Kornél Szori

98% Enantioselectivity in the asymmetric synthesis of a useful chiral building block by heterogeneous method: Enantioselective hydrogenation of ethyl-benzoylformate over cinchona modified Pt/Al2O3 catalysts in the acetic acid

Abstract Extremely high (98%) enantioselectivity of the hydrogenation of ethyl benzoylformate on Pt/Al 2 O 3 modified with dihydrocinchonidine was achieved. The difference between the rates of racemic and enantioselective hydrogenation was less significant than in the case of ethyl pyruvate. This indicates that ligand acceleration is a welcome effect but no necessary prerequisite for achieving high enantioselectivity.

Heterogeneous Asymmetric Reactions. 29. Enantioselective Hydrogenation of Ethyl Benzoylformate over Dihydrocinchonidine-Modified Platinum–Alumina Catalyst in Acetic Acid

The enantioselective hydrogenation of ethyl benzoylformate to (R)-ethyl mandelate over dihydrocinchonidine (DHCD)-modified Pt/Al2O3 catalyst in acetic acid was studied as a function of modifier concentration, hydrogen pressure and reaction temperature. The maximum enantioselectivity obtained under optimized conditions (DHCD concentration 1 mmol dm-3, 25 bar H2, 0 °C, AcOH/toluene 1:1) was 98% ee. The difference between the rates of racemic and enantioselective hydrogenation was less significant than in the case of ethyl pyruvate. This indicates that the high reaction rate in the enantioselective heterogeneous hydrogenation of α-ketoesters is not a necessary condition of the chiral induction.

Heterogeneous asymmetric reaction: Part 35. Enantioselective hydrogenation of 2-oxoglutaric acid over cinchona modified Pt/Al2O3 catalysts

Abstract 2-Oxoglutaric acid (OGA) may be converted to the important chiral building block (R)-5-oxo-tetrahydrofuran-2-carboxylic acid ((R)-OTC) by enantioselective hydrogenation on cinchona alkaloid modified Pt/alumina catalyst with 92% e.e. in water as solvent.

Asymmetric synthesis of alkyl 5-oxotetrahydrofuran-2-carboxylates by enantioselective hydrogenation of dialkyl 2-oxoglutarates over cinchona modified Pt/Al2O3 catalysts

The first direct asymmetric synthesis of chiral alkyl 5-oxo-tetrahydrofuran-2-carboxylates (up to 96% ee), which are important building blocks in the synthesis of natural products by heterogeneous cinchona-modified Pt-catalyzed hydrogenation of α-ketoglutaric acid esters and subsequent cyclization of hydroxy esters is described.

Chemical evolution of biomolecule building blocks. Can thermodynamics explain the accumulation of glycine in the prebiotic ocean

It has always been a question of considerable scientific interest why amino acids (and other biomolecule building blocks) formed and accumulated in the prebiotic ocean. In this study, we suggest an answer to this question for the simplest amino acid, glycine. We have shown for the first time that classical equilibrium thermodynamics can explain the most likely selection of glycine (and the derivative of its dipeptide) in aqueous media, although glycine is not the lowest free energy structure among all (404) possible constitutional isomers. Species preceding glycine in the free energy order are either supramolecular complexes of small molecules or such molecules likely to dissociate and thus get back to the gas phase. Then, 2-hydroxyacetamide condensates yielding a thermodynamically favored derivative of glycine dipeptide providing an alternative way for peptide formation. It is remarkable that a simple equilibrium thermodynamic model can explain the accumulation of glycine and provide a reason for the importance of water in the formation process.