Studies on Diazepines. XXV.1)Syntheses of Fully Unsaturated 1,4-Oxazepines and 1H-1,4-Diazepines Using Photochemical Valence Isomerization of Tricycloheptene Systems

Abstract

3-Azatricyclo[4.1.0.02,5]hept-3-ene derivatives prepared from pyridines via five steps were found to be useful synthons for fully unsaturated monocyclic seven-membered heterocyclic rings. Photolysis of the 7-oxa derivatives 15 resulted in valence isomerization with ring opening to give the 1,4-oxazepines (19), which are the first examples of fully conjugated 1,4-oxazepines. Similarly, the 7-aza derivatives 16, upon irradiation, afforded the novel lH-l,4-diazepines (20). The 2,7-dimethyl-1,4-oxazepine (19c) and 2,7-dimethyl-1,4-diazepine (20c) underwent thermal ring conversion, giving rise to the 1,3-oxazepine (22) and 1,3-diazepine (24), respectively. © 1987, The Pharmaceutical Society of Japan. All rights reserved.