Photocatalytic arylation/alkylation of olefins/alkynes via halogen-atom transfer mediated by NHC-BH3

Abstract

A versatile method for radical reductive cross-coupling of iodides and activated olefins under mild conditions, facilitated by NHC-BH₃ through photocatalysis, was developed. This method exhibits high efficiency and regioselectivity, achieving yields of up to 98% for aryl, heterocyclic, and alkyl iodides. The reaction employs a minimal amount (1.0 mol%) of photocatalyst and can be performed on a gram scale. Importantly, this approach avoids the use of transition metal co-catalysts, eliminating the need for traditional C–I bond cleavage steps such as oxidative addition, migration insertion, and halogen exchange. This work unveils a novel mechanism for the reductive coupling of iodides in a photocatalytic NHC-BH₃ system, providing insights into iodide modification and the functional exploration of NHC-BH₃.