Photo-/electrochemical catalyzed oxidative R 1 -H/R 2 -H cross-coupling with hydrogen evolution has become an increasingly important issue for molecular synthesis. The dream of construction of C−C/C−X bonds from readily available C− H/X−H with release of H 2 can be facilely achieved without external chemical oxidants, providing a greener model for chemical bond formation. Given the great influence of these reactions in organic chemistry, we give a summary of the state of the art in oxidative R 1 -H/R 2 -H cross-coupling with hydrogen evolution via photo/electrochemistry, and we hope this review will stimulate the development of a greener synthetic strategy in the near future.

The dearomatization of arenes represents a powerful synthetic methodology to provide three-dimensional chemicals of high added value. Here we report a general and practical protocol for regioselective dearomative annulation of indole and benzofuran derivatives in an electrochemical way. Under undivided electrolytic conditions, a series of highly functionalized five to eight-membered heterocycle-2,3-fused indolines and dihydrobenzofurans, which are typically unattainable under thermal conditions, can be successfully accessed in high yield with excellent regio-and stereo-selectivity. This transformation can also tolerate a wide range of functional groups and achieve good efficiency in large-scale synthesis under oxidant-free conditions. In addition, cyclic voltammetry, electron paramagnetic resonance (EPR) and kinetic studies indicate that the dehydrogenative dearomatization annulations arise from the anodic oxidation of indole into indole radical cation, and this process is the ratedetermining step.

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