Allene formation by coupling of propargylic ethers with olefins via β-alkoxide elimination of zirconacycle intermediates

A zirconoceneethylene complex reacted with propargylic ethers to give allene derivatives in good yields via β-alkoxide elimination. Deuterolysis of the reaction mixture revealed that the final product after elimination still had a zirconiumcarbon bond. Coupling of styrene and propargylic ethers was mediated by Cp2ZrBu2 (Negishi reagent) to give phenethyl allene derivatives. β-Alkoxide elimination from zirconacyclopentadienes bearing two α-CH2OMe groups was also observed. One CH2OMe group was easily eliminated. Elimination of the second CH2OMe group was dependent on its structure.