Leung Ken C-F, Aricó Fabio, Cantrill Stuart J, Stoddart J Fraser
California NanoSystems Institute and Department of Chemistry and Biochemistry, The University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095-1569, USA.
J Am Chem Soc. 2005 Apr 27;127(16):5808-10. doi: 10.1021/ja0501363.
The versatility and efficiency of dynamic covalent chemistry (DCC) has been exploited in the convergent synthesis of mechanically interlocked dendrimers that are based upon the mutual recognition expressed between secondary dialkylammonium ions and crown ether-like macrocycles. Reversible imine bond formation is employed to clip two acyclic fragments, one of them a diformylpyridine unit bearing a dendritic side chain, and the other a complementary dianiline in the shape of the di(o-aminophenyl)ether of tetraethylene glycol, around each arm of a tritopic trisammonium ion core, thereby affording a branched [4]rotaxane. This template-directed strategy has been demonstrated to work in very high yields (>90%) with successive generations (G0-G2) of a modified Fréchet-type dendritic wedge attached to the 4-position of the diformylpyridine unit. Reduction of these dynamic dendritic systems is achieved upon treatment with borane.THF and results in kinetically stable compounds. The inherent modularity of the overall process should allow for the rapid and straightforward access to many other analogous mechanically interlocked systems in which either the branched core or the dendritic periphery can be modified to suit the needs of any given application of these molecules. Indeed, the dynamic nature of the initial thermodynamically mediated assembly could be utilized in order to amplify particular products from a potential library as a result of a selective recognition process.
动态共价化学（DCC）的多功能性和效率已被用于基于二级二烷基铵离子与冠醚类大环之间相互识别的机械互锁树枝状大分子的收敛合成。利用可逆的亚胺键形成来连接两个无环片段，其中一个是带有树枝状侧链的二甲醛吡啶单元，另一个是四甘醇二（邻氨基苯基）醚形状的互补二苯胺，围绕一个三位三铵离子核心的每个臂，从而得到一个支化的[4]轮烷。这种模板导向策略已被证明能以非常高的产率（>90%）适用于连接到二甲醛吡啶单元4位的修饰的弗雷谢型树枝状楔形物的连续几代（G0-G2）。用硼烷·四氢呋喃处理这些动态树枝状体系可实现还原，并得到动力学稳定的化合物。整个过程固有的模块化特性应能使人们快速直接地获得许多其他类似的机械互锁体系，其中支化核心或树枝状外围都可以进行修饰，以满足这些分子任何特定应用的需求。实际上，初始热力学介导组装的动态性质可被利用，以便通过选择性识别过程从潜在文库中扩增特定产物。
