General and practical approach to the syntheses of linear homoallylic alcohols*

We have demonstrated that metal-mediated allylation of aldehydes can afford γ-homoallylic alcohols or α-linear homoallylic alcohols by judicious choice of the solvents. A new mechanism has been proposed to account for this new α-selective metal-mediated allylation reaction. On the other hand, the metal-mediated prenylation under the same conditions to obtain α-prenyl alcohols was unsuccessful. Detailed mechanistic studies have resulted in the discovery of a new method to obtain compounds with diverse structures via an oxonium-ene cyclization. Suppressing the oxonium-ene reaction during the reaction has resulted in the formation of α-prenyl alcohols. A highly enantioselective process to obtain α-prenyl product in high optical purity has also been accomplished.