- Metallocene compounds, including the catalyst, the catalyst used in the process of olefin polymers, olefin homopolymers and copolymers and
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PROBLEM TO BE SOLVED: To solve shortcomings of metallocene compounds of the present technology standard and to provide metallocenes that increase desirable characteristics such as high melting point, high molar mass homopolymers and high molar mass copolymers, and do so at higher productivities when used as components of supported catalysts under industrially relevant polymerization conditions at temperatures of from 50 to 100°C.SOLUTION: Certain metallocene compounds are provided that, when used as a component in a supported polymerization catalyst under industrially relevant polymerization conditions, afford high molar mass homo polymers or copolymers like polypropylene or propylene/ethylene copolymers without the need for any α-branched substituent in either of the two available 2-positions of the indenyl ligands.
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Paragraph 0186
(2017/11/01)
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- Metallocene compounds, catalysts comprising them, process for producing an olefin polymer by use of the catalysts, and olefin homo- and copolymers
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Certain metallocene compounds are provided that, when used as a component in a supported polymerization catalyst under industrially relevant polymerization conditions, afford high molar mass homo polymers or copolymers like polypropylene or propylene/ethylene copolymers without the need for any α-branched substituent in either of the two available 2-positions of the indenyl ligands. The substituent in the 2-position of one indenyl ligand can be any radical comprising hydrogen, methyl, or any other C2-C40 hydrocarbon which is not branched in the α-position, and the substituent in the 2-position of the other indenyl ligand can be any C4-C40 hydrocarbon radical with the proviso that this hydrocarbon radical is branched in the β-position. This metallocene topology affords high melting point, very high molar mass homo polypropylene and very high molar mass propylene-based copolymers. The activity/productivity levels of catalysts including the metallocenes of the present invention are exceptionally high.
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Page/Page column 53
(2012/11/07)
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- Total synthesis of the large non-ribosomal peptide polytheonamide B
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Polytheonamide B is by far the largest non-ribosomal peptide known at present, and displays extraordinary cytotoxicity (EC50 =68 pg ml -1 , mouse leukaemia P388 cells). Its 48 amino-acid residues include a variety of non-proteinogenic d- and l-amino acids, and the absolute stereochemistry of these amino acids alternate in sequence. These structural features induce the formation of a stable β-strand-type structure, giving rise to an overall tubular structure over 30A? in length. In a biological setting, this fold is believed to transport cations across the lipid bilayer through a pore, thereby acting as an ion channel. Here, we report the first chemical construction of polytheonamide B. Our synthesis relies on the combination of four key stages: syntheses of non-proteinogenic amino acids, a solid-phase assembly of four fragments of polytheonamide B, silver-mediated connection of the fragments and, finally, global deprotection. The synthetic material now available will allow studies of the relationships between its conformational properties, channel functions and cytotoxicity.
- Inoue, Masayuki,Shinohara, Naoki,Tanabe, Shintaro,Takahashi, Tomoaki,Okura, Ken,Itoh, Hiroaki,Mizoguchi, Yuki,Iida, Maiko,Lee, Nayoung,Matsuoka, Shigeru
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supporting information; scheme or table
p. 280 - 285
(2010/09/03)
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- METALLOCENE COMPOUNDS, CATALYSTS COMPRISING THEM, PROCESS FOR PRODUCING AN OLEFIN POLYMER BY USE OF THE CATALYSTS, AND OLEFIN HOMO-AND COPOLYMERS
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Certain metallocene compounds are provided that, when used as a component in a supported polymerization catalyst under industrially relevant polymerization conditions, afford high molar mass homo polymers or copolymers like polypropylene or propylene/ethylene copolymers without the need for any α-branched substituent in either of the two available 2-positions of the indenyl ligands. The substituent in the 2-position of one indenyl ligand can be any radical comprising hydrogen, methyl, or any other C2-C40 hydrocarbon which is not branched in the α-position, and the substituent in the 2-position of the other indenyl ligand can be any C4-C40 hydrocarbon radical with the proviso that this hydrocarbon radical is branched in the β-position. This metallocene topology affords high melting point, very high molar mass homo polypropylene and very high molar mass propylene-based copolymers. The activity/productivity levels of catalysts including the metallocenes of the present invention are exceptionally high.
