Origin of the Selectivity and Activity in the Rhodium-Catalyzed Asymmetric 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.