Mechanism and Reaction Channels of Iron-Catalyzed Primary Amination of Alkenes by Hydroxylamine Reagents
Yu Zhou, Jie Ni, Zhen Lyu, Yang Li, Ting Wang, Gui‐Juan Cheng
Abstract
Iron-catalyzed N-transfer by hydroxylamine-derived reagents has emerged as an appealing method for the straightforward synthesis of unprotected primary amines. Here, we studied the detailed reaction mechanism of the FePc-catalyzed aminofunctionalization of styrene with AcO-NH 3 OTf and PivO-NH 3 OTf by quantum chemical calculations and mass spectrometry experiments. An inner-sphere heterolytic N–O cleavage mechanism was proposed for the hydroxylamine activation. It affords an unprotected iron-amido species ([PcFeNH 2 ] + ), which has been detected by mass spectrometry. The iron-amido species acts as the active aminating intermediate and reacts with styrene to form a radical intermediate, followed by nucleophilic addition with methanol to generate the product. Electronic structure analysis revealed σ- and π-channels in the N-transfer process for the iron-amido species. This reported iron–nitrogen complex resembles the iron-oxo species to possess both σ- and π-channels, unveiling the mechanistic connections with iron-oxo chemistry.