Sun Yuanyuan, Li Ying, Li Xiaoyan, Meng Lingpeng, Zeng Yanli
College of Chemistry and Materials Science, Hebei Key Laboratory of Inorganic Nano-materials, Hebei Normal University, Shijiazhuang, 050024, China.
Phys Chem Chem Phys. 2022 Aug 10;24(31):18877-18887. doi: 10.1039/d2cp01913b.
With the continuous development of halogen bonds, halogen bond donors have been used as clean and efficient catalysts in organic reactions. In this work, with inorganic halides (I, IBr, ICl, and ICl) as catalysts and the iso-Nazarov cyclization as the benchmark reaction, we aim at investigating the role of the halogen bond in the catalytic mechanism. The halogen bond catalyzed iso-Nazarov cyclization reaction involves three steps: carbon-carbon coupling process, [1,2]-H shift process, and [1,4]-H shift process. The halogen-bonding interaction promotes the charge accumulation of the oxygen atom in the carbonyl group and decreases the activation energy of the reaction. The catalytic activity of the halogen bond donor is enhanced in the order of I < IBr < ICl < ICl, and it could be predicted that the partial covalent interaction of the I⋯O halogen bond between the catalyst ICl and the oxygen atom of the reactant may exhibit good catalytic activity in the experiments. In the [1,4]-H shift process, the two-step hydrogen bond/halogen bond co-catalyzed mechanism exhibits the lowest reaction energy barrier than the one-step water co-catalyzed proton transfer mechanism and the direct one.
随着卤键的不断发展，卤键供体已被用作有机反应中清洁高效的催化剂。在本工作中，以无机卤化物（I、IBr、ICl和ICl）为催化剂，异Nazarov环化反应为基准反应，旨在研究卤键在催化机理中的作用。卤键催化的异Nazarov环化反应包括三个步骤：碳-碳偶联过程、[1,2]-H迁移过程和[1,4]-H迁移过程。卤键相互作用促进了羰基中氧原子的电荷积累，降低了反应的活化能。卤键供体的催化活性按I < IBr < ICl < ICl的顺序增强，可以预测，催化剂ICl与反应物氧原子之间的I⋯O卤键的部分共价相互作用在实验中可能表现出良好的催化活性。在[1,4]-H迁移过程中，两步氢键/卤键共催化机理比一步水共催化质子转移机理和直接机理表现出最低的反应能垒。
