Molecular Oxygen‐Induced Transamidation of Unactivated Amides in Diethyl Carbonate in the Presence of a Palladium Catalyst.

Herein we disclose a palladium‐catalyzed procedure for the transamidation of structurally diverse amides with amines based on the use of molecular oxygen as palladium‐activating agent. The reaction, which is scalable and amenable for the preparation of enantioenriched compounds, is carried out in a bio‐degradable solvent often used as a fuel additive, diethyl carbonate. As a result of the 10−4 mol% of catalyst required, final products are isolated containing palladium impurities in a concentration of 0.1 ppm. Two kinetically different mechanistic pathways are proposed for this reaction on account of a number of experiments such as kinetic curves, TEM images, catalyst poisoning experiments, UPLC‐ESI‐MS identification of intermediates and EPR spectra of reaction crude. [ABSTRACT FROM AUTHOR]