To a solution of 2-[(2-aminoethyl)amino]-8-(2,6-difluorophenyl)-4-(2-methylphenyl)pyrido[2,3-d]pyrimidin-7(8H)-one (20 mg, 0.050 mmol) in isopropanol (2 mL) was added diphenyl cyanocarbonimidate (12 mg, 0.050 mmol) and the mixture was stirred for about 1 hour at about 20° C. A 2M solution of ammonia in isopropanol (2 ml) was added and the mixture stirred at about 20° C. for about 3 days. The solvent was evaporated and the residue redissolved in 2M ammonia in isopropanol (2 mL). The mixture was irradiated with microwave at about 60° C. for about 40 min. The mixture was stored in a sealed tube for 7 days. The solvent was evaporated and the crude product was purified to give the title compound (14 mg, 59%). LC-MS m/z 475 (M+H)+, 2.93 min (ret time).
