scholarly journals Monovalent Nickel-Mediated Radical Formation: A Concerted Halogen-Atom Dissociation Pathway Determined by Electroanalytical Studies

2021 ◽  
Author(s):  
Qiao Lin ◽  
Yue Fu ◽  
Peng Liu ◽  
Tianning Diao
Keyword(s):  
Halogen Atom ◽  
Radical Formation ◽  
Dissociation Pathway ◽  
Monovalent Nickel

Photocatalytic Alkylation of Pyrroles and Indoles with α-Diazo Esters

2019 ◽  
Author(s):  
Łukasz Ciszewski ◽  
Jakub Durka ◽  
Dorota Gryko
Keyword(s):  
Aromatic Compounds ◽  
Reaction Pathway ◽  
Alkylating Agents ◽  
Catalytic Amount ◽  
Radical Formation ◽  
Reaction Selectivity ◽  
Diazo Esters ◽  
Electron Withdrawing Substituents

This article describes direct photoalkylation of electron-rich aromatic compounds with diazo compoiunds. C-2 alkylated indoles and pyrroles are obtained with good yields even though the photocatalyst (Ru(bpy)3Cl2) loading is as low as 0.075 mol %. For substrates bearing electron-withdrawing substituents the addition of a catalytic amount of N,N-dimethyl-4-methoxyaniline is required. Both EWG-EWG and EWG-EDG substituted diazo esters are suitable as alkylating agents. The reaction selectivity and mechanistic experiments suggest that carbenes/carbenoid intermediates are not involved in the reaction pathway, instead radical formation is proposed.

Visible Light-Induced Sulfonylation/Arylation of Styrenes in a Double Radical Three-Component Photoredox Reaction

2019 ◽  
Author(s):  
Benjamin Lipp ◽  
Lisa Marie Kammer ◽  
Murat Kucukdisli ◽  
Adriana Luque ◽  
Jonas Kühlborn ◽  
...  
Keyword(s):  
Visible Light ◽  
Radical Formation ◽  
Three Component Reaction ◽  
Broad Variety ◽  
Styrene Derivatives ◽  
Mechanistic Investigations

Simultaneous sulfonylation/arylation of styrene derivatives is achieved in a photoredox-catalyzed three-component reaction using visible light. A broad variety of difunctionalized products is accessible in mostly excellent yields and high diastereoselectivity. The developed reaction is scalable and suitable for the modification of styrene-functionalized biomolecules. Mechanistic investigations suggest the transformation to be operating through a designed sequence of radical formation and radical combination.<br>

Reductive Dehalogenation of Environmental Contaminants: A Critical Review

1989 ◽  
Vol 24 (2) ◽  
pp. 299-322 ◽  
Author(s):  
R. M. Baxter
Keyword(s):  
Hydrogen Atom ◽  
Aromatic Compounds ◽  
Reductive Dechlorination ◽  
Halogen Atom ◽  
Environmental Contaminants ◽  
Methanogenic Bacteria ◽  
Photochemical Reactions ◽  
Reductive Dehalogenation ◽  
Iron Porphyrins ◽  
Aliphatic Compounds

Abstract It is generally recognized that reductive processes are more important than oxidative ones in transforming, degrading and mineralizing many environmental contaminants. One process of particular importance is reductive dehalogenation, i.e., the replacement of a halogen atom (most commonly a chlorine atom) by a hydrogen atom. A number of different mechanisms are involved in these reactions. Photochemical reactions probably play a role in some instances. Aliphatic compounds such as chloroethanes, partly aliphatic compounds such as DDT, and alicyclic compounds such as hexachlorocyclohexane are readily dechlorinated in the laboratory by reaction with reduced iron porphyrins such as hematin. Many of these are also dechlorinated by cultures of certain microorganisms, probably by the same mechanism. Such compounds, with a few exceptions, have been found to undergo reductive dechlorination in the environment. Aromatic compounds such as halobenzenes, halophenols and halobenzoic acids appear not to react with reduced iron porphyrins. Some of these however undergo reductive dechlorination both in the environment and in the laboratory. The reaction is generally associated with methanogenic bacteria. There is evidence for the existence of a number of different dechlorinating enzymes specific for different isomers. Recently it has been found that many components of polychlorinated biphenyls (PCBs), long considered to be virtually totally resistant to environmental degradation, may be reductively dechlorinated both in the laboratory and in nature. These findings suggest that many environmental contaminants may prove to be less persistent than was previously feared.

In vivo thiyl free radical formation from hemoglobin following administration of hydroperoxides

1990 ◽  
Vol 277 (2) ◽  
pp. 402-409 ◽  
Author(s):  
Kirk R. Maples ◽  
Christopher H. Kennedy ◽  
Sandra J. Jordan ◽  
Ronald P. Mason
Keyword(s):  
Free Radical ◽  
Radical Formation ◽  
Free Radical Formation

scholarly journals Hydralazine-dependent carbon dioxide free radical formation by metabolizing mitochondria.

1988 ◽  
Vol 263 (23) ◽  
pp. 11296-11301 ◽  
Author(s):  
P K Wong ◽  
J L Poyer ◽  
C M DuBose ◽  
R A Floyd
Keyword(s):  
Carbon Dioxide ◽  
Free Radical ◽  
Radical Formation ◽  
Free Radical Formation
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