Enantioselective Hydrogenation of α-Ketoacids Using Platinum Catalysts Modified With Cinchona Alkaloids

Platinum functionalized multiwall carbon nanotube composites as recyclable catalyst for highly efficient asymmetric hydrogenation of methyl pyruvate

A highly efficient platinum nanoparticle functionalized carbon nanocomposite is demonstrated to be a recyclable heterogeneous catalyst for asymmetric hydrogenation of methyl pyruvate.

Role of the Solvent in the Adsorption−Desorption Equilibrium of Cinchona Alkaloids between Solution and a Platinum Surface: Correlations among Solvent Polarity, Cinchona Solubility, and Catalytic Performance

The role that the nature of the solvent plays in defining the extent of cinchona alkaloid adsorption-desorption equilibrium on platinum surfaces has been studied both by testing their solubility in 54 different solvents and by probing the stability of adsorbed cinchona in the presence of those solvents. The solubilities vary by as much as 5-6 orders of magnitude, display volcano-type correlations with solvent polarity and dielectric constant, and follow a cinchonine < cinchonidine < quinine, quinidine sequence. The adsorption-desorption equilibrium shifts toward the solution with increasing dissolving power of the solvent. The relevance of these results to the behavior of cinchona as chiral modifiers in hydrogenation catalysis is discussed.

Heterogeneous asymmetric reactions. Part 24. Heterogeneous catalytic enantioselective hydrogenation of the C==N group over cinchona alkaloid modified palladium catalyst

The enantioselective hydrogenation of C==N-C group containing compounds over modified metal catalysts is as yet an uninvestigated research area. This work contains results obtained on the hydrogenation of 1-pyrroline-2-carboxylate esters and sodium salt over cinchona alkaloid-modified alumina-supported Pd catalyst. The effect of the reaction parameters and the structure of the alkaloid molecule on hydrogenation rate and enantioselectivity allowed us to assume that on the catalyst surface only a weak interaction exists between the modifier and the substrate, resulting in the low enantiomeric excesses (up to 20%) obtainable in these reactions.