Copper(ii) ketimides in sp(3) C–H amination

Commercially available benzophenone imine (HN[double bond, length as m-dash]CPh(2)) reacts with β-diketiminato copper(ii) tert-butoxide complexes [Cu(II)]–O(t)Bu to form isolable copper(ii) ketimides [Cu(II)]–N[double bond, length as m-dash]CPh(2). Structural characterization of the three coordinate copper(ii) ketimide [Me(3)NN]Cu–N[double bond, length as m-dash]CPh(2) 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[double bond, length as m-dash]CPh(2) readily capture alkyl radicals R˙ (PhCH(˙)Me and Cy˙) to form the corresponding R–N[double bond, length as m-dash]CPh(2) products in a process that competes with N–N coupling of copper(ii) ketimides [Cu(II)]–N[double bond, length as m-dash]CPh(2) to form the azine Ph(2)C[double bond, length as m-dash]N–N[double bond, length as m-dash]CPh(2). Copper(ii) ketimides [Cu(II)]–N[double bond, length as m-dash]CAr(2) serve as intermediates in catalytic sp(3) C–H amination of substrates R–H with ketimines HN[double bond, length as m-dash]CAr(2) and (t)BuOO(t)Bu as oxidant to form N-alkyl ketimines R–N[double bond, length as m-dash]CAr(2). This protocol enables the use of unactivated sp(3) C–H bonds to give R–N[double bond, length as m-dash]CAr(2) products easily converted to primary amines R–NH(2)via simple acidic deprotection.