A Twist of the Twist Mechanism, 2‑Iodoxybenzoic Acid (IBX)-Mediated Oxidation of Alcohol Revisited: Theory and Experiment

2-Iodoxybenzoic acid (IBX) is an important species for the oxidation of alcohols to aldehydes or ketones. An often-cited mechanism involving a hypervalent twist as the rate-determining step (RDS) is inconsistent with kinetic isotope effect (KIE) experiments. The computations with larger basis sets reveal that the reductive elimination involving the C–H bond cleavage is the RDS (rate-determining step). Further computational/experimental studies suggest that the reactivity can be improved by adjusting the trans influence with Lewis acids.