Enantiomerically pure tetrahydro-5-oxo-2-furancarboxylic esters from dialkyl 2-oxoglutarates

Enantiomerically pure tetrahydro-5-oxo-2-furancarboxylic esters can be prep ared either by enzymatic resolution of the racemic gamma-lactones themselve s or by bioreduction with baker's yeast of dialkyl 2-oxoglutarates and subs equent cyclization of the resulting dialkyl 2-hydroxyglutarates. The best r esults were obtained by the former route, by which the desired compounds we re isolated in high enantiomeric excess. Bioreductions were less satisfacto ry. In fact the hydroxyester intermediates were initially formed as racemic mixtures and their final enantiomeric enrichment was reached by asymmetric destruction, occurring in the bioreaction medium, however at the same time large amounts of alkyl 4-hydroxybutanoates were formed as side products. ( C) 1999 Elsevier Science Ltd. All rights reserved.