Oxidative tandem alkoxide conjugate addition to nitroalkenes/radical 5-exo cyclizations—a versatile synthesis of functionalized 3-nitrotetrahydrofurans

Jahn, Ullrich; Rudakov, Dmytro; Jones, Peter G.

doi:10.1016/j.tet.2011.12.010

Cited by 14 publications

(2 citation statements)

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“…First, inorganic metal salt based single electron transfer (SET) reagents were evaluated for their effectiveness to enable the oxidative dearomatization using KOH as a base. Mild reagents such as Mn(OAc) 3 15 and CuCl 2 16 only gave a negligible amount of anticipated product or turned out to be completely ineffective; in contrast, strong SET reagents such as Ce(NH 4 ) 2 (NO 3 ) 6 and Ag 2 O caused extensive decomposition of the alcohol intermediate. To our delight, K 3 [Fe(CN) 6 ], which was used in Kende's initial report,10 was very effective in promoting the one‐pot transformation and gave the cis ‐disubstituted dihydroazulenone in 85 % yield.…”

Section: Resultsmentioning

confidence: 99%

A Critical Review of Biological Processes and Technologies for Landfill Leachate Treatment

et al. 2015

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The most common method to deal with the huge production of municipal wastes is still the disposal in landfills which, however, generates a leachate with high contents of organic and nitrogen pollutants. Requirements must be fixed by law to control leachate release from such landfills, and effective treatment processes and technologies must be applied to reduce its impact on the environment. Biological processes for leachate treatment are discussed in this review, in the former part of which attention is paid to leachate formation and its qualitative and quantitative features, while the latter deals with the state‐of‐the‐art of the most effective biotechnological treatments presently employed. Processes, alternative methods, and technological improvements are compared, with special focus on novel technologies to remove nitrogen pollutants from leachate, highlighting advantages and drawbacks of each treatment.

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Section: Resultsmentioning

confidence: 99%

A Critical Review of Biological Processes and Technologies for Landfill Leachate Treatment

et al. 2015

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“…1247 Besides enolates, nitronates can be oxidized by ferrocenium to the α-nitro C radical, which can be trapped by TEMPO. 1248 For bis-sulfinyl carbanions, oxyamination through SET oxidation, 5-exo-cyclization, and TEMPO trapping is also possible, as documented by the conversion of the enantiopure bis-sulfinyl 254 to the tetrahydrofuran 255 (Scheme 76) which was formed in high diastereoselectivity. 1249,1250 The oxidizable anion is first generated by nucleophilic addition of lithium allyl alcoholate to 254.…”

Section: Trapping Of C-centered Radicalsmentioning

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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Synthesis of Highly Substituted Tetrahydrofurans by Catalytic Polar‐Radical‐Crossover Cycloadditions of Alkenes and Alkenols

Grandjean

Nicewicz

2013

Angewandte Chemie

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Oxidative tandem alkoxide conjugate addition to nitroalkenes/radical 5-exo cyclizations—a versatile synthesis of functionalized 3-nitrotetrahydrofurans

Cited by 14 publications

References 95 publications

A Critical Review of Biological Processes and Technologies for Landfill Leachate Treatment

A Critical Review of Biological Processes and Technologies for Landfill Leachate Treatment

Organic Synthesis Using Nitroxides

Synthesis of Highly Substituted Tetrahydrofurans by Catalytic Polar‐Radical‐Crossover Cycloadditions of Alkenes and Alkenols

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