Hydroxy‐Directed Ruthenium‐Catalyzed Alkene/Alkyne Coupling: Increased Scope,Stereochemical Implications,and Mechanistic Rationale

The recognition of the dual binding mode of propargyl and allyl alcohols to [Cp*Ru] fragments fostered the development of a highly regioselective intermolecular Alder‐ene‐type reaction of alkynes with 1,2‐disubstituted alkenes. The increased substrate scope opens new perspectives in stereochemical terms. As the loaded catalyst is chiral‐at‐metal, stereochemical information is efficiently relayed from the propargylic site to the emerging C−C bond. This interpretation is based on the X‐ray structure of the first Cp*Ru complex carrying an intact enyne ligand, and provides valuable insights into bonding and activation of the substrates. Computational data draw a clear picture of the principles governing regio‐ and stereocontrol.