Copper(II) Ketimides in sp3 C-H Amination

Commercialy available benzphenone imine (HN=CPh2) reacts with b-diketiminato copper(II) tert-butoxide complexes [CuII]-OtBu to form isolable copper(II) ketimides [CuII]-N=CPh2. Structural characterization of the three coordinate copper(II) ketimide [Me3NN]Cu-N=CPh2 reveals a short Cu-Nketimide distance (1.700(2) Å) with a nearly linear Cu-N-C linkage (178.9(2)°). Copper(II) ketimides [CuII]-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 [CuII]-N=CPh2 to form the azine Ph2C=N-N=CPh2. Copper(II) ketimides [CuII]-N=CAr2 serve as intermediates in catalytic sp3 C-H amination of substrates R-H with ketimines HN=CAr2 and tBuOOtBu 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.</p