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 s aturated alcohols 6a-c, respectively. The microbial saturation of substrate s adsorbed on a nonpolar resin proceeds in high chemical yields and shows c omplete enantioselectivity in the formation of the (S)-(+) isomers. Enantio pure 6a-c are versatile chiral building blocks for the synthesis of bisabol ane sesquiterpenes. Their usefulness is shown in the preparation of (S)-(+) -curcuphenol, (S)-(+)-xanthorrhizol, (S)-(-)-curcuquinone and (S)-(+)-curcu hydroquinone.