Field Of Radical Chemistry Research Articles

A General Radical Functionalization of Quinoxalin-2(1H)-ones via a Donor-Acceptor Inversion Strategy.

The radical donor-acceptor inversion strategy represents a highly promising approach in the field of radical chemistry. The present study initially describes a metal-free, versatile, and modular approach for the radical functionalization of quinoxalin-2(1H)-ones via a strategy of radical donor-acceptor inversion under simple reaction conditions. More than 66 examples were provided in moderate yields. The mechanistic study has confirmed that the driving force behind this radical reaction is the in situ formation of a salt through the interaction between quinoxalin-2(1H)-ones and acid/HFIP, which exhibits potent oxidation properties. Additionally, it has been observed that the evident hydrogen bonding between quinoxalin-2(1H)-ones and HFIP can effectively mitigate the oxidation potential.

HFIP‐Triggered Reduction Radical Coupling of Enamides with Alkynes Towards β‐Keto Alkylamides via H‐Bonding Electron Transfer

AbstractThis study presents metal‐free protocols for the reduction radical coupling of enamides with diverse alkynes, triggered by 1,1,1,3,3,3‐Hexafluoro‐2‐propanol (HFIP), enabling access to β‐keto alkylamides. The established approach demonstrates remarkable efficiency, facile gram‐scale synthesis, and outstanding functional group tolerance. Mechanistic investigations have revealed that the radical reaction is initiated through H‐bonding electron transfer (Hb‐ET) between enamides and HFIP promoted by acids. Notably, the introduction of Hb‐ET protocols for generating radicals represents a highly promising approach in the field of radical chemistry.

Visible light-promoted alkylation of electron-deficient alkenes with alkylsilyl peroxides

We report a photochemical approach for the generation of alkyl radicals from alkylsilyl peroxides (ASPs) in the absence of any transition metal or photocatalyst. This operationally simple protocol utilizes Hantzsch ester as a photoreductant to efficiently induce the OO bond cleavage of various ASPs via single-electron transfer, generating the corresponding alkyl radicals under mild conditions. The radicals generated by this method participate in a Giese-type addition with a wide range of electron-deficient alkenes. This study broadens the methods by which radicals can be generated from ASPs, and thus improves their applicability and versatility in the field of radical chemistry.

Modulating stereoselectivity in allylic C(sp3)-H bond arylations via nickel and photoredox catalysis

While significant progress has been made in developing selective C-H bond cross-couplings in the field of radical chemistry, the site and stereoselectivity remain a long-standing challenge. Here, we present the successful development of stereodivergent allylic C(sp3)-H bond arylations through a systematic investigation of the direction and degree of stereoselectivity in the cross-coupling process. In contrast to the signature photosensitized geometrical isomerization of alkenes, the catalytic reaction demonstrates the feasibility of switching the C-C double bond stereoselectivity by means of ligand control as well as steric and electronic effects. Computational studies explain the stereochemical outcome and indicate that excitation of a Ni-allyl complex from singlet to a triplet state results in a spontaneous change of the allyl group coordination and that the subsequent isomerization can be directed by the choice of the ligand to achieve E/Z selectivity.

Exploiting attractive non-covalent interactions for the enantioselective catalysis of reactions involving radical intermediates

The past decade has seen unprecedented growth in the development of new chemical methods that proceed by mechanisms involving radical intermediates. This new attention has served to highlight a long-standing challenge in the field of radical chemistry - that of controlling absolute stereochemistry. This Review will examine developments using a strategy that offers enormous potential, in which attractive non-covalent interactions between a chiral catalyst and the substrate are leveraged to exert enantiocontrol. In a simplistic sense, such an approach mimics the modes of activation and control in enzyme catalysis and the realization that this can be achieved in the context of small-molecule catalysts has had sizable impact on the field of asymmetric catalysis in recent years. This strategy is now starting to quickly gather pace as a powerful approach for control of enantioselectivity in radical reactions and we hope that this focused survey of progress so far will inspire future developments in the area.

New Organic Chemistry and Materials Science of Curved π-Conjugated Molecules

A key molecule in a number of functional materials is the π-conjugated molecule because of the impressive range of properties, including light absorption and emission, as well as charge transportation. Often used as active components of organic electronic and photoelectronic materials and sensors, they have attracted a great deal of attention from the research community for these valuable properties that have considerable potential for commercialisation. A variety of new π-conjugated molecules have been designed and synthesised, from smaller molecules to macromolecules (polymers). Professor Shigeru Yamago, from the Institute for Chemical Research at Kyoto University, is an expert in the field of radical chemistry, and heads up a research team that has developed a new and efficient method for synthesising structurally uniform curved and hooped π-conjugated molecules. Yamago and his team are seeking to clarify how the structure of these molecules affects their physical properties and reactivities. They hope to eventually find applications for them as organoelectronic and organophotoelectronic materials, sensors and other devices in materials science.

Happy Birthday to Bernd Giese

Happy Birthday to Bernd Giese

Silver‐Based Radical Reactions: Development and Insights

AbstractSilver‐mediated reactions have recently emerged as a frontier area in organic chemistry. Indeed, the remarkable property of silver as a single‐electron oxidant has led to its exploitment into the field of radical chemistry. The excellent reactivity and high selectivity exhibited by silver salts in the activation of different organic substrates place them among the most prominent reagents in free radical reactions. The present review aims to provide the readers with a critical overview of silver‐based radical reactions, especially emphasizing the reactivity, selectivity and a detailed description of the reaction mechanism with particular attention to the role of Ag(I)‐based catalysts/reactants. The selected examples have been classified according to the type of radicals generated, namely carbon‐centered radicals and heteroatom (such as nitrogen, oxygen, phosphorus, sulfur)‐centered radicals. The generation of such radicals as well as their application in synthetic processes including oxidation, addition, coupling, and radical cascades have been described in detail.magnified image

Nitrogen-Centered Radical Scavengers

As reactants in radical reactions, nitrogen-centered scavengers can offer valuable alternatives to ionic methods regarding the synthesis of nitrogen-containing compounds. In this review article, we present developments, scope, limitations and future challenges in this field of radical chemistry.

ChemInform Abstract: The Invention of Chemical Reactions: The Last Five Years

Abstract Recent progress at Texas A&M University and in France in the field of radical chemistry, based on the thiocarbonyl function, has been summarized.

Unprecedented Aromatic Homolytic Substitutions and Cyclization of AmideIminyl Radicals: Experimental and Theoretical Study

Amide-iminyl radicals are versatile and efficient intermediates in cascade radical cyclizations of N-acylcyanamides. They are easily trapped by alkenes or (hetero-)aromatic rings and cyclize into a series of new heterocyclic compounds which bear a pyrroloquinazoline moiety. As an illustration of the synthetic importance of these compounds, the total synthesis of the natural antitumor compound luotonin A was achieved through a tin-free radical cascade cyclization process. Not only do amide-iminyl radicals lead to new tetracyclic heterocycles but these nitrogen-centered radical species also react in aromatic homolytic substitutions. Indeed, the amide-iminyl radical moiety unprecedentedly displaces methyl, methoxy, and fluorine radicals from an aromatic carbon atom. This seminal reaction in the field of radical chemistry has been developed experimentally and its mechanism has additionally been investigated by a theoretical study.

The Invention of Chemical Reactions: the Last Five Years.

Recent progress at Texas A&M University and in France in the field of radical chemistry, based on the thiocarbonyl function, has been summarized.