- Photoinduced redox initiation for fast polymerization of acrylaytes based on latent superbase and peroxides
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The article presents a highly effective strategy for photopolymerization of acrylates via photolatent redox-accelerated reaction based on the synergistic photoinitiating systems containing photolatent superbase and readily available peroxides. Polymerization of acrylates could be instantly initiated with the effective interaction between the photogenerated amine and peroxides. Due to the persistent interaction of produced longeval amine with peroxides, remarkable post conversion after irradiation, which is significant for radiation crosslinking of photo-screened materials, was thus initially achieved in photoinitiated free radical polymerization. To explore the synergistic interactions of the photoinitiating systems, the effect of peroxide structures and QA-DBU:BPO ratios had been examined by RTIR, showing that all peroxides are applicable as the final conversion rate of acrylates is concerned. Further, BPO and CHP significantly accelerated the photopolymerization rate in air atmosphere. The synergistic efficiency of QA-DBU and BPO as a photopolymerization initiatiation system was close to that of the conventional D-1173 photoinitiator.
- He, Minghui,Huang, Xun,Huang, Yugang,Zeng, Zhaohua,Yang, Jianwen
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Read Online
- A thioxanthone-based photocaged superbase for highly effective free radical photopolymerization
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Thioxanthone-based N-phthalimidoamino acid ammonium salt (thioxanthen-DBU) as a photocaged base was synthesized and characterized. The photochemical properties and initiation mechanism were analyzed. It was found that the compound absorbs over the UV and visible region with relatively high absorption coefficients. Furthermore, the covalent binding of N-phthalimidoamino acid and type II chromophores (thioxanthone, TX) remarkably improved the photoreactivity. Specifically, in combination with a benzoyl peroxide initiator, thioxanthen-DBU was able to initiate the amine-mediated redox photopolymerization of trimethylol propane triacrylate (TMPTA), and an excellent photopolymerization profile was obtained.
- He, Ming-Hui,Xu, Rui-Xin,Chen, Guang-Xue,Zeng, Zhao-Hua,Yang, Jian-Wen
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Read Online
- Photoinduced Proton-Transfer Polymerization: A Practical Synthetic Tool for Soft Lithography Applications
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Proton-transfer photopolymerization through the thiol-epoxy click reaction is shown to be a versatile new method for the fabrication of micro- A nd nanosized polymeric patterns. In this approach, complexation of a guanidine base, diazabicycloundecene (DBU), with benzoylphenylpropionic acid (ketoprofen) generates a photolabile salt. Under illumination at a wavelength of 365 nm, the salt undergoes a photodecarboxylation reaction to release DBU as a base. The base-catalyzed ring opening reaction then creates cross-linked poly(β-hydroxyl thio-ether) patterns. The surface chemistry of these patterns can be altered through alkylation of the thio-ether linkages. For example, a reaction with bromoacetic acid produces a hitherto unknown sulfonium/carboxylate-based zwitterionic motif that endows antibiofouling capacity to the micropatterns.
- Khan, Anzar,Yeo, Hyunki
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p. 3479 - 3488
(2020/02/27)
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- Basicities and Nucleophilicities of Pyrrolidines and Imidazolidinones Used as Organocatalysts
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The Br?nsted basicities pKaH (i.e., pKa of the conjugate acids) of 32 pyrrolidines and imidazolidinones, commonly used in organocatalytic reactions, have been determined photometrically in acetonitrile solution using CH acids as indicators. Most investigated pyrrolidines have basicities in the range 16 aH aH aH 12.6) and the 2-imidazoliummethyl-substituted pyrrolidine A21 (pKaH 11.1) are outside the typical range for pyrrolidines with basicities comparable to those of imidazolidinones. Kinetics of the reactions of these 32 organocatalysts with benzhydrylium ions (Ar2CH+) and structurally related quinone methides, common reference electrophiles for quantifying nucleophilic reactivities, have been measured photometrically. Most reactions followed second-order kinetics, first order in amine and first order in electrophile. More complex kinetics were observed for the reactions of imidazolidinones and several pyrrolidines carrying bulky 2-substituents, due to reversibility of the initial attack of the amines at the electrophiles followed by rate-determining deprotonation of the intermediate ammonium ions. In the presence of 2,4,6-collidine or 2,6-di-tert-butyl-4-methyl-pyridine, the deprotonation of the initial adducts became faster, which allowed the rate of the attack of the amines at the electrophiles to be determined. The resulting second-order rate constants k2 followed the correlation log?k2(20 °C) = sN(N + E), where electrophiles are characterized by one parameter (E) and nucleophiles are characterized by the two solvent-dependent parameters N and sN. In this way, the organocatalysts A1-A32 were integrated in our comprehensive nucleophilicity scale, which compares n-, -, and σ-nucleophiles. The nucleophilic reactivities of the title compounds correlate only poorly with their Br?nsted basicities.
