The enantiomerically enriched diastereoisomers of the chiral 1,3-dioxane odorants Floropal ¾ (1) and Magnolan ¾ (2) were prepared by an enzyme-mediated approach. Their olfactory properties were evaluated to investigate differences in the odor perception for the stereoisomers.

The four stereoisomers of the rose oxide analogue Doremox® were prepared in enantiomerically enriched form by enantiospecific bakers' yeast reduction of suitable derivatives and by lipase-mediated kinetic resolution of diol precursors.Key words: yeast, lipase, odorant, reduction, kinetic resolution.

An enzymatic approach to the synthesis of all the possible stereoisomers of (E) and (Z), cis and trans-girones in enantiomerically pure form from commercial Irone Alpha ¾ is described. A very efficient resolution of racemic trans-g-irone, affording both the enantiomers in high ee and chemical purity, is also presented. Olfactory evaluation of ()-and (À)-3b and full configuration assignment of the irone isomers contained in samples of Italian iris oil are reported.