Synthesis of 6-Substituted 2-(N-Acetylamino)pyridines and 2-Aminopyridines by Cyclization of 5-Oximinoalkanenitriles

Article abstract of DOI:10.1021/jo00056a021

Oxime derivatives of 5-oxoalkanenitriles (C6 chain or longer) were cyclized in most cases with a combination of AcCl and Ac2O, or Ac2O and HCl to 6-substituted 2-(N-acetylamino)pyridines.Alkaline hydrolysis gave the corresponding 2-aminopyridines in overall yields of 40-65 percent, with the exception of pyridine 3e.Oxime derivatives of 5-oxopentanenitriles did not cyclize but gave glutaronitriles instead.In some experiments with 5-oximinohexanenitrile (1a), 2,4-dimethyl-5-(2-cyanoethyl)oxazole (9) was detected in addition to the main product, 2-(N-acetylamino)-6-methylpyridine (2a).Formation of these compounds can be explained on the basis of a common intermediate 7 formed through rearrangement of the O-acetylated 5-oximinohexanenitrile (4).