291-64-5Relevant academic research and scientific papers
Titania-photocatalyzed transfer hydrogenation reactions with methanol as a hydrogen source: Enhanced catalytic performance by Pd-Pt alloy at ambient temperature
Zhao, Yubao,Pan, Feng,Li, Hui,Xu, Guo Qin,Chen, Wei
, p. 454 - 458 (2014)
Hydrogenation reactions are of great importance in scientific research and in industry productions. Herein, we designed a novel system to realize photocatalytic transfer hydrogenation by using solar light as the energy input and methanol as the hydrogen source. In this reaction, titania loaded with Pd-Pt bimetallic alloy nanocrystals as a cocatalyst exhibited photocatalytic performance that was remarkably superior to that exhibited by titania with Pd or Pt alone as the cocatalyst. This work has shed light on the rational design of multifunctional catalysts through selecting appropriate bimetallic alloys as efficient cocatalysts. Light up, as if you have a catalyst: Photocatalytic transfer hydrogenation is efficiently realized on Pd-Pt/TiO2 under mild reaction conditions with the use of light irradiation as the energy input and methanol as the hydrogen source at ambient temperature. The Pd-Pt alloy cocatalyst exhibits enhanced catalytic performance relative to that of the monometallic Pd or Pt component. Copyright
SELECTIVE, HOMOGENEOUS HYDROGENATION OF CYCLOHEPTATRIENE TO CYCLOHEPTENE CATALYZED BY (η4-CYCLOOCTA-1,5-DIENE)(η6-CYCLOHEPTA-1,3,5-TRIENE)RUTHENIUM(0)
Airoldi, M.,Deganello, G.,Dia, G.,Gennaro, G.
, p. 391 - 403 (1980)
In the presence of small amounts of 4-COD)(η6-C8H10)> (1), cycloheptatriene is hydrogenated to cycloheptene, under one atmosphere of hydrogen at room temperature in homogeneous phase.The formation of a small amount of cyclooctene and the existence of an induction period, which do not occur when 4-COD)(η6-C7H8)> (2) is used as the catalyst, suggest that 2 is the real catalyst.The selectivity of this hydrogenation is 100percent in n-hexane as solvent, 99.5percent in THF, and low in ethanol.Conversion is quantitative in THF and ethanol, but not more than 65percent in n-hexane.In the presence of 1 or 2, cycloheptene is rapidly hydrogenated to cycloheptane in THF and ethanol, but not in n-hexane.A mechanism for these catalytic hydrogenations is proposed, and discussed on the basis of the dominant role of the solvents.Increase of temperature and/or pressure of hydrogen increases the rate of hydrogenation.
Rational Design of an Iron-Based Catalyst for Suzuki–Miyaura Cross-Couplings Involving Heteroaromatic Boronic Esters and Tertiary Alkyl Electrophiles
Byers, Jeffery A.,Crockett, Michael P.,Li, Bo,Wong, Alexander S.
supporting information, p. 5392 - 5397 (2020/03/04)
Suzuki–Miyaura cross-coupling reactions between a variety of alkyl halides and unactivated aryl boronic esters using a rationally designed iron-based catalyst supported by β-diketiminate ligands are described. High catalyst activity resulted in a broad substrate scope that included tertiary alkyl halides and heteroaromatic boronic esters. Mechanistic experiments revealed that the iron-based catalyst benefited from the propensity for β-diketiminate ligands to support low-coordinate and highly reducing iron amide intermediates, which are very efficient for effecting the transmetalation step required for the Suzuki–Miyaura cross-coupling reaction.
Iron-Catalyzed Suzuki-Miyaura Cross-Coupling Reactions between Alkyl Halides and Unactivated Arylboronic Esters
Crockett, Michael P.,Tyrol, Chet C.,Wong, Alexander S.,Li, Bo,Byers, Jeffery A.
supporting information, p. 5233 - 5237 (2018/09/12)
An iron-catalyzed cross-coupling reaction between alkyl halides and arylboronic esters was developed that does not involve activation of the boronic ester with alkyllithium reagents nor requires magnesium additives. A combination of experimental and theoretical investigations revealed that lithium amide bases coupled with iron complexes containing deprotonated cyanobis(oxazoline) ligands were best to obtain high yields (up to 89%) in catalytic cross-coupling reactions. Mechanistic investigations implicate carbon-centered radical intermediates and highlight the critical importance of avoiding conditions that lead to iron aggregates. The new iron-catalyzed Suzuki-Miyaura reaction was applied toward the shortest reported synthesis of the pharmaceutical Cinacalcet.
Triazolylidene Iridium Complexes for Highly Efficient and Versatile Transfer Hydrogenation of C=O, C=N, and C=C Bonds and for Acceptorless Alcohol Oxidation
Mazloomi, Zahra,Pretorius, René,Pàmies, Oscar,Albrecht, Martin,Diéguez, Montserrat
, p. 11282 - 11298 (2017/09/25)
A set of iridium(I) and iridium(III) complexes is reported with triazolylidene ligands that contain pendant benzoxazole, thiazole, and methyl ether groups as potentially chelating donor sites. The bonding mode of these groups was identified by NMR spectroscopy and X-ray structure analysis. The complexes were evaluated as catalyst precursors in transfer hydrogenation and in acceptorless alcohol oxidation. High-valent iridium(III) complexes were identified as the most active precursors for the oxidative alcohol dehydrogenation, while a low-valent iridium(I) complex with a methyl ether functionality was most active in reductive transfer hydrogenation. This catalyst precursor is highly versatile and efficiently hydrogenates ketones, aldehydes, imines, allylic alcohols, and most notably also unpolarized olefins, a notoriously difficult substrate for transfer hydrogenation. Turnover frequencies up to 260 h-1 were recorded for olefin hydrogenation, whereas hydrogen transfer to ketones and aldehydes reached maximum turnover frequencies greater than 2000 h-1. Mechanistic investigations using a combination of isotope labeling experiments, kinetic isotope effect measurements, and Hammett parameter correlations indicate that the turnover-limiting step is hydride transfer from the metal to the substrate in transfer hydrogenation, while in alcohol dehydrogenation, the limiting step is substrate coordination to the metal center.
