4‐Amino‐TEMPO as <i>N</i>‐Nucleophile in Palladium‐Catalyzed Aminocarbonylation

Gergely, Máté; Takács, Attila; Kollár, László

doi:10.1002/jhet.2635

Cited by 3 publications

(2 citation statements)

References 34 publications

(34 reference statements)

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“…With 4-hydroxyl-TEMPO esterification and with 4-amino-TEMPO amide couplings are possible starting from the free alcohol and amine moieties, respectively. Further, 4-amino-TEMPO can engage in palladium-catalyzed aminocarbonylation of vinyl iodides, albeit with low yield . Interestingly, the hydrogenation of 4-ethynyl-4-hydroxy-TEMPO leads to the reduction of both the alkyne and the nitroxide functionality with Raney nickel/H 2 , while platinum/H 2 chemoselectively reacts with the nitroxide moiety, and selective hydrogenation of the triple bond is achieved with palladium black/H 2 …”

Section: Physical Properties and Reactivitymentioning

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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Section: Physical Properties and Reactivitymentioning

confidence: 99%

Organic Synthesis Using Nitroxides

Leifert

Studer

2023

Chem. Rev.

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“…The reactions of iodobenzene and iodoalkenes such as 1-iodocyclohexene, 4-tertbutyl-1-iodocyclohexene, α-iodostyrene, and 17-iodoandrost-16-ene with the free radical 4-amino-TEMPO afforded amides and ketoamides for iodobenzene and selectively amides for all the other cases. The free radical was partially reduced under aminocarbonylation conditions; however, the pure carbonylated products with a stable radical moiety were obtained after isolation (Figure 7) [45]. In palladium-catalyzed aminocarbonylation of 2-iodopyridine, 3-iodopyridine and iodopyrazine were coupled with CO and various primary and secondary amines.…”

Section: Reactions In Conventional Solventsmentioning

confidence: 99%

27 Years of Catalytic Carbonylative Coupling Reactions in Hungary (1994–2021)

2022

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Palladium-catalyzed carbonylation reactions, in the presence of nucleophiles, serve as very potent tools for the conversion of aryl and alkenyl halides or halide equivalents to carboxylic acid derivatives or to other carbonyl compounds. There are a vast number of applications for the synthesis of simple building blocks as well as for the functionalization of biologically important skeletons. This review covers the history of carbonylative coupling reactions in Hungary between the years 1994 and 2021.

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A general palladium‐catalyzed carbonylation synthesis of aurones with aryl bromides using CO₂

Huang

Zhou

Dong

et al. 2023

Journal of Heterocyclic Chem

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A general and efficient strategy synthesis of aurones by carbonylation reaction of aryl bromides and terminal aromatic alkynes using CO2 has been established. Various terminal aromatic alkynes and 2‐bromophenol by using CO2 with hydrosilane could be leveraged to provide various aurones in good yields under mild reaction conditions. Moreover, palladium‐catalyzed carbonylation reaction mechanism is proposed for the preparation of aurones.

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4‐Amino‐TEMPO as N‐Nucleophile in Palladium‐Catalyzed Aminocarbonylation

Cited by 3 publications

References 34 publications

Organic Synthesis Using Nitroxides

Organic Synthesis Using Nitroxides

27 Years of Catalytic Carbonylative Coupling Reactions in Hungary (1994–2021)

A general palladium‐catalyzed carbonylation synthesis of aurones with aryl bromides using CO₂

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4‐Amino‐TEMPO as N‐Nucleophile in Palladium‐Catalyzed Aminocarbonylation

Cited by 3 publications

References 34 publications

Organic Synthesis Using Nitroxides

Organic Synthesis Using Nitroxides

27 Years of Catalytic Carbonylative Coupling Reactions in Hungary (1994–2021)

A general palladium‐catalyzed carbonylation synthesis of aurones with aryl bromides using CO2

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A general palladium‐catalyzed carbonylation synthesis of aurones with aryl bromides using CO₂