96443-41-3Relevant academic research and scientific papers
Catalysis of Diene Polymerization and Diels-Alder Reactions by an Octahedral Tungsten Nitrosyl Lewis Acid. X-ray Crystal Structure of the η1-Acrolein Complex (cis-Me3P)(trans-NO)(CO)3W-O=C(H)C(H)=CH2
Honeychuck, Robert V.,Bonnesen, Peter V.,Farahi, Judah,Hersh, William H.
, p. 5293 - 5296 (1987)
Cyclopentadiene and isoprene are polymerized by 0.1 mol percent (Me3P)(CO)3(NO)W-FSbF5 (1), and catalysis of the Diels-Alder reactions of cyclopentadiene or butadiene with α,β-unsaturated enones is also induced by as little as 0.1 mol percent 1; the X-ray structure of the adduct of 1 and acrolein, the presumed catalytic intermediate, reveals a simple Lewis acid interaction of the tungsten with the acrolein oxygen.
Method for preparing single-configuration C-2-position-monosubstituted norbornene derivative
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, (2021/07/01)
The invention discloses a method for preparing a single-configuration C-2-position-monosubstituted norbornene derivative. The method comprises the following steps of: firstly, preparing exo-isomer enriched exo-isomer mixed 5-norbornene-2-carboxylic ester by taking commercial exo-isomer/endoisomer mixed 5-norbornene-2-carboxylic acid and large-steric-hindrance monohydric alcohol as raw materials; separating 5-norbornene-2-carboxylate with a single configuration through common column chromatography separation or fractionation; and finally, preparing the C-2-position-monosubstituted norbornene derivative with the single configuration from the separated 5-norbornene-2-carboxylate with the single configuration. The raw materials used in the invention are easy to obtain, the preparation process is simple, and the C-2-position-monosubstituted norbornene derivative with high purity (greater than 98%) and single configuration can be obtained.
Bis-selenonium Cations as Bidentate Chalcogen Bond Donors in Catalysis
He, Xinxin,Wang, Xinyan,Tse, Ying-Lung Steve,Ke, Zhihai,Yeung, Ying-Yeung
, p. 12632 - 12642 (2021/10/21)
Lewis acids are frequently employed in catalysis but they often suffer from high moisture sensitivity. In many reactions, catalysts are deactivated because of the problem that strong Lewis acids also bond to the products. In this research, hydrolytically stable bidentate Lewis acid catalysts derived from selenonium dicationic centers have been developed. The bis-selenonium catalysts are employed in the activation of imine and carbonyl groups in various transformations with good yields and selectivity. Lewis acidity of the bis-selenonium salts was found to be stronger than that of the monoselenonium systems, attributed to the synergistic effect of the two cationic selenonium centers. In addition, the bis-selenonium catalysts are not inhibited by strong bases or moisture.
Improving the efficiency of the Diels-Alder process by using flow chemistry and zeolite catalysis
Seghers,Protasova,Mullens,Thybaut,Stevens
supporting information, p. 237 - 248 (2017/08/14)
The industrial application of the Diels-Alder reaction for the atom-efficient synthesis of (hetero)cyclic compounds constitutes an important challenge. Safety and purity concerns, related to the instability of the polymerization prone diene and/or dienophile, limit the scalability of the production capacity of Diels-Alder products in a batch mode. To tackle these problems, the use of a high-pressure continuous microreactor process was considered. In order to increase the yields and the selectivity towards the endo-isomer, commercially available zeolites were used as a heterogeneous catalyst in a microscale packed bed reactor. As a result, a high conversion (≥95%) and endo-selectivity (89:11) were reached for the reaction of cyclopentadiene and methyl acrylate, using a 1:1 stoichiometry. A throughput of 0.87 g h-1 during at least 7 h was reached, corresponding to a 3.5 times higher catalytic productivity and a 14 times higher production of Diels-Alder adducts in comparison to the heterogeneous lab-scale batch process. Catalyst deactivation was hardly observed within this time frame. Moreover, complete regeneration of the zeolite was demonstrated using a straightforward calcination procedure.
Dual responsive polymeric nanoparticles prepared by direct functionalization of polylactic acid-based polymers via graft-from ring opening metathesis polymerization
Veccharelli, Kate M.,Tong, Venus K.,Young, Jennifer L.,Yang, Jerry,Gianneschi, Nathan C.
, p. 567 - 570 (2016/01/12)
Polylactic acid (PLA) has found widespread use in plastics and in biomedical applications due to its biodegradability into natural benign products. However, PLA-based materials remain limited in usefulness due to difficulty of incorporating functional groups into the polymer backbone. In this paper, we report a strategy for PLA functionalization that establishes the preparation of highly derivatized materials in which ring opening metathesis polymerization (ROMP) is employed as a graft-from polymerization technique utilizing a norbornene-modified handle incorporated into the PLA backbone. As a demonstration of this new synthetic methodology, a PLA-derived nanoparticle bearing imidazole units protected with a photolabile group was prepared. The morphology of this material could be controllably altered in response to exposure of UV light or acidic pH as a stimulus. We anticipate that this graft-from approach to derivatization of PLA could find broad use in the development of modified, biodegradable PLA-based materials.
