Chemoenzymatic synthesis of enantioenriched 5-oxo-tetrahydro-3-furancarboxylic acid derivatives

(R)-(+)-Paraconic acid 4, (S)-(−)-terebic acid 6 and their corresponding methyl and ethyl esters having ee’s ranging from 60% to 92% were obtained by enzymatic resolution of their racemates. The enzymatic resolution of racemic ethyl γ-methylparaconates 14a and 14b allowed the isolation of the unreacted ester (2R,3R)-(+)-14a and that of the lactonic acid (2S,3R)-(−)-5b with 80% and 93% ee, respectively, the former by the use of Horse liver acetone powder (HLAP), the latter using α-chymotrypsin (α-CT). The enantiomeric ethyl (2S,3S)-(−)-14a and (2S,3R)-(−)-14b, both with >99% ee, were obtained by baker’s yeast reduction of diethyl acetylsuccinate. [Copyright &y& Elsevier]