Reactive intermediates. Part XXII. Formation of 2H-azirines by oxidation of N-aminophthalimide in the presence of alkynes

Abstract

2H-Azirines (2) are isolated in low to moderate yields after oxidation of N-aminophthalimide by lead tetra-acetate in the presence of the alkynes propyne, but-2-yne, pent-1-yne, and hex-3-yne. A mechanism for the reaction is proposed which involves the transient formation and rearrangement of 1H-azhines (1). Some unsuccessful attempts to generate 1H-azirines by alternative routes are described. Reports that the products of the reactions of 1,2,3-triazole-4,5-dicarboxylic acid with acetic anhydride and of p-benzoquinone with p-nitrophenyl azide are 1H-azirines are shown to be incorrect.