- Catalyst-Free Hydrodefluorination of Perfluoroarenes with NaBH4
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Presented is an economical means of removing fluorine from various highly fluorinated arenes using NaBH4. The procedure was adapted for different classes of perfluoroarenes. A novel isomer of an emerging class of organic dyes based on the carbazole phthalonitrile motif was succinctly synthesized in two steps from tetrafluorophthalonitrile, demonstrating the utility of the hydrodefluorination procedure. Initial exploration of the dye shows it to be photoactive and capable of facilitating contrathermodynamic styrenoid E/Z isomerization.
- Schoch, Timothy D.,Mondal, Mukulesh,Weaver, Jimmie D.
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supporting information
p. 1588 - 1593
(2021/03/03)
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- Copper-Catalyzed Defluorinative Hydroarylation of Alkenes with Polyfluoroarenes
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A catalytic defluorinative hydroarylation of alkenes with polyfluoroarenes in the presence of dppbz-ligated Cu catalyst and silanes was developed. This method provides a straightforward and alternative avenue to synthetic important polyfluorinated arenes with readily available and bench-stable alkenes as latent nucleophiles, and therefore avoids conventional reliance on stoichiometric quantities of organometallic reagents. This reaction proceeds under very mild conditions and exhibits good functional group compatibility and high level of regioselectivity. The synthetic potential of this method was further demonstrated by a gram-scale synthesis, and an array of experimental studies were also carried out to elaborate the probable mechanism.
- Fu, Bin,Li, Xiaohong,Xiong, Tao,Yuan, Xiuping,Zhang, Qian,Zhang, Qiao
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supporting information
p. 23056 - 23060
(2020/10/19)
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- C-F Activation in Perfluorinated Arenes with Isonitriles under UV-Light Irradiation
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Due to the great value of fluorinated arenes in agrochemistry, medicinal chemistry and materials science, development of methods for preparation of fluorinated arenes is of high importance. They can be either accessed by arene fluorination or by partial arene defluorination. However, the carbon-fluorine bond belongs to the strongest σ-bonds, which renders C-F activation highly challenging. Here it is shown that aryl and alkyl isonitriles efficiently activate the strong C-F bond in perfluoroarenes by simple UV irradiation under mild conditions. Reactions proceed by formal direct insertion of the isonitrile into the C-F bond without any transition metal. Activation occurs at arene C-F bonds whereas aliphatic C-F bonds remain unreacted. For selected perfluoroarenes C-F activation occurs with high regioselectivity and resulting imidoyl fluorides are transformed into other valuable compounds. Theoretical studies give insights into the reaction mechanism.
- Dewanji, Abhishek,Mück-Lichtenfeld, Christian,Bergander, Klaus,Daniliuc, Constantin G.,Studer, Armido
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supporting information
p. 12295 - 12298
(2015/08/25)
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- Photocatalytic hydrodefluorination: Facile access to partially fluorinated aromatics
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Polyfluorinated aromatics are essential to materials science as well as the pharmaceutical and agrochemical industries and yet are often difficult to access. This Communication describes a photocatalytic hydrodefluorination approach which begins with easily accessible perfluoroarenes and selectively reduces the C-F bonds. The method allows facile access to a number of partially fluorinated arenes and takes place with unprecedented catalytic activity using a safe and inexpensive amine as the reductant.
- Senaweera, Sameera M.,Singh, Anuradha,Weaver, Jimmie D.
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supporting information
p. 3002 - 3005
(2014/03/21)
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- Novel fluorinated prodrugs for activation by carboxypeptidase G2 showing good in vivo antitumor activity in gene-directed enzyme prodrug therapy
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Sixteen novel polyfluorinated benzoic acid mustards have been synthesized for use in gene-directed enzyme prodrug therapy (GDEPT). Eight of these were benzoic acid L-glutamate mustards for evaluation as prodrugs and the other eight were the active drugs formed by the action of the bacterial enzyme carboxypeptidase G2 (CPG2). All of the di- and trifluorinated prodrugs were efficiently cleaved by the enzyme. In contrast, the tetrafluorinated prodrugs were found to be competitive inhibitors of CPG2, the first such inhibitors to have been described. The di- and trifluorinated prodrugs were differentially cytotoxic to human breast carcinoma cells (MDA MB 361) expressing CPG2, compared to control cells that did not express the enzyme. The difluorinated prodrug {4-[bis(2-bromoethyl)amino]-3,5-difluorobenzoyl}-L-glutamic acid and its iodoethylamino analogue were effective substrates for the enzyme and showed excellent therapeutic activity in CPG2-expressing MDA MB 361 xenografts, either curing or greatly inhibiting tumor growth and extending the life of the animals.
- Davies, Lawrence C.,Friedlos, Frank,Hedley, Douglas,Martin, Jan,Ogilvie, Lesley M.,Scanlon, Ian J.,Springer, Caroline J.
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p. 5321 - 5328
(2007/10/03)
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- Reactivity and reaction pathways of alkylalkoxybenzene radical cations. Part 2. Effects of 2-alkyl substituents on the relative importance of deprotonation over de-tert-butylation of 2-alkyl-5-tert-butyl-1,4-dimethoxybenzene radical cations
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The 2-alkyl-5-tert-butyl-1,4-dimethoxybenzene radical cations 1+·a-e (2-alkyl = Me, Et, i-Pr, c-PrCH2 and PhCH2) generated in one-electron oxidauon of their parent compounds 1a-e by pentafluorobenzoyl peroxide or cerium(IV) sulfate were characterized by EPR spectrometry. The product analysis shows that under certain conditions 1+·a-e may collapse through two competitive pathways, i.e. deprotonation and de-tert-butylation. The deprotonation of 1+·a-e is further assured by EPR observations of the corresponding benzyl radical intermediates. The relative importance of the two pathways is greatly dependent on the structure of the alkyl substituents, the nature of the solvents and the reaction temperature. For deprotonation, the reactivity order is found to be c-PrCH2 >Me >PhCH2 >Et ? i-Pr. Copyright
- Zhao, Cheng-Xue,Gong, Yue-Fa,He, Hai-Ying,Jiang, Xi-Kui
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p. 688 - 694
(2007/10/03)
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