Ru(II) catalyzed dehydrogenative annulation of 2-arylimidazo[1,2-a]pyridines with maleimides

[Display omitted] •First report on Ru(II) catalyzed double CH activation.•Ru(II) is cost effective compared to Rh(III) and Ir(III) complexes.•An oxidative [4+2] cycloaddition of maleimide is reported.•A diverse range of polyheterocycles have been prepared. Ru(II) catalyzed annulation of 2-arylimidazo[1,2-a]pyridines with maleimides has been achieved for the synthesis of a diverse range of benzo[e]pyrido[1′,2′:1,2]imidazo[4,5-g]isoindole derivatives. The reaction proceeds through a Ru(II)-catalyzed CH metalation of 2-arylimidazo[1,2-a]pyridine followed by maleimide insertion and intramolecular cyclization. This method is simple and atom-economical to produce the pharmaceutically relevant benzo[e]pyrido[1′,2′:1,2]imidazo[4,5-g]isoindole derivatives with a wide substitution pattern.