Consecutive C–F bond activation and C–F bond formation of heteroaromatics at rhodium: the peculiar role of FSi(OEt)<sub>3</sub>
作者:A. L. Raza、T. Braun
DOI:10.1039/c5sc00877h
日期:——
C–F activation of 2,3,5,6-tetrafluoropyridine at [RhSi(OEt)3}(PEt3)3] (1) yields [Rh2-(3,5,6-C5F3HN)}(PEt3)3] (2) and FSi(OEt)3, but in an unprecedented consecutive reaction FSi(OEt)3 acts as a fluoride source to give [Rh(4-C5F4N)(PEt3)3] (4) by regeneration of the C–F bond and C–H activation. Analogous refluorination steps were observed for other 2-pyridyl rhodium complexes. NMR spectroscopic studies
[RhSi(OEt) 3 }(PEt 3 ) 3 ] ( 1 ) 处 2,3,5,6-四氟吡啶的 C-F 活化得到 [Rh2-(3,5,6-C 5 F 3 ) HN)}(PEt 3 ) 3 ] ( 2 ) 和 FSi(OEt) 3,但在前所未有的连续反应中,FSi(OEt) 3充当氟化物源,得到 [Rh(4-C 5 F 4 N)(PEt 3 ) 3 ] ( 4 ) 通过 C-F 键的再生和 C-H 的活化。对于其他 2-吡啶基铑配合物也观察到类似的再氟化步骤。NMR 波谱研究揭示了伴随 C-H 活化的 C-F 键形成的可行性与中间存在的 H 2引起的竞争反应(例如加氢脱氟反应)之间的微妙平衡。