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Catalytic C(sp2)–H Amination Reactions Using Dinickel Imides

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journal contribution
posted on 16.10.2020, 14:34 by Ian G. Powers, John M. Andjaba, Matthias Zeller, Christopher Uyeda
C–H amination reactions are valuable transformations for the construction of C–N bonds. Due to their relatively high bond dissociation energies, C­(sp2)–H bonds are generally not susceptible toward direct nitrene insertion, necessitating alternative mechanisms for C–H activation. Here, we report that cationic dinuclear (NDI)­Ni2 (NDI = naphthyridine–diimine) complexes catalyze intramolecular nitrene insertions into aryl and vinyl C­(sp2)–H bonds. Mechanistic studies suggest that a bridging imido ligand supported at a Ni2 site induces C–H activation by a 1,2-addition pathway to generate an azametallacyclic intermediate. This organometallic mechanism contrasts with the electrocyclization/1,2-shift mechanism proposed for analogous transformations using Rh2 catalysts. The implications of these mechanistic differences for the stereoselectivity and chemoselectivity of C–H amination are described.