Ligand-free Pd(II)-catalyzed cyclization of α-chloroimino-N-arylamides to synthesis of quinoxalin-2(1H)-ones

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 alpha-aryl-alpha-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. (C) 2020 Elsevier Ltd. All rights reserved.