General procedure for the synthesis of 2-amino-4-cyanopyrimidine from zinc cyanide and 2-amino-4-iodopyrimidine: a solution of N-methylpyrrolidone (NMP, 75 mL) containing 2-amino-4-iodopyrimidine (4.09 g, 18.5 mmol) was placed in a flask and purged with argon for 5 min to remove oxygen. Subsequently, zinc cyanide (2.28 g, 19.4 mmol) and tetrakis(triphenylphosphine)palladium(0) (1.71 g, 1.48 mmol) were added, and the reaction mixture was stirred at 80 °C for 2 hours. After completion of the reaction, the mixture was cooled to room temperature, ethyl acetate (EtOAc, 200 mL) and 30% ammonia (NH4OH, 200 mL) were added, and stirring was continued for 1 hour. The organic and aqueous layers were separated and the aqueous layer was extracted with ethyl acetate (4 x 200 mL). All organic layers were combined and concentrated under reduced pressure. Ether (Et2O, 30 mL) was added to the concentrate, the precipitate was collected by filtration and washed with ether to afford 2-amino-4-cyanopyrimidine (1.66 g, 13.8 mmol, 75% yield) as a white solid. The product was characterized by 1H NMR (400 MHz, DMSO-d6): δ 8.51 (d, J = 4.7 Hz, 1H), 7.31 (br.s, 2H), 7.08 (d, J = 4.7 Hz, 1H). Mass spectrum (ESI, cation mode) m/z: 121.1 ([M+H]+).
