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104-46-1Relevant academic research and scientific papers
Rhodium(III)-Catalyzed Selective Monoarylation of β or γ C(sp3)-H Bonds Assisted by a Trimethylpyrazole Group
Yuan, Chunchen,Tu, Guangliang,Zhao, Yingsheng
, p. 356 - 359 (2017)
The selective arylation of unactivated β or challenging γ primary and secondary β-C(sp3)-H bonds has been developed with a Cp*Rh(III) catalyst assisted by a trimethylpyrazole group. A rarely reported six-membered rhodacycle has been identified in rhodium-catalyzed C(sp3)-H activation reactions. Preliminary mechanistic studies have revealed that a concerted metalation-deprotonation pathway might be involved in the C-H activation step.
Didecyldimethylammonium bromide (DDAB): a universal, robust, and highly potent phase-transfer catalyst for diverse organic transformations
Chidambaram, Mandan,Sonavane, Sachin U.,de la Zerda, Jaima,Sasson, Yoel
, p. 7696 - 7701 (2007)
Didecyldimethylammonium bromide (DDAB) has been scrutinized in comparison with traditional phase-transfer catalysts in variety of liquid-liquid reactions. It was found to be an exceptionally comprehensive, durable, and highly efficient phase-transfer catalyst (PTC) in a number of representative organic transformations such as C- and N-alkylations, isomerization, esterification, elimination, cyanation, bromination, and oxidation under very mild conditions of temperature and mixing. It was confirmed that DDAB is an exceedingly accessible and concurrently a highly liphophilic phase-transfer catalyst. This unprecedented characteristic renders DDAB to be a multipurpose catalyst that functions effectively both in mass transfer controlled and chemically controlled phase-transfer reactions.
Electronic properties of a cationic triphenylphosphine ligand decorated with a (η5-C5H5)Fe group in late-transition-metal complexes
Malchau, Christian,Loose, Florian,Mees, Yannick,Duppe, Jens,Sun, Yu,Niedner-Schatteburg, Gereon,Thiel, Werner R.
, p. 3335 - 3343 (2020)
The synthesis and characterization of a series of novel cationic multimetallic transition-metal complexes based on the cationic phosphine ligand (η6-diphenylphosphinobenzene)(η5-cyclopentadienyl)iron(II) hexafluorophosphate (1) are reported. Complexes of ligand 1 with the late transition metals ruthenium, osmium, rhodium, and iridium as well as palladium and platinum were isolated in generally good yields, and the solid-state structures of most of them were determined. On the basis of the 195Pt?31P NMR coupling constant measured for trans-(1)2PtCl2 and the carbonyl absorption band in the IR spectrum of trans-(1)2Rh(CO)Cl, the electronic influence of the ligand on the metal center was evaluated. These measurements are supported by density functional theory (DFT) calculations, performed on the corresponding tricarbonylnickel(0) complex in order to determine the Tolman electronic parameter (TEP) of ligand 1.
Diastereomer-differentiating photochemistry of β-arylbutyrophenones: Yang cyclization versus type II elimination
Singhal, Nidhi,Koner, Apurba L.,Mal, Prasenjit,Venugopalan, Paloth,Nau, Werner M.,Moorthy, Jarugu Narasimha
, p. 14375 - 14382 (2005)
The diastereomers of ketones 2 and 3 are shown to exhibit distinct photochemical reactivities due to conformational preferences; while the anti isomers of 2 and 3 undergo efficient Yang cyclization in 75-90% yields with a remarkable diastereoselectivity (> 90%), the syn isomers predominantly undergo Norrish Type II elimination. The differences in the product profiles of the diastereomers are consistent with a mechanistic picture involving the formation of precursor diastereomeric triplet 1,4-biradicals in which the substituents at α and β-positions stabilize the cisoid (cyclization) or transoid (elimination) geometry. The fact that such a diastereomeric relationship does indeed ensue at the triplet-excited-state itself is demonstrated via the nanosecond laser-flash photolysis of model ketones 1. The diastereomeric discrimination in the product profiles observed for ketones 2 and 3 as well as in the triplet lifetimes observed for ketones 1 can both be mechanistically traced back to different conformational preferences of the ground-state diastereomeric ketones and the intermediary 1,4-biradicals. Additionally, it emerges from the present study that the syn and anti diastereomers of ketones 2 and 3 represent two extremes of a broad range of widely examined butyrophenones, which lead to varying degrees of Yang photocyclization depending on the alkyl substitution pattern.
Mechanism of Base-Catalyzed Reactions in Phase-Transfer-Systems with Poly(ethylene glycols) as Catalysts. The Isomerization of Allylanisole
Neumann, Ronny,Sasson, Yoel
, p. 3448 - 3451 (1984)
The mechanism of base-catalyzed reactions with poly(ethylene glycol) (PEG) as phase-transfer catalysts was studied by using the isomerization of allylanisole as a model reaction.The reaction kinetics showed the reaction to be chemical reaction controlled.The reaction system was a three-phase system consisting of an organic solvent phase, a PEG-potassium hydroxide complex phase, and a basic aqueous phase.The reaction mechanism included diffusion of the substrate from the solvent to the complex phase reaction and back diffusion of the product.The concentration of theaqueous phase is also important.When the aqueous phase is unsaturated there is no reaction.Concentrations above saturation increase rate because the basic complex becomes more potent under anhydrous conditions.The chain length and chain end moiety of the PEG catalysts have significant influence on the reaction rate.In general, short chain catalysts were more effective per gram but not per mole of catalyst.Etherification of the terminal hydroxyl group reduced activity.When alkoxide species were used as bases the trends were reversed, long chain catalysts being more effective and etherification increasing activity.
