Substrate-Controlled Divergent Reductive Cyclization of 2-Arylanilines Using CO as a Switching Reagent.

Capturing CO is highly valued in the field of organic synthesis, especially underdeveloped dual-CO conversion. In this study, we detail a novel reductive cyclization of 2-indolylanilines with dual CO as a difunctional reagent in the presence of PMHS [poly(methylhydrosiloxane)], delivering methyl-substituted quinoxalines. Furthermore, another chemoselective cyclization with 2-pyrrolylanilines is also realized by converting mono-CO. Mechanistic investigations shed light upon the fact that this substrate-controlled divergence mainly depends on the formation of -diacylative intermediates.