- Metal Ion Catalysis in the β-Elimination Reactions of N-[2-(4-Pyridyl)ethyl]quinuclidinium and N-[2-(2-Pyridyl)ethyl]quinuclidinium in Aqueous Solution
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Catalysis of the β-elimination reaction of N-[2-(4-pyridyl)ethyl]quinuclidinium (1) and N-[2-(2-pyridyl)ethyl]quinuclidinium (2) by Zn2+ and Cd2+ in OH-/H2O (pH = 5.20-6.35, 50 °C, and μ = 1 M KCl) has been studied. In the presence of Zn2+, the elimination reactions of both isomers occur from the Zn2+-complexed substrates (C). The equilibrium constants for the dissociation of the Zn 2+-complexes are as follows: Kd = 0.012 ± 0.003 M (isomer 1) and Kd = 0.065 ± 0.020 M (isomer 2). The value of kH2OC for isomer 1 is 4.81 × 10-6 s -1. For isomer 2 both the rate constants for the water and OH--induced reaction of the Zn2+-complexed substrate could be measured, despite the low concentration of OH- in the investigated reaction mixture [kH2OC 0 = 1.97 × 10-6 s-1 and kOH-C = 21.9 M -1 s-1, respectively]. The measured metal activating factor (MetAF), i.e., the reactivity ratio between the complexed and the uncomplexed substrate, is 8.1 × 104 for the OH--induced elimination of 2. This high MetAF can be compared with the corresponding proton activating factor (Alunni, S.; Conti, A.; Palmizio Errico, R. J. Chem. Soc., Perkin Trans. 2 2000, 453), PAF = 1.5 × 106 and is in agreement with an E1cb irreversible mechanism (AxhD E* + DN) (Guthrie, R. D.; Jencks, W. P. Acc. Chem. Res. 1989, 22, 343). A value of kH2OC ≥ 23 × 10 -7 s-1 is estimated for the Cd2+-complexed isomer 2, while catalysis by Cd2+ has not been observed for isomer 1.
- Alunni, Sergio,Del Giacco, Tiziana,De Maria, Paolo,Fifi, Giorgia,Fontana, Antonella,Ottavi, Laura,Tesei, Ilaria
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- Mechanisms of Acid-Base Catalysis of β-Elimination Reactions in Systems Activated by a Pyridine Ring
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β-Elimination reactions from 1 (in quinuclidine/quinuclidinium chloride, imidazole/imidazolium, and acetate/acetic acid buffers) and from 2 (in imidazole/imidazolium and acetate/acetic acid buffers) with formation of 4-vinylpyridine and 2-vinylpyridine, respectively, were studied. The results of a kinetic study of acid-base catalysis and H/D exchange are consistent with NH+, the protonated substrate, as the species that undergoes carbon deprotonation with an E1cb mechanism. The comparison with previously studied reactions in acetohydroxamate/acetohydroxamic acid buffer confirms this assignment. The high proton activating factor, PAF, value observed (PAF = 1.2 × 10 6 with isomer 1 in quinuclidine/quinuclidinium buffer) can be explained with the high stability by the resonance of the intermediate carbanion.
- Alunni, Sergio,Ottavi, Laura
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- A study of the OH--induced β-elimination reactions of 2-(4-chloroethyl)pyridine, 2-(2-chloroethyl)pyridine, 1-methyl-2-(4-chloroethyl) pyridinium iodide and 1-methyl-2-(2-chloroethyl)pyridinium iodide in acetonitrile/water
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Second-order rate constants have been determined for the title reactions in OH-/H2O and in OH-/ (CH3CN/H 2O) [30/70, 60/40, and 85/15 (v/v) mixtures]. A relatively small increase in reactivity is observed for the four substrates upon increasing the percentage of CH3CN in the solvent mixture. The methyl activating factors (kOH-NCH3/kOH-N) are also slightly affected by the solvent composition. On the other hand, the high acceleration of the reaction by methylation of the pyridine ring amounts to 104-106 according to an E1cb mechanism.
- Alunni, Sergio,Del Giacco, Tiziana,De Maria, Paolo,Fontana, Antonella,Gasbarri, Carla,Ottavi, Laura
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- Air-Stable Triazine-Based Ni(II) PNP Pincer Complexes As Catalysts for the Suzuki-Miyaura Cross-Coupling
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Air-stable, thermally robust, and well-defined cationic Ni(II) PNP pincer complexes based on the 2,4-diaminotriazine scaffold are described. These complexes are active catalysts for the Suzuki-Miyaura cross-coupling of a wide range of aryl, heteroaryl (including benzoxazole, thiazole, pyridine, pyrimidine, thiazole), primary and secondary alkyl halides, and pseudohalides with different organoboronate reagents giving excellent to good isolated yields. Neutral deprotonated complexes seem to play a key role in the catalytic process.
