Silver-Catalyzed Regio- and Stereoselective Addition of Carboxylic Acids to Ynol Ethers

A silver-catalyzed <i>trans</i> addition of carboxylic acids to ynol ethers is described. The reaction has a broad scope with respect to carboxylic acids and ynol ethers, delivering (<i>Z</i>)-α-alkoxy enol esters in good yields with excellent regio- and stereoselectivity. Meaningfully, the Ni-catalyzed selective coupling of alkenyl C–OPiv bonds of (<i>Z</i>)-α-alkoxy enol esters with boronic acids enables a convenient route to the access of (<i>E</i>)-enol ethers. As such, the two-step procedure, consisted of a hydrocarboxylation and a subsequent Suzuki–Miyaura coupling, offers a formal <i>trans</i> hydroarylation of ynol ethers, thus providing a good complementary method to our previous report