Synthesis, characterization and in vitro biological evaluation of [Ru(η6-arene)(N,N)Cl]PF6 compounds using the natural products arenes methylisoeugenol and anethole
Delgado, Ricardo A.,Galdámez, Antonio,Villena, Joan,Reveco, Patricio G.,Thomet, Franz A.
, p. 131 - 137 (2015)
Abstract Five new organometallic Ru(II) compounds (VI-X) with the general formula [Ru(η6-arene)(N,N)Cl]PF6, where arene-N,N correspond to methylisoeugenol-bipyridine (VI); anethole-bipyridine (VII); methylisoeugenol-ethylenediamine (VIII); anethole-ethylenediamine (IX) and methylisoeugenol-1,2-diaminobenzene (X), have been synthesized, fully characterized and biologically evaluated in vitro. The reaction conditions based on the reduction of [Ru(1,5-COD)Cl2]n in situ with methyleugenol and estragole, which are natural ligands, induced an alkene isomerization on the allylic substituent of coordinated arenes. The Ru(II)-arene bond formation and isomerization of the CC bond on the allyl substituent was confirmed using 1H NMR spectroscopy; this result was validated for compound VIII by X-ray diffraction. An XRD analysis revealed the presence of both enantiomers of the complex in the single-crystal. Compounds IX and X exhibited a better cytotoxic activity in vitro than carboplatin, which is a commercial drug, against three human tumor cell lines (MCF-7, PC-3 and HT-29).
Phospholes as efficient ancillaries for the rhodium-catalyzed hydroformylation and hydroaminomethylation of estragole
Oliveira, Kelley C.B.,Carvalho, Sabrina N.,Duarte, Matheus F.,Gusevskaya, Elena V.,Dos Santos, Eduardo N.,Karroumi, Jamal El,Gouygou, Maryse,Urrutigo?ty, Martine
, p. 10 - 16 (2015)
The hydroaminomethylation (HAM) of estragole, a bio-renewable starting material, with di-n-butylamine was studied for the first time resulting in three novel amines. The process consists of the alkene hydroformylation followed by the in situ reductive amination of primarily formed aldehydes. In order to control chemo- and regioselectivities, three classes of phosphorus(III) compounds were employed as ancillaries for rhodium(I) catalysts: phosphine, phosphites and phospholes. Phosphole-promoted systems have showed the best overall performance, being more selective in the hydrofomylation step than non-promoted or phosphite-promoted systems, as well as more efficient in the reductive amination step than the standard triphenylphosphine based system. It has been found that both the double bond isomerization (a concurrent reaction) and the enamine hydrogenation (the last step in the HAM process) are favored by less electron-donating ligands, with phospholes presenting an excellent compromise to ensure high chemoselectivity and reasonably fast formation of target amines.
Catalyst Decomposition during Olefin Metathesis Yields Isomerization-Active Ruthenium Nanoparticles
Higman, Carolyn S.,Lanterna, Anabel E.,Marin, M. Luisa,Scaiano, Juan C.,Fogg, Deryn E.
, p. 2446 - 2449 (2016)
The second-generation Grubbs catalyst, RuCl2(H2IMes)(PCy3) (=CHPh) [GII; H2IMes=1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene, Cy=cyclohexyl], is shown to decompose during olefin metathesis to gen
Isomerization during olefin metathesis: An assessment of potential catalyst culprits
Higman, Carolyn S.,Plais, Lucie,Fogg, Deryn E.
, p. 3548 - 3551 (2013)
Two ruthenium hydride complexes commonly proposed as agents of unintended isomerization during olefin metathesis are examined for their activity in isomerization of estragole, a representative allylbenzene. Neither proves kinetically competent to account for the levels of isomerization observed during cross-metathesis of estragole by the second-generation Grubbs catalyst. A structure-activity analysis of selected ruthenium hydride complexes indicates that higher isomerization activity correlates with a more electrophilic metal center. It wasn't me: Two Ru hydrides thought to trigger double-bond migration during olefin metathesis are examined for their isomerization activity. Neither can account for the high levels of undesired isomerization seen during self-metathesis of estragole, a model allylbenzene substrate. Higher activity is found to correlate with a less electron-rich Ru center. Copyright
Support Functionalization with a Phosphine-Containing Hyperbranched Polymer: A Strategy to Enhance Phosphine Grafting and Metal Loading in a Hydroformylation Catalyst
Garcia, Marco A. S.,Heyder, Rodrigo S.,Oliveira, Kelley C. B.,Costa, Jean C. S.,Corio, Paola,Gusevskaya, Elena V.,dos Santos, Eduardo N.,Bazito, Reinaldo C.,Rossi, Liane M.
, p. 1951 - 1960 (2016)
We present the design of a hydroformylation catalyst through the immobilization of air-stable Rh nanoparticles (NPs) on a magnetic support functionalized with a hyperbranched polymer that bears terminal phosphine groups. The catalyst modification with the hyperbranched polymer improved the metal–support interaction, the metal loading, and the catalytic activity. The catalyst was active for the hydroformylation of natural products, such as estragole, and could be used in successive reactions with negligible metal leaching. The phosphine grafting played a key role in the recyclability of Rh NPs under hydroformylation conditions. The catalytic activity was maintained in successive reactions, even if the catalyst was exposed to air during each recovery procedure. The modification of the support with hyperbranched polyester allowed us either to increase the number of Rh active species or to obtain more active Rh species on the catalyst surface.