Reduced graphene oxide supported nickel-palladium alloy nanoparticles as a superior catalyst for the hydrogenation of alkenes and alkynes under ambient conditions
?etinkaya, Yasin,Metin, ?nder,Balci, Metin
, p. 28538 - 28542 (2016/04/08)
Addressed herein is the superior catalytic performance of reduced graphene oxide supported Ni30Pd70 alloy nanoparticles (rGO-Ni30Pd70) for the direct hydrogenation of alkenes and alkynes to alkanes, which surpasses the commercial Pd/C catalyst both in activity and stability. A variety of cyclic or aromatic alkenes and alkynes (a total of 17 examples) were rapidly reduced to the corresponding alkanes with high yields (>99%) via the presented direct hydrogenation protocol under ambient conditions. Compared to the commercially available Pd/C (10 wt%) catalyst, the rGO-Ni30Pd70 catalyst provided higher yields in shorter reaction times under the optimized conditions. Moreover, the rGO-Ni30Pd70 catalysts were more stable and durable than the commercial Pd/C catalysts by preserving their initial activity after five consecutive runs in the hydrogenation reactions.
Bisphosphine compd., and Bisphosphine compound and a transition metal catalyst, and method of manufacturing the same (by machine translation)
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Paragraph 0554; 0560; 0561, (2016/11/17)
PROBLEM TO BE SOLVED: To provide a bisphosphine compound with a new bidentate phosphine ligand having a highly bulky substituent group on a phosphorus atom, which enables highly efficient and highly selective progress in various organic synthesis reactions, especially, cross coupling reaction, and a transition metal catalyst using the bisphosphine compound as a ligand, and a method for manufacturing them.SOLUTION: There are provided a bisphosphine compound represented by general formula (A) or general formula (B) and a transition metal catalyst using the bisphosphine compound as a ligand, and a method for manufacturing them.
Carbon-carbon bond formation reactivity of a four-coordinate NHC-supported iron(II) phenyl compound
Liu, Yuesheng,Xiao, Jie,Wang, Lei,Song, You,Deng, Liang
, p. 599 - 605 (2015/03/05)
The preparation and characterization of a NHC-coordinated (NHC = N-heterocyclic carbene) ferrous phenyl complex [(IPr2Me2)2FePh2] (1; IPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) as well as its C-C bond formation reactivity have been studied. The four-coordinate iron(II) phenyl complex was prepared from the reaction of ferrous chloride with PhMgBr and IPr2Me2. It reacts with nonactivated primary and secondary alkyl bromides and chlorides to furnish cross-coupling products and the iron(II) monophenyl species (IPr2Me2)2FePhX (X = Br (2), Cl). When it is treated with cyclooctatetraene (cot) or [Cp2Fe][BArF4] in the presence of PMe3, it undergoes coordination or one-electron oxidation induced reductive elimination of biphenyl to form the corresponding iron(0) or iron(I) species [(IPr2Me2)2Fe(?·4-cot)] (3) or [(IPr2Me2)2Fe(PMe3)2][BArF4] (4). All of these iron-containing products have been fully characterized by various spectroscopic methods. Complex 1 and (IPr2Me2)2FeCl2 catalyze the reaction of n-C8H17Br with (p-tolyl)MgBr to afford the cross-coupling product in moderate yields (49% and 47%), whereas the reactions employing 4 and 1/PMe3 as catalysts give the cross-coupling product in very low yields. The results reflect the complexity of the reaction mechanism of iron-catalyzed coupling reactions.
Highly nucleophilic dipropanolamine chelated boron reagents for aryl-transmetallation to iron complexes
Dunsford, Jay J.,Clark, Ewan R.,Ingleson, Michael J.
supporting information, p. 20577 - 20583 (2015/12/04)
New aryl- and heteroarylboronate esters chelated by dipropanolamine are synthesised directly from boronic acids. The corresponding anionic borates are readily accessible by deprotonation and demonstrate an increase in hydrocarbyl nucleophilicity in comparison to other common borates. The new borates proved competent for magnesium or zinc additive-free, direct boron-to-iron hydrocarbyl transmetallations with well-defined iron(ii) (pre)catalysts. The application of the new borate reagents in representative Csp2-Csp3 cross-coupling led to almost exclusive homocoupling unless coupling is performed in the presence of a zinc additive.
The potential of methylsiloxanes as solvents for synthetic chemistry applications
Ab Rani, Mohd Azri,Borduas, Nadine,Colquhoun, Victoria,Hanley, Robert,Johnson, Henry,Larger, Solene,Lickiss, Paul D.,Llopis-Mestre, Veronica,Luu, Selina,Mogstad, Martin,Oczipka, Philipp,Sherwood, James R.,Welton, Tom,Xing, Jun-Yi
, p. 1282 - 1296 (2014/03/21)
The potential use of volatile methylsiloxanes (VMSs) as solvents for chemicals synthesis has been explored. Assessment of the environmental impact of these VMS solvents is made and found to be significantly lower than those of the non-polar organic solvents that they have the potential to replace. The polarities of the VMSs, as expressed by empirical polarity measurements, and miscibilities with other liquids are found to be similar to those of alkane solvents. Finally, some uses of VMSs as solvents for both organic and inorganic transformations are described. The VMSs provide environmentally more sustainable (greener) alternatives to the nonpolar solvents that they have the potential to replace.
