Luche Reduction

In 1978, the French chemist Jean Louis Luche reported that by using a mixture of lanthanide chlorides and sodium borohydride, α,β-unsaturated ketones could be selectively converted to allylic alcohols. After further work, it was determined that a mixture of cerium chloride and sodium borohydride gave the best results. Conversion of enones into the corresponding allylic alcohols by this method became known as the Luche reduction.

This discovery was significant as the reduction of unsaturated carbonyl compounds usually gave a mixture of 1,2 and 1,4 reduction products, while Luche’s method provided the 1,2 reduction product exclusively and in high yields. Reactions are conducted at or below room temperature and without the requirement for drying or an inert atmosphere, allowing for the presence of many functional groups. These conditions also provide for the chemoselective reduction of ketones in the presence of aldehydes, which undergo rapid acetalization, preventing their reduction.

The Luche reduction has been utilized in several important total synthesis campaigns, including those of several amaryllidaceae  alkaloids such as narciclasine in the laboratory of Tomas Hudlicky.