Photocatalytic α-Alkylation of Amines with Alkyl Halides

Abstract

α-Branched amines represent essential building blocks for organic synthesis. They are traditionally prepared through nucleophilic addition to imines. These methods often require highly reactive organometallic reagents and proceed under rigorous air- and moisture-free conditions. Here we describe an alternative approach that involves a C-alkylation of amines with alkyl bromides. Mechanistically, the reaction likely involves photocatalytic generation of an α-amino radical and a stabilized carbon-centered radical (allyl, benzyl, α-carbonyl) followed by radical recombination. This approach offers a mild, atom-economical, redox neutral synthesis of α-branched amines that shows broad scope and avoids premetalated reagents.