- Assessing the Activity of Lewis Bases Organocatalysts in Halonium-Induced Carbocyclization Reactions
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Lewis bases were evaluated as catalysts for halocarbocyclization reactions of alkynylstyrenes and a cinnamylaniline derivative. Phosphines and phosphorus chalcogenides exhibited high activity for the conversion of alkynylstyrenes in the presence of N -halosuccinimides with up to a 30-fold increase of the initial reaction rate with respect to the background reaction. Phosphorus sulfides and selenides showed the best catalytic activity for the iodocarbocyclization of a cinnamylaniline derivative in the presence of diiodohydantoin. An asymmetric variant of the iodocarbocyclization reaction of an alkynylstyrene using a chiral phosphorus selenide resulted in a modest enantioselectivity.
- Grandclaudon, Charlotte,Ruamps, Mirko,Duboc, Rapha?l,Michelet, Véronique,Toullec, Patrick Y.
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supporting information
p. 1181 - 1186
(2018/04/16)
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- Bicyclic bridgehead phosphoramidite (briphos) ligands with tunable π-acceptor ability and catalytic activity in the rhodium-catalyzed conjugate additions
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A new type of bicyclic bridgehead phosphoramidites (briphos) is reported, where the geometrical constraints significantly enhance the π-acceptor ability compared with its monocyclic analogs. The briphos is shown to be highly efficient and tunable for Rh(I
- Lee, Ansoo,Ahn, Seihwan,Kang, Kyungjun,Seo, Min-Seob,Kim, Yeonjoon,Kim, Woo Youn,Kim, Hyunwoo
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supporting information
p. 5490 - 5493
(2015/02/19)
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- Substituent effects on 31P NMR chemical shifts and 1J P-Se of triarylselenophosphates
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The effect of electron-withdrawing (EW) and electron-releasing (ER) substituents on the 31P NMR chemical shifts and the structural parameters of a series of tris-(p-X-aryl)selenophosphates is reported in this article. Similarly to O-aryl phosphates and O-aryl thiophosphates, EW groups attached to aromatic rings induce a shielding effect on the 31P NMR signal. After a detailed experimental and theoretical analysis, we confirmed that the selenium atom is the main part responsible for the charge density transfer toward phosphorus through a back-bonding effect. The obtained 1JP-Se values for the complete series agree with this observation. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.
- Dominguez, Zaira,Hernandez, Javier,Silva-Gutierrez, Lorena,Salas-Reyes, Magali,Sanchez, Mario,Merino, Gabriel
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experimental part
p. 772 - 784
(2010/07/05)
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- REACTIONS OF GROUP 16 ELEMENTS
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Reactions of Group 16 elements involving the addition of atoms such as sulfur, selenium or tellurium to organic or inorganic molecules comprising use of an ionic liquid as a reaction medium.
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Page/Page column 29-30
(2008/06/13)
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- Palladium-catalyzed activation of E-E and C-E bonds in diaryl dichalcogenides (E = S, Se) under microwave irradiation conditions
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The first example of palladium-catalyzed stereoselective addition of diphenyl disulfide and diphenyl diselenide to the triple bond of terminal alkynes under microwave irradiation conditions is described. It was found that both the element-element (E-E) and carbon-element bonds can be activated in the catalytic system studied. The products of both reactions were isolated in quantitative yields. According to quantum-chemical calculations, the reaction mechanism involves the oxidative addition of the E-E bond to Pd0. Depending on the microwave power and reaction conditions, the next stage is either the reaction with alkyne or the carbon-element bond activation. The product of the oxidative addition of Ph2Se2 to Pd 0, namely, dinuclear complex [Pd2(SePh) 4(PPh3 2], was detected by 31P{ 1H}NMR spectroscopy directly in the Ph2Se 2/PPh3 melt formed under microwave irradiation conditions.
- Ananikov,Orlov,Beletskaya
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p. 576 - 587
(2007/10/03)
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- Reaction of three-coordinate phosphorus compounds with organophosphorus pseudohalogens. Part 4. The mechanism of interaction between bis(phosphinoyl) diselenides [R1R2P(O)Se]2 with three-coordinate phosphorus compounds
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The reaction of bis(phosphinoyl) diselenides R1R2P(O)Se-SeP(O)R1R2 1 with P(III) compounds has been investigated and its mechanistic features have been elucidated by variable temperature 31P NMR spectroscopy. These studies show that in most cases phosphonium intermediates [>P(O)-Se-P+-O-P(Se)P(Se)-O-P+-O-P(Se)a phosphorane intermediate is observed. In the isomerization 7→10 and 13→16 the pathway of decomposition (deselenization, deoxygenation or dealkylation) to give stable end products is influenced by electronic and steric factors.
- Krawczyk, Ewa,Skowronnska, Aleksandra,Michalski, Jan
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p. 1135 - 1140
(2007/10/03)
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