An efficient metal-free synthesis of 2-(pyrazin-2-yl)benzimidazoles from quinoxalinones and diaminomaleonitrile via a novel rearrangement

A simple and highly efficient metal-free method for the synthesis of 2-(pyrazin-2-yl)benzimidazoles has been developed on the basis of the novel ring contraction of 3-aroyl- and 3-alkanoylquinoxalin-2-ones with diaminomaleonitrile.