Enantioselective electrochemical cobalt-catalyzed aryl C-H activation reactions.

Abstract

Enantioselective redox transformations typically rely on costly transition metals as catalysts and often stoichiometric amounts of chemical redox agents as well. Electrocatalysis represents a more sustainable alternative, in particular through the use of the hydrogen evolution reaction (HER) in place of a chemical oxidant. In this work, we describe strategies for HER-coupled enantioselective aryl carbon-hydrogen bond (C-H) activation reactions using cobalt in place of a precious metal catalyst for the asymmetric oxidation. Thus, highly enantioselective carbon-hydrogen and nitrogen-hydrogen (C-H and N-H) annulations of carboxylic amides were achieved, which gave access to point and axially chiral compounds. Furthermore, the cobalt-mediated electrocatalysis enabled the preparation of various phosphorus (P)-stereogenic compounds by selective desymmetrization through dehydrogenative C-H activation reactions.