Terminal Copper-Nitrene Species in Angewandte Chemie

High-valent terminal copper-nitrene species have been postulated as key intermediates in copper-catalyzed aziridination and amination reactions. The high reactivity of these intermediates has prevented their characterization for decades, thereby making the mechanisms ambiguous. Very recently, the Lewis acid adduct of a copper-nitrene intermediate was trapped at á90ñáC and shown to be active in various oxidation reactions. Herein, we describe for the first time the synthesis and spectroscopic characterization of a terminal copper(II)-nitrene radical species that is stable at room temperature in the absence of any Lewis acid. The azide derivative of a triazamacrocyclic ligand that had previously been utilized in the stabilization of aryl-CuIII intermediates was employed as an ancillary ligand in the study. The terminal copper(II)-nitrene radical species is able to transfer a nitrene moiety to phosphines and abstract a hydrogen atom from weak CáH bonds, leading to the formation of oxidized products in modest yields.

The results were published today in Angewandte Chemie International Edition:
T. Corona, L. Ribas, M. Rovira, E.R. Farquhar, X. Ribas, K. Ray, and A. Company
“Characterization and Reactivity Studies of a Terminal Copper-Nitrene Species”
Angew. Chem. Int. Ed. 2016, 55, 14005-14008
[abstract]
DOI: 10.1002/anie.201607238