Catalytic Hydrogenation of Itaconic Acid in a Biotinylated Pyrphos-Rhodium(I) System in a Protein Cavity
The construction of a chiral catalyst system embedded at a specific site in a protein has been studied. The preparation of the biotinylated Pyrphos–Rh(I) complex attached to the binding site in avidin and its application to the asymmetric hydrogenation of itaconic acid have been investigated. By introducing the chiral Pyrphos–Rh(I) moiety into the constrained environment of the protein cavity it was found that the enantioselectivity of the system was significantly influenced by the tertiary conformation within the avidin cavity. The effects of reaction conditions such as temperature, hydrogen pressure, and the pH value of the buffer on enantioselectivity are reported.