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This paper reveals that visible light irradiation with Ru(phen)(3)Cl-3 as photocatalyst can induce ethyl 2-(N-arylcarbamoyl)-2-chloroiminoacetates to undergo N Cl cleavage to give alpha-(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. |
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