Directed Photochemically Mediated Nickel-Catalyzed (Hetero)arylation of Aliphatic C–H Bonds
R. Thomas Simons, Meganathan Nandakumar, Kitae Kwon, Suraj K. Ayer, Venneti N. Murty, Jennifer L. Roizen
Abstract
Site-selective functionalization of unactivated C(sp 3 )–H centers is challenging because of the ubiquity and strength of alkyl C–H bonds. Herein, we disclose a position-selective C(sp 3 )–C(sp 2 ) cross-coupling reaction. This process engages C(sp 3 )–H bonds and aryl bromides, utilizing catalytic quantities of a photoredox-capable molecule and a nickel precatalyst. Using this technology, selective C–H functionalization arises owing to a 1,6-hydrogen atom transfer (HAT) process that is guided by a pendant alcohol-anchored sulfamate ester. These transformations proceed directly from N–H bonds, in contrast to previous directed, radical-mediated, C–H arylation processes, which have relied on prior oxidation of the reactive nitrogen center in reactions with nucleophilic arenes. Moreover, these conditions promote arylation at secondary centers in good yields with excellent selectivity.