We report a new class of synthetic molecular pumps that use a stepwise information ratchet mechanism to achieve the kinetic gating required to sequester their macrocyclic substrates from bulk solution. Threading occurs as a result of active template reactions between the pump terminus amine and an acyl electrophile, whereby the bond-forming reaction is accelerated through the cavity of a crown ether. Carboxylation of the resulting amide results in displacement of the ring to the collection region of the thread. Conversion of the carbamate to a phenolic ester provides an intermediate rotaxane suitable for further pumping cycles. In this way rings can be ratcheted onto a thread from one or both ends of appropriately designed molecular pumps. Each pumping cycle results in one additional ring being added to the thread per terminus acyl group. The absence of pseudorotaxane states ensures that no dethreading of intermediates occurs during the pump operation. This facilitates the loading of different macrocycles in any chosen sequence, illustrated by the pump-mediated synthesis of a [4]rotaxane containing three different macrocycles as a single sequence isomer. A [5]rotaxane synthesized using a dual-opening transamidation pump was structurally characterized by single-crystal X-ray diffraction, revealing a series of stabilizing CH···O interactions between the crown ethers and the polyethylene glycol catchment region of the thread.

中文翻译：

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转酰胺基驱动分子泵

我们报告了一类新的合成分子泵，它使用逐步信息棘轮机制来实现将大环底物从本体溶液中隔离所需的动力学门控。由于泵末端胺和酰基亲电试剂之间的活性模板反应而发生螺纹，从而通过冠醚的空腔加速成键反应。生成的酰胺的羧基化导致环移位到线的收集区域。氨基甲酸酯转化为酚酸酯提供了适合进一步泵送循环的中间体轮烷。以这种方式，可以将环从适当设计的分子泵的一端或两端棘轮到螺纹上。每个泵送循环导致一个额外的环被添加到每个末端酰基的螺纹中。不存在假轮烷状态确保在泵操作期间不会发生中间体的脱线。这有助于以任何选定的序列加载不同的大环，例如泵介导的 [4] 轮烷合成，其中包含三个不同的大环作为单一序列异构体。使用双开口转酰胺泵合成的[5]轮烷通过单晶X射线衍射对结构进行表征，揭示了冠醚与线的聚乙二醇捕获区域之间的一系列稳定的CH···O相互作用。通过泵介导合成含有三个不同大环作为单序列异构体的[4]轮烷来说明。使用双开口转酰胺泵合成的[5]轮烷通过单晶X射线衍射对结构进行表征，揭示了冠醚与线的聚乙二醇捕获区域之间的一系列稳定的CH···O相互作用。通过泵介导合成含有三个不同大环作为单序列异构体的[4]轮烷来说明。使用双开口转酰胺泵合成的[5]轮烷通过单晶X射线衍射对结构进行表征，揭示了冠醚与线的聚乙二醇捕获区域之间的一系列稳定的CH···O相互作用。