Palladium/benzoic acid-catalyzed hydroalkoxylation of alkynes

The reaction of the internal alkyne 1 with alcohols 2 in the presence of a catalytic amount of Pd(PPh3)4 and benzoic acid in dioxane at 100°C gave the allylic ethers 3 in good to high yields. The reaction proceeds via the palladium/benzoic acid-catalyzed isomerization of the alkyne 1 to allene 6, followed by the addition of alcohols 2 to the π-allylpalladium intermediate 7 formed by the hydropalladation of the resulting allene 6. Furthermore, the intramolecular reaction of alkynes having a hydroxy group at the terminus of the carbon chain gave five- and six-membered cyclic ethers in good yields.