Experimental and theoretical study of Hoveyda–Grubbs catalysts modified by perfluorohexyl ponytail in the alkoxybenzylidene ligand
摘要:
The alkoxybenzylidene ligand of Hoveyda-Grubbs 1st and 2nd generation catalysts was modified with one or two perfluorohexyl groups by Ullmann reaction with the aim to improve both the fluorophilicity and activity of the catalyst. While bis(perfluorohexylation) resulted in inability of the ligand to exchange tricyclohexylphosphine ligand of parent Grubbs catalysts, mono(perfluorohexylation) and subsequent ligand exchange resulted in the formation of complexes of light fluorous properties and substantially higher activity in model RCM reactions. Modification of the mesityl group of the unsaturated NHC ligand by polyfluoroalkyl ponytails resulted in the formation of ruthenium precatalyst furnishing active catalytic intermediate with light fluorous properties. DFT computations of the model initiation reaction of ethene with Hoveyda-Grubbs 2nd generation catalyst or its pentafluoroethylated counterpart revealed that in the latter, the intermediate ruthenacyclobutane can form and decompose with significantly lower energies, thus explaining its higher activity. (C) 2013 Elsevier B.V. All rights reserved.
Experimental and theoretical study of Hoveyda–Grubbs catalysts modified by perfluorohexyl ponytail in the alkoxybenzylidene ligand
摘要:
The alkoxybenzylidene ligand of Hoveyda-Grubbs 1st and 2nd generation catalysts was modified with one or two perfluorohexyl groups by Ullmann reaction with the aim to improve both the fluorophilicity and activity of the catalyst. While bis(perfluorohexylation) resulted in inability of the ligand to exchange tricyclohexylphosphine ligand of parent Grubbs catalysts, mono(perfluorohexylation) and subsequent ligand exchange resulted in the formation of complexes of light fluorous properties and substantially higher activity in model RCM reactions. Modification of the mesityl group of the unsaturated NHC ligand by polyfluoroalkyl ponytails resulted in the formation of ruthenium precatalyst furnishing active catalytic intermediate with light fluorous properties. DFT computations of the model initiation reaction of ethene with Hoveyda-Grubbs 2nd generation catalyst or its pentafluoroethylated counterpart revealed that in the latter, the intermediate ruthenacyclobutane can form and decompose with significantly lower energies, thus explaining its higher activity. (C) 2013 Elsevier B.V. All rights reserved.
A metal-free photochemical strategy for the direct aromatic perfluoroalkylation of phenols is reported. This operationally simple approach occurs at ambient temperature and under illumination by a fluorescent light bulb. The chemistry is driven by the ability of phenolate anions, transiently generated upon deprotonation of phenols, to directly reach an electronically excited state upon light absorption
A simple procedure for the perfluoroalkylation of the aromatic ring of phenols under mildly basic conditions is described. Treatment of a variety of phenols with perfluoroalkyl iodide in the presence of the radical initiator V-70L and Cs2CO3 provided the corresponding perfluoroalkylated products in moderate to good yields. Generally, the reaction proceeded smoothly at room temperature to yield regioselectively
描述了在温和碱性条件下苯酚芳环全氟烷基化的简单程序。在自由基引发剂V-70L和Cs 2 CO 3的存在下用全氟烷基碘处理各种酚,以中等至良好的产率提供了相应的全氟烷基化产物。通常,反应在室温下平稳进行,得到区域选择性的全氟烷基化产物。
[EN] FLUOROUS METAL CHELATES COMPOSITIONS<br/>[FR] COMPOSITIONS DE CHÉLATES MÉTALLIQUES FLUORITIQUES
申请人:THE REGENTS OF THE UNIVEFISITY OF CALIFORNIA
公开号:WO2020118307A1
公开(公告)日:2020-06-11
This disclosure provides compositions of SALTAME core containing compounds and associated methods for use in tracking cells by magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), and related methods.
This disclosure provides compositions of SALTAME core containing compounds and associated methods for use in tracking cells by magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), and related methods.
Experimental and theoretical study of Hoveyda–Grubbs catalysts modified by perfluorohexyl ponytail in the alkoxybenzylidene ligand
The alkoxybenzylidene ligand of Hoveyda-Grubbs 1st and 2nd generation catalysts was modified with one or two perfluorohexyl groups by Ullmann reaction with the aim to improve both the fluorophilicity and activity of the catalyst. While bis(perfluorohexylation) resulted in inability of the ligand to exchange tricyclohexylphosphine ligand of parent Grubbs catalysts, mono(perfluorohexylation) and subsequent ligand exchange resulted in the formation of complexes of light fluorous properties and substantially higher activity in model RCM reactions. Modification of the mesityl group of the unsaturated NHC ligand by polyfluoroalkyl ponytails resulted in the formation of ruthenium precatalyst furnishing active catalytic intermediate with light fluorous properties. DFT computations of the model initiation reaction of ethene with Hoveyda-Grubbs 2nd generation catalyst or its pentafluoroethylated counterpart revealed that in the latter, the intermediate ruthenacyclobutane can form and decompose with significantly lower energies, thus explaining its higher activity. (C) 2013 Elsevier B.V. All rights reserved.