl sulfoxide (10 mL) was added of 20 drops of acetic acid and 2-methylpyrrolidine (1.37 mL, 13.5 mmol). The resulting mixture was stirred at room temperature for 6 h followed by an addition of sodium triacetoxyborohydride (2.86 g, 13.5 mmol). The reaction was stirred at room temperature overnight then purified by Gilson Preparatory HPLC. This compound was then separated to give the title compound as 98.6% chirally pure.