- An, Feng,Maji, Biplab,Min, Elizabeth,Ofial, Armin R.,Mayr, Herbert
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supporting information
p. 1526 - 1547
(2020/02/04)
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- A 1, 8 - diazabicyclo synthetic method (by machine translation)
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The present invention provides a 1, 8 - diazabicyclo synthetic method, the technical scheme of the DBU synthetic route to an innovative design. Specific perspective, the invention first of all the use of ε-caprolactam, acrylonitrile and hydroquinone reaction generating N - (β - cyanoethyl) - ε-caprolactam, on this basis, will it and to toluene sulfonic acid in catalytic reaction under the condition, and then carry on ice bath, and then under the protection of nitrogen with benzyl chloride reaction, the resulting product to EDTA as the catalyst with high sodium borate reaction, the product of the reaction 3 - phenylpropanoic acid mixed with 4 - nitro benzyl chloride reaction to obtain the product. For the reaction product, filtered and the filtrate is extracted with ethyl acetate, the combined solid-liquid separation after solid phase, then the solid phase for reducing the drying to obtain the final product. The invention adopts the brand new synthetic route, its mild reaction conditions, material cost is relatively low, promotion prospect. (by machine translation)
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Paragraph 0014-0017
(2019/06/27)
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- Base-induced reversible H2 addition to a single Sn(ii) centre
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A range of amines catalyse the oxidative addition (OA) of H2 to [(Me3Si)2CH]2Sn (1), forming [(Me3Si)2CH]2SnH2 (2). Experimental and computational studies point to 'frustrated Lewis pair' mechanisms in which 1 acts as a Lewis acid and involve unusual late transition states; this is supported by the observation of a kinetic isotope effect for Et3N. When DBU is used the energetics of H2 activation are altered, allowing an equilibrium between 1, 2 and adduct [1·DBU] to be established, thus demonstrating reversible oxidative addition/reductive elimination (RE) of H2 at a single main group centre.
- Turnell-Ritson, Roland C.,Sapsford, Joshua S.,Cooper, Robert T.,Lee, Stella S.,F?ldes, Tamás,Hunt, Patricia A.,Pápai, Imre,Ashley, Andrew E.
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p. 8716 - 8722
(2018/12/10)
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- MANUFACTURING METHOD OF DIAZABICYCLO COMPOUND
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PROBLEM TO BE SOLVED: To provide a manufacturing method for providing a diazabicyclo compound from hydrochloric acid having a diazabicyclo group, which is suitable for industrial production. SOLUTION: There is provided a method for manufacturing a diazabicyclo compound by neutralization with using 20 wt.% to 50 wt.% of an alkali metal hydroxide solution or 10 wt.% to 50 wt.% of an alcohol solution of alkali metal alkoxide of 2.0 times molar equivalent to 3.5 times molar equivalent to hydrochloric acid having a diazabicyclo group. SELECTED DRAWING: None COPYRIGHT: (C)2018,JPO&INPIT
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Paragraph 0018; 0042; 0044; 0048
(2018/06/08)
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- A rechargeable hydrogen battery based on Ru catalysis
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Apart from energy generation, the storage and liberation of energy are among the major problems in establishing a sustainable energy supply chain. Herein we report the development of a rechargeable H2 battery which is based on the principle of the Ru-catalyzed hydrogenation of CO2 to formic acid (charging process) and the Ru-catalyzed decomposition of formic acid to CO2 and H2 (discharging process). Both processes are driven by the same catalyst at elevated temperature either under pressure (charging process) or pressure-free conditions (discharging process). Up to five charging-discharging cycles were performed without decrease of storage capacity. The resulting CO2/H2 mixture is free of CO and can be employed directly in fuel-cell technology. Simple but efficient: A readily accessible Ru catalyst is the basis for a reversible H 2/CO2-driven battery. At elevated temperatures both the reduction of CO2 to formic acid and the decomposition of formic acid were realized with 0.075 mol % of the Ru complex. Several charging and discharging cycles were performed with comparable storage-release efficiency. Furthermore, the partial removal of defined gas amounts is possible under pressure.
