Photoredox Ni-Catalyzed Selective Coupling of Organic Halides and Oxalates to Esters via Alkoxycarbonyl Radical Intermediates

Abstract

A new approach for radical cross coupling of organic halides and oxalates toward esters has been developed via photoredox nickel dual catalysis. This method has been demonstrated for transformation of a wide range of aryl, heteroaryl, alkenyl, and alkyl bromides to various esters under mild conditions. Notably, fluoro-, chloro-, or iodo-substituents on the aryl bromides remain after the coupling reaction, which has been applied for the easy synthesis of drug molecules from simple aryl dihalides. Mechanistic studies indicate that an (alkoxycarbonyl)Ni(I) species might be generated via oxidation of Ni(0) species with an alkoxycarbonyl radical intermediate. Selective alkoxycarbonyl radical coupling over decarboxylative alkyl radical coupling is achieved here.