ENZYMATIC RESOLUTION OF THE ETHYL ACETALS OF (R)-4-HYDROXYALK-2-YNALS AND (S)-4-HYDROXYALK-2-YNALS

4-hydroxyalk-2-ynals diethylacetals have been efficiently resolved by enatioselective acetylation mediated by Pseudomonas fluorescens lipase affording the acetylated (R)-enantiomers in preference, independent of the length and bulk of the alkyl substituent at the carbinol group. Reduction with LiAlH4 of unreacted or acetylated isomers affords the corresponding ethylenic acetals with the hydrogen deriving from the hydride in the beta position in respect to the allylic hydroxyl.