Selective Approaches to α‐ and β‐Arylated Vinyl Ethers

We developed simple and efficient protocols for palladium‐catalyzed regioselective α‐ and β‐arylations of structurally diverse vinyl ethers. Both catalytic methods proceed under relatively mild reactions conditions applying to a broad substrate range including more complex compounds providing arylated glucal or isochromene. Lacking the common requirement of a large reagent excess, the transformations are highly economic and limiting the waste production. Results from computational studies (DFT) provided insight into the key factors determining the pronounced regioselectivities of the investigated reactions. Benzyl vinyl ethers have selectively been arylated at either α or β position by fine‐tuned Heck‐type palladium catalyses. In contrast to previous protocols, no excess of arylating reagent or substrate chelation is necessary. For achieving good yields and high α/β‐selectivities various factors determining the catalytic system had to be optimized. The results of DFT computational studies correlate selectivity with electron richness on the Pd center.