Non-sacrificial photocatalysis

Photocatalytic C H bond functionalization has become one of the most promising strategies to prepare complex molecules from readily available starting materials. However, the utilization of stoichiometric oxidants in the oxidative C H bond functionalization reactions could deliver side reactions and/or stoichiometric wastes, thereby reducing the appeal of these transformations. One general strategy that has emerged to overcome this constraint is non-sacrificial photocatalysis which allows electrons and protons released from the photoredox cycle to produce hydrogen gas. The non-sacrificial strategy offers a convenient protocol for clean and highly efficient bond formations from a variety of R H bonds. It allows oxidant-sensitive compounds that would otherwise be very difficult to synthesize. In this chapter, recent dramatic developments of non-sacrificial photocatalysis for dehydrogenations and dehydrogenative coupling reactions are discussed via the established scenarios, the types of bond formations, and specific reaction classes. We focus on reactions, the most prominent mechanistic pathways, and the representative products under non-sacrificial photocatalytic conditions. The goal of the chapter is to highlight recent advances in this field and offer an up-to-date reference for chemists exploring greener synthetic strategies in this interesting area.