Ir‐Catalyzed Cascade Reaction Promotes the Formation of Geometrically Selective Enones from Bis‐allyl Alcohols

Enone compounds are well‐known as useful building blocks that can be converted into a variety of valuable compounds. This study describes a synthetic method to synthesize E‐selective or multi‐substituted enones by an Ir‐catalyzed cascade reaction under reducing conditions. We found that the cascade reaction, including reduction/isomerization/dehydration, proceeds by treating bis‐allyl alcohol with Crabtree's catalyst in a hydrogen atmosphere, which forms the desired product with high diastereoselectivity. We investigated acceptable catalysts to the reaction and the synthesis of enone using di‐, tri‐ and tetrasubstituted olefin substrates. Additionally, the given results suggested a hypothesis of reaction mechanism. A cascade reaction including reduction, isomerization, and dehydration provides E‐selective or multi‐substituted enones from bis‐allyl alcohols treated with Crabtree's catalyst. This reaction proceeds smoothly at room temperature under a hydrogen atmosphere.