Iron-Catalyzed C−H Activation with Propargyl Acetates: Mechanistic Insights into Iron(II) by Experiment, Kinetics, Mössbauer Spectroscopy, and Computation

Abstract

An iron-catalyzed C−H/N−H alkyne annulation was realized by using a customizable clickable triazole amide under exceedingly mild reaction conditions. A unifying mechanistic approach combining experiment, spectroscopy, kinetics, and computation provided strong support for facile C−H activation by a ligand-to-ligand hydrogen transfer (LLHT) mechanism. Combined Mössbauer spectroscopic analysis and DFT calculations were indicative of high-spin iron(II) species as the key intermediates in the C−H activation manifold.