Origin of the Selectivity and Activity in the Rhodium-CatalyzedAsymmetric Hydrogenation Using Supramolecular Ligands

The reaction mechanism of the asymmetric hydrogenation of functionalized alkenes catalyzed by a supramolecular rhodium complex has been investigated. In-depth NMR analysis combined with X-ray crystal structure determination show that hydrogen bonds are formed between the catalyst and the substrate in the early stages of the mechanism. Detailed kinetic data obtained from UV-vis stopped-flow experiments and gas-uptake experiments confirm that the hydrogen bonds are playing a crucial role in the mechanism. A complete DFT study of the various competitive paths of the reaction mechanism allowed us to identify how these hydrogen bonds are involved in the determining steps of the reaction.