Zanichelli Valeria, Ragazzon Giulio, Orlandini Guido, Venturi Margherita, Credi Alberto, Silvi Serena, Arduini Arturo, Secchi Andrea
Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Università di Parma, Parco Area delle Scienze 17/A, I-43124 Parma, Italy.
Org Biomol Chem. 2017 Aug 16;15(32):6753-6763. doi: 10.1039/c7ob01642e.
A substrate can modify its chemical features, including a change of its reactivity, as a consequence of non-covalent interactions upon inclusion within a molecular host. Since the rise of supramolecular chemistry, this phenomenon has stimulated the ingenuity of scientists to emulate the function of enzymes by designing supramolecular systems in which the energetics and selectivity of reactions can be manipulated through programmed host-guest interactions and/or steric confinement. In this paper we investigate how the engulfment of a positively charged pyridinium-based guest inside the π-rich cavity of a tris-(N-phenylureido)calix[6]arene host affects its reactivity towards a S2 reaction. We found that the alkylation of complexed substrates leads to the formation of pseudorotaxanes and rotaxanes with faster kinetics and higher yields with respect to the standard procedures exploited so far. More importantly, the strategy described here expands the range of efficient synthetic routes for the formation of mechanically interlocked species with a strict control of the mutual orientation of their non-symmetric molecular components.
由于非共价相互作用，当被包含在分子主体中时，底物可以改变其化学特性，包括反应活性的变化。自超分子化学兴起以来，这种现象激发了科学家们的创造力，他们通过设计超分子体系来模拟酶的功能，在这些体系中，反应的能量学和选择性可以通过程序化的主客体相互作用和/或空间限制来操控。在本文中，我们研究了带正电荷的吡啶鎓基客体被包裹在三（N-苯基脲基）杯[6]芳烃主体富含π的空腔内时，如何影响其对S2反应的反应活性。我们发现，与迄今为止所采用的标准方法相比，络合底物的烷基化反应能以更快的动力学和更高的产率生成准轮烷和轮烷。更重要的是，本文所述策略拓宽了有效合成路线的范围，能够在严格控制其不对称分子组分的相互取向的情况下形成机械互锁物种。
