1191-99-7Relevant articles and documents
Small bite-angle P-OP ligands for asymmetric hydroformylation and hydrogenation
Fernandez-Perez, Hector,Benet-Buchholz,Vidal-Ferran, Anton
, p. 3634 - 3637 (2013)
A series of small bite-angle phosphine-phosphite (P-OP) ligands have been synthesized by a two-step method. The key intermediate was prepared by an unprecedented asymmetric carbonyl reduction of a phosphamide using the CBS (Corey-Bakshi-Shibata) catalyst. The topology of these ligands (a configurationally stable stereogenic carbon with two heteroatom substituents) and their small bite-angle (created by the close proximity of the two ligating groups to the metal center) together provide a rigid asymmetric environment around this center, enabling high stereoselectivity in hydroformylations and hydrogenations of standard substrates.
Tautomerism and vapor-phase transformations of 2-hydroxytetrahydrofuran
Lebedev,Leite,Fleisher,Stonkus
, p. 775 - 778 (2000)
The relative stability of 2-hydroxytetrahydrofuran and the tautomeric 4-hydroxybutanal was determined by the semi-empirical AM1 method. It was concluded that the cyclic tautomer predominates in the gas phase at 25°C. Vapor-phase dehydration of 2-hydroxytetrahydrofuran in the presence of porcelain and silica gel L leads to a quantitative yield of 2,3-dihydrofuran.
Highly efficient rhodium catalysts for the asymmetric hydroformylation of vinyl and allyl ethers using C1-symmetrical diphosphite ligands
Gual, Aitor,Godard, Cyril,Castillon, Sergio,Claver, Carmen
, p. 463 - 477 (2010)
Here, we describe the successful application of novel glucofuranose-derived 1,3-diphosphites in the rhodium-catalysed asymmetric hydroformylation of vinyl acetate, 2,5-dihydrofuran and 2,3-dihydrofuran. In the hydroformylation of vinyl acetate, total regioselectivity and high ee (up to 73%) were obtained. When 2,3- and 2,5-dihydrofuran were the substrates, total chemo- and regioselectivities were achieved together with ees up to 88%. These results correspond to the highest ee values reported to date in the asymmetric hydroformylation of these substrates. The HP-NMR studies of the [RhH(CO) 2(L)] species (L=15 and 17) demonstrated that both ligands coordinate to the Rh centre in an eq-eq fashion. The complex [RhH(CO)2(15)] was detected as a single isomer with characteristic features of eq-eq coordination. However, the broadening of the corresponding signals indicated that this species is rapidly interchanging in solution. In contrast, complex [RhH(CO) 2(17)] was detected as a mixture of two conformational isomers at low temperature due to the greater flexibility of the monocyclic backbone of this ligand.
Hoveyda-Type Quinone-Containing Complexes – Catalysts to Prevent Migration of the Double Bond under Metathesis Conditions
Kajetanowicz, Anna,Milewski, Mariusz,Rogińska, Joanna,Gajda, Roman,Wo?niak, Krzysztof
, p. 626 - 638 (2017)
Three new quinone-containing Hoveyda-type complexes have been synthesised and fully characterised. Their ability to suppress undesired double-bond migration along the carbon chain during metathesis reactions was examined. It was proved that these catalysts decrease the amounts of undesired side-products with a shifted double bond in the reaction mixture.
Rh-catalyzed asymmetric hydroformylation of heterocyclic olefins using chiral diphosphite ligands. Scope and limitations
Mazuela, Javier,Coll, Mercedes,Pamies, Oscar,Dieguez, Montserrat
, p. 5440 - 5445 (2009)
(Chemical Equation Presented) We used a series of diphosphite ligands to study the effect of the ligand backbone, the length of the bridge, and the substituents of the biphenyl moieties and determine the scope of this type of ligand in the Rh-catalyzed asymmetric hydroformylation of several hetereocylic olefins. By carefully selecting the ligand components, we achieved high chemo-, regio-, and enantioselectivities in different substrate types. Unprecedentedly high enantioselectivities for five-membered heterocyclic olefins were therefore obtained. Note that both enantiomers of the hydroformylation products can be synthesized using the same ligand by a simple substrate change. For the seven-membered heterocyclic dioxepines, our results are among the best obtained. Also, both enantiomers of the hydroformylation products can be obtained by using pseudoenantiomer ligands or by carefully tuning the ligand parameters.
Synergistic chemiluminescence nanoprobe: Au clusters-Cu2+-induced chemiexcitation of cyclic peroxides and resonance energy transfer
Lv, Yi,Song, Hongjie,Su, Yingying,Sun, Mingxia,Zhang, Kexin
, p. 3151 - 3154 (2020)
An interesting chemiluminescence (CL) phenomenon of cyclic peroxides originating from tetrahydrofuran hydrogen peroxide (THF-HPO) in the presence of BSA-stabilized Au NCs (Au?BSA NCs) was found for the first time. In this CL system, Au?BSA NCs can greatly accelerate the decomposition of THF-HPO, and then chemiluminescence resonance energy transfer (CRET) occurs between excited dioxetane derivatives and the Au?BSA NCs, yielding enhanced CL emission which can be further enhanced more than 10 times by the addition of copper ions. Based on this, a synergistic CL nanoprobe with a special signal amplification strategy was developed.
Method for synthesizing cyclopropanecarboxaldehyde from 1,4-butanediol
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Paragraph 0054-0058; 0064-0068, (2021/03/13)
The invention relates to a method for synthesizing cyclopropanecarboxaldehyde from 1,4-butanediol. The method has the advantages of accessible raw materials, low cost and simple technique, can implement one-step reaction, has high efficiency, and can implement continuous operation.
Highly Electrophilic Titania Hole as a Versatile and Efficient Photochemical Free Radical Source
Hainer, Andrew,Marina, Nancy,Rincon, Stefanie,Costa, Paolo,Lanterna, Anabel E.,Scaiano, Juan C.
supporting information, p. 4531 - 4535 (2019/03/19)
Photogenerated holes in nanometric semiconductors, such as TiO2, constitute remarkable powerful electrophilic centers, capable of capturing an electron from numerous donors such as ethers, or nonactivated substrates like toluene or acetonitrile, and constitute an exceptionally clean and efficient source of free radicals. In contrast with typical free radical precursors, semiconductors generate single radicals (rather than pairs), where the precursors can be readily removed by filtration or centrifugation after use, thus making it a convenient tool in organic chemistry. The process can be described as an example of dystonic proton coupled electron transfer.