Highly Efficient Nickel(II) Chloride/Bis(tricyclohexylphosphine)nickel(II) Chloride‐Cocatalyzed Hydrodefluorination of Fluoroarenes and Trifluorotoluenes with Superhydride

Zhao, Wenwen; Wu, Jingjing; Cao, Song

doi:10.1002/adsc.201100783

Cited by 51 publications

(12 citation statements)

References 38 publications

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“…Some of these reactions are marred by the use of toxic and explosive reagents, production of stoichiometric metal waste, poor selectivity, and low functional‐group tolerance. Nevertheless, there has been an intense research interest in developing more efficient and reliable transition‐metal‐catalyzed hydrodehalogenation processes (mostly involving, Pd, Rh, Ru, Ni, and Fe) using Grignard reagents, alcohol and base,, hydrides,,, formic acid or its salt, hydrazine, and molecular hydrogen ,,,. Obviously, from an ecological perspective, the later reagent is considered to be the most efficient, clean, and atom‐economical reductant…”

Section: Methodsmentioning

confidence: 99%

A Biomass‐Derived Non‐Noble Cobalt Catalyst for Selective Hydrodehalogenation of Alkyl and (Hetero)Aryl Halides

et al. 2017

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Hydrodehalogenation is astraightforwardapproach for detoxifications of harmful anthropogenic organohalidebased pollutants,aswell as removal of halide protecting groups used in multistep syntheses.An ovel sustainable catalytic material was prepared from biowaste (chitosan) in combination with an earth-abundant cobalt salt. The heterogeneous catalyst was fully characterized by transmission electron microscope,X -rayd iffraction, and X-ray photoelectron spectroscopym easurements,a nd successfully applied to hydrodehalogenation of alkyla nd (hetero)aryl halides with broad scope (> 40 examples) and excellent chemoselectivity using molecular hydrogen as ar eductant. The general usefulness of this method is demonstrated by successful detoxification of non-degradable pesticides and fire retardants.M oreover,t he potential of the catalyst as adeprotection tool is demonstrated in am ultistep synthesis of (AE)-peronatin B( alkaloid).Hydrodehalogenation constitutes an important organic transformation where ahalogen atom is formally substituted with ahydrogen atom. It has become an enabling technology for degradation of anthropogenic and environmentally deleterious chemicals into their less noxious congeners.T he former are often produced in industrial processes and can include polyhalogenated organic pollutants (such as,p olychlorodioxins and polychlorophenols), toxic and persistent pesticides,and fire retardants.[1, 2] Furthermore,hydrodehalogenation reactions are often used in organic synthesis for deprotection chemistry,s ince halides can selectively block one of two reaction sites with similar reactivity without strongly influencing the electronics of the system. [2,3] Additionally,s tereoselective hydrodehalogenation of prochiral gem-dihalo-organic compounds affords chiral halo-organic compounds. [4] Hydrodehalogenation reactions have been performed with various methods,s uch as metal-halogen exchange, [2, 5] metal-mediated reduction, [2,6] photochemical reduction, [7] and reductive radical dehalogenation.[8] Some of these reactions are marred by the use of toxic and explosive reagents, production of stoichiometric metal waste,poor selectivity,and low functional-group tolerance.Nevertheless,there has been an intense research interest in developing more efficient and reliable transition-metal-catalyzed hydrodehalogenation processes (mostly involving,Pd, [9] Rh, [10] Ru, [11] Ni, [4,12] and Fe [13] ) using Grignard reagents, [12c,13] alcohol and base, [9a, 10c, 11a,c] hydrides, [4,9b,c, 12b,d,14] formic acid [9h] or its salt, [9e] hydrazine, [9d] and molecular hydrogen. [9c,f,g,10a,b, 11b,12a] Obviously,f rom an ecological perspective,t he later reagent is considered to be the most efficient, clean, and atom-economical reductant. [15] Fort he last decade,t he implementation of cheap,e arth abundant, non-noble metals for (de)hydrogenation reactions has attracted significant interest in homogeneous and heterogeneous catalysis.[16] As acomplement to molecularly defined organometallic complexes,heter...

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Section: Methodsmentioning

confidence: 99%

A Biomass‐Derived Non‐Noble Cobalt Catalyst for Selective Hydrodehalogenation of Alkyl and (Hetero)Aryl Halides

et al. 2017

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“…In 2012, Cao et al illustrated a cocatalyst system composed of nickel(II) chloride, and bis(tricyclohexylphosphine)nickel(II)chloride was able to hydrodefluorinate various aryl fluorides in the presence of superhydride (Eq. 70) [124]. The hydrodefluorination of heterocycle-polyfluoroarenes has also been reported by Zhang et al in 2013.…”

Section: ð68; 69þmentioning

confidence: 64%

Activation and Formation of Aromatic C–F Bonds

LaBerge

Love

2015

Topics in Organometallic Chemistry

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The presence of aryl C-F bonds in pharmaceuticals and agrochemicals is increasing rapidly. Incorporation of a fluorine substituent into biologically relevant molecules yields many benefits such as decreased metabolism, solubility, hydrophobicity and decreased negative side effects. Since there are no known examples of naturally occurring aryl fluorides all must be accessed through chemical synthesis. The formation and activation of aryl C-F bonds is a challenging endeavor, nevertheless several strategies are possible. Recent developments towards the synthesis of fluoroaromatics, as well as routes to selectively remove fluorine from polyfluoroaromatics are surveyed.

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“…In continuation of the research on the hydrodefluorination reaction, Cao and coworkers reported various reaction conditions for different types of C-F bonds [24,[63][64][65]. They found that C-F bonds of fluoroarenes are more easily reduced with LiAl(O t Bu) 3 H than C-F bonds of α,α,α-trifluorotoluenes under the catalysis of NiCl 2 (PCy 3 ) 2 (Scheme 24d) [66].…”

Section: Page 25 Of 29mentioning

confidence: 95%

Review of recent advances in CF bond activation of aliphatic fluorides

Shen

Huang

Liu

et al. 2015

Journal of Fluorine Chemistry

227

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Highly Efficient Nickel(II) Chloride/Bis(tricyclohexylphosphine)nickel(II) Chloride‐Cocatalyzed Hydrodefluorination of Fluoroarenes and Trifluorotoluenes with Superhydride

Abstract: A simple and highly efficient approach for the hydrodefluorination of both fluoroarenes and trifluorotoluenes in the presence of lithium tri-

Cited by 51 publications

References 38 publications

A Biomass‐Derived Non‐Noble Cobalt Catalyst for Selective Hydrodehalogenation of Alkyl and (Hetero)Aryl Halides

A Biomass‐Derived Non‐Noble Cobalt Catalyst for Selective Hydrodehalogenation of Alkyl and (Hetero)Aryl Halides

Activation and Formation of Aromatic C–F Bonds

Review of recent advances in CF bond activation of aliphatic fluorides

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