Copper(II) Anilides in sp3 C-H Amination

We report a series of novel beta-diketiminato copper(II) anilides [Cl2NN]Cu-NHAr that participate in C-H amination. Reaction of H2NAr (Ar = 2,4,6-Cl3C6H2 (Ar-Cl3), 3,5-(CF3)(2)C6H3 (Ar-F6), or 2-py) with the copper(II) t-butoxide complex [Cl2NN]-Cu-(OBu)-O-t yields the corresponding copper(II) anilides [Cl2NN]-Cu-NHAr. X-ray diffraction of these species reveal three different bonding modes for the anilido moiety: kappa(1)-N in the trigonal [Cl2NN]Cu-NHArCl3 to dinuclear bridging in {[Cl2NN]Cu}(2)(mu-NHArF6)(2) and kappa(2)-N,N in the square planar [Cl2NN]Cu(kappa(2)-NH-2-py). Magnetic data reveal a weak antiferromagnetic interaction through a pi-stacking arrangement of [Cl2NN]Cu-NHArCl3; solution EPR data are consistent with monomeric species. Reaction of [Cl2NN]Cu-NHAr with hydrocarbons R-H (R-H = ethylbenzene and cyclohexane) reveals inefficient stoichiometric C-H amination with these copper(II) anilides. More rapid C-H amination takes place, however, when (BuOOBu)-Bu-t-Bu-t is used, which allows for HAA of R-H to occur from the (BuO center dot)-Bu-t radical generated by reaction of [Cl2NN]Cu and (BuOOBu)-Bu-t-Bu-t. The principal role of these copper(II) anilides [Cl2NN]Cu-NHAr is to capture the radical R-center dot generated from HAA by (BuO center dot)-Bu-t to give functionalized aniline R-NHAr, resulting in a novel amino variant of the Kharasch-Sosnovsky reaction.