Microbial stereoselective one-step conversion of diols to chiral lactones in yeast cultures

Abstract

It has been shown that whole cells of different strains of yeast catalyze stereoselective oxidation of meso diols to the corresponding chiral lactones. Among screening-scale experiments, Candida pelliculosa ZP22 was selected as the most effective biocatalyst for the oxidation of monocyclic diols 3a–b with respect to the ratio of high conversion to stereoselectivity. This strain was used in the preparative oxidation, affording enantiomerically-enriched isomers of lactones: (+)-(3aR,7aS)-cis-hexahydro-1(3H) -isobenzofuranone (2a) and (+)-(3aS,4,7,7aR)-cis-tetrahydro-1(3H)-isobenzofuranone (2b). Scaling up the culture growth, as well as biotransformation conditions has been successfully accomplished. Among more bulky substrates, bicyclic diol 3d was totally converted into enantiomerically-pure exo-bridged (+)-(3aR,4S,7R,7aS)-cis-tetrahydro-4,7- methanoisobenzofuran -1(3H)-one (2d) by Yarrovia lipolytica AR71. Microbial oxidation of diol 3f by Candida sake AM908 and Rhodotorula rubra AM4 afforded optically-pure cis-3- butylhexahydro-1(3H) -isobenzofuranone (2f), however with low conversion.