Concerning the mechanism of the FeCl₃-catalyzed α-oxyamination of aldehydes: Evidence for a non-SOMO activation pathway

The mechanism of a recently reported aldehyde α-oxyamination reaction has been studied using a combination of kinetic, spectrometric, and spectrophotometric techniques. Most crucially, the use of a validated cyclopropane-based radical-clock substrate has demonstrated that carbon-oxygen bond formation occurs predominantly through an enamine activation manifold. The mechanistic details reported herein indicate that, as has been proposed for previously studied alcohol oxidations, complexation between TEMPO and a simple metal salt leads to electrophilic ionic reactivity.