Heterocyclic imines and amines. Part XV. Reactions of hydrazines with 1,3-di-iminoisoindoline and related compounds

Abstract

The ring-expansion reactions of 1,3-di-iminoisoindoline with hydrazine are detailed. In the cold, 1,4-diamino-phthalazine is given; in boiling butanol, 1,4-dihydrazinophthalazine; and under reflux, bis-(4-aminophthalazin-1-yl) together with phthalazin-1 (2H)-one, which is the major product at higher temperature. Methylhydrazine likewise effects ring expansion to give 4-amino-1,2-dihydro-1-imino-2-methylphthalazine, which is hydrolysed to 4-amino-2-methylphthalazin-1 (2H)-one, also obtained from 3-iminoisoindolinone and methylhydrazine and by methylation of 4-aminophthalazin-1 (2H)-one. Phenylhydrazine merely displaces an exocyclic imino-group of di-iminoisoindoline and of 3-iminoisoindolinone to yield phenylhydrazonoisoindolines or tautomers. Hydrazine adds to phthalonitrile in the presence of ethoxide, and reacts with monothiophthalimide, to give hydra-zonoisoindolines which readily isomerise to aminophthalazines. The structures of the benzoyl derivatives of 4-aminophthalazinone have been established.