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

A zirconocene-ethylene complex reacted with propargylic ethers to give alle ne derivatives in good yields via beta-alkoxide elimination. Deuterolysis o f the reaction mixture revealed that the final product after elimination st ill had a zirconium-carbon bond. Coupling of styrene and propargylic ethers was mediated by Cp2ZrBu2 (Negishi reagent) to give phenethyl allene deriva tives. beta-Alkoxide elimination from zirconacyclopentadienes bearing two a lpha-CH2OMe groups was also observed. One CH2OMe group was easily eliminate d. Elimination of the second CH2OMe group was dependent on its structure. ( C) 2000 Elsevier Science S.A. All rights reserved.