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首页> 外文期刊>Journal of the American Chemical Society >Asymmetric [2 + 2] Olefin Cross Photoaddition in a Self-Assembled Host with Remote Chiral Auxiliaries
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Asymmetric [2 + 2] Olefin Cross Photoaddition in a Self-Assembled Host with Remote Chiral Auxiliaries

机译：具有远程手性助剂的自组装宿主中的不对称[2 + 2]烯烃交叉Photoaddition

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Similar to the pockets of enzymes, cavities of synthetic hosts can activate unreactive compounds to promote reactions in selective ways. Recent self-assembled cages and capsules are showing an improved ability to accelerate and promote reactions with high regio- and stereoselectivity within their cavities. However, asymmetric synthesis in chiral cavities still remains relatively unexplored, mainly because of the difficulty in preparing large chiral cages and capsules in optically pure forms. We have developed a variety of thermal and photochemical reactions within the cavity of the self-assembled M_6L_4 cage 1. Simply replacing the ethylenediamine end-cap on each Pd center with chiral diamines result in chiral derivatives of 1 while maintaining the cavities' electronic nature, size, and T symmetry element. Here, we report that such a simple chiral modification at the periphery of the cage is sufficient for remotely controlling the previously unknown, chiral [2 + 2] olefin cross photoaddition between fluoranthene and maleimide derivatives (2 and 3, respectively) (Figure la). For related studies, Stang and co-workers reported modification of an M_6L_4 cage with chiral diphosphine auxiliaries, but the reactions within the cavity have not been reported.6 Raymond and co-workers used a racemic cage to induce moderate diastereoselectivity in an organometallic transformation. Inoue and co-workers have extensively studied asymmetric anthracene photodimerization and cyclooctene photoisomerization within cyclodextrins.
机译：类似于酶的口袋，合成宿主的腔可以激活未反应的化合物，从而以选择性的方式促进反应。最近的自组装笼和胶囊显示出在其腔内具有高区域选择性和立体选择性的加速和促进反应的能力。然而，手性腔体中的不对称合成仍相对未开发，主要是因为难以制备光学纯形式的大手性笼和胶囊。我们已经在自组装M_6L_4笼子1的腔体内开发了各种热化学反应和光化学反应。简单地用手性二胺取代每个Pd中心的乙二胺端帽，就可以得到1的手性衍生物，同时保持腔体的电子特性，尺寸和T对称元素。在这里，我们报告说，在笼子外围进行这种简单的手性修饰足以远程控制荧蒽和马来酰亚胺衍生物（分别为2和3）之间以前未知的手性[2 + 2]烯烃交叉光加成反应（图1a） 。对于相关研究，Stang及其同事报道了使用手性二膦助剂修饰M_6L_4笼的方法，但尚未报道腔内的反应。6Raymond及其同事使用消旋笼在有机金属转化中诱导中等非对映选择性。井上和同事们广泛研究了环糊精内部的不对称蒽光二聚化和环辛烯光异构化。

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