Optically active P-hydroxycarboxylic acids production

The groups of Masamune [4] and Evans [5] reported the synthesis of optically active p-hydroxycarboxylic acids by means of stereoselective chiral aldol condensation via boron enolates. (S)- and (i )-p-Hydroxyisobutyric acid of high optical purity (98% e.e.) were obtained by means of Masamune s method. However, these methods do not seem favorable for industrial production of p-hydroxycarboxylic acids because these reactions need equal amounts of the chiral starting material for the synthesis of optically active p-hydroxycar-boxylic acids (Scheme 2). 

Kaneka developed industrial production methods not only for the (S) form but also (R) form of p-hydroxycarboxylic acids involving the microbial stereoselective p-oxidation of fatty acids. And now we are producing various kinds of optically active P-hydroxycarboxylic acids by means of this method and are using them for the synthesis of the intermediates of pharmaceuticals. 

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