Photocatalytic and electrocatalytic α-C–H functionalization of tertiary amines

Abstract

We present a comprehensive review of the photochemical and electrochemical methodologies employed in the α-C–H functionalization of tertiary amines. The discussion starts with an introduction to α-C–H functionalization strategies, emphasizing the generation of radical species. The iminium ion and α-aminoalkyl radical are identified as key intermediates interacting with various organic functional groups. The review is divided into two main sections: photocatalytic and electrocatalytic α-C–H functionalization. In the photocatalytic section, we classify the functionalization into photocatalyst-mediated and photocatalyst-free approaches. Photocatalyst-mediated functionalization is further categorized into four mechanisms: Nucleophilic substitution, Transition-metal complexing, Giese-type reaction, and Radical-radical cross-coupling. Photocatalyst-free functionalization focuses on the direct excitation of the substrate and the EDA complex pathways, with particular emphasis on the latter. The electrocatalytic section explores both direct and indirect electrolysis techniques, highlighting the role of redox mediators in the indirect approach. Each section critically analyzes recent research examples from the past five years. This review aims to elucidate the current state of α-C–H functionalization research and suggest promising directions for future investigations.