Accelerated Electrophotocatalytic C(sp³)−H Heteroarylation Enabled by an Efficient Continuous‐Flow Reactor**

Abstract

Electrophotocatalytic transformations are garnering attention in organic synthesis, particularly for accessing reactive intermediates under mild conditions. Moving these methodologies to continuous‐flow systems, or flow ElectroPhotoCatalysis (f‐EPC), showcases potential for scalable processes due to enhanced irradiation, increased electrode surface, and improved mixing of the reaction mixture. Traditional methods sequentially link photochemical and electrochemical reactions, using flow reactors connected in series, yet struggle to accommodate reactive transient species. In this study, we introduce a new flow reactor concept for electrophotocatalysis (EPC) that simultaneously utilizes photons and electrons. The reactor is designed with a transparent electrode and employs cost‐effective materials. We used this technology to develop an efficient process for electrophotocatalytic heteroarylation of C(sp3)–H bonds. Importantly, the same setup can also facilitate purely electrochemical and photochemical transformations. This reactor represents a significant advancement in electrophotocatalysis, providing a framework for its application in flow for complex synthetic transformations.

Unleashing the potentiality of metals: synergistic catalysis with light and electricity

“…29 Based on this foundation, in 2023, Noël further reported the accelerated electro-photocatalytic C(sp 3 )–H heteroarylation achieved using iron( iii ) chloride as a catalyst in an efficient continuous-flow reactor setup (Scheme 2). 30 The possible mechanism of the reaction is as follows: firstly, the chlorine ligand binds to the iron center to form a tetrachloroiron complex, which then absorbs violet light and transitions to an excited state. Subsequently, the Fe–Cl bond undergoes homolytic cleavage, producing chlorine radicals and reduced Fe( ii ) species.…”