Visible-light photocatalysis and electrocatalysis are two powerful strategies for the promotion of chemical reactions that have received tremendous attention in recent years. In contrast, processes that combine these two modalities, an area termed electrophotocatalysis, have until recently remained quite rare. However, over the past several years a number of reports in this area have shown the potential of combining the power of light and electrical energy to realize new catalytic transformations. Electrophotocatalysis offers the ability to perform photoredox reactions without the need for large quantities of stoichiometric or superstoichiometric chemical oxidants or reductants by making use of an electrochemical potential as the electron source or sink. In addition, electrophotocatalysis is readily amenable to the generation of open-shell photocatalysts, which tend to have exceptionally strong redox potentials. In this way, potent yet selective redox reactions have been realized under relatively mild conditions. This Perspective highlights recent advances in the area of electrophotocatalysis and provides some possible avenues for future work in this growing area.

The conversion of carbonyls to olefins is a transformation of great importance for complex molecule synthesis. Standard methods use stoichiometric reagents that have poor atom economy and require strongly basic conditions, which limit their functional group compatibility. An ideal solution would be to catalytically olefinate carbonyls under nonbasic conditions using simple and widely available alkenes, yet no such broadly applicable reaction is known. Here, we demonstrate a tandem electrochemical/electrophotocatalytic reaction to olefinate aldehydes and ketones with a broad range of unactivated alkenes. This method involves the oxidation-induced denitrogenation of cyclic diazenes to form 1,3-distonic radical cations that rearrange to yield the olefin products. This olefination reaction is enabled by an electrophotocatalyst that inhibits back-electron transfer to the radical cation intermediate, thus allowing for the selective formation of olefin products. The method is compatible with a wide range of aldehydes, ketones, and alkene partners.

The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.

The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A screen of diamide PCCP ligands revealed a correlation of steric demand and regioselectivity, with smaller ligands being optimal, while the addition of Lewis acid enabled efficient reactions at room temperature. A range of substrates including both terminal and non-terminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition metal catalysis.

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