Abstract
The currently available methods via allylic organometallic compounds for the stereoselective synthesis of homoallyl alcohols are summarized. Usually, Z-allylic organometallics give erythro adducts upon treatment with aldehydes, while E-derivatives afford threo products. Interestingly, allylic stannanes react with aldehydes in the presence of BF3·OEt2 to give erythro products regardless of the geometry of the double bond. A short and stereoselective synthesis of the Prelog-Djerassi lactone is realized via this method. The metal effect on the stereoselection of enolate reaction is also summarized. Zirconium and tin enolates give erythro aldols irrespective of the enolate geometry. α-Mercurioketones undergo a. rapid reaction with aldehydes in the presence of BF3·OEt2 to give the kinetic erythro aldols. These erythro selections are explained by the acyclic mechanism.
