Iodoarene mediated efficient aerobic oxidation of aldehydes for carboxylic acids

Abstract

Carboxylic acids are important chemical compounds with a wide range of applications in chemical science, pharmaceutics and material science. Despite tremendous progress in their synthesis with metal-catalysts over the past decade, sustainable, efficient metal-free strategies for aerobic oxidation of aldehydes in aqueous phase are highly desired. In particular, diverse carboxylic acids still remain difficult to be efficiently accessed with existing metal-free methods. Herein, a highly efficient iodoarene-mediated aerobic oxidation method for carboxylic acids in aqueous phase is reported. This approach unlocks access to a highly expanded number of carboxylic acids bearing functional groups on aromatic aldehydes and saturated/unsaturated aliphatic aldehydes. Detailed mechanistic studies using computation studies, isotope labelling, electron paramagnetic resonance studies and spectroscopic measurements provide strong support for the interception of hypervalent iodine intermediates through aldehyde hydrate.