Generation of Photoinduced Phenalenyl‐Based Radicals: Towards Designing Reductive C−C Coupling Catalysis.

Organic photoredox catalysis is a versatile tool for accessing a wide range of synthetic transformations. Towards the development of a new class of organophotoredox catalysts, we have employed phenalenyl, an odd alternant hydrocarbon (OAH), for reductive C−C coupling reactions. Phenalenyl can adopt a stable open‐shell state (radical), using its non‐bonding molecular orbital. To date, chemically induced phenalenyl‐based radicals have been extensively explored in designing various intriguing organic materials and recently towards electron transfer catalysis. However, the photochemical generation of phenalenyl‐based radicals is rare. In this work, we report the photoinduced generation of phenalenyl‐based radicals with detailed mechanistic studies such as steady‐state absorption, time‐resolved transient absorption spectroscopy, and in‐situ absorption kinetic experiments to authenticate the generation of photo‐induced phenalenyl radicals. In addition, we present results demonstrating that this novel catalytic species can be applied to reductive pinacol coupling catalysis and reductive alkylation of terminal alkynes. [ABSTRACT FROM AUTHOR]