TEMPO and Silver‐Mediated Intermolecular Phosphonylation of Alkenes: Stereoselective Synthesis of (<i>E</i>)‐Alkenylphosphonates

Wang, Lei; Yang, Zhen; Zhu, Huihui; Liu, Haitao; Lv, Shuaipeng; Xu, Yilin

doi:10.1002/ejoc.201801678

Cited by 15 publications

(4 citation statements)

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“…In the presence of an alkene, the trifluoromethyl radical adds to it before being trapped by an amidoxyl radical . Similarly, P radicals generated by oxidation with silver salts can add to styrene derivatives, and trapping with TEMPO results in the corresponding alkoxyamines that readily eliminate TEMPOH to eventually provide ( E )-alkenylphosphonates …”

Section: Nitroxides In Free-radical Chemistrymentioning

confidence: 99%

“…1269 Similarly, P radicals generated by oxidation with silver salts can add to styrene derivatives, and trapping with TEMPO results in the corresponding alkoxyamines that readily eliminate TEMPOH to eventually provide (E)-alkenylphosphonates. 1270 The group of Chemler developed copper-mediated intramolecular cyclization of sulfonamides 1271,1272 or diarylamines 1273 to alkenes through an aminocupration. It was suggested that after the aminocupration, the resulting copper-(II)−carbon bond is homolytically cleaved, and the generated alkyl radical is then trapped with TEMPO.…”

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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“…Because of its unique properties, the synthesis of alkenyl phosphonate has been widely developed. ,, A representative method starts from functional olefins (Scheme a). Traditionally, the vinyl phosphorus compounds are prepared from the reactions of functional olefins with P–H species, for example, enaminone phosphonation by the cleavage of C(sp 2 )–N bond, decarboxylative phosphorylation of cinnamic acids, Hirao-type coupling of P–H reagents with alkenyl halides or alkenyl triflates, desulfonative coupling of various sulfones with phosphites, phosphonation of nitroolefins through denitration process, and direct coupling of styrenes and H -phosphites …”

Section: Introductionmentioning

confidence: 99%

Preparation of Vinylphosphonates from Ketones Promoted by Tf₂O

Xin

Lian

et al. 2023

J. Org. Chem.

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An efficient triflic anhydride promoted phosphorylation of ketone was disclosed, and vinylphosphorus compounds were prepared under solvent-and metal-free conditions. Both aryl and alkyl ketones could perform smoothly to give vinyl phosphonates in high to excellent yields. In addition, the reaction was easy to carry out and easy to scale up. Mechanistic studies suggested that this transformation might involve nucleophilic vinylic substitution or a nucleophilic addition−elimination mechanism.

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“…19,20 To overcome these drawbacks, the use of porous scaffolds or hydrogels as effective local delivery carriers has been reported. [21][22][23][24][25][26] PTT agents have been hybridized with polymers or ceramics to construct photothermal composite scaffolds. 27,28 Furthermore, PTT agents and anticancer drugloaded thermosensitive liposomes have been incorporated into polymer porous scaffolds to form composite scaffolds with good photothermal conversion and controllable drug release properties.…”

Section: Introductionmentioning

confidence: 99%