Reaction of Methyl (E)-2-Phenyl-1-azirine-3-acrylates with Hydrazines and Amidines. Synthetic and Mechanistic Implications

Article abstract of DOI:10.1021/jo00001a004

1-Azirines 2a-b react with hydrazine in methanol to produce hexahydropyrrolo<3,2-c>pyrazol-5-ones 3a-b.The process is suggested to involve intramolecular interception of an unstable 4-aminopyrazoline intermediate resulting from C=N bond cleavage.Reaction of 2a with phenylhydrazine similarly affords 3c.In dimethyl sulfoxide, on the other hand, formamidine, guanidine, and hydrazine afford imidazole 4, pyrimidines 5a-b, amino-s-triazine 6, or triazole 9 as a consequence of C-C bond cleavage in aziridine intermediate 8.The intermediacy of tautomers is proposed to account for the diversity of products in this case.