- Transition metal-free cross-dehydrogenative arylation of unactivated benzylic C-H bonds
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The cross-dehydrogenative arylation of benzylic C-H bonds with arenes provides straightforward access to synthetically useful 1,1-diarylmethanes, from readily available starting materials. Current approaches suffer from limited substrate scope, requirement for large excesses of alkyl arene and/or non-trivial reaction set up. We report a transition metal-free cross-dehydrogenative arylation of benzylic C-H bonds using alkyl benzene derivatives and electron-rich arenes as coupling partners. The method proceeds through the in situ generation of a reactive benzyl fluoride intermediate which then reacts with the nucleophilic arene. The reaction tolerates a wide variety of functional groups including unprotected polar functionality and has been applied to the late-stage benzylation of several biologically relevant molecules.
- Spencer, Andrew R. A.,Grainger, Rachel,Panigrahi, Adyasha,Lepper, Thomas J.,Bentkowska, Katarzyna,Larrosa, Igor
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- Light-Mediated Formal Radical Deoxyfluorination of Tertiary Alcohols through Selective Single-Electron Oxidation with TEDA2+.
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The synthesis of tertiary alkyl fluorides through a formal radical deoxyfluorination process is described herein. This light-mediated, catalyst-free methodology is fast and broadly applicable allowing for the preparation of C?F bonds from (hetero)benzylic, propargylic, and non-activated tertiary alcohol derivatives. Preliminary mechanistic studies support that the key step of the reaction is the single-electron oxidation of cesium oxalates—which are readily available from the corresponding tertiary alcohols—with in situ generated TEDA2+. (TEDA: N-(chloromethyl)triethylenediamine), a radical cation derived from Selectfluor.
- Aguilar Troyano, Francisco José,Ballaschk, Frederic,Jaschinski, Marcel,?zkaya, Yasemin,Gómez-Suárez, Adrián
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p. 14054 - 14058
(2019/11/11)
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- Photoredox-catalyzed deoxyfluorination of activated alcohols with Selectfluor
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Herein we disclose a deoxyfluorination of alcohols with an electrophilic fluorine source via visible-light photoredox catalysis. This radical-mediated C–F coupling is capable of fluorinating secondary and tertiary alcohols efficiently, complementing previously reported nucleophilic deoxyfluorination protocols.
- González-Esguevillas, María,Miró, Javier,Jeffrey, Jenna L.,MacMillan, David W.C.
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p. 4222 - 4227
(2019/06/13)
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- Targeted fluorination with the fluoride ion by manganese-catalyzed decarboxylation
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We describe the first catalytic decarboxylative fluorination reaction based on the nucleophilic fluoride ion. The reported method allows the facile replacement of various aliphatic carboxylic acid groups with fluorine. Moreover, the potential of this method for PET imaging has been demonstrated by the successful 18F labeling of a variety of carboxylic acids with radiochemical conversions up to 50-%, representing a targeted decarboxylative 18F labeling method with no-carrier-added [18F]fluoride. Mechanistic probes suggest that the reaction proceeds through the interaction of the manganese catalyst with iodine(III) carboxylates formed in situ from iodosylbenzene and the carboxylic acid substrates. Nucleophile first: An efficient manganese porphyrin catalyzed decarboxylative fluorination reaction based on a nucleophilic fluorine source is described. The potential of the described method for use in PET imaging has been demonstrated by the successful 18F labeling of various aliphatic carboxylic acids, representing the first decarboxylative 18F labeling method with no-carrier-added [18F]fluoride.
- Huang, Xiongyi,Liu, Wei,Hooker, Jacob M.,Groves, John T.
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supporting information
p. 5241 - 5245
(2015/04/27)
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- Fluorodecarboxylation, rearrangement and cyclisation: the influence of structure and environment on the reactions of carboxylic acids with xenon difluoride
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The reactions of structurally diverse carboxylic acids with XeF2 in both CH2Cl2/Pyrex and CH2Cl2/PTFE have been studied. Pyrex appears to be a very effective heterogeneous catalyst for an electrophilic mode of reaction of polarised XeF2, leading to rearrangement, cyclisation and cationic products. In CH2Cl2/PTFE, fluorodecarboxylation is the main mode of reaction, in accordance with previous studies, and may occur via a SET reaction of unpolarised XeF2.
- Ramsden, Christopher A.,Shaw, Maxine M.
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experimental part
p. 3321 - 3324
(2009/08/09)
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- Observations on the Reaction of Xanthate Esters with 4-Methyl(difluoroiodo)benzene: a New Method for the Conversion of Alcohols to Alkyl Fluorides
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Treatment of a range of S-methyldithiocarbonates (xanthates) with 4-methyl(difluoroiodo)benzene gives the corresponding alkyl fluorides.
- Koen, Mark J.,Guyader, Frederic Le,Motherwell, William B.
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p. 1241 - 1242
(2007/10/02)
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