The Isomerization of Aziridine Derivatives

Derivatives of aziridine or ethylenimine are isomerized by acids, nucleophilic reagents, or pyrolysis. All of the isomerizations reported so far are ring‐opening reactions, predominantly involving cleavage of the carbon‐nitrogen bond of the ring, although a few isomerizations are known in which the carbon‐carbon bond of the ring is broken. Isomerization of appropriate aziridine derivatives provides useful synthetic pathways leading to heterocyclic systems such as oxazolines, imidazolines (and related systems), imidazolidinoes, thiazolines, pyrazolines, and triazolines. Other isomerizations form N‐unsaturated amides, anils, and isocyanates.