Evidence for the formation of radical anion in the reductive cleavage of carbon–bromine bond in 4′-bromomethylbiphenyl-2-carbonitrile

2005 ◽  
Vol 414 (1-3) ◽  
pp. 55-60 ◽  
Author(s):  
M. Arun Prasad ◽  
M.V. Sangaranarayanan
Keyword(s):  
Radical Anion ◽  
Reductive Cleavage

Reductive cleavage mechanism of diphenyl ether and apparent ipso trapping of an intermediate radical anion with a silyl ether

1982 ◽  
Vol 47 (22) ◽  
pp. 4250-4254 ◽  
Author(s):  
Kundanbhai M. Patel ◽  
Richard J. Baltisberger ◽  
Virgil I. Stenberg ◽  
Neil F. Woolsey
Keyword(s):  
Radical Anion ◽  
Diphenyl Ether ◽  
Reductive Cleavage ◽  
Silyl Ether ◽  
Intermediate Radical

scholarly journals Electro-mediated PhotoRedox Catalysis for Selective C(sp3)-O Cleavages of Phosphinates to Carbanions

2021 ◽  
Author(s):  
Xianhai Tian ◽  
Tobias Karl ◽  
Sebastian Reiter ◽  
Shahboz Yakubov ◽  
Regina de Vivie-Riedle ◽  
...  
Keyword(s):  
Radical Anion ◽  
Reductive Cleavage ◽  
Photoredox Catalysis ◽  
Structural Variations ◽  
Aryl Chlorides ◽  
Anion Form

We report a novel example of electro-mediated photoredox catalysis (e-PRC) in the reductive cleavage of C(sp<sup>3</sup>)-O bonds of phosphinates to alkyl carbanions. As well as deoxygenations, olefinations are reported which are <i>E</i>-selective and can be made <i>Z</i>-selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for a more intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity-determining C(sp<sup>3</sup>)-O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions i) tolerate aryl chlorides/bromides and ii) do not give rise to Birch-type reductions.

scholarly journals Electro-mediated PhotoRedox Catalysis for Selective C(sp3)-O Cleavages of Phosphinates to Carbanions

2021 ◽  
Author(s):  
Xianhai Tian ◽  
Tobias Karl ◽  
Sebastian Reiter ◽  
Shahboz Yakubov ◽  
Regina de Vivie-Riedle ◽  
...  
Keyword(s):  
Radical Anion ◽  
Reductive Cleavage ◽  
Photoredox Catalysis ◽  
Structural Variations ◽  
Aryl Chlorides ◽  
Anion Form

We report a novel example of electro-mediated photoredox catalysis (e-PRC) in the reductive cleavage of C(sp<sup>3</sup>)-O bonds of phosphinates to alkyl carbanions. As well as deoxygenations, olefinations are reported which are <i>E</i>-selective and can be made <i>Z</i>-selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for a more intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity-determining C(sp<sup>3</sup>)-O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions i) tolerate aryl chlorides/bromides and ii) do not give rise to Birch-type reductions.

Reductive Cleavage of Secondary Sulfonamides: Converting Terminal Functional Groups into Versatile Synthetic Handles

2019 ◽  
Author(s):  
Patrick Fier ◽  
Suhong Kim ◽  
Kevin M. Maloney
Keyword(s):  
Functional Groups ◽  
Late Stage ◽  
Reductive Cleavage ◽  
Bioactive Molecules ◽  
General Method

Sulfonamides are pervasive in drugs and agrochemicals, yet are typically considered as terminal functional groups rather than synthetic handles. To enable the general late-stage functionalization of secondary sulfonamides, we have developed a mild and general method to reductively cleave the N-S bonds of sulfonamides to generate sulfinates and amines, components which can further react <i>in-situ</i> to access a variety of other medicinally relevant functional groups. The utility of this platform is highlighted by the selective manipulation of several complex bioactive molecules.

Association of radical anion with alkali cations. IV. ESR study of the 4-nitrobenzophenone radical anion

1980 ◽  
Vol 45 (2) ◽  
pp. 369-375 ◽  
Author(s):  
Stanislav Miertuš ◽  
Ondrej Kyseľ
Keyword(s):  
Hyperfine Splitting ◽  
Radical Anion ◽  
Esr Spectroscopy ◽  
Supporting Electrolyte ◽  
Esr Spectra ◽  
Proton Donor ◽  
Alkali Cations

The 4-nitrobenzophenone radical anion prepared by electrolysis was studied by ESR spectroscopy. On the basis of the interpretation of ESR spectra, the conformation of this system was estimated. The effect of the concentration of supporting electrolyte and of the presence of a proton-donor agent (C2H5OH) was examined. It is assumed that changes in hyperfine splitting constants are caused by association.

Stability of radical anions derived from substituted 5-nitrofurans investigated by ESR spectroscopy

1985 ◽  
Vol 50 (7) ◽  
pp. 1594-1601 ◽  
Author(s):  
Jiří Klíma ◽  
Larisa Baumane ◽  
Janis Stradinš ◽  
Jiří Volke ◽  
Romualds Gavars
Keyword(s):  
Radical Anion ◽  
High Stability ◽  
Esr Spectroscopy ◽  
Reaction Path ◽  
Order Reaction ◽  
Second Order ◽  
Radical Anions ◽  
Second Order Reaction ◽  
Unpaired Electron Density ◽  
The Stability

It has been found that the decay in dimethylformamide and dimethylformamide-water mixtures of radical anions in five of the investigated 5-nitrofurans is governed by a second-order reaction. Only the decay of the radical anion generated from 5-nitro-2-furfural III may be described by an equation including parallel first- and second-order reactions; this behaviour is evidently caused by the relatively high stability of the corresponding dianion, this being an intermediate in the reaction path. The presence of a larger conjugated system in the substituent in position 2 results in a decrease of the unpaired electron density in the nitro group and, consequently, an increase in the stability of the corresponding radical anions.

Benzyl ethers of methyl α-D-glucopyranoside

1980 ◽  
Vol 45 (7) ◽  
pp. 1959-1963 ◽  
Author(s):  
Dušan Joniak ◽  
Božena Košíková ◽  
Ludmila Kosáková
Keyword(s):  
Kinetic Study ◽  
Spectrophotometric Determination ◽  
Reductive Cleavage ◽  
Ether Bond ◽  
Benzyl Ethers ◽  
Acid Catalyzed ◽  
Model Substances ◽  
Hydrolysis Of

Methyl 4-O-(3-methoxy-4-hydroxybenzyl) and methyl 4-O-(3,5-dimethoxy-4-hydroxybenzyl)-α-D-glucopyranoside and their 6-O-isomers were prepared as model substances for the ether lignin-saccharide bond by reductive cleavage of corresponding 4,6-O-benzylidene derivatives. Kinetic study of acid-catalyzed hydrolysis of the compounds prepared was carried out by spectrophotometric determination of the benzyl alcoholic groups set free, after their reaction with quinonemonochloroimide, and it showed the low stability of the p-hydroxybenzyl ether bond.

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