Enzyme directed diastereoselectivity in chemical reductions: studies towards the preparation of all four isomers of 1-phenyl-1,3-butanediol

Enzymes play an important role in guiding the diastereoselectivity of the final products during the chemical reduction of the intermediates (R)- and (S)-3-hydroxy-1-phenyl-1-butanone, prepared by bioreduction of 1-phenyl-1,3-butadione. For example, the presence of an oxidoreductase such as Pichia capsulata during a one pot, two step, enzymo-chemical reduction of 1-phenyl-1,3-butadione produced corresponding (1R,3S)-1-phenyl-1,3-butanediol (desimilar to98%), similarly Zygosaccharomyces rouxii furnished (IS,3R)-1-phenyl-1,3-butanediol (desimilar to98%). On the other hand chemical reduction of (R)- and (S)-3-hydroxy-1-phenyl-1-butanone after the exclusion of the enzymes resulted in complete loss of diastereoselectivity, leading to the formation of all four isomers of 1-phenyl-1,3-butanediol. Moreover the yields of the final products are higher in the one-pot transformations than in the two step sequential reactions. (C) 2004 Elsevier Ltd. All rights reserved.