122899-23-4Relevant academic research and scientific papers
Palladium-catalyzed heteroaryl thioethers synthesis overcoming palladium dithiolate resting states inertness: Practical road to sulfones and NH-sulfoximines
Guilbaud, Johan,Labonde, Marine,Selmi, Awatef,Kammoun, Majed,Cattey, Hélène,Pirio, Nadine,Roger, Julien,Hierso, Jean-Cyrille
, p. 52 - 58 (2018/04/11)
We provide efficient synthetic access to heteroaryl sulfones in two-steps using a simple palladium–1,1′-bis[(diphenyl)phosphanyl]ferrocene catalyst to form in high yields variously functionalized heteroaromatic thioethers. Pyridinyl-containing substrates can be subsequently selectively oxidized into sulfones and NH-sulfoximines by using very mild oxidation conditions with a high functional group tolerance. In the palladium-catalyzed C–S coupling of heteroaromatic thiols, reactivity limitation is attached with electron-deficient thiols. We show that this limitation can be resolved by the successful use of 2-bromoheteroarenes in the C–S coupling. We established herein that this choice of heteroaryl electrophilic reagent in palladium-catalyzed C–S bond formation allows overcoming palladium dithiolate out-of-cycle resting state inertness. This was illustrated in the stoichiometric reactivity study of the palladium dithiolate formed from 4-trifluoromethylbenzen-1-thiol –isolated and characterized by multinuclear NMR and XRD– with both 2-chloropyridine and 2-bromopyridine.
Thioetherification of Chloroheteroarenes: A Binuclear Catalyst Promotes Wide Scope and High Functional-Group Tolerance
Platon, Mélanie,Wijaya, Novi,Rampazzi, Vincent,Cui, Luchao,Rousselin, Yoann,Saeys, Mark,Hierso, Jean-Cyrille
, p. 12584 - 12594 (2016/08/25)
A constrained binuclear palladium catalyst system affords selective thioetherification of a wide range of functionalized arenethiols with chloroheteroaromatic partners with the highest turnover numbers (TONs) reported to date and tolerates a large variety of reactive functions. The scope of this system includes the coupling of thiophenols with six- and five-membered 2-chloroheteroarenes (i.e., functionalized pyridine, pyrazine, quinoline, pyrimidine, furane, and thiazole) and 3-bromoheteroarenes (i.e., pyridine and furane). Electron-rich congested thiophenols and fluorinated thiophenols are also suitable partners. The coupling of unprotected amino-2-chloropyridines with thiophenol and the successful employment of synthetically valuable chlorothiophenols are described with the same catalyst system. DFT studies attribute the high performance of this binuclear palladium catalyst to the decreased stability of thiolate-containing resting states. Palladium loading was as low as 0.2 mol %, which is important for industrial application and is a step forward in solving catalyst activation/deactivation problems.
Monosubstitution versus Disubstitution in the SRN1 Reaction of Dihalobenzenes with Sulfanions. The Role of the Monosubstitution Product and of Its Anion Radical
Amatore, C.,Beugelmans, R.,Bois-Choussy, M.,Combellas, C.,Thiebault, A.
, p. 5688 - 5695 (2007/10/02)
The competition between mono- and disubstitution of dihalobenzenes by a series of aromatic sulfanions, via the SRN1 reaction, is shown to involve two radical chains.The first one, recognized in earliest works, involves one branching point at the level of the monosubstituted product anion radical.Reoxidation of the latter via electron transfer to the parent dihalide affords the monosubstituted product.Conversely, the route to the disubstituted product is opened when cleavage of the carbon-halogen bond in the monosubstituted product anion radical occurs before the electron transfer takes place; the disubstitution product is then obtained in its reduced (anion radical) form.Reoxidation of the latter, to afford the neutral disubstituted product, may involve competitively the parent dihalide or the neutral monosubstituted product, depending on the electron affinity of the arylthio moiety.In the first case the electron transfer propagates the first chain; in the second a new chain leading to the disubstitution is activated.The role of the two imbricated chains, under photochemical conditions, and thus that of the monosubstitution product is discussed quantitatively on the basis of the pertinent rate constants determined by cyclic voltammetry.
