Directed Solid-Phase Synthesis of Trisubstituted Imidazo[4,5-c]pyridines and Imidazo[4,5-b]pyridines
文摘
An efficient method is described for the solid-supported synthesis of imidazo[4,5-b]pyridines and imidazo[4,5-c]pyridines from 2,4-dichloro-3-nitropyridine. The key pyridine building block was reacted with polymer-supported amines, followed by replacement of the second chlorine with amines, nitro group reduction, and imidazole ring closure with aldehydes. Depending on the combination of polymer-supported and solution-phase reagents, the strategy allowed for the simple preparation of the target trisubstituted derivatives with variable positioning of the pyridine nitrogen atom. Additionally, after a slight modification of the method, the preparation of strictly isomeric imidazopyridines was possible.
Keywords:
solid-phase synthesis; imidazo[4,5-b]pyridines; imidazo[4,5-c]pyridines; 1-deazapurines; 3-deazapurines; 2,4-dichloronitropyridine