Cu-Catalyzed C(sp3)–N Coupling and Alkene Carboamination Enabled by Ligand-Promoted Selective Hydrazine Transfer to Alkyl Radicals

Selective delivery of an N-nucleophile onto an alkyl radical is a challenging step in redox catalysis. In this work, di-tert-butyl hydrazodiformate was found to be a unique effective amination reagent in Cu-catalyzed C(sp3)–N bond formation reactions that involve alkyl radical intermediates. This method is applicable to both electron-deficient and electron-rich radicals, and we were thus able to achieve the direct C–N coupling of activated bromides, as well as the carboamination of general alkenes based on this chemistry. Mechanistic studies suggest that the hydrazodiformate forms a reducing dinuclear complex with Cu and the ligand which, upon 1e-oxidation, turns into an open-shell species with the major spin density on N atoms. With the assistance of a ligand, this species can selectively deliver the hydrazine moiety onto an alkyl radical (prior to halide transfer), leading to the formation of a C(sp3)–N bond. The products obtained with this amination method could be easily deprotected to afford alkyl hydrazines and further derived to primary amines or N-heterocycles.