Nucleophilic α- and β-Additions Enable Redox-Neutral Aziridination of Conjugated Hydroxamates.

Abstract

Aziridination of olefins using nonprotected primary amines as nitrogen donors under oxidative conditions is highly desirable but poses challenges due to the incompatibility of nonprotected amines with oxidants. To address this issue, a strategy to leverage an internal oxidant is proposed. This method enables nucleophilic α- and β-additions of amines to conjugated hydroxamates, allowing for the assembly of complex aziridines from simple and safe building blocks. Benefiting from this internal oxidant concept, electron-rich anilines are directly employed to access N-aryl aziridines. Beyond aziridination, olefin 1,2-diamination can also be achieved when secondary amines are used. Mechanistic studies suggest that an α-lactam intermediate is involved in this aziridination to enable the redox-transposition. In a broader context, this transformation represents a novel type of nucleophilic α-addition, which is rare compared to the more common β-addition (the Michael addition).