Yeast-Mediated Resolution of β-Keto Esters of Prochiral Alcohols

Article abstract of DOI:10.1021/jo00011a031

Several racemic alcohols were converted to their β-keto esters with diketene, and the resulting compounds were subjected to kinetic resolution by means of baker's yeast.The unreacted keto esters were separated from the reduced hydroxy esters by chromatography, and the products were analyzed for levels of enantiomeric excess.Chiral shift reagents, Mosher esters, and optical rotation of the enantiomers of the alcohols were the criteria used to determine the optical integrity of the resolved alcohols after hydrolysis of the esters.Absolute sterochemistry was determined for the resolution products of all the substrates.Some rationale is advanced to account for the observed levels of enantiomeric excess and for the apparent diastereospecifity of the enzymatic resolution.The utility of this process as means of resolution of prochiral alcohols as well as an application of such resolution to the preparation of both enantiomers of a pyrrolizidine alkaloid synthon are indicated.