Metal-free three-component cyanoalkylation of quinoxalin-2(1H)-ones with vinylarenes and azobis(alkylcarbonitrile)s

We have unveiled an efficient synthesis of cyanoalkylated quinoxalin-2(1H)-ones via a three-component radical cascade reaction of quinoxalin-2(1H)-ones with vinylarenes and azobis(alkylcarbonitrile)s. K2S2O8 takes part in the reaction as a sole oxidant under base, additive, and metal-free conditions, producing the three-component products in moderate to good yields. The protocol also works with phenylacetylene in the absence of vinyl arenes and provides the respective product. Furthermore, different control experiments with radical scavengers like 2,2,6,6-tetramethylpiperidine-1-oxyl and diphenyl ethylene prove the generation of radicals during the reaction.

Automated summary

An efficient synthesis of cyanoalkylated quinoxalin-2(1H)-ones via a three-component radical cascade reaction has been developed, using K2S2O8 as the sole oxidant under base, additive, and metal-free conditions. The reaction also works with phenylacetylene in the absence of vinylarenes, demonstrating the generation of radicals during the reaction through control experiments with radical scavengers.