13041-70-8Relevant articles and documents
Efficient synthesis of trisubstituted alkenes in an aqueous-organic system using a versatile and recyclable Rh/m-TPPTC catalyst
Genin, Emilie,Michelet, Véronique,Genêt, Jean-Pierre
, p. 4157 - 4161 (2004)
We have found that the use of [Rh(cod)OH]2 associated with the water-soluble ligand m-TPPTC was highly efficient for the Rh-catalyzed arylation of alkynes. Aryl and alkyl alkynes were transformed to alkenes using 3mol% rhodium catalyst and 2.5equiv of boronic acid at 100°C in a biphasic water/toluene system in 80-99% yield. The reaction was found to be totally regioselective for alkyl arylalkynes and alkyl silylated alkynes. The Rh/m-TPPTC system was for the first time recycled with no loss of the activity and with excellent purity of the desired alkene.
On the Formation of Palladium (II) Iodide Nanoparticles: An In Situ SAXS/XAS Study and Catalytic Evaluation on an Aryl Alkenylation Reaction in Water Medium
Latocheski, Eloah,Marques, Marcelo V.,Albuquerque, Brunno L.,Schuh, Thalia J.,Signori, Aline M.,Oliveira, Daniela C.,Pal, Taransankar,Domingos, Josiel B.
, p. 684 - 688 (2019)
The synthesis of small spherical palladium(II) iodide nanoparticles is reported for the first time. The formation of the particles by ligand exchange, in the presence of poly(vinyl pyrrolidone) in aqueous medium at room temperature, was investigated by in situ time-resolved synchrotron-based SAXS and XANES/EXAFS analysis. These new nanomaterials exhibit a double catalytic role in an aryl alkenylation chemical reaction, working without a base or ligand, in aqueous milieu. There is strong experimental evidence to suggest that the mechanism follows a single-electron transfer (SET) pathway with the participation of iodide as a radical promoter and the palladium atoms as activator of the alkene moiety. This new protocol could evolve into a broadly applicable radical reaction for the functionalization of alkenes.
Microwave-promoted palladium-catalyzed coupling reactions
Larhed, Mats,Hallberg, Anders
, p. 9582 - 9584 (1996)
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Bimodal fluorescence signaling based on control of the excited-state conformational twisting and the ground-state protonation processes
Yang, Jye-Shane,Hwang, Chung-Yu,Chen, Mon-Yao
, p. 3097 - 3102 (2007)
Amino-based fluoroionophores 1 and 2 can selectively sense alkaline earth metal ions in MeCN under both neutral and acidic conditions by different signaling mechanisms. The fluoroionophoric behavior for the neutral probes is characterized by an 'off-on' photoinduced electron transfer (PET)-like fluorescence intensity response due to a switching from a twisted internal charge transfer (TICT) to a planar internal charge transfer (PICT) state. For the protonated probes (i.e., 1/H+ and 2/H+), the fluorescing species is the localized stilbene fluorophores, but dual fluorescence is induced upon metal-ion recognition through a deprotonation process.
An Amine-Assisted Ionic Monohydride Mechanism Enables Selective Alkyne cis-Semihydrogenation with Ethanol: From Elementary Steps to Catalysis
Huang, Zhidao,Wang, Yulei,Leng, Xuebing,Huang, Zheng
supporting information, p. 4824 - 4836 (2021/04/07)
The selective synthesis of Z-alkenes in alkyne semihydrogenation relies on the reactivity difference of the catalysts toward the starting materials and the products. Here we report Z-selective semihydrogenation of alkynes with ethanol via a coordination-induced ionic monohydride mechanism. The EtOH-coordination-driven Cl- dissociation in a pincer Ir(III) hydridochloride complex (NCP)IrHCl (1) forms a cationic monohydride, [(NCP)IrH(EtOH)]+Cl-, that reacts selectively with alkynes over the corresponding Z-alkenes, thereby overcoming competing thermodynamically dominant alkene Z-E isomerization and overreduction. The challenge for establishing a catalytic cycle, however, lies in the alcoholysis step; the reaction of the alkyne insertion product (NCP)IrCl(vinyl) with EtOH does occur, but very slowly. Surprisingly, the alcoholysis does not proceed via direct protonolysis of the Ir-C(vinyl) bond. Instead, mechanistic data are consistent with an anion-involved alcoholysis pathway involving ionization of (NCP)IrCl(vinyl) via EtOH-for-Cl substitution and reversible protonation of Cl- ion with an Ir(III)-bound EtOH, followed by β-H elimination of the ethoxy ligand and C(vinyl)-H reductive elimination. The use of an amine is key to the monohydride mechanism by promoting the alcoholysis. The 1-amine-EtOH catalytic system exhibits an unprecedented level of substrate scope, generality, and compatibility, as demonstrated by Z-selective reduction of all alkyne classes, including challenging enynes and complex polyfunctionalized molecules. Comparison with a cationic monohydride complex bearing a noncoordinating BArF- ion elucidates the beneficial role of the Cl- ion in controlling the stereoselectivity, and comparison between 1-amine-EtOH and 1-NaOtBu-EtOH underscores the fact that this base variable, albeit in catalytic amounts, leads to different mechanisms and consequently different stereoselectivity.
A photocatalyst-free visible-light-mediated solvent-switchable route to stilbenes/vinyl sulfones from β-nitrostyrenes and arylazo sulfones
Chawla, Ruchi,Dutta, P. K.,Jaiswal, Shefali,Yadav, Lal Dhar S.
supporting information, p. 6487 - 6492 (2021/08/03)
Photocatalyst-free visible-light-mediated reactions, based on the presence of a visible-light-absorbing functional group in the starting material itself in order to exclude the often costly, hazardous, degradable and difficult to remove or recover photoredox catalysts, have been gaining momentum recently. We have employed this approach to develop a denitrative photocatalyst-free visible-light-mediated protocol for the arylation/sulfonylation of β-nitrostyrenes employing arylazo sulfones (bench-stable photolabile compounds) in a switchable solvent-controlled manner. Arylazo sulfones served as the aryl and sulfonyl radical precursors under blue LED irradiation for the synthesis oftrans-stilbenes and (E)-vinyl sulfones in CH3CN and dioxane/H2O 2?:?1, respectively. The absence of any metal, photocatalyst and additive; excellent selectivity (E-stereochemistry) and solvent-switchability; and the use of visible light and ambient temperature are the prime assets of the developed method. Moreover, we report the first photocatalyst-free visible light-driven route to synthesize stilbenes and vinyl sulfones from readily available β-nitrostyrenes.
