Applications of biocatalysis in fragrance chemistry: the enantiomers of alpha-, beta-, and gamma-irones

The history of iris extracts, and of the isolation and enzyme-mediated synthesis of their odoriferous principle, the "irones", will be used to describe the improvement brought about by chemistry and biocatalysis in the development of natural fragrances. In particular, this tutorial review will discuss how the progress in the field of enzyme chemistry allowed the optimisation of accelerated procedures for the preparation of natural irone extracts, and the synthesis of all the ten isomers of irone, starting from commercial irone alpha.