Catalyst-Controlled Chemodivergent Annulation to Indolo/Pyrrolo-Fused Diazepine and Quinoxaline

Abstract

Catalyst-controlled chemodivergent annulation between o-indolo anilines and diazo compounds has explored for the synthesis of indolo-fused diazepine and quinoxaline Under the Rh(III) catalyst, reaction proceeded through the free amine assisted C2-H activation followed by amidation leading to the diazepino [1,7-alpha]indole in a highly selective manner. While with Ru(II) catalyst, reaction involves formation Ru-carbene complex followed by -NH2 group insertion and cascade cyclization via metallo-ene type reaction, beta-hydride elimination to furnish the indolo[1,2-alpha]quinoxaline as the predominating product. This strategy directs modular approach towards the construction of unique indolo-fused diazepine/quinoxaline as well as pyrrolo-fused diazepine/quinoxaline scaffolds in excellent yields.