453537-17-2Relevant academic research and scientific papers
Oxycyanation of Vinyl Ethers with 2,2,6,6-Tetramethyl-N-oxopiperidinium Enabled by Electron Donor-Acceptor Complex
Liu, Jia-Li,Zhu, Ze-Fan,Liu, Feng
, p. 720 - 723 (2018)
An efficient and mild oxycyanation of vinyl ethers with 2,2,6,6-tetramethyl-N-oxopiperidinium and TMSCN is described. The mechanistic studies indicated that the formation of an electron donor-acceptor complex and subsequent single-electron-transfer proces
A Nickel-Catalyzed Carbonyl-Heck Reaction
Vandavasi, Jaya Kishore,Hua, XiYe,Halima, Hamdi Ben,Newman, Stephen G.
supporting information, p. 15441 - 15445 (2017/11/10)
The use of transition-metal catalysis to enable the coupling of readily available organic molecules has greatly enhanced the ability of chemists to access complex chemical structures. In this work, an intermolecular coupling reaction that unites organotriflates and aldehydes is presented. A unique catalyst system is identified to enable this reaction, featuring a Ni0 precatalyst, a tridentate Triphos ligand, and a bulky amine base. This transformation provides access to a variety of ketone-containing products without the selectivity- and reactivity-related challenges associated with more traditional Friedel–Crafts reactions. A Heck-type mechanism is postulated, wherein the π bond of the aldehyde takes the role of the olefin in the insertion/elimination steps.
Exploring the Catalytic Reactivity of Nickel Phosphine-Phosphite Complexes
Kampmann, Sven S.,Man, Nikki Y. T.,McKinley, Allan J.,Koutsantonis, George A.,Stewart, Scott G.
, p. 1842 - 1853 (2015/12/26)
In this study, we present an investigation into various nickel phosphite and phosphite-phosphine complexes for use in the Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions and the ammonia arylation reaction. In these coupling reactions, it was discovered that the Ni[P(OEt)3]4, (dppf)Ni[P(OPh)3]2, and (binap)Ni[P(OPh)3]2 catalysts were the most effective. In addition, an optimisation process for these catalytic systems as well as functional group compatibility are discussed.
Mild and efficient nickel-catalyzed heck reactions with electron-rich olefins
Gogsig, Thomas M.,Kleimark, Jonatan,Nilsson Lill, Sten O.,Korsager, Signe,Lindhardt, Anders T.,Norrby, Per-Ola,Skrydstrup, Troels
supporting information; experimental part, p. 443 - 452 (2012/03/07)
A new efficient protocol for the nickel-catalyzed Heck reaction of aryl triflates with vinyl ethers is presented. Mild reaction conditions that equal those of the corresponding palladium-catalyzed Heck reaction are applied, representing a practical and more sustainable alternative to the conventional regioselective arylation of vinyl ethers. A catalytic system comprised of Ni(COD)2 and 1,1″-bis(diphenylphosphino)ferrocene (DPPF) in combination with the tertiary amine Cy2NMe proved effective in the olefination of a wide range of aryl triflates. Both electron-deficient and electron-rich arenes proved compatible, and the corresponding aryl methyl ketone could be secured after hydrolysis in yields approaching quantitative. Good functional group tolerance was observed matching the characteristics of the analogous Pd-catalyzed Heck reaction. The high levels of catalytic activity were explained by the intermediacy of a cationic nickel(II) complex potentially responsible for the successive β-hydride elimination and base promoted catalyst regeneration. Although these elementary reactions are normally considered challenging, DFT calculations suggested this pathway to be favorable under the applied reaction conditions.
Hydrogen-bonding-promoted oxidative addition and regioselective arylation of olefins with aryl chlorides
Ruan, Jiwu,Iggo, Jonathan A.,Berry, Neil G.,Xiao, Jianliang
supporting information; experimental part, p. 16689 - 16699 (2011/02/23)
The first, general, and highly efficient catalytic system that allows a wide range of activated and unactivated aryl chlorides to couple regioselectively with olefins has been developed. The Heck arylation reaction is likely to be controlled by the oxidative addition of ArCl to Pd(0). Hence, an electron-rich diphosphine, 4-MeO-dppp, was introduced to facilitate the catalysis. Solvent choice is critical, however; only sluggish arylation is observed in DMF or DMSO, whereas the reaction proceeds well in ethylene glycol at 0.1-1 mol % catalyst loadings, displaying excellent regioselectivity. Mechanistic evidence supports that the arylation is turnover-limited by the oxidative addition step and, most importantly, that the oxidative addition is accelerated by ethylene glycol, most likely via hydrogen bonding to the chloride at the transition state as shown by DFT calculations. Ethylene glycol thus plays a double role in the arylation, facilitating oxidative addition and promoting the subsequent dissociation of chloride from Pd(II) to give a cationic Pd(II)-olefin species, which is key to the regioselectivity observed.
