Three-Component Condensation of 4-Imino-1-Phenylimidazolidin-2-One with Aldehydes and Meldrum's Acid: Synthesis of Imidazo[4,5-b]Pyridine-2,5(4H,6H)-Diones and 5-Substituted 1-Phenylhydantoins

A convenient method for the synthesis of previously unknown imidazo[4,5-b]pyridine-2,5(4H,6H)-diones has been developed, based on a three-component condensation of 4-imino-1-phenylimidazolidin-2-one with aldehydes and Meldrum's acid. The possibility of accessing 5-substituted 1-phenylhydantoins based on the acid hydrolysis of imidazo[4,5-b]pyridine-2,5(4H,6H)-diones was shown.