81069-42-3Relevant academic research and scientific papers
Palladium Nanoparticles Anchored on Magnesium Organosilicate: An Effective and Selective Catalyst for the Heck Reaction
Dos Santos, Beatriz F.,Da Silva, Beatriz A. L.,De Oliveira, Aline R.,Sarragiotto, Maria H.,Rinaldi, Andrelson W.,Domingues, Nelson Luís C.
supporting information, p. 1301 - 1306 (2020/11/04)
A new and effective palladium catalyst supported on a magnesium organosilicate for application in the Heck reaction is presented. A group of compounds comprising 22 examples were synthesized in moderate to high yields (up to 99%) within a short time. The palladium supported on magnesium organosilicate catalyst was characterized as an amorphous solid by SEM, containing around 33% of palladium inside the solid, and even with this low quantity of palladium, the catalyst was very efficient in the Heck reaction. Besides, based on the Scherrer equation, the crystallite size of the synthesized palladium nanoparticles was ultrasmall (around 1.3 nm). This strategy is a simple and efficient route for the formation of C-C bonds via the Heck cross-coupling reaction.
Effect of Reaction Media on Photosensitized [2+2]-Cycloaddition of Cinnamates
Abramov, Alex,Reiser, Oliver,Díaz Díaz, David
, p. 649 - 656 (2020/05/25)
The outcome of photosensitized [2+2]-cycloaddition reactions of various cinnamates has been compared in different reaction media, including homogeneous organic solutions under inert conditions, degassed water, and aerated physical gels. The reactions were performed under LED blue light (λmax=455 nm) irradiation and [Ir{dF(CF3)ppy}2(dtb-bpy)]PF6 (1.0 mol%) as photocatalyst. The processes were optimized taking into consideration solvent, gelator, and substrate. Comparative kinetics analyses, as well as the effect of the reaction media on the diastereoselectivity of the process, were evaluated during this investigation. In a number of cases, carrying out the reaction in a less polar solvent, like toluene or highly polar solvent, like water had a tremendous impact on the diastereoselectivity of the process, pointing towards an effect on the stabilization of the putative diradical intermediate in this medium. Moreover, while for reactions run in homogeneous solution oxygen needs to be excluded, no erosion in yield is observed when the photoadditions were run in aerated gel media.
Bu 4 N + -Controlled Addition and Olefination with Ethyl 2-(Trimethylsilyl)acetate via Silicon Activation
Das, Manas,Manvar, Atul,Fox, Ian,Roberts, Dilwyn J.,O'Shea, Donal F.
supporting information, p. 2401 - 2406 (2017/09/30)
Catalytic Bu 4 NOAc as silicon activator of ethyl 2-(trimethylsilyl)acetate, in THF, was utilized for the synthesis of β-hydroxy esters, whereas employing catalytic Bu 4 NOTMS gave α,β-unsaturated esters. The established reaction conditions were applicable to a diverse range of aromatic, heteroaromatic, aliphatic aldehydes and ketones. Reactions were achieved at room temperature without taking any of the specialized precautions that are in place for other organometallics. A stepwise olefination pathway via silylated β-hydroxy esters with subsequent elimination to form the α,β-unsaturated ester has been demonstrated. The key to selective product formation lies in use of the weaker acetate activator which suppresses subsequent elimination whereas stronger TMSO - activator (and base) facilitates both addition and elimination steps. The use of tetrabutyl ammonium salts for both acetate and trimethylsilyloxide activators provide enhanced silicon activation when compared to their inorganic cation counterparts.
An Abnormal N-Heterocyclic Carbene-Based Palladium Dimer: Aqueous Oxidative Heck Coupling under Ambient Temperature
Hota, Pradip Kumar,Vijaykumar, Gonela,Pariyar, Anand,Sau, Samaresh Chandra,Sen, Tamal K.,Mandal, Swadhin K.
supporting information, p. 3162 - 3170 (2015/11/03)
Herein we report the synthesis of a new abnormal N-heterocyclic carbene (aNHC)-based ligand and its use in synthesizing an acetate bridged C-H activated palladium dimer (1). In complex 1, the carbene ligand displays an abnormal mode of binding with the palladium(II) ion. We used complex 1 as a catalyst for the oxidative Heck coupling reaction of arylboronic acids with electron-deficient as well as electron-rich olefins at ambient temperature in water to produce selectively the β-arylated products in good to excellent yields.
N,N,N′,N′-Tetramethylenediamine dioxide (TMEDAO2) facilitates atom economical/open atmosphere Ley-Griffith (TPAP) tandem oxidation-Wittig reactions
Read, Christopher D. G.,Moore, Peter W.,Williams, Craig M.
supporting information, p. 4537 - 4540 (2015/09/15)
N,N,N′,N′-Tetramethylethylenediamine dioxide (TMEDAO2) was explored as a more atom economical co-oxidant for the Ley-Griffith oxidation of alcohols to aldehydes. TMEDAO2 was found to selectivity oxidise benzylic and allylic alcohols in comparable yields to that of the standard Ley-Griffith co-oxidant (NMO). Importantly TMEDAO2 facilitated tandem Ley-Griffith-Wittig reactions with stabilised ylides, in good to excellent yields, without the requirement of anhydrous conditions.
