PDF(Pubmed)
Abstract：
Studies have shown that the incorporation of fluorine into materials can improve their properties, but C-F bonds are not readily formed in nature. Although some researchers have studied the reaction of fluorinating alkenes catalyzed by hypervalent iodine, far too little attention has been paid to its reaction mechanism. This study aimed to explore the mechanism of the hypervalent iodine-catalyzed 1,4-difluorination of dienes. We found that the catalyst is favorable for the activation of C1=C2 double bonds through halogen bonds, and then two HFs interact with one F atom in the catalyst via hydrogen bonds, resulting in the cleavage of I-F bonds and the formation of [F-H∙∙∙F]-. Subsequently, the catalyst interacts with C1, and the roaming [F-H···F]- attacks C4 from the opposite side of the catalyst. After the fluorination step is completed, the nucleophile F- substitutes the catalyst via the SN2 mechanism. Our calculations demonstrated that the interaction between HF and F- is favorable for the stabilization of the transition state within the fluorination process for which the presence of two HFs in the reaction is the best. We also observed that [F-H∙∙∙F]- attacking C4 from the opposite side of the catalyst is more advantageous than attacking from the same side. This study therefore offers a novel perspective on the mechanism of the hypervalent iodine-catalyzed fluoridation of dienes.
摘要：
研究表明，在材料中掺入氟可以改善其性能，但是C-F键在自然界中不容易形成。尽管一些研究人员研究了高价碘催化氟化烯烃的反应，对其反应机理的关注太少了。本研究旨在探讨高价碘催化二烯烃1,4-二氟化反应的机理。我们发现该催化剂有利于通过卤素键活化C1=C2双键，然后两个HF通过氢键与催化剂中的一个F原子相互作用，导致I-F键的分裂和[F-H‧F]-的形成。随后，催化剂与C1相互作用，漫游的[F-H··F]-从催化剂的另一侧攻击C4。氟化步骤完成后，亲核试剂F-通过SN2机理取代催化剂。我们的计算表明，HF和F-之间的相互作用有利于氟化过程中过渡态的稳定，对于氟化过程中两个HF的存在最好。我们还观察到，从催化剂的另一侧攻击C4比从同一侧攻击更有利。因此，这项研究为高价碘催化的二烯氟化机理提供了新的视角。
