非環状系化合物の立体制御における金属効果

アリル有機金属および金属エノラートの反応

抄録

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.