Process for preparing imidazopyridine derivatives

Abstract From the Canadian patent

A process is disclosed for preparing imidazopyridine derivatives of the general formula: (I), where R1 is hydrogen or an alkyl group and R2 R3 and R4 are, identical or different and are each hydrogen an alkyl, cycloalkyl, aryl or aralkyl group or a halogen atom in which process a 2-amino-3-nitropyridine is hydrogenated in the presence of a hydrogenation catalyst and the hydrogenation product is condensed with a carboxylic acid simultaneously present in the reaction mixture to give the end product. The imidazopyridine derivatives are intermediates for the preparation of angiotensin II antagonists.