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- 5-[4-(3,3-Dimethylbutoxycarbonyl)phenyl]-4-pentynoic acid and its derivatives inhibit ionotropic γ-aminobutyric acid receptors by binding to the 4'-ethynyl-4-n-propylbicycloorthobenzoate site
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Acyclic noncompetitive antagonists of ionotropic γ-aminobutyric acid (GABA) receptors, bearing an ester or ether linkage, were designed, synthesized, and assayed for their inhibition of the specific binding of [3H]4'-ethynyl-4-n-propylbicycloorthobenzoate (EBOB), a radiolabeled noncompetitive antagonist, to rat brain and housefly head membranes. 5-[4-(3,3-Dimethylbutoxycarbonyl)phenyl]-4-pentynoic acid (DBCPP), a butyl benzoate analogue, was found to competitively inhibit the binding of [3H]EBOB in rat brain membranes, with an IC50 of 88 nM. The potency conferred by the p-substituent decreased in the order C=C(CH2)2COOH>C=C(CH2)2COOCH3>C=CH>Br. Pentyl phenyl ethers were equally potent compared with butyl benzoates, while phenyl pentanoates and benzyl butyl ethers were less potent. These compounds were generally less active in housefly head membranes than in rat brain membranes. The introduction of an isopropyl group into the 1-position of the 3,3-dimethylbutyl group of a butyl benzoate and two benzyl butyl ethers caused an increase in potency in housefly GABA receptors, whereas this modification at the corresponding position of other compounds led to an unchanged or decreased potency. In the case of rat receptors, this modification resulted in a decrease in potency except for a phenyl pentanoate. To confirm that DBCPP interferes with GABA receptor function, we performed whole-cell patch clamp experiments with rat dorsal root ganglion neurons in the primary culture. Repeated co-applications of GABA and DBCPP suppressed GABA-induced whole-cell currents with an IC50 of 0.54 μM and a Hill coefficient of 0.7. These findings indicate that DBCPP and its derivatives inhibit ionotropic GABA receptors by binding to the EBOB site and that there might be structural difference in the noncompetitive antagonist-binding site between rat and housefly GABA receptors. Copyright (C) 2000 Elsevier Science Ltd.
- Hamano, Hiroshi,Nagata, Keiichi,Fukada, Nobuo,Shimotahira, Hiroshi,Ju, Xiu-Lian,Ozoe, Yoshihisa
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p. 665 - 674
(2007/10/03)
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- Synthesis and antiallergy activity of [1,3,4]thiadiazolo[3,2-a]-1,2,3-triazolo[4,5-d]pyrimidin-9(3H)-one derivatives. II. 6-Alkyl- and 6-cycloalkylalkyl derivatives
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A series of 6-alkyl- or 6-(cycloalkylalkyl)-[1,3,4]thiadiazolo[3,2-a]-1,2,3-triazolo[4,5-d]pyr imidin-9(3H)-ones 1b-o was synthesized from the corresponding 1,3,4-thiadiazol-5-amines 3b-o and the antiallergic activities of the products were evaluated. Among the compounds 6-(2-cyclohexylethyl)-[1,3,4]thiadiazolo[3,2-a]-1,2,3-triazolo[4,5-d]p yrimidin-9(3H)-one 1h, whose X-ray crystallographic stereostructure is shown, was found to be a promising new antiallergic agent, which has low toxicity and dual activity as a leukotriene D4 receptor antagonist and as an orally active mast cell stabilizer.
- Yokohama,Miwa,Aibara,Fujiwara,Matsumoto,Nakayama,Iwamoto,Mori,Moroi,Tsukada,Isoda
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p. 2391 - 2398
(2007/10/02)
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- Chelates as intermediates in nucleophilic additions to alkoxy ketones according to Cram's rule (cyclic model)
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Chelates have been considered intermediates in the often highly stereoselective reactions of α-alkoxy and similarly substituted ketones for over 30 years,10 but without mechanistic evidence. It is now shown, by stop-flow ("rapid injection") NMR kinetics,15 that the specific rates of reaction of ketones C6H5COCH(OR)CH3 with Me2Mg, where R = (i-Pr)3 ("TIPS"), t-BuPh2Si, t-BuMe2Si, Et3Si, Me3Si, and Me, parallel the diastereoselectivity of the reaction; i.e., the fastest reacting compound (R = Me) is the one which gives the highest proportion of the product predicted by Cram's chelate rule. The major product of the slowest reacting compound (R = TIPS) is not in accord with Cram's chelate rule, and this compound reacts at the same specific rate as the parent, C6H5COCH2CH3. This is in accord with earlier work indicating that TIPSO does not chelate. Compounds intermediate in the series react at intermediate rates and give the two diastereomeric products in proportions which can be calculated by assuming two competing reactions (cf. Figure 2): one proceeding via the chelated transition states giving the product predicted by the chelate rule and one not involving chelation which gives the same product composition as the R = TIPS compound. Direct steric effects on carbonyl reactivity due to the remote bulky silyloxy substituents have been excluded by the study of carbon analogues bearing similar bulky groups. Thus, the kinetic effect in the above series appears to be due to steric hindrance to chelation; hence, the parallel of specific rate and stereoselectivity demonstrates that high stereoselectivity is associated with strong chelation, as postulated by Cram and Kopecky in 1959.10.
