Copper(Ⅱ) Anilides in sp~3 C-H Amination

摘要

We report a series of novel β-diketiminato copper-n(Ⅱ) anilides [Cl_2NN]Cu-NHAr that participate in C-H amination.nReaction of H_2NAr (Ar = 2,4,6-Cl_3C_6H_2 (Ar~(C13)), 3,5-(CF_3)_2C_6H_3n(Ar~(F6)), or 2-py) with the copper(Ⅱ) t-butoxide complex [Cl_2NN]-nCu-~tOBu yields the corresponding copper(Ⅱ) anilides [Cl_2NN]-nCu-NHAr. X-ray diffraction of these species reveal three differentnbonding modes for the anilido moiety: k~1-N in the trigonaln[Cl_2NN]Cu-NHAr~(C13) to dinuclear bridging in {[Cl_2NN]Cu}_2(μ-nNHAr~(F6))_2 and k~2-N,N in the square planar [Cl_2NN]Cu(k~2-NH-2-npy). Magnetic data reveal a weak antiferromagnetic interactionnthrough a π-stacking arrangement of [Cl_2NN]Cu-NHAr~(C13); solution EPR data are consistent with monomeric species. Reactionnof [Cl_2NN]Cu-NHAr with hydrocarbons R-H (R-H = ethylbenzene and cyclohexane) reveals inefficient stoichiometric C-Hnamination with these copper(Ⅱ) anilides. More rapid C-H amination takes place, however, when ~tBuOO~t Bu is used, which allowsnfor HAA of R-H to occur from the ~tBuO~● radical generated by reaction of [Cl_2NN]Cu and ~tBuOO~t Bu. The principal role of thesencopper(Ⅱ) anilides [Cl_2NN]Cu-NHAr is to capture the radical R~● generated from HAA by ~tBuO~● to give functionalized anilinenR-NHAr, resulting in a novel amino variant of the Kharasch-Sosnovsky reaction.