[R′CH(OH)CHCHCO2R], which are ubiquitous structures in biologically active natural products and useful building blocks for organicsynthesis of chiral compounds. From the optically pure (R)-2-(2-benzothiazolylsulfinyl)acetates (>99% ee) prepared by the enzymatic kinetic resolution of (±)-2-(2-benzothiazolylsulfinyl)acetates, opticallyactive 4-hydroxyalk-2-enoates (up to 91% ee) have been obtained in good