SYNTHETIC APPROACHES TOWARD THE BI(2H-AZIRINE) SYSTEM

Three different approaches toward the synthesis of the bi(2H-azirine) system (2) were investigated. The first route is based on a modified Neber reaction in which the bis(trimethylhydrazonium) salt of 2, 3-dimethyl-1, 4-diphenyl-1, 4-butanedione was treated with base. No indication of any bi(2H-azirine) could be detected in this reaction. In a second approach, the reaction of 2-styryl-3-phenyl-2H-azirine with iodine azide was investigated. The major product isolated fromthis reaction was l-phenyl-5-(l-azidocinnamyl)tetrazole. Subsequent studies with model systems showed that the reaction of iodine azide with 3-phenyl-2-substituted 2H-azirines gives azidotetrazoles in moderate yield. The reaction is believed to involve the addition of iodine azide across the C-N double bond followed by ring opening of a transient iodoaziridine. Attack of azideon the incipient carbonium ion followed by electrocyclization of the azidoimine formed readily accommodates the formation of the tetrazole ring. The third approach utilized for the synthesi of the bi(2H-azirine) system involved an attempt to dimerize 2-chloro-2H-azirines with activated metals or by electrolysis. A sample of 2-chloro-2-methyl-2-phenyl-2H-azirine was found to rearrange to the isomeric 2-chloro-3-methyl-2-phenyl-2H-azirine in solution. This rearrangement is consistent with the intermediacy of an azacyclopropenyl ion-chloride pair. All attempts atdimerization proved unsuccessful. © 1979, American Chemical Society. All rights reserved.