Total Synthesis of 4-Acetyl-1,3-Dihydroimidazo[4,5- c ]Pyridin-2-One, a New Microbial Metabolite from a Streptomyces Species

The structure of a new secondary metabolite from Streptomyces sp. was determined as 4-acetyl-1,3-dihydroimidazo[4,5-c]pyridin-2-one by synthesis of the natural product itself and of the regioisomeric 7-acetylimidazo[4,5-b]pyridine derivative. The former compound was prepared, in 28% overall yield, in a sequence of nitration, reduction, condensation, and Stille reaction of 4-aminopyridine, while the regioisomer was obtained in 5% overall yield by amination, nitration, reduction, condensation, and oxidation of 4-ethylpyridine.