Photocatalyzed redox-neutral decarboxylative alkylation of heteroaryl methanamines

Abstract

A redox-neutral decarboxylative coupling reaction of heteroaryl methylamines with NHPI esters derived from aliphatic carboxylic acids has been developed. By employing a copper complex as a photocatalyst with blue LED irradiation, NHPI esters underwent one-electron reduction and heteroaryl methenamine derivatives underwent one-electron oxidation in one photo-redox catalytic cycle to form radical intermediates, respectively, followed by the recombination of these two radicals to form new C–C bonds. The methodology is illustrated by the transformation of different kinds of heteroaromatic compounds as well as primary, secondary and tertiary alkyl carboxylic acids. The reaction can be scaled up and NHPI can be recovered. Also, the reaction can be conducted in a one-pot in situ activation manner.