Acyl nitroxides. Part 2. Reactions with hydrocarbons

Hussain, Syeed; Jenkins, Terence C.; Perkins, M. J.; Siew, Nancy P. Y.

doi:10.1039/p19790002803

Cited by 13 publications

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“…A number of challenges had to be addressed in developing such a transformation. For instance, there are no examples of general synthetic methods proceeding by way of intermolecular additions of oxygen-centered radicals to alkenes. , Furthermore, such a process would have a greater activation entropy than the previously disclosed intramolecular dioxygenation. We report herein the successful development of an intermolecular direct aerobic dioxygenation of alkenes employing a simple hydroxamic acid derivative that overcomes these significant challenges.…”

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confidence: 99%

Metal-Free, Aerobic Dioxygenation of Alkenes Using Simple Hydroxamic Acid Derivatives

2011

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The dioxygenation of alkenes using molecular oxygen and a simple hydroxamic acid derivative has been achieved. The reaction system consists of readily prepared methyl N-hydroxy-N-phenylcarbamate and molecular oxygen with a radical initiator, offering an alternative to common dioxygenation processes catalyzed by precious transition metals. This transformation capitalizes on the unique reactivity profile of hydroxamic acid derivatives in radical-mediated alkene addition processes.

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confidence: 99%

Metal-Free, Aerobic Dioxygenation of Alkenes Using Simple Hydroxamic Acid Derivatives

2011

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“…In early contributions, amidoxyl radicals were used for intra- as well as intermolecular H-atom abstraction at benzylic or allylic positions. However, due to the higher BDE of imidoxyl radicals, allylic and benzylic oxidations are mostly conducted with PINO as HAT reagent. , The most important reaction in this context is the allylic or benzylic oxidation with oxygen as trapping reagent for the intermediate C radical 144 (Scheme a).…”

Section: Oxidation Reactionsmentioning

confidence: 99%

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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“…Indeed, we have found that, like Fremy's radical 1, they oxidize monohydric phenols to quinones, often in excellent yield [16]. Other oxidations may be effected often in high yield [18,19].…”

Section: Acyl T-alkyl Nitroxidesmentioning

confidence: 99%

Acyl nitroxides

Perkins

1986

Res Chem Intermed

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Acyl nitroxides. Part 2. Reactions with hydrocarbons

Cited by 13 publications

References 0 publications

Metal-Free, Aerobic Dioxygenation of Alkenes Using Simple Hydroxamic Acid Derivatives

Metal-Free, Aerobic Dioxygenation of Alkenes Using Simple Hydroxamic Acid Derivatives

Organic Synthesis Using Nitroxides

Acyl nitroxides

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