Nickel-Catalyzed Direct Arylation of C(sp3)–H Bonds in Aliphatic Amides via Bidentate-Chelation Assistance

The Ni-catalyzed, direct arylation of C­(sp3)–H (methyl and methylene) bonds in aliphatic amides containing an 8-aminoquinoline moiety as a bidentate directing group with aryl halides is described. Deuterium-labeling experiments indicate that the C–H bond cleavage step is fast and reversible. Various nickel complexes including both Ni­(II) and Ni(0) show a high catalytic activity. The results of a series of mechanistic experiments indicate that the catalytic reaction does not proceed through a Ni(0)/Ni­(II) catalytic cycle, but probably through a Ni­(II)/Ni­(IV) catalytic cycle.