Towards mild conditions by predictive catalysis via sterics in the Ru-catalyzed hydrogenation of thioesters

Abstract

• Milstein's reported discovery of hydrogenation of thioesters directly toward thiols and alcohols catalyzed by a Ru-acridine. • Reaction mechanism and precise description of the rate determining step described by DFT calculations. • Steric maps via%VBur rationalize the path to milder conditions. • Sterical demanding substituents on the P atoms of the PNP pincer ligands reduces the kinetic cost of the rate determining step. The Milstein's reported discovery of hydrogenation of thioesters directly toward thiols and alcohols catalyzed by a Ru-acridine complex has been studied here by DFT calculations to know the origin of the different performance depending on the nature of the substituents. Unveiling the reaction mechanism leads to a deeper understanding of the steric and electronic properties on the nature of the limiting step of the reaction. Steric maps and Conceptual DFT have been the tools to rationalize the reactivity patterns. In addition, the nature of the catalyst has been studied, replacing the substituents on the phosphorous atoms by less sterically demanding groups with the aim to move to milder reaction conditions.