1522-34-5Relevant academic research and scientific papers
Rh(I)-bisphosphine-catalyzed asymmetric, intermolecular hydroheteroarylation of α-substituted acrylate derivatives
Filloux, Claire M.,Rovis, Tomislav
supporting information, p. 508 - 517 (2015/01/30)
Asymmetric hydroheteroarylation of alkenes represents a convenient entry to elaborated heterocyclic motifs. While chiral acids are known to mediate asymmetric addition of electron-rich heteroarenes to Michael acceptors, very few methods exploit transition metals to catalyze alkylation of heterocycles with olefins via a C-H activation, migratory insertion sequence. Herein, we describe the development of an asymmetric, intermolecular hydroheteroarylation reaction of α-substituted acrylates with benzoxazoles. The reaction provides 2-substitued benzoxazoles in moderate to excellent yields and good to excellent enantioselectivities. Notably, a series of mechanistic studies appears to contradict a pathway involving enantioselective protonation of a Rh(I)-enolate, despite the fact that such a mechanism is invoked almost unanimously in the related addition of aryl boronic acids to methacrylate derivatives. Evidence suggests instead that migratory insertion or beta-hydride elimination is enantiodetermining and that isomerization of a Rh(I)-enolate to a Rh(I)-heterobenzyl species insulates the resultant α-stereocenter from epimerization. A bulky ligand, CTH-(R)-Xylyl-P-Phos, is crucial for reactivity and enantioselectivity, as it likely discourages undesired ligation of benzoxazole substrates or intermediates to on- or off-cycle rhodium complexes and attenuates coordination-promoted product epimerization.
METHODS OF MANUFACTURING BENZOQUINOLINE COMPOUNDS
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Paragraph 0249; 0250, (2015/06/10)
The present invention relates to new methods of manufacturing benzoquinoline inhibitors of vesicular monoamine transporter 2 (VMAT2), and intermediates thereof.
Theoretical investigation of the reaction of dialkylzincs with α-alkoxycarbonyl radicals. Evaluation of α-bromoacrylates as radical acceptors in radical-polar crossover processes
Vibert, Fran?ois,Maury, Julien,Lingua, Hugo,Besson, Eric,Siri, Didier,Bertrand, Michèle P.,Feray, Laurence
, p. 8991 - 9002 (2015/11/02)
The evaluation of ethyl α-bromoacrylate as radical acceptor in dialkylzinc radical-polar cascades addresses the question of the parameters controlling homolytic substitution at zinc by α-alcoxycarbonyl radicals. Under non-degassed medium ethyl α-bromoacrylate reacts with diethylzinc to give a bromocyclopropane. The reaction involves successively radical addition, SH2 at zinc, conjugate addition of the resulting enolate to the electrophilic substrate and ring closure. Theoretical calculations were performed to get a better insight into the detailed mechanism. They highlight the impact of zinc(II) chelation on the formal SH2 step. Additional experiments performed in the presence of other electrophiles-aldehydes and acylsilanes-are discussed.
Group 4 metallocenes useful as catalysts for the polymerization of olefins
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Page/Page column 21, (2012/02/04)
A complex of formula (I): wherein M is zirconium or hafnium; each X is a sigma ligand; L is a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-SiR'2-, -R'2Ge-,
Process for olefin polymerisation using group 4 metallocene as catalysts
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Page/Page column 21-22, (2012/02/04)
A process for the preparation of a random propylene copolymer comprising polymerising propylene and at least one C2-10 alpha olefin (especially ethylene) in the presence of a catalyst; wherein said catalyst comprises: (i) a complex of formula (I): wherein
PROCESS FOR OLEFIN POLYMERISATION USING GROUP 4 METALLOCENE AS CATALYSTS
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Page/Page column 37-38, (2012/01/14)
A process for the preparation of a random propylene copolymer comprising polymerising propylene and at least one C2-10 alpha olefin (especially ethylene) in the presence of a catalyst; wherein said catalyst comprises: (i) a complex of formula (I): wherein
Preparation and characterization of tetrabenazine enantiomers against vesicular monoamine transporter 2
Yu, Qian-Sheng,Luo, Weiming,Deschamps, Jeffery,Holloway, Harold W.,Kopajtic, Theresa,Katz, Jonathan L.,Brossi, Arnold,Greig, Nigel H.
scheme or table, p. 105 - 109 (2010/11/18)
As a clinical medication for the treatment of hyperkinetic movement disorders, in conditions such as Huntington's disease, tetrabenazine (TBZ) has always been used in its racemic form. To establish whether or not its beneficial therapeutic actions are enantiospecific, a practical total synthetic route was developed to yield each enantiomeric form to allow their chemical and pharmacological characterization. We briefly summarize the total synthesis of TBZ and report a detailed procedure for resolution of TBZ into its enantiomers, (+)-TBZ and (-)-TBZ. This allowed determination of the optical rotation and absolute configurations of each TBZ enantiomer, based on X-ray crystallographic analysis, together with characterization of their inhibitory action at the vesicular monoamine transporter 2, where (+)-TBZ proved 3-fold more active than (-)-TBZ.
New series of antiprion compounds: Pyrazolone derivatives have the potent activity of inhibiting protease-resistant prion protein accumulation
Kimata, Ayako,Nakagawa, Hidehiko,Ohyama, Ryo,Fukuuchi, Tomoko,Ohta, Shigeru,Suzuki, Takayoshi,Miyata, Naoki
, p. 5053 - 5056 (2008/03/13)
To find effective antiprion compounds, we synthesized and evaluated various pyrazolone derivatives. Seven of 19 compounds showed inhibition of PrP-res accumulation and the remarkably active compound 13 showed an IC50 value of 3 nM in both ScN2a and F3 cell lines. Findings from studies on physicochemical and biochemical properties suggest that the action mechanism of these compounds does not correlate with any antioxidant activities, any of hydroxyl radical scavenging activities, or any SOD-like activities.
Hydroxyl radical scavenging by edaravone derivatives: Efficient scavenging by 3-methyl-1-(pyridin-2-yl)-5-pyrazolone with an intramolecular base
Nakagawa, Hidehiko,Ohyama, Ryo,Kimata, Ayako,Suzuki, Takayoshi,Miyata, Naoki
, p. 5939 - 5942 (2007/10/03)
We synthesized various 3-methyl-1-phenyl-5-pyrazolone (edaravone) derivatives and evaluated their oxidation potential and hydroxyl radical scavenging activity. It was found 3-methyl-1-(pyridin-2-yl)-5-pyrazolone had a much higher ability to scavenge the radical than did edaravone itself. Its efficient radical scavenging activity was assumed to be due to the increase of its anion form, an active form, by a hydrogen-bonded intramolecular base.
