Redox-mediated Ni-catalyzed cross coupling represents one of the most ubiquitous classes of redox-mediated reactions. However, despite their impressive ability to furnish bonds with high selectivity under mild conditions, comparatively little attention has been given to their mechanisms, knowledge of which is necessary for the rational optimization of these methodologies. We present mechanistic studies on the redox-mediated Ni-catalyzed etherification of aryl bromides through a combination of spectroscopic, electrochemical, and synthetic approaches. We demonstrate that a self-sustained Ni(I/III) cycle is operative under both photoredox and electrochemical conditions, and report the characterization of a Ni(I)-Ni(II) dimeric intermediate. Discovery of deleterious bimetallic processes that terminate the productive Ni(I/III) pathway allowed us to optimize the reaction for energy efficiency. Furthermore, we report strategies for accessing this and related carbon-heteroatom cross couplings thermally through attenuation of the off-cycle pathways.

Mechanism and optimization of redox-mediated Ni-catalyzed cross coupling

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.