烷烃的立体选择性活化是化学领域长期面临的重大挑战。尽管含金属的酶可以非常容易和选择性地氧化烷烃,但化学方法在很大程度上仅限于基于过渡金属的催化碳氢官能化。
烷烃可以质子化形成五配位碳离子,并在强布朗斯特酸的存在下裂解成较小的碳氢化合物。然而,以前尚未实现对此类反应的催化立体控制。
该文中,研究发现,强酸和受限酸催化各种环丙烷高度对映选择性裂解为相应的烯烃,扩大了催化选择性烷烃活化的边界。计算研究表明,长期争论的环丙鎓离子参与其中。
附:英文原文
Title: Catalytic asymmetric fragmentation of cyclopropanes
Author: Ravindra Krushnaji Raut, Satoshi Matsutani, Fuxing Shi, Shuta Kataoka, Margareta Poje, Benjamin Mitschke, Satoshi Maeda, Nobuya Tsuji, Benjamin List
Issue&Volume: 2024-10-11
Abstract: The stereoselective activation of alkanes constitutes a long-standing and grand challenge for chemistry. Although metal-containing enzymes oxidize alkanes with remarkable ease and selectivity, chemical approaches have largely been limited to transition metal–based catalytic carbon–hydrogen functionalizations. Alkanes can be protonated to form pentacoordinated carbonium ions and fragmented into smaller hydrocarbons in the presence of strong Brnsted acids. However, catalytic stereocontrol over such reactions has not previously been accomplished. We show here that strong and confined acids catalyze highly enantioselective fragmentations of a variety of cyclopropanes into the corresponding alkenes, expanding the boundaries of catalytic selective alkane activation. Computational studies suggest the involvement of the long-debated cycloproponium ions.
DOI: adp9061
Source: https://www.science.org/doi/10.1126/science.adp9061
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