C-H functionalization via electrophotocatalysis and photoelectrochemistry: complementary synthetic approach

Photoelectrochemical (PEC) cells are well documented as an important tool for energy and environmental applications. Most commonly used to produce hydrogen fuel from water splitting, PEC cells have also been directed toward pollutant degradation, carbon dioxide reduction, and production of solar fuels. Their application in organic synthesis, however, remains in its infancy. Motivated by the desire for green and sustainable synthetic methods, the merger of photochemistry and electrochemistry is envisaged to become a new strategy to accompany the modern organic chemists. PEC cells are desirable due to their abundance and convenience, the inexpensive and clean nature of sunlight, and the rich variety of photoelectrode materials and redox mediators, as well as their ability to utilize mild reaction conditions. This perspective describes some of the recent developments in PEC-driven organic synthesis by combining electrochemistry and photoredox catalysis in a single system. Specific emphasis has been given for reactions concerning C–H activations, whereby new chemical bonds are forged, whether they be for the late stage functionalization of interesting compounds or the conjoining of two molecular building blocks. This combination is emerging as a powerful system that can achieve reactions that previous methodologies would find difficult or impossible, and it can do so in an environmentally friendly, energy-saving manner with high atom and step economies.