Combined Carbometalation-Zinc Homologation-Allylation Reactions as a New Approach for Alkoxyallylation of Aldehydes

The combined carbometalation reaction of ynol ethers followed by a zinc homologation and further allylation reactions lead to an efficient preparation of allylic vicinal diols. The stereochemical outcome of the reaction shows that the substituent of the aldehyde occupies a pseudoaxial position in a Zimmerman-Traxler transition state.