Organic "magic rings" - The hydrogen bond-directed assembly of catenanes under thermodynamic control
Organic "magic rings" - The hydrogen bond-directed assembly of catenanes under thermodynamic control
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DOI：
10.1021/ja983106r
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发表时间：
1999-02-24
影响因子：
15
通讯作者：
Wilson, AJ
中科院分区：
文献类型：
--
作者：
Kidd, TJ;Leigh, DA;Wilson, AJ
目前用于制备机械互锁环（连环烷）的大多数策略的一个共同特征是，最终的大环化反应通常在动力学控制下进行。因此，如果环闭合不通过已经螺纹的前体进行，则会产生无法“纠正”的非互锁大环的“错误”。在热力学控制下的链烷形成（“严格自组装”2）以前已经通过使用弱的、可逆形成的金属配体键3实现了，结果是通常用于直接机械联锁的强组分间相互作用可以被利用来产生非常高的链烷收率。在几个著名的例子中，Fujita等人描述了金属大环可以通过疏水结合几乎完全转化为[2]链烷的系统，这一壮举被认为是让人联想到魔术师的魔术，即看似“魔法”的环相互连接。在这里，我们报告了类似的方法可以应用于全有机环体系，通过利用氢键介导的自互补大环组装和当前一代的高通用性烯烃复分解催化剂在可逆开环和关环（RORCM）反应中。5-7在适当的RORCM条件下（可能只有在需要外部试剂的化学转化条件下），共价的数量、类型、立体化学或序列实际上没有净变化
A common feature of most current strategies used to prepare mechanically interlocked rings (catenanes) is that the final macrocyclization reaction is generally carried out under kinetic control. 1, 2 As a result, if ring closure does not proceed via an already threaded precursor,“mistakes” snoninterlocked macrocyclessare produced that cannot be “corrected”. Catenane formation under thermodynamic control (“strict self-assembly” 2) has previously been achieved with use of weak, reversibly formed, metal-ligand bonds3 with the result that the strong intercomponent interactions normally employed to direct mechanical interlocking can be exploited to bring about very high yields of catenanes. 3b-g In several celebrated examples, 3b-e Fujita et al. have described systems where metallomacrocycles can be converted almost exclusively into [2] catenanes through hydrophobic bindings a feat noted as being reminiscent of the conjurors trick of interlocking seemingly “magic” rings. Here we report that a similar approach can be applied to wholly organic ring systems by exploiting the hydrogen bond-mediated assembly of selfcomplementary macrocycles and the current generation of highly versatile olefin metathesis catalysts4 in reversible ring opening and closing (RORCM) reactions. 5-7 Under appropriate RORCM conditions (in which, possibly uniquely for a chemical transformation requiring external reagents, there is virtually8 no net change in the number, type, stereochemistry, or sequence of covalent