A Highly Regio- and Stereoselective Formation of Bicyclo[4.2.0]oct-5-ene Derivatives through Thermal Intramolecular [2 + 2] Cycloaddition of Allenes
作者:Hiroaki Ohno、Tsuyoshi Mizutani、Yoichi Kadoh、Akimasa Aso、Kumiko Miyamura、Nobutaka Fujii、Tetsuaki Tanaka
DOI:10.1021/jo0700528
日期:2007.6.1
Thermal [2 + 2] cycloaddition of allenes with an additional multiple bond is described. By simply heating the allenenes or allenynes having a three-atom tether in an appropriate solvent such as dioxane or DMF, the distal double bond of the allenic moiety regioselectively participates in the cycloaddition to form bicyclo[4.2.0]oct-5-ene derivatives in good to excellent yields. In all the reactions of
描述了具有额外多重键的丙二烯的热[2 + 2]环加成。通过在适当的溶剂(例如二恶烷或DMF)中简单地加热具有三原子系链的烯丙基或烯丙基,烯丙基部分的远端双键区域选择性地参与环加成反应,形成双环[4.2.0] oct-5-ene衍生物产量高到极好。在丙二烯的所有反应中,烯烃的几何结构已完全转移至环加合物。虽然末端异戊烯的反应提供了作为单一异构体的双环环丁烷衍生物,但是一些具有轴向手性的内部异丁烯的环加成产生了环加合物的非对映异构体混合物。这些结果与通过具有共平面的烯丙基的双自由基中间体的逐步机理很好地一致。