To a solution of 1′-[5-amino-6-(methylamino)pyrimidin-4-yl]spiro[indole-3,4′-piperidin]-2(1H)-one (100 mg, 0.30 mmol) in anhydrous ethanol (12 mL) were added pyrimidine-5-carbaldehyde (38 mg, 0.35 mmol, Apollo Scientific Ltd.) and catalytic amount of hydrochloric acid (0.05 mL, 4N, Dioxane, Aldrich). The reaction mixture was heated to 80° C. for 18 hours. The reaction mixture was cooled to room temperature and concentrated under reduced pressure. The product was purified by preparatory HPLC (reverse-phase, acetonitrile/water with 0.1% formic acid) to give 35.0 mg (28% yield) of the title compound.
