Deazapurine derivatives XIII 5,7‐Disubstituted imidazo[4,5‐b]pyridines. A new synthesis of 1‐deazaguanine

Abstract
A number of 7‐substituted‐5‐acetamido imidazo[4,5‐b]pyridines, useful in ribose coupling reactions, were synthesized by application of the ring‐closure reaction with ethyl orthoformate and acetic anhydride. A new synthesis of 1‐deazaguanine, using mild reaction conditions and a possible preparation of 1‐deazaxanthine is described.