Heterocycle Construction via Transition Metal-Catalyzed C-H Functionalization and C-Heteroatom Bond Formation

Heterocycles are fundamental building blocks for natural products and biologically active compounds. Over the past decades, substantial progress has been made in transition metal-catalyzed C-H bond functionalization. The majority of C-H functionalization studies have been focused on the formation of C-C bond, and the synthesis of heterocyclic compounds has been generally achieved from further elaboration of the resulting products after C-H functionalization. However, in very recent years, direct C-heteroatom coupling via C-H functionalization followed by C-heteroatom (heteroatom = N, O, S, P, etc.) bond formation has been extensively developed, providing efficient protocols for synthesizing various heterocycles. In this review, a brief overview is given of the recent advances in the field. The synthetic strategies are categorized and presented according to (1) types of C-H bonds (Csp2-H and Csp3-H) and (2) types of Cheteroatom bonds formed.