School of Chemistry, University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh EH9 3JJ, United Kingdom.
J Am Chem Soc. 2010 Jan 13;132(1):315-20. doi: 10.1021/ja9080716.
Template approaches to rotaxanes normally require at least n - 1 template sites to interlock n components. Here we describe the one-pot synthesis of [3]rotaxanes in which a single metal template site induces formation of axles through each cavity of a bicyclic macrocycle. Central to the approach is that a portion of the bicyclic molecule acts as a ligand for a transition metal ion that mediates covalent bond formation through one or other macrocyclic cavity, depending on the ligand's orientation, making a mechanical bond. The ligand can then rotate so that the transition metal can catalyze the formation of a second axle through the other macrocycle. Using this strategy with the Cu(I)-catalyzed azide-alkyne cycloaddition (the CuAAC reaction) generates a [3]rotaxane with two identical axles in up to 86% yield. [3]Rotaxanes with two different axles threaded through the macrobicyclic rings can also be created using a single template site, either by having copper(I) sequentially form both mechanical bonds (via the CuAAC reaction) using different sets of building blocks for each axle or by using two different reactions catalyzed by two different metal ions: a palladium(II)-mediated alkyne homocoupling to assemble the first thread through one cavity, followed by a copper(I)-mediated CuAAC reaction to form the second axle through the other ring.
通常，轮烷的模板方法至少需要 n-1 个模板位点来互锁 n 个组件。在这里，我们描述了一锅法合成[3]轮烷，其中单个金属模板位点通过双环大环的每个腔诱导轴的形成。该方法的核心是双环分子的一部分充当过渡金属离子的配体，该过渡金属离子通过一个或另一个大环腔介导共价键形成，具体取决于配体的取向，形成机械键。然后，配体可以旋转，使得过渡金属可以通过另一个大环催化第二个轴的形成。使用这种策略与 Cu（I）-催化的叠氮化物-炔烃环加成（CuAAC 反应），可以以高达 86%的收率生成具有两个相同轴的[3]轮烷。通过单个模板位点也可以创建穿过大环的两个不同轴的[3]轮烷，方法是使用不同的构建块序列通过每个轴形成两个机械键（通过 CuAAC 反应），或者使用两种不同的反应由两个不同的金属离子催化：钯（II）介导的炔烃同偶联反应通过一个腔组装第一个线程，然后是铜（I）介导的 CuAAC 反应通过另一个环形成第二个轴。