Remote Tris(pentafluorophenyl)borane-Assisted Chiral Phosphoric Acid Catalysts for the Enantioselective Diels-Alder Reaction
Hatano, Manabu,Ishihara, Hideyuki,Goto, Yuta,Ishihara, Kazuaki
, p. 564 - 570 (2016/03/12)
Tris(pentafluorophenyl)borane-assisted chiral supramolecular phosphoric acid catalysts were developed for the model Diels-Alder reaction of α-substituted acroleins with cyclopentadiene. Two remotely coordinated tris(pentafluorophenyl)boranes should help to increase the Bronsted acidity of the active center in the supramolecular catalyst and create effective bulkiness for the chiral cavity. The prepared supramolecular catalysts acted as not only conjugated Bronsted acid-Bronsted base catalysts but also bifunctional Lewis acid-Bronsted base catalysts with the addition of a central achiral Lewis acid source such as catecholborane.
PRODUCTION METHOD OF EXO-TYPE NORBORNENE COMPOUND
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Paragraph 0024-0025, (2017/01/02)
PROBLEM TO BE SOLVED: To provide a production method of a norbornene compound, in particular, exo-enriched 2-acyl-5-norbornene containing many exo isomers, which is useful as a source material precursor of monomers for electronic materials and optical materials. SOLUTION: The production method of an exo-type norbornene compound is characterized by bringing an endo-type norbornene compound having an acyl group at a second position expressed by the formula below into contact with a tertiary amino compound (B) to carry out epimerization. The production method is carried out in a batch process where distillation purification is performed after the reaction or in a continuous process where purification is performed by reactive distillation. In the formula, R represents a hydrogen atom or an alkyl group or a phenyl group which may have a substituent. COPYRIGHT: (C)2015,JPOandINPIT
Chiral Dawson-Type Hybrid Polyoxometalate Catalyzes Enantioselective Diels-Alder Reactions
Xuan, Wen-Jing,Botuha, Candice,Hasenknopf, Bernold,Thorimbert, Serge
supporting information, p. 16512 - 16516 (2015/11/09)
Can achiral organocatalysts linked to chiral polyanionic metal oxide clusters provide good selectivity in enantioselective C-C bond formations? The answer to this question is investigated by developing a new active hybrid polyoxometalate-based catalyst for asymmetric Diels-Alder reaction. Chirality transfer from the chiral anionic polyoxometalate to the covalently linked achiral imidazolidinone allows Diels-Alder cycloaddition products to be obtained with good yields and high enantioselectivities when using cyclopentadiene and acrylaldehydes as partners.
Enantioselective catalysts based on the chiral fragment (η5-C5Me5)Ir(Prophos) for Diels-Alder reactions
Carmona, Daniel,Viguri, Fernando,Asenjo, Ainara,Lahoz, Fernando J.,García-Ordu?a, Pilar,Oro, Luis A.
, p. 119 - 124 (2014/03/21)
The aqua complex (SIr,RC)-[(η5-C 5Me5)Ir(Prophos)(H2O)][SbF6] 2 [Prophos = (R)-propane-1,2-diyl-bis(diphenylphosphane)] is an active precursor for the asymmetric Diels-Alder reaction of acyclic enals with cyclopentadiene, 2,3-dimethylbutadiene and isoprene. Enantioselectivities up to 78% ee are achieved. The intermediate Lewis acid-dienophile complex (S Ir,RC)-[(η5-C5Me 5)Ir(Prophos)(ethyl acrolein)][SbF6]2 has been isolated and completely characterized, including the X-ray crystal structure determination. Structural parameters indicate that the disposition of the coordinated dienophile is controlled by CH/π attractive interactions established between a phenyl group of the Prophos ligand and the aldehyde proton of the coordinated enal. Proton NMR data indicate that these interactions are maintained in solution. From diffractometric and spectroscopic data, the origin of the enantioselectivity is discussed.
Carbocations as lewis acid catalysts in diels-alder and Michael addition reactions
Bah, Juho,Franzen, Johan
, p. 1066 - 1072 (2014/02/14)
In general, Lewis acid catalysts are metal-based compounds that owe their reactivity to a low-lying empty orbital. However, one potential Lewis acid that has received negligible attention as a catalyst is the carbocation. We have demonstrated the potential of the carbocation as a highly powerful Lewis acid catalyst for organic reactions. The stable and easily available triphenylmethyl (trityl) cation was found to be a highly efficient catalyst for the Diels-Alder reaction for a range of substrates. Catalyst loadings as low as 500 ppm, excellent yields, and good endo/exo selectivities were achieved. Furthermore, by changing the electronic properties of the substituents on the tritylium ion, the Lewis acidity of the catalyst could be tuned to control the outcome of the reaction. The ability of this carbocation as a Lewis acid catalyst was also further extended to the Michael reaction. Copyright
