Practical N-Hydroxyphthalimide-Mediated Oxidation of Sulfonamides to N-Sulfonylimines

Wang, Jian; Yi, Wen-Jing

doi:10.3390/molecules24203771

Cited by 7 publications

(8 citation statements)

References 45 publications

(49 reference statements)

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“…The method allows us to produce high concentrations of PINO at room temperature. PIDA has the mild and highly selective oxidizing properties and was used for the C–O and C–C bond formation in the presence of NHPI , and also for the NHPI-mediated oxidation of sulfonamides to N -sulfonylimines . Previously, we have successfully used this method for recording the EPR spectra of the imide- N -oxyl radicals and also for determining the rate constants of the H-abstraction from the C–H bonds , of organic compounds by PINO.…”

Section: Resultsmentioning

confidence: 99%

Kinetics of N-oxyl Radicals’ Decay

et al. 2020

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N-oxyl radicals of various structures were generated by oxidation of corresponding N-hydroxy compounds with iodobenzene diacetate, [bis(trifluoroacetoxy)]iodobenzene, and ammonium cerium(IV) nitrate in acetonitrile. The decay rate of N-oxyl radicals follows first-order kinetics and depends on the structure of N-oxyl radicals, reaction conditions, and the nature of the solvent and oxidant. The values of the self-decay constants change within 1.4 × 10 −4 s −1 for the 3,4,5,6-tetraphenylphthalimide-N-oxyl radical to 1.4 × 10 −2 s −1 for the 1-benzotriazole-N-oxyl radical. It was shown that the rate constants of the phthalimide-N-oxyl radicalsʼ self-decay with different electron-withdrawing or -donor substituents in the benzene ring are higher than that of the unsubstituted phthalimide-N-oxyl radical in most cases. The solvent effect on the process of phthalimide-N-oxyl radical self-decomposition was investigated. The dependence of the rate constants on the Gutmann donor numbers was shown.

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Section: Resultsmentioning

confidence: 99%

Kinetics of N-oxyl Radicals’ Decay

et al. 2020

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“…In the latter example, acetate acts as the nucleophile that reacts with the intermediately formed imine. For oxidation of benzylic amines, imidoxyl radicals can also be used. − …”

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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“…This reaction possessed wider substrate scope under mild conditions. Reaction mechanism involved the selective cross‐coupling between the PINO radical and the benzylic radical which originated from abstraction of hydrogen from mesitylene as shown in Scheme 14 [37] …”

Section: Nhpi Catalyzed Strategies For Different Types Of Bond Format...mentioning

confidence: 99%

Recent Advances in N‐Hyrdoxypthalimide: As a Free Radical Initiator and its Applications

Bhardwaj

Grover²,

Rasool

et al. 2022

Asian J Org Chem

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N‐Hydroxypthalimide (NHPI) has become a powerful and versatile organocatalyst, it has been known to catalyze various free‐radical processes leading to the wide range of organic transformations. Primarily, phthalimido‐N‐oxyl (PINO) radical formed from NHPI is highly efficient abstraction species for carrying out radical chain reactions. In this review, we have discussed about the most important and successful reactions from last six years, with their plausible reaction mechanisms. This review broadly covers the type of bond formation such as carbon‐carbon, carbon‐oxygen and carbon‐nitrogen bond formations. We have also highlighted various types of reaction strategies where in combination with divergent reagent systems it helps to construct different types of molecules which further find applications in the synthesis of complex set of biologically active molecule. NHPI catalyzed oxidation reactions of different class of organic compounds are also reviewed.

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Practical N-Hydroxyphthalimide-Mediated Oxidation of Sulfonamides to N-Sulfonylimines

Cited by 7 publications

References 45 publications

Kinetics of N-oxyl Radicals’ Decay

Kinetics of N-oxyl Radicals’ Decay

Organic Synthesis Using Nitroxides

Recent Advances in N‐Hyrdoxypthalimide: As a Free Radical Initiator and its Applications

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