Intramolecular α-oxygenation of amines via n-heterocyclic carbene-catalyzed domino reaction of aryl aldehyde: Experiment and dft calculation

Abstract

We have developed an N-heterocyclic carbene (NHC)-catalyzed domino reaction with aryl aldehyde through a simple acyl azolium intermediate using phenyliodine(III) diacetate (PIDA) as an oxidant. Controlled experiments and density functional theory calculations supported a domino two-stage mechanism from aldehyde/amine to an α-oxygenation product, including NHC-catalyzed oxidation of the aldehyde to carboxylic acid via acyl azolium intermediate, and further, an addition of carboxylate to iminium intermediate. Our study reveals a new model for the oxidation of Breslow intermediate via electrophilic attack of the hydroxyl group by PIDA.