Intermolecular amination of allenes via 2-fold photocatalytic nitrene transfer reactions

The amination with monovalent, nitrogen- based intermediates constitutes an important reaction for the construction of valuable amines. The high basicity of reagents, reaction intermediates, or products, however, poses significant challenges to metal-catalyzed amination through coordination and blocking of catalytically active sites and hampering of their efficiency. In this context, high- yielding intermolecular amination reactions of allenes remain an unsolved challenge in organic synthesis, and general methods are not available. Herein, we describe a photochemical approach toward the intermolecular amination of allenes via free nitrene radical anions as the key reactive intermediate. This reaction proceeds without the participation of catalyst-bound nitrogen species and can thus overcome current limitations. We report on the application in the amination of allenes to give azetidine and cyclopropyl amines with a broad and general substrate scope. Experimental and theoretical studies were performed to provide an understanding of the reaction mechanism and rationalize the high efficiency of this photocatalytic approach.

Automated summary

The amination with monovalent, nitrogen-based intermediates is important in organic synthesis, but the high basicity of reagents poses challenges to metal-catalyzed amination. We describe a photochemical approach using free nitrene radical anions as reactive intermediates for intermolecular amination of allenes, which overcomes current limitations.