设计了一种立体选择性策略,用于用氧桥取代四卤代降冰片基衍生物的1,2-二卤代烯烃桥,所述氧桥涉及逐步控制的氧化,如此形成的二酮的裂解以及两个桥头卤素的分子内S N 2的迭代式置换。四个高度应变五环双氧杂桥接衍生物的合成10,27,28,和29与有趣的结构变化被呈现。这两个氧杂桥彼此同构,在10和27中被中央环己烷和环庚烷环隔开,而在它们之间彼此相反并被中央环戊烷和呋喃环隔开。28和29。在高度对称的双-氧杂桥联衍生物10的情况下,两个顺式氧杂桥将中央环己烷环约束为船形。首次制备了1,2,3,4-四卤代5,5-二甲氧基环戊-1,3-二烯与环戊二烯的内,反,内2:1双加合物,而先前未开发的双加合物的反应活性揭示了呋喃和环庚三烯的衍生物。
Synthesis of a Novel, Highly Symmetric Bis-Oxa-Bridged Compound
作者:Faiz Ahmed Khan、Jyotirmayee Dash
DOI:10.1021/ja017371f
日期:2002.3.1
A highly oxygenated, novel pentacyclic bis-oxa-bridged compound 8 was synthesized with remarkable efficiency starting from readily available tetrachloro-5,5-dimethoxyclopentadiene and 1,4-cyclohexadiene in three steps. The ruthenium-catalyzed oxidation of 2:1 bis-adduct 1 followed by a one-pot transformation of the resulting bis-alpha-diketone 3 furnished (after esterification) the title compound in an overall yield of 29.1%. The versatility of this simple method was further demonstrated with other norbornyl alpha-diketones to obtain the corresponding strained oxa-bridged derivatives.