The Regio‐ and Stereospecific Intermolecular Dehydrative Alkoxylation of Allylic Alcohols Catalyzed by a Gold(I) N‐Heterocyclic Carbene Complex

A 1:1 mixture of AuCl(IPr)] (IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidine) and AgClO₄ catalyzes the intermolecular dehydrative alkoxylation of primary and secondary allylic alcohols with aliphatic primary and secondary alcohols to form allylic ethers. These transformations are regio‐ and stereospecific with preferential addition of the alcohol nucleophile at the γ‐position of the allylic alcohol syn to the departing hydroxyl group and with predominant formation of the E stereoisomer. The minor α regioisomer is formed predominantly through a secondary reaction manifold involving regioselective γ‐alkoxylation of the initially formed allylic ether rather than by the direct α‐alkoxylation of the allylic alcohol.