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 α‐(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. magnified image