- Tetramethylammonium Fluoride Alcohol Adducts for SNAr Fluorination
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Nucleophilic aromatic fluorination (SNAr) is among the most common methods for the formation of C(sp2)-F bonds. Despite many recent advances, a long-standing limitation of these transformations is the requirement for rigorously dry, aprotic conditions to maintain the nucleophilicity of fluoride and suppress the generation of side products. This report addresses this challenge by leveraging tetramethylammonium fluoride alcohol adducts (Me4NF·ROH) as fluoride sources for SNAr fluorination. Through systematic tuning of the alcohol substituent (R), tetramethylammonium fluoride tert-amyl alcohol (Me4NF·t-AmylOH) was identified as an inexpensive, practical, and bench-stable reagent for SNAr fluorination under mild and convenient conditions (80 °C in DMSO, without the requirement for drying of reagents or solvent). A substrate scope of more than 50 (hetero) aryl halides and nitroarene electrophiles is demonstrated.
- Bland, Douglas C.,Lee, So Jeong,Morales-Colón, Mariá T.,Sanford, Melanie S.,Scott, Peter J. H.,See, Yi Yang
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supporting information
p. 4493 - 4498
(2021/06/28)
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- Derisking the Cu-Mediated 18F-Fluorination of Heterocyclic Positron Emission Tomography Radioligands
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Molecules labeled with fluorine-18 (18F) are used in positron emission tomography to visualize, characterize and measure biological processes in the body. Despite recent advances in the incorporation of 18F onto arenes, the development of general and efficient approaches to label radioligands necessary for drug discovery programs remains a significant task. This full account describes a derisking approach toward the radiosynthesis of heterocyclic positron emission tomography (PET) radioligands using the copper-mediated 18F-fluorination of aryl boron reagents with 18F-fluoride as a model reaction. This approach is based on a study examining how the presence of heterocycles commonly used in drug development affects the efficiency of 18F-fluorination for a representative aryl boron reagent, and on the labeling of more than 50 (hetero)aryl boronic esters. This set of data allows for the application of this derisking strategy to the successful radiosynthesis of seven structurally complex pharmaceutically relevant heterocycle-containing molecules.
- Taylor, Nicholas J.,Emer, Enrico,Preshlock, Sean,Schedler, Michael,Tredwell, Matthew,Verhoog, Stefan,Mercier, Joel,Genicot, Christophe,Gouverneur, Véronique
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supporting information
p. 8267 - 8276
(2017/06/27)
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- Accelerating palladium-catalyzed C-F bond formation: Use of a microflow packed-bed reactor
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A flow process for Pd-catalyzed C-F bond formation is described. A microreactor with a packed-bed design allows for easy handling of large quantities of insoluble CsF with precise control over reaction times, efficient mixing, and the ability to safely handle elevated temperatures and pressures. A variety of aryl triflates, including heteroaryl ones, were converted into aryl fluorides in short reaction times (see scheme).
- Noel, Timothy,Maimone, Thomas J.,Buchwald, Stephen L.
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supporting information; experimental part
p. 8900 - 8903
(2011/10/19)
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- Metal-Catalyzed Carbon-Fluorine Bond Formation
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One aspect of the invention relates to a metal-catalyzed conversion of aryl halides and sulfonates to the corresponding aryl fluorides. Another aspect of the invention relates to a metal-catalyzed conversion of heteroaryl halides and sulfonates to the corresponding heteroaryl fluorides. Another aspect of the invention relates to a metal-catalyzed conversion of vinyl halides and sulfonates to the corresponding vinyl fluorides. In certain embodiments, simple fluoride sources, such as AgF and CsF, are used. In certain embodiments, the transformations tolerate a wide range of functional groups, allowing for introduction of fluorine atoms into highly functionalized organic molecules.
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Page/Page column 17
(2011/02/18)
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- The o-Amino-Trifluoromethyl Functionality as a Novel Synthon for 4-Fluoroquinolines
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2-Substituted 4-fluoroquinolines 3 are obtained by the reaction of 2-(trifluoromethyl)aniline (1) with lithium enolates 2 derived from methyl ketones.A similar reaction of 1 with lithium enolate of acetaldehyde produces 4-fluoroquinoline. 1-Fluoro-3-phenyl-4,6-phenanthroline (18) is obtained by treatment of lithium enolate of acetophenone with 4-(trifluoromethyl)quinolin-3-amine (17).By contrast, (Z)-N-carboxamides 10 and 12 are the products of the reaction of 1 with the respective enolate ions derived from 3-pentanone and isobutyl phenyl ketone.A unified mechanism for the formation of quinolines and carboxamides is proposed.
- Strekowski, Lucjan,Kiselyov, Alexander S.,Hojjat, Maryam
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p. 5886 - 5890
(2007/10/02)
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