Hydrogen-bond-directed catalysis: Faster, regioselective and cleaner heck arylation of electron-rich olefins in alcohols
Hyder, Zeynab,Ruan, Jiwu,Xiao, Jianliang
experimental part, p. 5555 - 5566 (2009/06/17)
A general method for the regioselective Heck reaction of electronrich olefins is presented. Fast, highly regioselective Pd-catalysed α-arylation of electron-rich olefins, vinyl ethers (1a-d), hydroxyl vinyl ethers (1e,f), enamides (1g,h) and a substituted vinyl ether (1i) has been accomplished with a diverse range of aryl bromides (2a-r), for the first time, in cheap, green and easily available alcohols with no need for any halide scavengers or salt additives. The reaction proceeds with high efficiency, leading exclusively to the a-products, in 2-propanol and particularly in ethylene glycol. In the latter, the arylation can be catalysed at a palladium loading of 0.1 mol% and finish in as short a time as 0.5 h. The remarkable performance of the alcohol solvents in promoting a regiocontrol is attributed to their hydrogen-bond- donating capability, which is believed to facilitate the dissociation of halide anions from PdII, and hence, the generation of a key ionic Pd II-olefin intermediate responsible for the a product. This belief is further strengthened by the study of a benchmark arylation reaction in 21 different solvents. The study revealed that exclusive α-regioselective arylation takes place in almost all of the protic solvents, and there is a rough correlation between the α-arylation rates and the solvent parameter ETN. The method is simpler, cleaner and more general than those established thus far.
The Heck reaction of electron-rich olefins with regiocontrol by hydrogen-bond donors
Mo, Jun,Xiao, Jianliang
, p. 4152 - 4157 (2007/10/03)
No salt please: Halide scavengers AgOTf and TlOAc are not required for the Heck coupling of electron-rich olefins with aryl bromides and chlorides. Using ammonium additives, these reactions can be carried out in either an imidazolium ionic liquid or a common molecular solvent, thus furnishing 1,1′- disubstituted olefins in high yields with excellent regioselectivities. (Chemical Equation Presented).
Synthesis of functionalised acetophenone
Sun, Li,Pei, Wen,Shen, Chen
, p. 388 - 389 (2007/10/03)
Nickel catalysed Heck arylation of the electron-rich olefin n-butyl vinyl ether with a wide variety of aryl bromides has been accomplished in the ionic liquid [bmim][BF4], affording an efficient green chemistry synthetic procedure for preparing functionalised acetophenone. The reaction gave a high regioselectivity and high yield without the need for the costely or toxic halide scavengers, leading predominantly to a branch-arylated α-product.
Ionic liquid-promoted, highly regioselective Heck arylation of electron-rich olefins by aryl halides
Mo, Jun,Xu, Lijin,Xiao, Jianliang
, p. 751 - 760 (2007/10/03)
Palladium-catalyzed regioselective Heck arylation of the electron-rich olefins, vinyl ethers 1a-d, enamides 1e-g, and allyltrimethylsilane 1h, has been accomplished in imidazolium ionic liquids with a wide range of aryl bromides and iodides instead of the commonly used, but commercially unavailable and expensive, aryl triflates. The reaction proceeded with high efficiency and remarkable regioselectivity without the need for costly or toxic halide scavengers, leading exclusively to substitution by aryl groups of diverse electronic and steric properties at the olefinic carbon α to the heteroatom of 1a-g and β to the heteroatom of 1h. In contrast, the arylation reaction in molecular solvents led to mixtures of regioisomers under similar conditions. Several lines of evidence point to the unique regiocontrol stemming from the ionic environment provided by the ionic liquid that alters the reaction pathway. The chemistry provides a simple, effective method for preparing branched, arylated olefins and contributes to the extension of Heck reaction to a wider range of substrates.
A new efficient tetraphosphine/palladium catalyst for the Heck reaction of aryl halides with styrene or vinylether derivatives
Feuerstein, Marie,Doucet, Henri,Santelli, Maurice
, p. 2191 - 2194 (2007/10/03)
cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/[PdCl(C 3H5)]2 system efficiently catalyses the Heck reaction of aryl halides with styrene and vinylether derivatives. High turnover numbers can be obtained for the reaction of several aryl halides with styrene and styrene derivatives. Lower turnover numbers have been observed in the presence of vinylethers.
