A highly divergent Pictet-Spengler approach for pyrrolo[1,2-a]quinoxalines from aryl amine using 1,2-dinitrobenzene as an oxidant

A convenient Pictet-Splengler approach for the synthesis of substituted pyrrolo[1,2-a]quinoxalines from aryl amine and 1-(2-aminoaryl)-pyrrole has been developed. This is the first domino protocol involving formation of benzaldehyde as an intermediate from benzyl amines and benzyl alcohols using 1,2-DNB as an oxidant, followed by its endo cyclization with 1-(2-aminophenyl)-pyrrole to furnish the pyrrolo[1,2-a]quinoxalines. Notably, this procedure exhibits good functional group tolerance as well as good to moderate yield of pyrrolo[1,2-a]quinoxaline.