Intramolecular Photochemical Dioxenone−Alkene [2 + 2] Cycloadditions as an Approach to the Bicyclo[2.1.1]hexane Moiety of Solanoeclepin A
作者:Richard H. Blaauw、Jean-François Brière、Remco de Jong、Jorg C. J. Benningshof、Angeline E. van Ginkel、Jan Fraanje、Kees Goubitz、Henk Schenk、Floris P. J. T. Rutjes、Henk Hiemstra
DOI:10.1021/jo0056500
日期:2001.1.1
solanoeclepin A (1), the most active natural hatching agent of potato cyst nematodes, was approached via an intramolecular [2 + 2] photocycloaddition. Aldehyde 12 containing the dioxenone chromophore served as a useful starting material, allowing the synthesis of a variety of photocycloaddition substrates via Grignard addition or via a Nozaki-Hiyama-Kishi reaction. Photolysis of the unsubstituted alkene 14 led
通过分子内[2 + 2]光环加成反应,合成了马铃薯鞘囊线虫最活跃的天然孵化剂solanoeclepin A(1)的双环[2.1.1]己烷亚结构。含有二烯酮生色团的醛12可用作有用的原料,允许通过格氏加成反应或通过Nozaki-Hiyama-Kishi反应合成各种光环加成底物。根据所谓的五律,未取代的烯烃14的光解产生预期的交叉环加合物双环[2.1.1]己烷15。但是,几种官能化的烯烃18、20和31表现出环加成区域选择性的完全逆转,分别提供了直环加合物双环[2.2.0]己烷21-26和4。通过广泛的NMR测量证明了它们的结构,X射线分析和随后的逆醛醇反应。后一种de Mayo方法允许形成螺-[3.5]壬烷35和螺[3.4]辛烷36以及环丁烷37和38。最后,更硬的内酯前体28的环化以期望的高收率发生。以完全的区域选择性和立体选择性的方式合成3个含有天然产物的核心双环[2.1.1]己烷骨架的化合物。