An expedient preparation of enantio‐enriched ambergris odorants starting from commercial ionone alpha

We report the enantioselective synthesis of the ambergris odorants (+)‐( S )‐ γ ‐ionone, (+)‐( S )‐ γ ‐dihydroionone, (−)‐ α ‐ambrinol, (+)‐( S )‐ γ ‐coronal, (−)‐( S )‐ γ ‐homocyclogeranyl chloride and (+)‐( S )‐ γ ‐homocyclogeraniol. At first, the enantio‐enriched (4 R ,6 S )‐4‐acetoxy‐ γ ‐ionone was prepared starting from commercial racemic ionone alpha by means of a chemo‐enzymatic process. This chiral building block was then converted into ( S )‐ γ ‐dihydroionone which was used as the starting material for the synthesis of the aforementioned odorants. Copyright © 2012 John Wiley & Sons, Ltd.