Enzyme-Mediated Syntheses of the Enantiomers of gamma-Irones.

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