Oxidative R1-H/R2-H Cross-Coupling with Hydrogen Evolution.

Oxidative R1-H/R2-H cross-coupling with hydrogen evolution serves as one of the most atom-economical methods for constructing new chemical bonds. This reaction strategy avoids substrate prefunctionalization steps in traditional cross-coupling reactions. Besides, hydrogen gas, which is recognized as a source of green energy, is the only byproduct during the reaction process. The major challenge in this reaction strategy is to achieve selective bond formation and hydrogen evolution at the same time. Over the past few years, novel synthetic techniques especially photochemistry and electrochemistry have provided possibilities for oxidative cross-coupling with H2 liberation. Both C-C and C-X bonds can be constructed without the use of any sacrificial reagents. In this perspective, we will discuss the concept of this reaction strategy and give an overview of its recent development.