On the selective reduction of the distal olefin in geraniol and farnesol derivatives

The selective reduction of the distal olefin of many types of terpenoid-based natural products has been commonly approached using gaseous HCl in CH2Cl2. We herein present evidence that this method is inefficient and produces many side products, whose formation, in our hands, was difficult to avoid (over several reaction runs). A more efficient procedure for geranyl acetate using 1 equiv. of TiCl4 in CH2Cl2 at −78°C is reported.