Competitive Aryl–Fluorine and Aryl–Halogen (Halogen = Cl, Br) Bond Cleavage with Iridium Porphyrin Complexes
摘要:
Base-promoted competitive Ar-F and Ar-X (X = Cl, Br) bond cleavage with iridium porphyrin complexes was investigated. Mechanistic studies suggested that Ir(ttp)(-) (ttp = 5,10,15,20-tetra-p-tolylporphyrinato dianion) cleaves the Ar-F bond via nucleophilic aromatic substitution and Ir-2(ttp)(2) cleaves the Ar-X (X = Cl, Br) bond via metalloradical ipso substitution. Therefore, a stronger base, polar solvent, lower temperature, and iridium anion precursor favor Ar-F bond cleavage, while a weaker base, nonpolar solvent, higher temperature, and Ir-2(ttp)(2) precursor favor Ar-X (X = Cl, Br) bond cleavage.
DOI:
10.1021/om301196t
作为产物:
描述:
三乙基硅烷 、 Ir(5,10,15,20-tetra-p-tolylporphyrinato)(BF4)(CO) 以
neat (no solvent) 为溶剂,
以61%的产率得到[Ir(5,10,15,20-tetra-p-tolylporphyrinato dianion)(SiEt3)]
参考文献:
名称:
铱(III)卟啉配合物对硅烷的碱促进的硅氢键活化
摘要:
通过无溶剂条件和非极性溶剂中的硅氢键活化(SiHA),通过铱(III)卟啉羰基氯与甲基与硅烷的反应,可方便地以中等至高收率合成铱(III)卟啉甲硅烷基。发现碱促进了SiHA反应。具体来说,K 3 PO 4用铱卟啉羰基氯加速SiHA,而KOAc则用铱卟啉甲基促进SiHA。机理实验表明,铱(III)卟啉羰基氯最初形成了铱卟啉阳离子,然后它可能通过杂化作用与硅烷反应生成铱卟啉氢化物。铱卟啉氢化物进一步与硅烷反应生成铱卟啉甲硅烷基。另一方面,铱(III)卟啉甲基和甲硅烷基经过氧化加成或σ键易位形成产物。在碱的存在下,可能形成五配位的氢化硅物质并与铱卟啉甲基反应形成铱卟啉阴离子,后者可进一步与硅烷反应生成质子化后的铱卟啉氢化物。
Consecutive aromatic C–F bond and C–H bond activations of aryl fluorides were achieved by iridium porphyrins to initially give aryl and finally fluoroaryl iridium porphyrins. The C–F bond activation product is generated first, which is the precursor for the C–H bond activation. Both experimental and theoretical results support that the C–F bond is cleaved by iridium porphyrin anion through nucleophilic