Intramolecular Radical Carboaminoxylation of Aryl Amines

Hartmann, Marcel; Gerleve, Carolin; Studer, Armido

doi:10.1055/s-0035-1560770

Cited by 5 publications

(3 citation statements)

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“…Aryl diazonium compounds also react efficiently with iron(II) salts, and by using a stoichiometric amount of the iron salt and stoichiometric TEMPO, alkene aryloxygenation was achieved. , The aryloxygenation can be combined with a cyclization as documented for the transformation of the diazonium salts 264 to dihydrobenzofurans 265 (Scheme ). Our group used iodide to generate aryl radicals from aryl diazonium salts and applied this method for oxidative 5- exo -cyclization to prepare dihydrobenzofurans, -indoles, and -benzothiophenes. , …”

Section: Nitroxides In Free-radical Chemistrymentioning

confidence: 99%

“…1283 Our group used iodide to generate aryl radicals from aryl diazonium salts and applied this method for oxidative 5-exo-cyclization to prepare dihydrobenzofurans, -indoles, and -benzothiophenes. 1284,1285 Zhou et al disclosed a multicomponent reaction that is terminated by an amidoxyl radical trapping step (Scheme 80). 1286 Reductive cleavage of an oxime ester 267 by a copper(I) complex gives an iminyl radical, which undergoes ring opening to an alkyl radical.…”

Section: Trapping Of C-centered Radicalsmentioning

confidence: 99%

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Organic Synthesis Using Nitroxides

Leifert

Studer

2023

Chem. Rev.

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Nitroxides, also known as nitroxyl radicals, are long-lived or stable radicals with the general structure R 1 R 2 N−O • . The spin distribution over the nitroxide N and O atoms contributes to the thermodynamic stability of these radicals. The presence of bulky N-substituents R 1 and R 2 prevents nitroxide radical dimerization, ensuring their kinetic stability. Despite their reactivity toward various transient C radicals, some nitroxides can be easily stored under air at room temperature. Furthermore, nitroxides can be oxidized to oxoammonium salts (R 1 R 2 N�O + ) or reduced to anions (R 1 R 2 N−O − ), enabling them to act as valuable oxidants or reductants depending on their oxidation state. Therefore, they exhibit interesting reactivity across all three oxidation states. Due to these fascinating properties, nitroxides find extensive applications in diverse fields such as biochemistry, medicinal chemistry, materials science, and organic synthesis. This review focuses on the versatile applications of nitroxides in organic synthesis. For their use in other important fields, we will refer to several review articles. The introductory part provides a brief overview of the history of nitroxide chemistry. Subsequently, the key methods for preparing nitroxides are discussed, followed by an examination of their structural diversity and physical properties. The main portion of this review is dedicated to oxidation reactions, wherein parent nitroxides or their corresponding oxoammonium salts serve as active species. It will be demonstrated that various functional groups (such as alcohols, amines, enolates, and alkanes among others) can be efficiently oxidized. These oxidations can be carried out using nitroxides as catalysts in combination with various stoichiometric terminal oxidants. By reducing nitroxides to their corresponding anions, they become effective reducing reagents with intriguing applications in organic synthesis. Nitroxides possess the ability to selectively react with transient radicals, making them useful for terminating radical cascade reactions by forming alkoxyamines. Depending on their structure, alkoxyamines exhibit weak C−O bonds, allowing for the thermal generation of C radicals through reversible C−O bond cleavage. Such thermally generated C radicals can participate in various radical transformations, as discussed toward the end of this review. Furthermore, the application of this strategy in natural product synthesis will be presented.

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Section: Nitroxides In Free-radical Chemistrymentioning

confidence: 99%

Section: Trapping Of C-centered Radicalsmentioning

confidence: 99%

Organic Synthesis Using Nitroxides

Leifert

Studer

2023

Chem. Rev.

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“…The reported strategies to form borylated compounds bearing benzocyclic skeletons generally involved the transition metal-catalyzed domino Heck/borylation process or the metal-photopromoted radical cascades using alkene-tethered aryl halides (Scheme c) . Meanwhile, radical cascades of allyl aryl diazonium salts could construct varieties of functionalized benzocyclic compounds through radical haloarylation, , carboarylation, oxoarylation, and thioarylation . On the basis of these findings and our recent efforts on radical cyclizations, we intended to explore a sustainable arylborylation sequence for the construction of the C–B bond starting from alkene-tethered aryldizaonium salts and boronic esters.…”

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confidence: 99%

Access to Benzocyclic Boronates via Light-Promoted Intramolecular Arylborylation of Alkenes

Liao

Qin

et al. 2023

J. Org. Chem.

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Benzocyclic boronates have attracted increasing research interest in drug chemistry and organic synthesis in recent years. Herein, we report a facile access to benzocyclic boronates through photopromoted intramolecular arylborylation of allyl aryldiazonium salts. This simple protocol features a broad scope, allowing the formation of variously functionalized borates bearing dihydrobenzofuran, dihydroindene, benzothiophene, and indoline skeletons under mild and sustainable conditions.

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