Whereas [4 + 2] cycloadditions are among the most powerful tools in the chemist’s synthetic arsenal, controlling reactivity and selectivity of [6 + 4] cycloadditions has proven to be extremely challenging. Such transformations, especially if compatible with simple hydrocarbon-based substrates, could ultimately provide a general approach to highly valuable and otherwise difficult to access 10-membered rings. We report here that highly acidic and confined imidodiphosphorimidate catalysts do not catalyze this reaction under homogeneous conditions. Notably, however, they can spontaneously precipitate an insoluble and double helix–shaped noncovalent organic framework, which acts as a distinctively reactive and stereoselective catalyst of [6 + 4] cycloadditions of simple dienes with tropone.

中文翻译：

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固体非共价有机双螺旋框架催化不对称[6 + 4]环加成


尽管[4 + 2]环加成是化学家合成武器库中最强大的工具之一，但控制[6 + 4]环加成的反应性和选择性已被证明极具挑战性。这种转化，特别是如果与简单的烃基底物兼容，最终可以提供一种通用方法来获得高价值且难以获得的10元环。我们在此报道，高酸性和受限的亚氨基二磷酸酯催化剂在均相条件下不会催化该反应。然而，值得注意的是，它们可以自发沉淀出不溶性的双螺旋形非共价有机骨架，该骨架充当简单二烯与托酮的[6 + 4]环加成反应的独特反应性和立体选择性催化剂。