Transformations of perfluoroxylenes and perfluoro-p-cymene under the action of Zn(Cu)-D-DMF-H2O.

Krasnov, V. I.; Platonov, V. E.; Beregovaya, I. V.; Shohegoleva, Lyudmila N.

doi:10.1016/s0040-4020(96)01090-3

Cited by 24 publications

(8 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Experimentally, the most extensively studied reductive fragmentation of perfluoroarenes has been accomplished via solvated electrons with dissolving metals (Scheme A). ,− The generally accepted mechanism in this reaction is electron transfer to give the metastable nonplanar radical anion 2b . Anion 2b undergoes unimolecular fragmentation to generate a σ-radical 2c .…”

Section: Perfluoroaryl Radicalsmentioning

confidence: 99%

Visible Light Photocatalysis for the Generation and Use of Reactive Azolyl and Polyfluoroaryl Intermediates

2016

View full text Add to dashboard Cite

Photocatalysis offers several mechanistically unique pathways that are not rivaled by mainstream catalysis. Primarily, the ability to convert photochemical energy into single electron oxidation and reduction events provides a new dimension for chemists to consider when choosing how to activate a molecule or approach a complex synthesis. Since most organic molecules do not absorb light in the visible region, they are impervious to direct visible light photochemistry, which provides an opportunity for photocatalysis in which a visible light absorbing compound can serve as a mediator. In this Account, we discuss the consequences of catalyst mediated, photoinduced electron transfer to several classes of reducible arenes. While the bulk of the work discussed within this Account utilizes iridium-based photocatalysts, in principle the chemistry is not limited to this class of photocatalyst, and the principles should be more general. Instead, this Account focuses largely on the consequences of single electron transfer to poly- and perfluorinated arenes and 2-halo azoles. Electron transfer converts these stable molecules into reactive intermediates whose behavior often depends entirely on the identity of the halogen that undergoes substitution. The result is both diverse chemistry and an alternative way of thinking about the chemical reactivity of these motifs. Specifically, we discuss our efforts and those of others to develop strategies for the generation of radicals or radical anions from perfluoroarenes and azoles and the behavior of these intermediates as implied by reactions in which they participate. The divergent pathway is illustrated by 2-bromoazoles, which yield azolyl radicals and can be utilized for addition to π-bonds, while use of the 2-chloroazole substrate leads to an entirely different reaction profile. Under the appropriate reaction conditions, the reactive and transient intermediates are useful coupling partners and often provide unrivaled access to new chemical space. The odd electron species can form challenging bonds with minimal prefunctionalization of the coupling partner. For instance, some of the intermediates can be utilized for C-H functionalizations to selectively make crowded amines or to synthesize biarenes substituted at every ortho position. While photocatalysis is not the only manner of accomplishing electron transfer, the catalytic generation of the reactive species in which the concentration of the transient odd electron species is kept low, provides a synthetic handle that can be used to improve reaction outcomes. This is elegantly demonstrated in a number of examples in which redox sensitive groups located on substrates survive the reaction. In addition, the underlying basic concepts associated with radical anion fragmentation are reviewed and provide the backdrop for discussion throughout the Account.

show abstract

Section: Perfluoroaryl Radicalsmentioning

confidence: 99%

Visible Light Photocatalysis for the Generation and Use of Reactive Azolyl and Polyfluoroaryl Intermediates

2016

View full text Add to dashboard Cite

show abstract

“…Being treated with Zn/Cu couple in aqueous DMF at 70 8C, perfluoroarenes with electron-accepting substituents and pentafluoropyridine undergo single hydrodefluorination at para-or ortho-position (g-and a-position in a pyridine framework) to give corresponding products in 30-50% yields [7][8][9]. The yields can be increased up to 70-80% by using an electrolyte (NH 4 Cl, NaCl) additive [10] (Scheme 1).…”

Section: Experimental Data and Synthetic Applicationsmentioning

confidence: 99%

“…The correlation of the DE PS* values of the isomeric perfluoroxylene RAs is, probably, one of the reasons for the ortho and meta isomers to lose fluoride anion from the ring, whereas the para isomer loses it from the trifluoromethyl group (see above) [8,9].…”

Section: Mechanismmentioning

confidence: 99%

Recent advances in practice and theory of polyfluoroarene hydrodehalogenation

Shteingarts

2007

Journal of Fluorine Chemistry

View full text Add to dashboard Cite

“…Perfluoroarenes have a lowered LUMO compared to their hydrocarbon analogs and offer a convenient mode of activation. It is established that addition of an electron into the LUMO generates a radical anion which undergoes fluoride extrusion to generate a radical which abstracts an H-atom . We posited that photoredox catalysiswhich has not been explored for HDF of fluorinated arenesmight have a distinct advantage over traditional methods in generating both the requisite radical anion as well as the H-atom source (eq 1, Scheme ). ,,, Specifically, we speculated that tris[2-phenylpyridinato-C 2 , N ]iridium(III), [Ir(ppy) 3 ] could be used to facilitate outersphere electron transfer to generate a perfluororadical anion ( B , Scheme ) which results in fragmentation to give radical C and a fluoride.…”

mentioning

confidence: 99%

Photocatalytic Hydrodefluorination: Facile Access to Partially Fluorinated Aromatics

2014

View full text Add to dashboard Cite

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.

show abstract

Transformations of perfluoroxylenes and perfluoro-p-cymene under the action of Zn(Cu)-D-DMF-H2O.

Cited by 24 publications

References 23 publications

Visible Light Photocatalysis for the Generation and Use of Reactive Azolyl and Polyfluoroaryl Intermediates

Visible Light Photocatalysis for the Generation and Use of Reactive Azolyl and Polyfluoroaryl Intermediates

Recent advances in practice and theory of polyfluoroarene hydrodehalogenation

Photocatalytic Hydrodefluorination: Facile Access to Partially Fluorinated Aromatics

Contact Info

Product

Resources

About