Luche reduction

Luche reduction is the selective organic reduction of ketones to alcohols with lanthanoid chlorides such as cerium(III) chloride and sodium borohydride as enones or in presence of aldehydes An enone forms an allyl alcohol in a 1,2-addition. Competing conjugate 1,4-addition is suppressed. The solvent is an alcohol such as methanol or ethanol.


 * [[image:Luche2.png|400px|Luche reduction of enones]]

The selectivity can be explained in terms of HSAB theory: carbonyl groups require hard nucleophiles for 1,2-addition. The hardness of the borohydride is increased by replacing hydride groups with alkoxide groups, a reaction catalyzed by the cerium salt. Another purpose for cerium is to increase the electrophilicity of the carbonyl group.

In one application a ketone is selectively reduced in presence of an aldehyde.


 * [[image:Luche-Reduktion.png|400px|Luche reduction]]