This paper addresses the problem of the strong and inert C–F bond activation of various fluoropyridines by zirconocene derivatives. Dicyclopropylzirconocene, [Cp₂Zr(c-C₃H₅)₂], thermally eliminates cyclopropane, giving the transient intermediate zirconabicyclobutane [Cp₂Zr(η²-c-C₃H₄)] that cleaves a C–F bond of pentafluoropyridine selectively at position 2, forming new Zr–F and C–C bonds stereoselectively to give [Cp₂ZrF{c-cis-CHCH₂CH(2-NC₅F₄)}]. DFT computations indicate the selectivity results from the initial formation of an azazirconacycle intermediate that undergoes ring opening and C–F bond cleavage. Transmetalation with a variety of cyclopropyl donors yields [Cp₂Zr(c-C₃H₅){c-cis-CHCH₂CH(2-NC₅F₄)}] with the selectivity depending on the nature of the donor. A synthetic cycle is realized when [Cp₂Zr(c-C₃H₅){c-cis-CHCH₂CH(2-NC₅F₄)}] reacts with pentafluoropyridine, yielding 2-(c-C₃H₅)NC₅F₄ and [Cp₂ZrF{c-cis-CHCH₂CH(2-NC₅F₄)}] with C–F bond activation. Attempts at converting this reaction sequence to a catalytic version failed due to either decomposition of the active species or multiple C–F bond substitutions by the transmetalating agent.

中文翻译：

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锆上的氟吡啶和环丙基之间的区域选择性C–F键激活/ CC键形成

本文探讨了锆茂衍生物对各种氟吡啶进行强而惰性的CF键活化的问题。Dicyclopropylzirconocene，混合[Cp ₂ Zr的（ç -C ₃ ħ ₅）₂ ]，热消除环丙烷，给瞬时中间体zirconabicyclobutane的[Cp ₂ Zr的（η ² - ç -C ₃ ħ ₄）]裂解的C-F键在位置2选择性五氟，形成新ZRF和C-C键立体选择性，得到的[Cp ₂ ZRF { ç -顺式- CHCH ₂ CH（2-NC ₅ ˚F₄ }}]。DFT计算表明，选择性的结果是氮杂碳环中间体的初始形成，该中间体经历开环和CF键断裂。转移金属化与各种环丙基供体产量的[Cp ₂ Zr的（ç -C ₃ ħ ₅）{ Ç -顺式- CHCH ₂ CH（2-NC ₅ ˚F ₄）}]具有取决于供体的性质的选择性。合成周期被实现时的[Cp ₂ Zr的（ç -C ₃ ħ ₅）{ Ç -顺式- CHCH ₂ CH（2-NC ₅˚F ₄）}]发生反应与五氟，得到2-（ç -C ₃ ħ ₅）NC ₅ ˚F ₄和混合[Cp ₂ ZRF { Ç -顺-CHCH ₂（2-NC CH ₅ ˚F ₄）}]与C- F键活化。由于活性物质的分解或由重金属化剂进行的多个CF键取代，尝试将该反应序列转换为催化形式失败。