Asymmetric Synthesis of the Both Enantiomers of α-Hydroxy Acids by the Diastereoselective Reduction of Chiral α-keto Amides with (Complex) Metal Hydrides in the Presence of Metallic Salt

Article abstract of DOI:10.1246/cl.1986.1897

Effects of the metallic salts and the reducing reagents in the diastereoselective reduction of chiral α-keto amides derived from (S)-proline methyl ester were examined.Lithium borohydride afforded (S)-α-hydroxy acids, whereas diisobutylaluminum hydride afforded (R)-isomers.In the presence of lithium bromide, reduction with LiBH4 afforded (S)-mandelic acid in over 80 percent e.e.