Nondirected Cu-Catalyzed sp3 C–H Aminations with Hydroxylamine-Based Amination Reagents: Catalytic and Mechanistic Studies

摘要

This work demonstrates the use of hydroxylamine-based amination reagents RSO2NH-OAc for the nondirected, Cu-catalyzed amination of benzylic C–H bonds. The amination reagents can be prepared on a gram scale, are benchtop stable, and provide benzylic C–H amination products with up to 86% yield. Mechanistic studies of the established reactivity with toluene as substrate reveal a ligand-promoted, Cu-catalyzed mechanism proceeding through Ph-CH2(NTsOAc) as a major intermediate. Stoichiometric reactivity of Ph-CH2(NTsOAc) to produce Ph-CH2-NHTs suggests a two-cycle, radical pathway for C–H amination, in which the decomposition of the employed diimine ligands plays an important role.