Rearrangement and cycloaddition routes to novel heterocyclic systems

Part I of this thesis describes the treatment of tetrahydro-4-oxoisoxazolo[2,3-alpyridinium, phenyl hydrazone (70) with boiling acetic anhydride to give pyrazolo [4,3-b]pyridine (75) and the pyrrolo[3,2-b] pyridone (74)» or on longer heating, further acetylation to give compounds (78) and (79) plus tri-N- (acetyl)phenylhydrazine (75)» The Introduction to Part I contains a brief review of the reaction of nucleophiles with differing substituted isoxazolium salts. Part II contains the synthesis of pyrido[3,2-c]pyridazine (87) from 2-vinyl pyridine (90) and diesters of azodicarboxylic acid. The synthesis is then extended to include other vinyl heterocyclic systems. The Introduction gives a review of addition of dienophiles to vinyl heterocyclic compounds with a brief summary of cycloaddition and ene reactions of diesters of azodicarboxylic acid