An Efficient Synthesis of 6-Nitro- and 6-Amino-3H-imidazo[4,5-b]pyridines by Cyclocondensation of 1-Substituted 1H-Imidazol-5-amines with 3-Nitro-4H-chromen-4-one.

The reaction of 3-nitro-4<italic>H</italic>-chromen-4-one with in situ generated 1-substituted 5-amino-1<italic>H</italic>-imidazoles affords a set of 1-substituted 6-nitro-3<italic>H</italic>-imidazo[4,5-<italic>b</italic>]pyridines which represent potential adenosine deaminase (ADA) inhibitors. Reduction of the nitro group results in the formation of the corresponding 6-amino-3<italic>H</italic>-imidazo[4,5-<italic>b</italic>]pyridines. [ABSTRACT FROM AUTHOR]