Asymmetric transfer hydrogenation of α-amino β-keto ester hydrochlorides through dynamic kinetic resolution
The development of Ru-catalyzed asymmetric transfer hydrogenation of α-amino β-keto ester hydrochlorides is described. The reaction proceeds through dynamic kinetic resolution to afford anti β-hydroxy α-amino esters with good diastereomeric ratios and high enantioselectivities.
Direct anti-selective asymmetric hydrogenation of α-amino-β-keto esters through dynamic kinetic resolution using Ru-axially chiral phosphine catalysts-stereoselective synthesis of anti-β-hydroxy-α-amino acids
The asymmetric hydrogenation of α-amino-β-keto esters using ruthenium (Ru) anti-selectively proceeds via a dynamic kinetic resolution to afford anti-β-hydroxy-α-amino acids with high enantiomeric purities, which are important chiral building blocks for the synthesis of medicines and natural products. A mechanistic investigation has revealed that the Ru-catalyzed asymmetric hydrogenation takes place via the hydrogenation of the double bond in the enol tautomer of the substrate.
Nitrate esters in the generation of amino acid radicals
Nitrate esters, prepared by treatment of β-hydroxy-α-amino acid derivatives with nitric acid, react with tributyltin hydride to give the corresponding alkoxyl radicals. These radicals readily undergo β-scission, providing a convenient route for the regiocontrolled production of α-carbon-centred amino acid radicals. By examining the partitioning of the alkoxyl radicals between the β-scission process and the competing hydrogen transfer reaction, it has been possible to evaluate the influence of electronic and steric effects on the β-scission reaction and the formation of the carbon-centred radicals.
Easton, Christopher J.,Ivory, Andrew J.,Smith, Craig A.
p. 503 - 507
(2007/10/03)
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