Self‐ or Acridinium‐Catalyzed Electrophotosynthesis of Thiocyanato Heterocycles from Activated Alkenes

Abstract

While the emergence of electrophotochemistry provides opportunities, such a chemistry at this stage suffers from limited reaction types and high photocatalyst loadings. A self‐catalyzed electrophotosynthesis as well as one with a low photocatalyst loading is presented. These external‐oxidant‐free cyclizations are enabling and applicable to a range of activated alkenes, affording a diverse array of thiocyanato heterocycles including 4‐pyrrolin‐2‐ones, isoquinoline‐1,3‐diones, indolo[2,1‐a]isoquinolin‐6(5H)‐ones, benzoimidazo[2,1‐a]isoquinolin‐6(5H)‐ones and indolin‐2‐ones, and the protocols are amenable to the late‐stage diversification of complex molecular architectures as well as gram‐scale syntheses. Sunlight could serve as the light source, and the reaction could be conducted in an all‐solar‐driven mode using a commercially available photovoltaic panel to produce electricity.

Electroreductive carboxylation of benzylphosphonium salts with CO2 through the cleavage of the C(sp3)–P bond

“…Organic electrosynthesis is defined as a green synthetic technique that avoids the use of redox reagents and many excellent studies on organic electrosynthesis have been carried out. 13 Inspired by previous examples of electrochemical carboxylation 14,15 and combined with our understanding of organic electrosynthesis, 16 we guess that alkyl phosphonium salts should be reduced to benzyl anions, which are then captured by CO 2 to generate carboxylic derivatives. Herein, we report the first electroreductive carboxylation of phosphonium salts through the cleavage of the C(sp 3 )–P bond.…”