Baker's yeast-mediated enantioselective synthesis of the bisabolane sesquiterpenes (+)-curcuphenol, (+)-xanthorrhizol, (-)-curcuquinone and (+)-curcuhydroquinone

Fermenting baker's yeast converts the unsaturated aldehydes 5a-c into the saturated alcohols 6a-c, respectively. The microbial saturation of substrates adsorbed on a nonpolar resin proceeds in high chemical yields and shows complete enantioselectivity in the formation of the (S)-(+) isomers. Enantiopure 6a-c are versatile chiral building blocks for the synthesis of bisabolane sesquiterpenes. Their usefulness is shown in the preparation of (S)-(+)-curcuphenol, (S)-(+)-xanthorrhizol, (S)-(-)-curcuquinone and (S)-(+)-curcuhydroquinone.