Studies on Ring-Opening of Heterocyclic Compounds.IV. : Alternative Preparation of N-Substituted Iminopyridinium and N-Substituted Iminoisoquinolinium Betaines

Ring opening of N-(2, 4-dinitrophenyl)pyridinium chloride (1) with acylhydrazine or arylhydrazine derivatives followed by cyclization of the resulting 5-(2, 4-dinitroanilino)-2, 4-pentadienal hydrazone (2a-l) gave N-acylimino or N-aryliminopyridinium betaines (3a-l) (Table I). N-Substituted imino-3-picolinium (3m-o), N-substituted imino-3, 5-lutidinium (3p-r), and N-substituted iminoisoquinolinium betaines (9a-l) were also prepared from 3-picoline, 3, 5-lutidine, and isoquinoline, respectively, by a similar procedure (Table II and III).