Oxidation of bis-sulfinyl carbanions as the pivot of ionic/radical tandem reactions

Vincent, Guillaume; Cheli, Saloua; Mallorquin, Rocio Martinez; Abramovitch, Adi; Beauvière, Sophie; Gomez, Catherine; Marek, Ilan; Malacrìa, Max; Goddard, Jean Philippe; Fensterbank, Louis

doi:10.1016/j.crci.2015.11.012

Cited by 4 publications

(3 citation statements)

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“…As indicated in Figure 2, the oxygen atom of TEMPO is linked to the methylene carbon centre of the 1‐naphthyl unit to form a C−O bond, as observed for numerous other TEMPO adducts.– [16b–19] The N−O and C−O bond lengths of 2 a are 1.469(2) and 1.423(3) Å, respectively, cf. literature values for the related adducts, sulfinyl cyclopentene–TEMPO (1.460(3) and 1.438(4) Å) [18] and TEMPO–boryldiene–TEMPO (1.445(5) and 1.430(6) Å) [19] …”

Section: Resultsmentioning

confidence: 99%

“…[16b-19] The NÀ O and CÀ O bond lengths of 2 a are 1.469(2) and 1.423(3) Å, respectively, cf. literature values for the related adducts, sulfinyl cyclopentene-TEMPO (1.460(3) and 1.438(4) Å) [18] and TEMPO-boryldiene-TEMPO (1.445(5) and 1.430(6) Å). [19] Reactions of bis(arylmethyl)tin dichlorides with arenes ?IMA tlsb = 2%?…”

Section: Chemistry-a European Journalmentioning

confidence: 95%

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Temperature‐Assisted Generation of Arylmethyl Radicals from Bis(arylmethyl)tin Dichlorides: Efficient Reagents for − Bond‐Forming Reactions

Dhanwant

Saini

Chivers

et al. 2023

Chemistry A European J

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The oxidative-addition reaction between an arylmethyl chloride (RCH 2 Cl; R=1-C 10 H 7 , 2,4,6-Me 3 C 6 H 2 , 4-MeC 6 H 4 , 3-MeC 6 H 4 , C 6 H 5 , 4-ClC 6 H 4 ) and tin powder in boiling toluene produces bis(arylmethyl)tin dichlorides, [(RCH 2 ) 2 SnCl 2 ] in good yields. At 160 °C in mesitylene bis(1-naphthylmethyl)tin dichloride undergoes SnÀ C homolytic cleavage to generate two 1-naphthylmethyl radicals (1-C 10 H 7 CH 2 * ) which were trapped by TEMPO (C 9 H 8 NO * ). Subsequently, the radicals (RCH 2 * ) produced in this manner were utilized for efficient substitution reactions with electron-rich arenes (R'H; R' = 2,4,6-Me 3 C 6 H 2 , 1,2,4,5-Me 4 C 6 H, 1,2,3,4,5-Me 5 C 6 ) to obtain a variety of unsymmetrical diarylmethanes (RR'CH 2 ). The addition of one equivalent of iodine (I 2 ) to the reaction mixture resulted in a significant increase in the yields of coupled products.

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Section: Resultsmentioning

confidence: 99%

Section: Chemistry-a European Journalmentioning

confidence: 95%

Temperature‐Assisted Generation of Arylmethyl Radicals from Bis(arylmethyl)tin Dichlorides: Efficient Reagents for − Bond‐Forming Reactions

Dhanwant

Saini

Chivers

et al. 2023

Chemistry A European J

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“…Besides enolates, nitronates can be oxidized by ferrocenium to the α-nitro C radical, which can be trapped by TEMPO . 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 ) which was formed in high diastereoselectivity. , The oxidizable anion is first generated by nucleophilic addition of lithium allyl alcoholate to 254 .…”

Section: Nitroxides In Free-radical Chemistrymentioning

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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Iron and Single Electron Transfer: All is in the Ligand

Murr

Fensterbank

Ollivier

2017

Israel Journal of Chemistry

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This account describes some advances we have made in the field of iron catalysis. Two types of reactivity have been uncovered. Based on the use of an iron(II) precatalyst in the presence of NaBH 4 , the first one consists in a SET which can be useful for the reductive dehalogenation of iodide and bromide derivatives. Switching to the noninnocent bis-iminopyridine ligands promotes a previously undescribed Csp 2 ÀH activation reaction leading to biaryl derivatives. First clues into the intricate nature of the mechanism were obtained and suggested that the redoxactive bis-iminopyridine ligand acts as an electron reservoir. The resulting buildup of electron density triggers the CÀH bond breaking. All these findings are discussed in light of the existing literature and perspectives are given.

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Oxidation of bis-sulfinyl carbanions as the pivot of ionic/radical tandem reactions

Cited by 4 publications

References 55 publications

Temperature‐Assisted Generation of Arylmethyl Radicals from Bis(arylmethyl)tin Dichlorides: Efficient Reagents for − Bond‐Forming Reactions

Temperature‐Assisted Generation of Arylmethyl Radicals from Bis(arylmethyl)tin Dichlorides: Efficient Reagents for − Bond‐Forming Reactions

Organic Synthesis Using Nitroxides

Iron and Single Electron Transfer: All is in the Ligand

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