Stereoselective alkylation-reduction of β-keto nitriles by the fungus Curvularia lunata

The alkylation-reduction (AR) reaction of beta -keto nitriles by growing cells of Curvularia lunata CECT 2130 has been explored. The reaction conditions for the ethylation of benzoylacetonitrile have been optimized in terms of both yield and stereoselectivity and the mechanism of this biotransformation vas studied. The scope of this reaction has been extended to other alkylations (R = Et, Pr, Bu, iso-Bu) and to a series of aromatic and heteroaromatic substrates, yielding the corresponding optically active alpha -alkyl beta -hydroxy nitrites. The yield (directly related to competing carbonyl reduction reaction) depends on the substrate bulk. whereas the enantiomeric and diastereomeric excesses (both up to 98%) seem to be dependent on several Factors. (C) 2001 Elsevier Science Ltd. All rights reserved.