Asymmetric Reduction of a Prochiral Carbonyl Group of Aliphatic γ- and δ-Keto Acids by Use of Fermenting Bakers' Yeast

Article abstract of DOI:10.1021/jo00228a039

With use of fermenting bakers' yeast, γ- and δ-keto acids, RCO(CH2)nCO2H (n = 2 and 3; R = C2H5, n-C3H7, n-C4H9, n-C5H17, n-C8H11, n-C11H23 and n-C13H27), were reduced to the corresponding γ- and δ-hydroxy acids which were isolated as γ- and δ-lactones in low to good yields with >98percent ee.The shortest γ- and δ-keto acid (R = CH3) failed to give the hydroxy acids.The reduction of 5-oxohexadecanoic acid (n = 3; R = n-C11H23) was examined under various conditions to improve the chemical yield.The absolute configurations of all of the lactones were determined to be R, even though the Prelog rule predicts the S configurations for the substrates having R = C2H5 and n-C3H7.The role of the carboxy group was discussed in comparison with the results obtained for the δ-keto esters.