ChemInform Abstract: Lewis Acid‐Catalyzed Intramolecular [2 + 2] Cycloaddition of α‐Ester‐Substituted Conjugated Dienyl‐ and Trienylphosphonates. New Synthesis of Functionalized Cyclic Terpenoids.

Abstract

Lewis Acid-Catalyzed Intramolecular [2 + 2] Cycloaddition of α-Ester-Substituted Conjugated Dienyl-and Trienylphosphonates. New Synthesis of Functionalized Cyclic Terpenoids. -The intramolecular cycloaddition is also applied to conjugated dienes bearing two ester groups. The cycloadduct (IVa) can easily be transformed into the sesquiterpene (VII) having a novel type of carbon skeleton and the adducts (XII), (XIII) and (XIV) are versatile intermediates for the synthesis of retinol derivatives. -(OKAUCHI, T.; KAKIUCHI, T.; KITAMURA, N.; UTSUNOMIYA, T.; ICHIKAWA, J.; MINAMI, T.; J.