Luche Reduction

The Luche reduction is a regioselective reduction to afford allyl alcohols from α,β-unsaturated ketones. When α,β-unsaturated ketones are reduced with sodium borohydride (NaBH₄), 1,4-reduction, not 1,2-reduction, preferentially occurs. It is considered that since the hydride of NaBH₄ is a “soft” nucleophile, the reaction proceeds at the β-position of the carbonyl compounds, which prefers a “soft” nucleophile. However, the hydride turns to “hard” in the presence of cerium(III) chloride and an alcohol solvent, resulting in preferential 1,2-reduction. Incidentally, an aldehyde is not reduced using this method because it forms an acetal, which is inert under these conditions.

Related category page

• Reduction [Synthetic Reagents]

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