In recent years, radical C–C bond cleavage reactions have been increasingly understood and used to perform transformations that complement traditional ionic processes. However, to date radical C–C bond cleavage/functionalization reactions have not been the subject of a dedicated review. Herein we summarize the most recent and significant developments in the radical activation and functionalization of carbon–carbon bonds, with an emphasis on both synthetic outcomes and reaction mechanisms, and highlight how these radical C–C bond cleavage reactions enable challenging transformations.

Cleavage of carbon-carbon bonds by radical reactions.

Visible-light photoredox catalysis enables easy access to acyl radicals under mild reaction conditions. Reactive acyl radicals, generated from various acyl precursors such as aldehydes, α-keto acids, carboxylic acids, anhydrides, acyl thioesters, acyl chlorides, or acyl silanes, can undergo a diverse range of synthetically useful transformations, which were previously difficult or inaccessible. This review summarizes the recent progress on visible-light-driven acyl radical generation using transition-metal photoredox catalysts, metallaphotocatalysts, hypervalent iodine catalysts or organic photocatalysts. 1 	Introduction 2 	The Scope of This Review 3 	Aldehydes as a Source of Acyl Radicals 4 	α-Keto Acids as a Source of Acyl Radicals 5 	Carboxylic Acids as a Source of Acyl Radicals 6 	Anhydrides as a Source of Acyl Radicals 7 	Acyl Thioesters as a Source of Acyl Radicals 8 	Acyl Chlorides as a Source of Acyl Radicals 9 	Acyl Silanes as a Source of Acyl Radicals 10 	Conclusions and Future Outlook

/pdf/acyl-radical-chemistry-via-visible-light-photoredox-4qjwbz02on.pdf

Acyl Radical Chemistry via Visible-Light Photoredox Catalysis.

Photogenerated acyl/alkoxycarbonyl/carbamoyl radicals for sustainable synthesis

Aryl diazonium salts are versatile building blocks in organic synthesis In light of the ever-increasing importance of aryl diazonium salts spanning most disciplines of the chemical sciences, we review the recent development of aryl diazonium chemistry over the past seven years (2013-2020) Special emphasis is put on various new transformations involving the generation of radical intermediates via thermal, photochemical, and electrochemical means Recent advances in the development of transition metal-catalyzed reactions using aryl diazonium salts are also reviewed Together, these newly developed transformations significantly expand the synthetic chemist's repertoire of aromatic carbon-carbon and carbon-heteroatom bond forming methods using aryl diazonium precursors, providing powerful tools for the synthesis and modification of complex molecular scaffolds

Recent Development of Aryl Diazonium Chemistry for the Derivatization of Aromatic Compounds

A mild and facile visible-light-mediated strategy has been proposed for the synthesis of 3-acyl quinoxalin-2(1H)-ones through acridine red catalyzed aerobic oxidative decarboxylative acylation of α-oxo-carboxylic acids with quinoxalin-2(1H)-ones at room temperature in air. Various 3-acyl quinoxalin-2(1H)-ones could be efficiently obtained in good yields with excellent functional group compatibility.

Visible-light-promoted acridine red catalyzed aerobic oxidative decarboxylative acylation of α-oxo-carboxylic acids with quinoxalin-2(1H)-ones

Carbamoyl Radicals via Photoredox Decarboxylation of Oxamic Acids in Aqueous Media: Access to 3,4-Dihydroquinolin-2(1 H)-ones.

An expedient organic photoredox Pschorr reaction has been developed that opens up a synthetic route to 6H-benzo[c]chromenes The process can be performed under mild conditions by using eosin Y as a photoredox catalyst and acetonitrile as the solvent The diazonium salts can be either preformed or generated in situ from the corresponding amines with t-BuONO The process is amenable to gram-sale synthesis of 6H-benzo[c]chromenes, which can be further transformed into both 6H-benzo[c]chromen-6-ones through oxidation or to 6H-benzo[c]chromen-6-amine through sp3 C–H bond amination The protocol provides an attractive route for the synthesis of a library of 6H-benzo[c]chromes

Organic Photoredox Catalysis for Pschorr Reaction: A Metal-Free and Mild Approach to 6H-Benzo[c]chromenes

An efficient silver-catalyzed tandem decarboxylative radical addition/cyclization of oxamic acids with alkenes has been developed. This method provides a novel and straightforward protocol toward a variety of 4-aryl-3,4-dihydroquinolin-2(1H)-ones, 4-(α-carbonyl)-3,4-dihydroquinolin-2(1H)-ones, and quinolin-2(1H)-ones in aqueous solution.

Silver-Catalyzed Decarboxylative Radical Addition/Cyclization of Oxamic Acids with Alkenes towards Quinolin-2-ones

The invention provides a 3,4-dihydro-2(1H)-quinolinone compound and a preparation method and application thereof The substituted oxamic acid and the substituted ethylene are adopted as raw materialsfor the first time; in the presence of an oxidizing agent and silver nitrate of catalytic amount and in an organic solvent and water, the reaction mixed liquid is stirred for 36-48 hours at a temperature of 50-100 DEG C; the product is subjected to extraction, drying, vacuum concentration and column chromatography to obtain a 3,4-dihydro quinoline-2(1H)-one derivative The 3,4-dihydro-2(1H)-quinolinone compound provided by the invention has the advantages of simple and easily available raw materials, mild reaction conditions, easiness in operation and perfect application value; experiments prove that the synthesized new 3,4-dihydro-2(1H)-quinolinone compound has new characteristics and bioactivity and particularly realizes a remarkable effect in preparation of anti-tumor drugs

3,4-dihydro-2(1H)-quinolinone compound and preparation method and application thereof

The invention provides a method for preparing a quinolinone compound. The method comprises the following steps: by taking substituted oxamic acid and substituted ethylene as raw materials for a firsttime, in the presence of an oxidant and a catalytic amount of silver nitrate, stirring a mixed reaction liquid at a certain temperature of 50-100 DEG C for 36-48 hours in an organic solvent and water,extracting a product, drying, performing vacuum concentration, and performing column chromatography, thereby obtaining a 3,4-dihydroquinoline-2(1H)-ketone derivative. The method is simple and easy inraw material obtaining, gentle in reaction condition, simple to operate, high in yield and very high in application value.

Jin Cheng'an

Papers

Carbamoyl Radicals via Photoredox Decarboxylation of Oxamic Acids in Aqueous Media: Access to 3,4-Dihydroquinolin-2(1 H)-ones.

Organic Photoredox Catalysis for Pschorr Reaction: A Metal-Free and Mild Approach to 6H-Benzo[c]chromenes

Silver-Catalyzed Decarboxylative Radical Addition/Cyclization of Oxamic Acids with Alkenes towards Quinolin-2-ones

3,4-dihydro-2(1H)-quinolinone compound and preparation method and application thereof

Method for preparing quinolinone compound