Data for "Revealing the Mechanism of TEMPO-Hypervalent Iodine(III) Oxidation of Alcohols"

This paper reports experimental and computational studies on the mechanism of a well-known procedure for the oxidation of alcohols to car-bonyl compounds using TEMPO and the iodine(III) reagent (diacetoxyiodo)benzene (PIDA) are reported. Kinetic data show that the assumed classical oxoammonium-hydroxylamine mechanism requires modification due to zero order behavior observed in TEMPO. Instead, a dual catalytic system is proposed featuring two rate determining steps involving a combina-tion of alcohol, hypervalent iodine species, and water, which is typically present in adventitious quantities and is necessary for the reaction to proceed. The use of different alcohols implies the mechanism to be general. Intramolecular radical trap probes rule out a radical mechanism, while an investigation of TEMPO derivatives suggests that TEMPO is involved prior to the rate determining step. Kinetic isotope effect studies demonstrate that TEMPO is also involved after the rate determining step. Electrochemical studies find that the oxoammonium form of TEMPO is reduced by PIDA, likely oxidizing the io-dine(III) to an iodine(V) species. Theoretical investigations prove the feasibility of a pathway involving an iodine(V) species, demonstrate good agreement with the experimentally derived kinetics, and support an updated mechanism. Finally, the demonstration of oxidative kinetic resolution of a secondary alcohol using a chiral iodine(III) reagent rationally extends the reactivity of this system to new chemistry and lends further support towards our mechanistic proposals.