title: A study of baker's yeast reduction of piperidone-carboxylates.
abstract: The stereoselective baker's yeast reduction of various N-protected piperidone-carboxylic acids have been studied, and the enantioselectivity was found to be widely dependent on whether fermenting or non-fermenting conditions were employed. Thus reaction of N-tert-butoxycarbonyl-4-oxopiperidine-3-carboxylic acid ethyl ester (6) with fermenting baker's yeast gave almost racemic N-tert-butoxycarbonyl-4-hydroxypiperidine-3-carboxylic acid ethyl ester (7), however, with complete diastereoselectivity. Reduction of 6 with non-fermenting yeast gave 7 with a 24-41% enantiomeric excess. Similarly, reduction of N-tert-butoxycarbonyl-3-oxopiperidine-4-carboxylic acid ethyl ester (17) with fermenting baker's yeast gave racemic N-tert-butoxycarbonyl-3-hydroxypiperidine-4-carboxylic acid ethyl ester [(+/-)-18] diastereoselectively. A convenient method for determining the enantiomeric excess of the hydroxypiperidine carboxylic acids derivatives was found in the reaction with Sanger's reagent followed by HPLC on a chiral column.
authors.affiliation: Department of Chemistry, Aarhus University, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Willert
authors.forename: M
authors.initials: M
authors.lastname: Bols
mesh_terms: D002264:Carboxylic Acids / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004139:Dinitrofluorobenzene / Q000378:metabolism; D004952:Esters / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010881:Piperidones / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
chemical_list: D002264:Carboxylic Acids; D004952:Esters; D010881:Piperidones; D004139:Dinitrofluorobenzene