- Hsu, Shih-Fan,Rommel, Susanne,Eversfield, Philipp,Muller, Keven,Klemm, Elias,Thiel, Werner R.,Plietker, Bernd
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supporting information
p. 7074 - 7078
(2014/07/08)
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- Application to photoreactive materials of photochemical generation of superbases with high efficiency based on photodecarboxylation reactions
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A thin film of polystyrene containing 4c was spin-coated on a CaF2 plate and irradiated with 365 nm light. The absorption band arising from the carboxylate of 4c at 1372 cm-1 in the FTIR spectrum decreased after UV irradiation. Radical UV curing materials that are well established in the marketplace have drawbacks because of high volume shrinkage and oxygen inhibition. The anionically cured film showed high transparency and no volume shrinkage, in contrast to a conventional radical UV curing system, which showed large volume shrinkage. This is probably due to relatively low quantum yields for photobase generation and weaker basicity of photo-generated bases, leading to low photosensitivity of photoreactive materials sensitized with photobase generators. Furthermore, many of the photobase generators reported are generally prepared via several synthetic steps.
- Arimitsu, Koji,Endo, Ryosuke
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p. 4461 - 4463
(2014/01/06)
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- Enhancing the anion affinity of urea-based receptors with a Ru(terpy) 22+ chromophore
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Covalent linking of a Ru(terpy)22+ substituent improves recognition and sensing properties of the urea subunit toward anions. Urea's anion affinity is enhanced by the electrostatic attraction exerted by the RuII cation and by the electron-withdrawing effect exerted by the entire polypyridine-metal complex. Such an enhancement of the anion affinity, which results from the combination of a through-space and a through-bond effect, is greater than that exerted by the classical neutral electron-withdrawing substituent nitrophenyl. Small yet significant modifications of π-π* and MLCT bands of the Ru(terpy)22+ chromophore, detected through UV-vis spectrophotometric titrations, allowed the determination of the constants for the formation of receptor-anion H-bond complexes in diluted MeCN solution. On 1H NMR titration experiments, carried out under more concentrated conditions, the interaction of a second Cl- ion was observed, taking place through an outer-sphere mechanism. The Ru(terpy) 22+ substituent favors the deprotonation of a urea N-H fragment on addition of a second equivalent of fluoride, with formation of HF2-.
- Baggi, Giorgio,Boiocchi, Massimo,Ciarrocchi, Carlo,Fabbrizzi, Luigi
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p. 5273 - 5283
(2013/06/26)
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- Solventless selective phosgene-free N-carbonylation of N-heteroaromatics (pyrrole, indole, carbazole) under mild conditions
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N-Heteroaromatics HetNH, such as pyrrole (1), indole (2) and carbazole (3), have been selectively N-carbonylated by a direct reaction with diphenyl carbonate (DPC), used as an environmental friendly carbonyl active species in place of toxic and hazardous phosgene. The carbonylation reaction can be effectively catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), which can act as a base catalyst by activating the HetNH substrate, and as a nucleophile catalyst by activating the organic carbonate. The influence of reaction parameters (temperature, reaction time, DBU load, DPC/HetNH molar ratio) on the productivity of the process has been also investigated. The synthetic methodology does not require severe temperature conditions, is solventless, simple (only one step), efficient and selective, and offers a new solution to the synthesis of synthetically versatile HetNCO2Ph derivatives through a route alternative to the current traditional phosgenation methods.
- Carafa, Marianna,Iannone, Francesco,Mele, Valentina,Quaranta, Eugenio
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p. 3377 - 3385
(2013/01/16)
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- POLYCARBONATES FOR DELIVERY OF DRUGS AND METHODS OF PREPARATION THEREOF
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A cyclic carbonate monomer has the formula (2): wherein i) t and t′ are integers independently having a value from 0 to 6 wherein t′ and t cannot both be zero, ii) each Q1 is a monovalent radical independently selected from the group consisting of hydrogen, halides, alkyl groups comprising 1 to 30 carbons, and aryl groups comprising 6 to 30 carbon atoms, iii) L′ is a divalent linking group comprising one or more carbons, and iv) S′ is a steroidal group.
