Ligand-free Pd(II)-catalyzed Cyclization of α-Chloroimino-N-arylamides to Synthesis of Quinoxalin-2(1H)-ones

Abstract A ligand-free Pd(II)-catalyzed synthesis of quinoxalin-2(1H)-ones has been developed. Pd(TFA)2 can induce ethyl 2-(N-arylcarbamoyl)-2-chloroiminoacetates to undergo Cyclization to afford quinoxalin-2(1H)-one products in high yields in the presence of Na2CO3. This catalytic system is also effective to convert α-aryl-α-chloroimino-N-arylamides to the corresponding quinoxalin-2(1H)-one products via tandem N-Cl cleavage and N-arylation in moderate yields. The reaction described herein constitutes simple and effective approach towards quinoxalin-2(1H)-one derivatives.