Copper(II) Ketimides in sp3 C-H Amination

Commercialy available benzphenone imine (HN=CPh₂) reacts with b-diketiminato copper(II) tert-butoxide complexes [Cu^II]-O^tBu to form isolable copper(II) ketimides [Cu^II]-N=CPh₂. Structural characterization of the three coordinate copper(II) ketimide [Me₃NN]Cu-N=CPh₂ reveals a short Cu-N_ketimide distance (1.700(2) Å) with a nearly linear Cu-N-C linkage (178.9(2)°). Copper(II) ketimides [Cu^II]-N=CPh₂ readily capture alkyl radicals R• (PhCH(•)Me and Cy•) to form the corresponding R-N=CPh₂ products that competes with N-N coupling of copper(II) ketimides [Cu^II]-N=CPh₂ to form the azine Ph₂C=N-N=CPh₂. Copper(II) ketimides [Cu^II]-N=CAr₂ serve as intermediates in catalytic sp³ C-H amination of substrates R-H with ketimines HN=CAr₂ and ^tBuOO^tBu as oxidant to form N-alkyl ketimines R-N=CAr₂. This protocol enables the use of unactivated sp³ C-H bonds to give R-N=CAr₂ products easily converted to primary amines R-NH₂ via simple acidic deprotection.