- Halogen-Bridged Methylnaphthyl Palladium Dimers as Versatile Catalyst Precursors in Coupling Reactions
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Halogen-bridged methylnaphthyl (MeNAP) palladium dimers are presented as multipurpose Pd-precursors, ideally suited for catalytic method development and preparative organic synthesis. By simply mixing with phosphine or carbene ligands, they are in situ converted into well-defined monoligated complexes. Their catalytic performance was benchmarked against state-of-the-art systems in challenging Buchwald–Hartwig, Heck, Suzuki and Negishi couplings, and ketone arylations. Their use enabled record-setting activities, beyond those achievable by optimization of the ligand alone. The MeNAP catalysts permit syntheses of tetra-ortho-substituted arenes and bulky anilines in near-quantitative yields at room temperature, allow mono-arylations of small ketones, and enable so far elusive cross-couplings of secondary alkyl boronic acids with aryl chlorides.
- Doppiu, Angelino,Goo?en, Lukas J.,Hu, Zhiyong,Pirkl, Nico,Sivendran, Nardana
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supporting information
p. 25151 - 25160
(2021/10/19)
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- Efficient Pd-Catalyzed Direct Coupling of Aryl Chlorides with Alkyllithium Reagents
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Organolithium compounds are amongst the most important organometallic reagents and frequently used in difficult metallation reactions. However, their direct use in the formation of C?C bonds is less established. Although remarkable advances in the coupling of aryllithium compounds have been achieved, Csp2?Csp3 coupling reactions are very limited. Herein, we report the first general protocol for the coupling or aryl chlorides with alkyllithium reagents. Palladium catalysts based on ylide-substituted phosphines (YPhos) were found to be excellently suited for this transformation giving high selectivities at room temperature with a variety of aryl chlorides without the need for an additional transmetallation reagent. This is demonstrated in gram-scale synthesis including building blocks for materials chemistry and pharmaceutical industry. Furthermore, the direct coupling of aryllithiums as well as Grignard reagents with aryl chlorides was also easily accomplished at room temperature.
- Dilchert, Katharina,Gessner, Viktoria H.,Gro?johann, Angela,Rodstein, Ilja,Scherpf, Thorsten,Steinert, Henning,Tappen, Jens
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supporting information
p. 20596 - 20603
(2020/09/09)
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- Expanding the Balz–Schiemann Reaction: Organotrifluoroborates Serve as Competent Sources of Fluoride Ion for Fluoro-Dediazoniation
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The Balz–Schiemann reaction endures as a method for the preparation of (hetero)aryl fluorides yet is eschewed due to the need for harsh conditions or high temperatures along with the need to isolate potentially explosive diazonium salts. In a departure from these conditions, we show that various organotrifluoroborates (RBF3?s) may serve as fluoride ion sources for solution-phase fluoro-dediazoniation in organic solvents under mild conditions. This methodology was successfully extended to a one-pot process obviating aryl diazonium salt isolation. Sterically hindered (hetero)anilines are fluorinated under unprecedentedly mild conditions in good-to-excellent yields. Taken together, this work expands the repertoire of RBF3?s to act as fluorine ion sources in an update to the classic Balz–Schiemann reaction.
- Mohy El Dine, Tharwat,Sadek, Omar,Gras, Emmanuel,Perrin, David M.
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supporting information
p. 14933 - 14937
(2018/09/25)
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- Synthesis of aryl fluorides from potassium aryltrifluoroborates and selectfluor mediated by iron(III) chloride
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The synthesis of fluorinated arenes by the iron-mediated fluorination of potassium aryltrifluoroborates with Selectfluor and potassium fluoride is described. The fluorination reaction uses commercially available reagents and without requiring the addition
- Dubbaka, Srinivas Reddy,Gadde, Satyanarayana,Narreddula, Venkateswara Reddy
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p. 854 - 860
(2015/03/14)
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- AROMATIC ACETYLCHOLINESTERASE INHIBITORS
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Compounds of general formula (I), stereosiomers and pharmaceutically acceptable salts thereof, wherein each of Z and Z' are independently H or F; Q is (a), CH(OH), (b); X is H, Br, Cl, F or CF3 ; Y is H, Br, Cl, F, OH, OR5, OC(O)R4, N3, CN, NO2, SO3 H, CO
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- Aryl fluoride syntheses involving reactions of aryllead triacetates with boron trifluoride-diethyl ether complex
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Aryllead(IV) triacetates react at room temperature with BF3.Et2O to give the corresponding aryl fluoride in moderate to good yields; triarylboroxines, electron rich aryltrimethylsilanes and some arenes, which yield aryllead triacetates in acid catalysed reactions with lead tetraacetate, are converted directly into aryl fluorides when stirred with lead tetraacetate in BF3.Et2O. An investigation of the mechanism of the fluoro-deplumbation reaction indicates that it probably proceeds by acid catalysed heterolytic cleavage of the C-Pb bond to produce an aryl cation.
- De Meio,Morgan,Pinhey
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p. 8129 - 8138
(2007/10/02)
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- GAS PHASE ISOPROPYLATION OF AROMATIC HYDROCARBONS. FLUORINE AND METHYL SUBSTITUENT EFFECTS ON REACTIVITY AND ORIENTATION.
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The isopropylation of substituted benzenes by s-C3H7+ cations is studied to evaluate the directive effects of fluorine, methyl group and their combinations as ring substituents in the gas-phase aromatic substitution.
- Attina, Marina,Petris, Giulia de,Giacomello, Pierluigi
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p. 3525 - 3528
(2007/10/02)
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