The synthesis of imidazo[4,5-d]pyridines from a substituted imidazole and acyl or sulfonyl acetonitrile

1-Aryl-5-amino-4-cyanoformimidoyl imidazoles were reacted with acyl and sulfonyl acetonitriles, under mild experimental conditions, leading to imidazo[4,5-b]pyridines and imidazo[4,5-b]pyridine-5-ones. A reaction intermediate could be isolated in the reaction with methyl cyanoacetate, under carefully controlled experimental conditions. This intermediate cyclized to imidazo[4,5-b]pyridine-5-one, in the presence of DBU. Reaction between 5-amino-4-cyanoformimidoyl-1-(4-fluorophenyl)imidazole and acetylacetone, occurred by a different pathway to give a 6-carbamoylpurine.