New and Convenient Chemoenzymatic Syntheses of (S)-2-Hydroxy-3-octanone, the Major Pheromone Component of Xylotrechus spp., and Its R-Enantiomer

New and efficient chemoenzymatic approaches for the synthesis of both enantiomers of 2-hydroxy-3-octanone in good yields and excellent enantioselectivity are presented. The S-enantiomer is a pheromone component of economically important pests in Japan, India, China, and other Asian countries. The enzymatic approaches involve transesterification of the racemic acyloin with vinyl acetate in the presence of Candida antarctica lipase B (CAL B) in 99% ee of both enantiomers (E = 167-618), or hydrolysis of the acetylated acyloin by double kinetic resolution with CAL B and C. antarctica lipase A (CAL A) in 96-98% ee of either enantiomer (E = 458). CAL A and CAL B induce reverse enantioselectivity.