Regioselective C-F Bond Activation/C-C Bond Formation between Fluoropyridines and Cyclopropyl Groups at Zirconium was written by Romero, Nuria;Dufrois, Quentin;Crespo, Natalie;Pujol, Anthony;Vendier, Laure;Etienne, Michel. And the article was included in Organometallics in 2020.Formula: C5F5N The following contents are mentioned in the article:
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. This study involved multiple reactions and reactants, such as 2,3,4,5,6-Perfluoropyridine (cas: 700-16-3Formula: C5F5N).
2,3,4,5,6-Perfluoropyridine (cas: 700-16-3) belongs to pyridine derivatives. Pyridine has a dipole moment and a weaker resonant stabilization than benzene (resonance energy 117 kJ·mol−1 in pyridine vs. 150 kJ·mol−1 in benzene). One of the examples of pyridines is the well-known alkaloid lithoprimidine, which is an A3 adenosine receptor antagonist and N,N-dimethylaminopyridine (DMAP) analog, commonly used in organic synthesis.Formula: C5F5N