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This paper reports that N -arylenamines can be converted into quinoxalines via tandem azidation/intramolecular C H amination under visible light irradiation by using 1-azidyl-1,2-benziodoxole as the azidating agent. The substituent was found to have a critical influence on the reaction, and thus different conditions were required to fit the substrates of varied structural features. The conversion of N -aryl-3-arylenamine esters into the corresponding quinoxalines proceeded well under metal-free conditions, whereas Cu(OAc) 2 was required when N -aryl-3-trifluoromethyl enamine esters were used as the substrates. This method was also applied to the preparation of 2,3-diarylquinoxalines by using Ru(bpy) 3 Cl 2 as the photoredox catalyst. The reactions revealed herein provide an efficient approach towards quinoxalines. [ABSTRACT FROM AUTHOR]

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]

28 examples [ABSTRACT FROM AUTHOR]

The reaction is mentioned to fail for chloroiminoacetates bearing an ortho-substituent. [ABSTRACT FROM AUTHOR]