Iron Corrole‐Catalyzed Intramolecular Amination Reactions of Alkyl Azides. Spectroscopic Characterization and Reactivity of [FeV(Cor)(NAd)]

Abstract

AbstractAs nitrogen analogues of iron‐oxo species, high‐valent iron‐imido species have attracted great interest in the past decades. FeV‐alkylimido species are generally considered to be key reaction intermediates in Fe(III)‐catalyzed C(sp3)─H bond aminations of alkyl azides but remain underexplored. Here, it is reported that iron‐corrole (Cor) complexes can catalyze a wide range of intramolecular C─H amination reactions of alkyl azides to afford a variety of 5‐, 6‐ and 7‐membered N‐heterocycles, including alkaloids and natural product derivatives, with up to 3880 turnover numbers (TONs) and excellent diastereoselectivity (>99:1 d.r.). Mechanistic studies including density functional theory (DFT) calculations and intermolecular hydrogen atom abstraction (HAA) reactions reveal key reactive FeV‐alkylimido intermediates. The [FeV(Cor)(NAd)] (Ad = adamantyl) complex is independently prepared and characterized through electron paramagnetic resonance (EPR), resonance Raman (rR) measurement, and X‐ray photoelectron spectroscopy (XPS). This complex is reactive toward HAA reactions with kinetic isotope effects (KIEs) similar to [Fe(Cor)]‐catalyzed intramolecular C─H amination of alkyl azides.