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- DBU-promoted nucleophilic activation of carbonic acid diesters
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The reactivity of carbonic acid diesters in the presence of the amidine base DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) has been investigated for the first time. Organic carbonates can be activated by DBU through the formation of N-alkoxycarbonyl ketene aminal 2 as the ultimate product. The latter species may form through deprotonation of the corresponding N-alkoxycarbonyl-amidinium cation 1+ by the amidine base. We have for the first time isolated and characterized, both in the solid state (X-ray crystal structure determination, IR) and in solution (NMR), a few 1+ chloride salts and studied their reactivity towards the organic base. The reactivity of both 1+ and 2 with methanol has also been explored. Ketene aminal 2 behaves as a "CO2R" carrier, as it can selectively transfer the alkoxycarbonyl group to the alcohol and regenerate the amidine base. Carbonic acid diesters can be activated by the amidine base DBU to give N-alkoxycarbonyl ketene aminal 2. The latter species may form through deprotonation of N-alkoxycarbonyl-amidinium cations 1+ by the amidine base and behave as carriers of the -C(O)OR group. Copyright
- Carafa, Marianna,Mesto, Ernesto,Quaranta, Eugenio
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experimental part
p. 2458 - 2465
(2011/06/10)
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- Reversible and robust CO2 capture by equimolar task-specific ionic liquid-superbase mixtures
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Integrated sorption systems consisting of 1:1 mixtures of an alcohol-functionalized ionic liquid and a superbase were found to be effective for CO2 capture under atmospheric pressure, eliminating the use of volatile n-alkanols or water. Conversely, by using the current approach, there is no longer a requirement for maintaining scrupulously dry conditions. The effect of ionic liquid structure, choice of superbase, their relative ratios, the sorption temperature, and the reaction time on the absorption and release of CO2 were investigated. Our results demonstrate that (i) this integrated ionic liquid-superbase system is capable of rapid and reversible capture of nearly one mole of CO2 per mole of superbase, (ii) the captured CO2 can be readily released by either mild heating or bubbling with an insert gas (N2, Ar), and (iii) this novel CO 2 chemisorption platform can be recycled with minimal loss of activity. This efficient and fully reversible catch-and-release process using non-volatile, task-specific ionic liquids provides an excellent alternative to current CO2 capture technologies, which are based largely around volatile alkanols or alkylamines. Furthermore, our integrated ionic liquid-superbase system can be used as a novel medium for supported liquid membranes, for which they demonstrate both good selectivity and permeability in model CO2/N2 gas separations.
- Wang, Congmin,Mahurin, Shannon M.,Luo, Huimin,Baker, Gary A.,Li, Haoran,Dai, Sheng
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scheme or table
p. 870 - 874
(2010/09/04)
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- Nucleophilicities and carbon basicities of DBU and DBN
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The nucleophilicity and Lewis basicity of DBU and DBN toward C sp2 centers have been measured: nucleophilicities increase in the series DMAP DBU DBN DABCO while Lewis basicities are DABCO DMAP DBU DBN. The Royal Society of Chemistry
- Baidya,Mayr, Herbert
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p. 1792 - 1794
(2008/12/22)
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- Process for the preparation of acid esters
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The present invention is directed to a process for the preparation of sterically hindered acid esters, e.g., organic phosphites, comprising contacting a sterically hindered hydroxyl-containing compound with an acid halide in the presence of an acid acceptor selected from the group consisting of: 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 4-(dimethylamino)pyridine (DMAP), 1,4-diazabicyclo[2.2.2]octane (DABCO), or mixtures thereof, wherein said an acid acceptor is present in an amount sufficient to drive the reaction to completion.
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- An Efficient Synthesis of Bicyclic Amidines by Intramolecular Cyclization
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A real step-saver! In a one-step procedure for the synthesis of bicyclic amidines, the azido group is used directly as the nucleophile in the ring-forming reaction. Many functionalized and chiral bicyclic amidines were synthesized in good yield under mild reaction conditions.
- Kumagai, Naoya,Matsunaga, Shigeki,Shibasaki, Masakatsu
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p. 478 - 482
(2007/10/03)
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- Coloring agent comprising transition metals
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The present invention relates to a composition for coloring keratin fibers and a method of using the same. The composition of the present invention contains at least one dye precursor, and one or more clathrate compounds that contain transition metal complexes.
