合成路线1

Treatment of substituted pyrimidine (I) with an aqueous solution of methylamine in HOAc/THF provides monomethylamino derivative (II), whose nitro group is hydrogenated over Ni-Raney in MeOH/HOAc to afford 5-amino compound (III). Condensation of (III) with aldehyde (IV) in HOAc/MeOH forms the Schiff base (V), which is converted into substituted purine (VI) by oxidative ring closure with FeCl3 in refluxing EtOH and posterior treatment with HCl in refluxing H2O/THF. Diazotization-substitution reaction of (VI) with diiodomethane, CuI and isoamyl nitrite in THF furnishes 2-iodo compound (VII), which is subjected to a cross-coupling reaction with alkyne (VIII) by means of bistriphenylphosphine palladium dichloride, cuprous iodide and Et3N in THF to afford 2-alkynyl compound (IX). Finally, the desired product is obtained by amination of (IX) with ammonia either in EtOH or in H2O/1,2-dimethoxyethane.