Persistent organonickel complexes as general platforms for Csp-Csp coupling reactions.

The importance of constructing Csp-Csp bonds has motivated the development of electrochemical, photochemical and thermal activation methods to reductively couple abundant aryl and alkyl electrophiles. However, these methodologies are limited to couplings of very specific substrate classes and require specialized sets of catalysts and reaction set-ups. Here we show a consolidation of these myriad strategies into a single set of conditions that enable reliable alkyl-aryl couplings, including those that were previously unknown.

Copper-Catalyzed Electrochemical C-H Fluorination.

We report the systematic development of an electrooxidative methodology that translates stoichiometric C-H fluorination reactivity of an isolable Cu fluoride complex into a catalytic process. The critical challenges of electrocatalysis with a highly reactive Cu species were addressed by the judicious selection of electrolyte, F source, and sacrificial electron acceptor. Catalyst-controlled C-H fluorination occurs with a preference for hydridic C-H bonds with high bond dissociation energies over weaker but less hydridic C-H bonds.

Controlling Ni redox states by dynamic ligand exchange for electroreductive Csp3-Csp2 coupling.

Cross-electrophile coupling (XEC) reactions of aryl and alkyl electrophiles are appealing but limited to specific substrate classes. Here, we report electroreductive XEC of previously incompatible electrophiles including tertiary alkyl bromides, aryl chlorides, and aryl/vinyl triflates. Reactions rely on the merger of an electrochemically active complex that selectively reacts with alkyl bromides through 1e processes and an electrochemically inactive Ni(phosphine) complex that selectively reacts with aryl electrophiles through 2e processes.