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- Process for producing alpha-olefin
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A production process for α-olefins making use of elimination reaction of a primary alcohol or an ether is characterized by use of an alumina catalyst in the presence of an amine. The production process for α-olefins according to the present invention can yield an α-olefin at a high proportion with respect to the entire olefin products and can maintain the reactivity of the catalyst and selectivity of the products for a prolonged time. In the process, unreacted material and ether intermediate byproduct produced in the process can be used in the reaction with the same catalyst. This allows industrially and environmentally favorable production process of α-olefins.
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- Therapeutic agents
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The invention provides compounds of formula I STR1 and pharmaceutically acceptable salts thereof; wherein R50 is hydrogen or C1-4 alkyl, A51 is oxygen, sulphur or a group of the formula --NR52 -- wherein R52 is hydrogen or C1-4 alkyl; A50 comprises i) a mono or bicyclic aromatic ring optionally containing one or more nitrogen, oxygen or sulphur atoms, ii) a cycloalkendiyl group, or iii) an acyclic bridging group having a chain of one, two or three atoms between the cyclobutenedione group and X50, said chain being a chain of one or two carbon atoms or a chain of one carbon atom and one or more nitrogen, oxygen or sulphur atoms or iv) a bond; X50 is either a bond or a spacer group providing a chain between A50 and B50 of one or two atoms length; B50 is a mono or bicyclic aromatic-ring optionally containing one or more nitrogen, oxygen or sulphur atoms; r is an integer from 1 to 6; and Het is a ring system optionally containing one or more nitrogen, oxygen or sulphur atoms or is a phosphonate, phosphinate or amine derivative (wherein each of A50, X50, B50 and Her are optionally substituted). The compounds have angiotensin II antagonist activity and are useful in the treatment of cardiovascular disorders such as hypertension.
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- Preparation of bidentate ligands
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A process is disclosed for preparing biaryl, bidentate ligands comprising: (1) contacting a biaryl compound having the structural formula: STR1 with a proton abstracting agent under conditions suitable to form a biaryl dianion, which is then (2) contacted with a Group V compound of the formula: STR2 where X' is halogen or a suitable leaving group.
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- Asymmetrical ester derivatives of 1,4-dihydrophyridine-3,5-dicarboxylic acid
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The present invention relates to novel asymmetrical esters derived from 1,4-dihydrophyridine-3,5-dicarboxylic acid, of the formula: STR1 in which: R1 represents a C1 -C4 alkyl group, R2 represents a C1 -C4 alkyl group, a benzyl group, a benzoyl group or a phenyl group optionally substituted by one or more C1 -C4 alkoxy, C1 -C4 alkyl, cyano, nitro, hydroxyl or trifluoromethyl groups or by one or more halogen atoms, and R3 and R4, which are identical or different, each represent the hydrogen atom, a nitro group or a chlorine atom, their optical isomers and diastereoisomers and also the corresponding addition salts. These novel esters are useful in therapy, especially as antihypertensives.
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- Preparation and Characterization of 6-Substituted 1,8-diazabicycloundec-7-ene
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The lithium 1,8-diazabicycloundec-6-ide (1) prepared from 1,8-diazabicycloundec-7-ene (DBU) and n-butyllithium reacts with alkyl halides and carbonyl compounds such as benzophenone, acetophenone, and benzaldehyde to give 6-substituted DBU derivatives in good yields.The reaction behavior of 6-substited DBU was also investigated.