Palladium chloride catalyzed photochemical Heck reaction
Waghmode, Suresh B.,Arbuj, Sudhir S.,Wani, Bina N.,Gopinath
supporting information, p. 348 - 351 (2013/06/04)
PdCl2 catalyzed carbon-carbon bond formation (Heck reaction) between substituted aryl halides and olefins was carried out without a ligand, under irradiation with UV-visible light. The results demonstrated that UV-visible light accelerated the rate of the reaction, leading to an excellent yield of corresponding products. The recovered palladium nanoparticles could be thermally recycled several times. PdCl2 gave excellent conversion up to the fifth addition of substrate.
Heterogeneous photocatalysed Heck reaction over PdCl2/TiO 2
Waghmode, Suresh B.,Arbuj, Sudhir S.,Wani, Bina N.
, p. 2911 - 2916 (2013/09/12)
The heterogeneous PdCl2/TiO2 efficiently catalyzes the C-C bond formation (Heck reaction) between aryliodides and olefins under photochemical and mild reaction conditions. This process gives good to excellent conversion under optimized reaction conditions. After completion of the reaction, Pd2+ is reduced to Pd0. Further, Pd0 can be easily converted into Pd2+ by heating with ammonium chloride at 400°C for 30 min and the regenerated catalyst could be reused up to the third recycle with good catalytic activity. The catalysts (before and after reaction, as well as regenerated) were systematically characterized using Transmission Electron Microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, temperature programmed reduction and DRUV-visible spectroscopy techniques.
Sustainable carbonecarbon bond formation catalyzed by new oxamate-containing palladium(II) complexes in ionic liquids
Fortea-Pérez, Francisco Ramón,Schlegel, Isabel,Julve, Miguel,Armentano, Donatella,De Munno, Giovanni,Stiriba, Salah-Eddine
, p. 102 - 108 (2013/10/08)
New and versatile bis(oxamato)palladate(II) complexes of formula (n-Bu 4N)2[Pd(2-Mepma)2]·4H2O (1a) and (n-Bu4N)2[Pd(4-Mepma)2]·2H 2O·MeCN (1b) (n-Bu4N+ = tetra-n-buthylammonium, 2-Mepma = N- 2-methylphenyloxamate and 4-Mepma = N-4-methylphenyloxamate) have been synthesized and characterized by spectroscopic methods and single crystal X-ray diffraction. Each palladium(II) ion in 1a and 1b is four-coordinate with two oxygen and two nitrogen atoms from two fully deprotonated oxamate ligands building a centrosymmetric square planar surrounding. Their catalytic role has been investigated for both Heck and Suzuki coupling reactions using a series of aryl iodide/bromide derivatives in tetra-n-butylammonium bromide (n-Bu 4NBr) as ionic liquid, i.e. molten salt. These precatalysts appear as highly efficient, easily recovered and reused at least eight times without any drastic loss of their exceptional reactivity or leaching from the ionic liquid medium.
P[N(i-Bu)CH2CH2]3N: Nonionic Lewis base for promoting the room-temperature synthesis of α,β-unsaturated esters, fluorides, ketones, and nitriles using Wadsworth - Emmons phosphonates
Chintareddy, Venkat Reddy,Ellern, Arkady,Verkade, John G.
supporting information; experimental part, p. 7166 - 7174 (2010/12/25)
The bicyclic triaminophosphine P(RNCH2CH2) 3N (R = i-Bu, 1c) serves as an effective promoter for the room-temperature stereoselective synthesis of α,β-unsaturated esters, fluorides, and nitriles from a wide array of aromatic, aliphatic, heterocyclic, and cyclic aldehydes and ketones, using a range of Wadsworth-Emmons (WE) phosphonates. Among the analogues of 1c [R = Me (1a), i-Pr (1b), Bn (1d)], 1a and 1b performed well, although longer reaction times were involved, and 1d led to poorer yields than 1c. Functionalities such as cyano, chloro, bromo, methoxy, amino, ester, and nitro were well tolerated. We were able to isolate and characterize (by X-ray means; see above) the reactive WE intermediate species formed from 2b and 1c.
A convenient method for the lewis base-catalyzed synthesis of α,β-unsaturated carboxylic esters using trimethylsilylketene ethyl trimethylsilyl acetal and carbonyl compounds
Michida, Makoto,Mukaiyama, Teruaki
, p. 704 - 705 (2008/12/21)
A highly useful method for the synthesis of α,β-unsaturated carboxylic esters from various carbonyl compounds that uses trimethylsilylbetene ethyl trimethylsilyl acetal in the presence of a Lewis base catalyst such as acetate salts was established. This procedure gives the corresponding esters in high yields with excellent E stereoselectivity under mild conditions. Copyright
