Lanthanide replacement in organic synthesis

23 Jun 2012

Scientists form the UK have performed the Luche-type reduction of α,β-unsaturated ketones in the presence calcium triflate.

The reduction of α,β-unsaturated ketones to synthesize allylic alcohols is commonly performed with sodium borohydride in the presence of cerium(III) chloride, otherwise known as the Luche reduction. However, trivalent lanthanide salts pose several disadvantages. They are very expensive, and although generally non-toxic, if administered intravenously they are significantly toxic.

However, in this work scientists from Imperial College London and Pfizer Ltd in Sandwich, led by Matthew Fuchter, developed a route to give allylic alcohols from α,β-unsaturated ketones using calcium triflate to replace cerium(III) chloride. This procedure also accomplished the regioselective 1,2-reduction of challenging α,β-unsaturated ketones such as 2-cyclopentenone with very good selectivity, and is suitable for the stereoselective reduction of α,β-aziridinyl ketones.