Enzyme-mediated synthesis of (R)- and (S)-alpha-ionone.

Diastereoisomeric enrichment through fractional crystallisation of C-nitrobenzoate derivatives of alpha-ionol, and enantioselective enzyme-mediated reactions of alpha-ionol and alpha-ionol acetate, were usefully combined to optimise two different procedures to enantiopure (S)- and (R)-ionone.