Asymmetric catalysis in fragrance chemistry: a new synthetic approach to enantiopure Phenoxanol®, Citralis® and Citralis Nitrile®

A new approach to the synthesis of the single stereomers of the fragrances Phenoxanol, Citralis and Citralis Nitrile is reported. The key step of the synthesis is the asymmetric hydrogenation of (Z)- or (E)-3-methyl-5-phenyl-pent-2-en-1-ol, which leads to the single enantiomers of Phenoxanol from which both enantiomers of Citralis are obtained by oxidation. Treatment of these compounds with hydroxylamine finally led to Citralis Nitrile without any loss of enantiopurity. The odour profiles of the single enantiomers of these fragrances are reported as well.