Visible-Light Mediated C-H Functionalizations: C-C Formation Enabled by Intermolecular Cleavage of Unactivated C-H Bonds

CH bond is one of the most inert and massive chemical bonds in organic molecules. Thus, the direct conversion of various inert CH bonds to functionalized molecules via carbon–carbon or carbon–heteroatom bond formation represents one of the most ideal and straightforward means to build molecular complexity and is an important theme in organic chemistry, pharmaceutical chemistry, and material sciences. The direct functionalization of CH bond is step- and atom-economic, circumventing the prefunctionalization of molecules, thus attractive and highly desirable for organic synthesis. Due to the inertness of CH bonds and other associated issues, direct transformations from CH bonds remain challenging and attract great effort from the chemistry community. Among the strategies for the direct functionalizations of CH bonds, visible-light-mediated CH functionalizations have gained much attention from the community and have emerged as a promising tool for transforming CH bonds to other chemical bonds. This article summarizes the recent progress on the visible-light-mediated CH functionalization reactions enabled CC bond-forming processes, including representative examples of transforming ◂◽.▸Csp2H and ◂◽.▸Csp3H bonds into various carbon–carbon bonds.