Greening Indolizine Chemistry: Advances in Electro-/Photochemical Direct C–H Functionalization

Abstract

Indolizines are a class of structurally unique N-heterocycles that have garnered significant attention due to their broad presence in natural products, bioactive molecules, and functional materials. These compounds exhibit a wide range of pharmacological activities. Their π-conjugated frameworks also make them attractive building blocks for organic optoelectronic materials. In recent years, direct C–H functionalization of the indolizines has emerged as a prominent research focus. Notably, electrochemical and visible-light-induced strategies, developed under the principles of green and sustainable chemistry, have provided new avenues for the late-stage diversification of indolizines. This review summarizes recent advances in electrochemical and photocatalytic C–H functionalization of indolizines, with an emphasis on the construction of C–C and C–X (X = S, Se, N, Cl, Br, etc.) bonds. Key developments in catalytic systems, substrate scope, mechanistic insights, and potential applications are discussed, aiming to offer valuable guidance for the green synthesis and further development of indolizine-based heterocycles.