- Chen, Xiangning,Hortelano, Edwin R.,Eliel, Ernest L.,Frye, Stephen V.
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p. 1778 - 1784
(2007/10/02)
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- Reactions of the neohexyl iodide complex [(η5-C5H5)Re(NO)(PPh3)(ICH 2CH2C(CH3)3)]+BF 4- and nucleophiles: Stereochemistry of carbon-iodine bond cleavage in highly accelerated SN2 reactions
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Reaction of (η5-C5H5)Re(NO)(PPh3)(CH 3), ICH2CH2C(CH3)3 (2), and HBF4·OEt2 in C6H5Cl gives neohexyl iodide complex [(η5-C5H5)Re(NO)(PPh3)(ICH 2CH2C(CH3)3)]+BF 4- (3, 81%). Complex 3 and PPh3 react (-40°C, CD2Cl2) to give [Ph3PCH2CH2C(CH3)3] +BF4- (7) and (η5-C5H5)Re(NO)(PPh3)(I) (6) in >99% spectroscopic yields. Complex 3 and [Ph3P..-N..-PPh3]+Br - (PPN+Br-) react (-40°C, CD2Cl2) to give BrCH2CH2C(CH3)3 (8) and 6 in 97-99% spectroscopic yields. Deuterated neohexyl halides erythro-ICHDCHDC(CH3)3 (erythro-2-d2), threo-2-d2, erythro-8-d2, and threo-8-d2 are prepared via (η5-C5H5)2Zr(Cl)(X) compounds. The labeled complexes erythro-3-d2 and threo-3-d2 are synthesized, and analogous reactions with PPN+Br- and PPh3 are conducted. Diastereomer ratios of the products 8-d2 and 7-d2, and all preceding deuterated compounds, are analyzed by 500-MHz 1H{2H} NMR spectroscopy. In all cases, the carbon-iodine bond in 3-d2 is cleaved with essentially complete inversion of configuration at carbon.
- Igau, Alain,Gladysz
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p. 2327 - 2334
(2008/10/08)
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- 2,4-Dioxa-, 2,4,9-Trioxa-, 2,4-Dioxa-9-aza-, 2-Oxa-4,9-diaza-, and 2,4,9-Triazaadamantanes
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The reaction of the trihalides 7a, b with sodium cyanide in dimethylformamide afforded the cyclopropanedicarbonitrile 9 instead of of the tricarbonitrile 7c which had been designed as a precursor to 2,4,9-triazaadamantanes.Both the photolysis and thermolysis of the remarkably stable triazide 13c proceeded in an ill-defined way, producing unidentifiable products among which neither the triazaadamantane 6a nor hydrolysis products of the triimine 14 could be detected.The readily cyclizing triketone 3l was obtained from the reaction of the tricarbonyl chloride 3k with an excess of lithium dimethylcuprate followed by careful work-up.It proved to be the key to several novel heteroadamantanes: Thus, methoxide brought about an intramolecular aldol addition and cyclization of 3l to the 2,4-dioxaadamantane 15.An excess of liquid ammonia converted 3l into the 2,4-dioxa-9-azaadamantane 16a almost quantitatively.The same ring system (16b) was formed in the reaction of 3l with 12 mol of hydrazine hydrate.In contrast, the reaction of 3l with a very large excess of hydrazine hydrate afforded the 2-oxa-4,9-diazaadamantane 16c.Finally, 3l reacted with dry hydrazine in ethanol to yield the 2,4,9-triazaadamantane 16d.The structures of the new compounds were established by IR and NMR spectroscopy.Analysis of the complex 1H NMR multiplets of the methylene protons of 15 and 16a - c by LAOCOON III shows that they arise exclusively from W-couplings of 2 - 3 Hz and geminal couplings.
- Quast, Helmut,Berneth, Claus-Peter
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p. 1345 - 1363
(2007/10/02)
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- Facile Conversion of Alkenes into Alkyl Bromides via Reaction of Organoboranes with Bromine or Bromine Chloride
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Organoboranes react with either bromine or bromine chloride in aqueous media to yield the corresponding alkyl bromides under surprisingly mild conditions.The reaction is ideal for the synthesis of functionally substituted organic bromides.Sodium bromide may be utilized as the bromine source via its in situ conversion to bromine chloride by using mild oxidizing agents.
- Kabalka, George W.,Sastry, Kunda A. R.,Hsu, Henry C.,Hylarides, Mark D.
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p. 3113 - 3115
(2007/10/02)
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