To 5-(5-formyl-1-benzothien-2-yl)-4-(1H-indol-4-ylamino)nicotinonitrile 223 (166 mg, 0.38 mmol) in THF (7 mL) was added dimethylamine in THF (2.0 M, 0.58 mL, 1.15 mmol) followed by acetic acid (126 mg, 2.09 mmol). The resulting mixture was stirred at r.t. for 1 h and additional dimethylamine (1.2 mL, 2.30 mmol) was added. After stirring at r.t. for an additional hour, Na(OAc)3BH (242 mg, 1.15 mmol) was added. The reaction mixture was stirred at r.t. for 2 h and was partitioned between diluted HCl and EtOAc. The combined aqueous extracts were basified with aqueous NaHCO3 and extracted with EtOAc. The combined organics were dried over Na2SO4, concentrated and purified by flash column chromatography to give 115 mg (65%) of 5-{5-[(dimethylamino)methyl]-1-benzothien-2-yl}-4-(1H-indol-4-ylamino)nicotinonitrile 224 as a pale yellow solid. MS: 424.2 (M+H); HPLC retention time: 2.1 min.(a).
