Visible Light-Induced Radical Cyclization of Ethyl 2-(N-Arylcarbamoyl)-2-Chloroiminoacetates: Synthesis of Quinoxalin-2(1H)-ones.

This paper reveals that visible light irradiation with Ru(phen)3Cl2 as photocatalyst can induce ethyl 2-(N-arylcarbamoyl)-2-chloroiminoacetates to undergo N-Cl cleavage to give a-(aminocarbonyl) iminyl radicals under an argon atmosphere. The subsequent cyclization of the thus formed iminyl radicals affords quinoxalin-2(1H)- one products in good yield in the presence of an inorganic base such as Na2CO3. The reactions proceeded very well even without using a photocatalyst when DMF was used as the solvent. These protocols provide a new, simple method for the generation of iminyl radicals, and the reactions described herein constitute an efficient method for the synthesis of quinoxalin-2(1H)-one derivatives. [ABSTRACT FROM AUTHOR]