Synthesis of imidazo[4,5-b]pyridines from aminoimidazolecarbaldehydes

4-Amino-1,2-dimethylimidazole-5-carbaldehyde (1) and 5-amino-1-methylimidazole-4-carbaldehydes 3 were prepared by reduction of the corresponding aminoimidazolecarbonitriles 2 and 4. Condensation of 1 and 3 with carbonitriles, ketones and polyfunctional carbonyl compounds bearing the -CH2CO- moiety afforded to the imidazo[4,5-b]pyridine derivatives.