- Matsumura, Noburu,Nishiguchi, Hiroshi,Okada, Masao,Yoneda, Shigeo
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p. 885 - 887
(2007/10/02)
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- Triazine derivatives, and pharmaceutical compositions comprising the same
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New triazine derivatives represented by the formula: STR1 wherein R1 is a 1,2,3,4-tetrahydroquinolyl, 2-oxo-1,2,3,4-tetrahydroquinolyl, 2-oxo-1,2-dihydroquinolyl, indolyl, 2-oxoindolinyl, benzothiazolyl, 2-oxobenzothiazolinyl, 3,4-dihydro-1H-2,1-benzothiazinyl in which the S atom being optionally oxidized, or 3-oxo-2,3-dihydro-4H-1,4-benzoxazinyl, each of which may have one or more substituent(s) selected from lower alkyl, hydroxy(lower)alkyl, lower alkylamino, lower alkanoyl, cyclic lower alkanoyl, lower alkoxy(lower)alkyl, lower alkylamino(lower)alkanoyl, benzyl, benzyloxy(lower)alkyl, lower alkoxycarbonyl(lower)alkyl and 4-(2-hydroxyethyl)piperazin-1-yl-carbonylmethyl; R2 is a hydrogen, lower alkenyl, benzyl, carboxy(lower)alkyl or lower alkoxycarbonyl(lower)alkyl; R3 and R4, which may be the same or different, are each hydrogen or lower alkyl or together represent a bond; provided that when R1 is 2-oxo-1,2,3,4-tetrahydroquinolyl which is unsubstituted or substituted by a lower alkyl, then, R4 is a hydrogen or R2 is a lower alkenyl, benzyl, carboxy(lower)alkyl or lower alkoxycarbonyl(lower)alkyl; and pharmaceutically acceptable salt thereof, which are useful in the treatment of hypertension, thrombosis and ulcer in human beings and animals.
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- Process for the preparation of 4-nitrodiphenylamines
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The invention relates to a process for the preparation of 4-nitrodiphenylamines by the reaction of halogenonitrobenzenes with primary aromatic amines in the presence of copper or a copper compound, a neutralizing agent and a cyclic diaza compound.
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- Kinetics and Tunneling in the Proton- and Deuteron-Transfer Reaction between 2,4,6-Trinitrotoluene and 1,8-Diazabicycloundec-7-ene in Some Aprotic Solvents
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The proton/deuteron-transfer reactions of 2,4,6-trinitrotoluene with 1,8-diazabicycloundec-7-ene in acetonitrile, 1,2-dichloroethane, and dichloromethane have been found to produce an ion pair.The reaction rates at 5-35 deg C of the proton- and deuteron-transfer reactions have been followed by a stopped-flow method.The reaction rate ratio kH/kD diminishes from 24.0 at 10 deg C to 18.3 at 30 deg C in acetonitrile and from 35.0 at 15 deg C to 27.1 at 30 deg C in 1,2-dichloroethane.The difference in the activation energies EaD - EaH is 2.3 and 2.1 kcal mol-1 in acetonitrile and 1,2-dichloroethane, respectively.The ratio of Arrhenius preexponential factors is 2.5 in acetonitrile and 2.0 in 1,2-dichloroethane.All these values are greater than the semiclassical limits which can be predicted since the primary kinetic isotope effect is brought about by loss of the zero-point energy difference between C-H and C-D bond at transition state.This remarkable isotope effect, when fitted to Bell's equation, indicates that there is a considerable contribution from proton tunneling.These results are discussed in comparison with those of other proton/deuteron-transfer reactions.
- Sugimoto, Naoki,Sasaki, Muneo,Osugi, Jiro
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p. 3418 - 3423
(2007/10/02)
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- The kinetics of proton and deuteron transfer from 1-(4-nitrophenyl)-1-nitroethane to 1,8-diazabicycloundec-7-ene in aprotic solvents
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1-(4-Nitrophenyl)-1-nitroethane reacts with the base 1,8-diazabicycloundec-7-ene (DBU) in both acetonitrile and toluene solvents in a normal second-order proton-transfer reaction, in contrast to its behaviour with the base 2,7-dimethoxy-1,8-bis(dimethylamino)naphthalene in acetonitrile.The primary isotope effect, kH/kD = 12.0 at 25 deg in toluene is very similar to that observed by other workers for the reaction of 4-nitrophenylnitromethane with DBU under the same conditions.In acetonitrile solvent a kH/kD ratio of 7.8 was found at 25 deg C.The isotope effecs on the activation parameters for the reaction in both solvents indicate that tunnelling of the proton through the potential energy barrier makes a significant contribution to the reaction rate.
- Leffek, Kenneth T.,Pruszynski, Przemyslaw
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p. 1692 - 1695
(2007/10/02)
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- Process for preparation of 3-halomethylcephems
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3-Halomethyl-3-cephems are provided by reacting a 3-methylenecepham with an alkali metal salt of a lower alcohol or a bicyclic amidine base in the presence of a positive halogenating agent at a temperature ranging from -80° to about 20° C. The 3-halomethylcephems provided by this invention are useful intermediates for the preparation of known cephalosporin antibiotics.
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