Visible Light Photoredox-Catalyzed Direct C–H Arylation of Quinoxalin-2(1H)-ones with Diaryliodonium Salts

Abstract

A photoredox-catalyzed direct arylation of quinoxalin-2-(1H)-ones using diaryliodonium triflates as the convenient, stable, and cheap aryl source is described. A broad variety of quinoxalin-2-(1H)-ones are shown to react with structurally and electronically diverse diaryliodonium triflates, allowing efficient access to a wide variety of pharmaceutically important 3-arylquinoxalin-2-(1H)-ones. The presented method is attractive with regard to operational simplicity, mild conditions, broad scope, scalability, and high functional group tolerance.

Atom Transfer Radical Addition Reactions of Quinoxalin-2(1H)-ones with CBr4 and Styrenes Using Mes-Acr-MeClO4 Photocatalyst

“…The quinoxalin-2­(1 H )-one scaffold is an important N -heterocyclic compound that has a wide range of applications including industrial and pharmaceutical industries. − Figures and show the substrate scope for the synthesis of derivatives 3f and 5a via ATRA under the optimized conditions (Table ). These reaction conditions prove compatible and yield satisfactory results for compounds bearing both electron-donating (EDG) and electron-withdrawing (EWG) groups.…”

Modern Photo- and Electrochemical Approaches to Aryl Radical Generation

“…Similarly to the method mentioned above, the Ru(II) based photocatalyst enables direct C3 arylation of quinoxalin-2-(1H)-ones employing easily available and stable diaryliodonium triflates (Scheme 45a). 153 Specifically, the reaction proceeds in the presence of Ru(bpy)3Cl2•6H2O (5 mol%) under blue LED irradiation (467 nm) in MeCN. The scope is rather broad, and allyl/propargyl groups are well tolerated in this protocol (Scheme 45b).…”

“…N-Substituted 2-arylbenzoimidazoles show a similar reactivity pattern toward diphenyliodonium triflates affording arylatedbenzimidazo[2,1-a]isoquinolin-6(5H)-ones (Scheme 47a). 153 This cascade operates under mild conditions and offers a broad substrate scope with appreciable functional group tolerance (Scheme 47b). For non-symmetrical diphenyliodonium triflates, the transfer of an electron-deficient and sterically less hindered aryl ring prevails.…”

Reaction of Diaryliodonium Salts with Potassium Alkyl Xanthates as an Entry Point to Accessing Organosulfur Compounds

“…2 In recent years, carbon−heteroatom bond-forming arylations with diaryliodonium salts under transition-metal-free conditions have emerged as a powerful and sustainable alternative and complement to the existing workhorse methods. 3 Many robust protocols for the arylation of various heteroatom nucleophiles utilizing diaryliodonium salts under relatively mild conditions have been disclosed. Most importantly, this methodology not only offers a complementary synthetic tool but also opens the possibility of making aromatic compounds that cannot be made available by other techniques.…”