Wang Heng-Ding, Fan Hong-Jun
State Key Laboratory of Molecular Reaction Dynamics, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China.
University of Chinese Academy of Sciences, Beijing, China.
Commun Chem. 2020 Sep 11;3(1):126. doi: 10.1038/s42004-020-00373-2.
The mechanism of silver(I) and copper(I) catalyzed cycloaddition between 1,2-diazines and siloxy alkynes remains controversial. Here we explore the mechanism of this reaction with density functional theory. Our calculations show that the reaction takes place through a metal (Ag, Cu) catalyzed [2+2] cycloaddition pathway and the migration of a silylium ion [triisopropylsilyl ion (TIPS)] further controls the reconstruction of four-member ring to give the final product. The lower barrier of this silylium ion mediated [2+2] cycloaddition mechanism (SMC) indicates that well-controlled [2+2] cycloaddition can obtain some poorly-accessible IEDDA (inverse-electron demand Diels-Alder reaction) products. Strong interaction of d metals (Ag, Cu) and alkenes activates the high acidity silylium ion (TIPS) in situ. This п-acid (Ag, Cu) and hard acid (TIPS) exchange scheme will be instructive in silylium ion chemistry. Our calculations not only provide a scheme to design IEDDA catalysts but also imply a concise way to synthesise 1,2-dinitrogen substituted cyclooctatetraenes (1,2-NCOTs).
银（I）和铜（I）催化的1,2 - 二嗪与硅氧基炔烃之间的环加成反应机理仍存在争议。在此，我们用密度泛函理论探索该反应的机理。我们的计算表明，该反应通过金属（Ag、Cu）催化的[2 + 2]环加成途径进行，并且甲硅烷基离子[三异丙基甲硅烷基离子（TIPS）]的迁移进一步控制四元环的重构以得到最终产物。这种由甲硅烷基离子介导的[2 + 2]环加成机理（SMC）的较低能垒表明，良好控制的[2 + 2]环加成能够获得一些难以得到的逆电子需求狄尔斯 - 阿尔德反应（IEDDA）产物。d金属（Ag、Cu）与烯烃的强相互作用原位活化了高酸性的甲硅烷基离子（TIPS）。这种π酸（Ag、Cu）和硬酸（TIPS）交换模式将对甲硅烷基离子化学具有指导意义。我们的计算不仅提供了一种设计IEDDA催化剂的方案，还暗示了一种合成1,2 - 二氮取代环辛四烯（1,2 - NCOTs）的简洁方法。
