Dual N-Heterocyclic Carbene/Photoredox-Catalyzed Coupling of Acyl Fluorides and Alkyl Silanes

Abstract

The combination of N-heterocyclic carbene (NHC) organocatalysis with photochemical activation is becoming increasingly established as an approach for conducting radical organic reactions under mild and practical conditions. As comparatively easy to prepare and handle organic compounds, alkyl silanes are attractive substrates for radical chemistry as desilylative mesolysis of the corresponding radical cations is known to be rapid. Here, we report the successful application of benzyl silane derivatives as source of alkyl radicals in dual NHC/ photoredox-catalyzed radical−radical coupling reactions with acyl fluorides. Relatively electron-rich benzyl silanes reacted smoothly to afford the corresponding ketones in generally good yields, while optimization of the NHC and photocatalyst allowed for a wider scope including primary benzyl substrates. Furthermore, initial experiments revealed that organosilanes bearing N-, O-and S-heteroatoms can also serve as alkyl radical sources under these conditions.