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A Convenient Synthesis of 5,6β-Epoxides of Some Cholesteryl Esters and Δ<sup>5</sup>-Ketosteroid Derivatives by Catalytic β-Stereoselective Epoxidation
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1989
Year
EngineeringCatalytic AmountBiochemistryNatural SciencesOrganic ChemistryCholesteryl EstersConvenient SynthesisCatalysisStereoselective SynthesisChemistryRuthenium Tetramesitylporphyrin ComplexCatalytic β-Stereoselective EpoxidationSynthetic ChemistryEnantioselective SynthesisBiomolecular EngineeringNatural Product Synthesis
The epoxidation of a series of cholesteryl esters by air in the presence of a catalytic amount of a ruthenium tetramesitylporphyrin complex is described. The preparative procedure, which requires only 4 to 5 mol % of the catalyst, leads to high conversion (76 to 94 %) and very high β-stereoselectivity (> 99 %). Similar results are obtained in the epoxidation of 3β-acetoxyandrost-5-ene-17-one, 3β-acetoxypregn-5-ene-20-one, and 3,3-ethylenedioxycholest-5-ene.