197729-33-2Relevant academic research and scientific papers
Coordination Chemistry and Mechanisms of Metal-Catalyzed C-C Coupling Reactions, Part 12. Nonaqueous Ionic Liquids: Superior Reaction Media for the Catalytic Heck-Vinylation of Chloroarenes
Boehm, Volker P. W.,Herrmann, Wolfgang A.
, p. 1017 - 1025 (2000)
Nonaqueous ionic liquids, that is molten salts, constitute an activating and stabilizing noninnocent solvent for the palladium-catalyzed Heck-vinylation of all types of aryl halides. Especially with chloroarenes an improved activity and stability of almost any known catalyst system is observed as compared to convetional, molecular solvents (e.g. dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP), or dioxane). Thus, even catalytic amounts of ligand-free PdCl2 yield stilbene from technically interesting chlorobenzene and styrene in high yield (turnover number (TON) = 18) without the need for further promoting salt additives such as tetraphenylphosphonium chloride. The scope of the new reaction medium is outlined for the first time for the vinylation of various aryl halides using different mono- and disubstituted olefins as well as a variety of known palladium(0) and palladium(II) catalyst systems. Furthermore, a novel means of catalyst recycling is presented and its scope is evaluated.
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.
Efficient synthesis of alkyl aryl ketones & ketals via palladium-catalyzed regioselective arylation of vinyl ethers
Liu, Mingcui,Hyder, Zeynab,Sun, Yawei,Tang, Weijun,Xu, Lijin,Xiao, Jianliang
supporting information; experimental part, p. 2012 - 2015 (2010/07/04)
The combination of Pd(OAc)2 with 1,3-bis(diphenylphosphino) propane (dppp) in ethylene glycol constitutes a high-performance catalytic system for highly regioselective arylation of a range of electron-rich vinyl ethers by aryl bromides to provide, upon hydrolysis, alkyl aryl ketones and cyclic ketals in good yields with up to 3.75 × 105 TON and 15625 h-1 TOF.
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.
Electron-deficient phosphines accelerate the heck reaction of electronrich olefins in ionic liquid
Liu, Shifang,Saidi, Ourida,Berry, Neil,Ruan, Jiwu,Pettman, Alan,Thomson, Nick,Xiao, Jianliang
body text, p. 60 - 64 (2010/04/23)
Using various substrates and ligands, we show that electron-deficient, bidentate phosphines are the ligands of choice for palladium-catalyzed arylation of electron-rich olefins. This is in contrast to the reaction of electron-deficient olefins, which bene
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.
Oxygen and base-free oxidative heck reactions of arylboronic acids with olefins
Ruan, Jiwu,Li, Xinming,Saidi, Ourida,Xiao, Jianliang
, p. 2424 - 2425 (2008/09/18)
A mild and efficient protocol for palladium-catalyzed oxidative Heck reactions of arylboronic acids with both electron-rich and -deficient olefins is described. In contrast to the normal oxidative Heck coupling, this new method works in the absence of a base, oxygen, or other external oxidants. With a wide variety of substrates tolerated, the method broadens the scope of palladium-catalyzed coupling reactions. Copyright
PALLADIUM CATALYSED HECK ARYLATION OR VINYLATION OF 1-SUBSTITUTED OLEFINS
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Page/Page column 13; 16-17, (2008/06/13)
The present invention relates to a process for preparing arylated or vinylated olefins.
Selective terminal heck arylation of vinyl ethers with aryl chlorides: A combined experimental-computational approach including synthesis of betaxolol
Datta, Gopal K.,Von Schenck, Henrik,Hallberg, Anders,Larhed, Mats
, p. 3896 - 3903 (2007/10/03)
Reaction conditions have been developed for palladium-catalyzed terminal (β-) arylation of acyclic vinyl ethers with high regioselectivity using inexpensive aryl chlorides as starting materials and the P(t-Bu)3 releasing preligand [(t-Bu3)PH]BF4 as the key additive. This swift and straightforward protocol exploits non-inert conditions and controlled microwave heating to minimize handling and processing times and uses aqueous DMF or environmentally friendly PEG-200 as the reaction medium. The selectivity for linear β-product in PEG-200 is slightly higher than in aqueous DMF. DFT calculations support a ligand-driven selectivity rationale, where the electronic and steric influence of bulky P(t-Bu)3 ligand provides improved β-selectivity in the essential insertion step also with electron-rich aryl chlorides. A tentative computational rationalization of the improved selectivity in non-methylated PEG is discussed. Finally the synthetic methodology was used to provide efficient access to linear p-[2- (cyclopropylmethoxy)-ethyl] phenol from p-nitrophenyl chloride, a key intermediate in the synthesis of the β-adrenergic blocking agent Betaxolol.
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.