- Mastalir, Matthias,St?ger, Berthold,Pittenauer, Ernst,Allmaier, Günter,Kirchner, Karl
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- Michael additions involving amino acid esters with alkenyl N-heterocycles
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Michael addition has been achieved with a variety of amino acid esters and 2- or 4-vinylpyridine. Similar reactions were accomplished with an alkenyl-substituted pyrimidine, pyrazine, thiazole, quinoxaline, benzoxazole, and quinolone. In reactions at a prochiral center, modest diastereoselectivities were observed with the formation of the new stereogenic carbon. NMR experiments indicate that the addition reaction is reversible under acidic conditions.
- Kennedy, Sean H.,Klumpp, Douglas A.
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- Visible-light-responsive catalysis of a zinc-introduced lacunary disilicoicosatungstate for the deoxygenation of pyridine N-oxides
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We herein report the synthesis and photoredox catalysis of a mononuclear zinc-introduced lacunary disilicoicosatungstate TBA7[{Zn(CH3CN)}(γ-SiW10O34){γ-SiW10O32(CH3CONH)}(μ-O)2] (II, TBA = tetra-n-butylammonium). POM II showed efficient photocatalytic activity in the selective deoxygenation of pyridine N-oxides under visible light irradiation (λ > 400 nm).
- Jeong, Jinu,Suzuki, Kosuke,Yamaguchi, Kazuya,Mizuno, Noritaka
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- Design and characterization of a heterocyclic electrophilic fragment library for the discovery of cysteine-targeted covalent inhibitors
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A fragment library of electrophilic small heterocycles was characterized through cysteine-reactivity and aqueous stability tests that suggested their potential as covalent warheads. The analysis of theoretical and experimental descriptors revealed correlations between the electronic properties of the heterocyclic cores and their reactivity against GSH that are helpful in identifying suitable fragments for cysteines with specific nucleophilicity. The most important advantage of these fragments is that they show only minimal structural differences from non-electrophilic counterparts. Therefore, they could be used effectively in the design of targeted covalent inhibitors with minimal influence on key non-covalent interactions.
- Keeley,ábrányi-Balogh,Keseru
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- Construction of α-Amino Azines via Thianthrenation-Enabled Photocatalyzed Hydroarylation of Azine-Substituted Enamides with Arenes
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α-Amino azines are widely found in pharmaceuticals and ligands. Herein, we report a practical method for accessing this class of compounds via photocatalyzed hydroarylation of azine-substituted enamides with the in situ-generated aryl thianthrenium salts as the radical precursor. This reaction features a broad substrate scope, good functional group tolerance, and mild conditions and is suitable for the late-stage installation of α-amino azines in complex structures.
- Zhang, Yu-Lan,Wang, Gang-Hu,Wu, Yichen,Zhu, Chun-Yin,Wang, Peng
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supporting information
p. 8522 - 8526
(2021/11/13)
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- KO-t-Bu Catalyzed Thiolation of β-(Hetero)arylethyl Ethers via MeOH Elimination/hydrothiolation
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Herein, we describe a KO-t-Bu catalyzed thiolation of β-(hetero)arylethyl ethers through MeOH elimination to form (hetero)arylalkenes followed by anti-Markovnikov hydrothiolation to afford linear thioethers. The system works well with a variety of β-(hetero)arylethyl ethers, including electron-deficient, electron-neutral, electron-rich, and branched substrates and a range of aliphatic and aromatic thiols.
- Shigeno, Masanori,Shishido, Yoshiteru,Hayashi, Kazutoshi,Nozawa-Kumada, Kanako,Kondo, Yoshinori
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supporting information
p. 3932 - 3935
(2021/08/24)
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- INHIBITORS OF FIBROBLAST ACTIVATION PROTEIN
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Compounds and compositions for modulating fibroblast activation protein (FAP) are described. The compounds and compositions may find use as therapeutic agents for the treatment of diseases, including hyperproliferative diseases.
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Paragraph 0192
(2020/07/14)
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- Oxidative Dehydroxymethylation of Alcohols to Produce Olefins
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Catalyst compositions for the conversion of aldehyde compounds and primary alcohol compounds to olefins are disclosed herein. Reactions include oxidative dehydroxymethylation processes and oxidative dehydroformylation methods, which are beneficially conducted in the presence of a sacrificial acceptor of H2 gas, such as N,N-dimethylacrylamide.
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Paragraph 0057; 0058
(2019/09/06)
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- Tandem Catalysis: Transforming Alcohols to Alkenes by Oxidative Dehydroxymethylation
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We report a Rh-catalyst for accessing olefins from primary alcohols by a C-C bond cleavage that results in dehomologation. This functional group interconversion proceeds by an oxidation-dehydroformylation enabled by N,N-dimethylacrylamide as a sacrificial acceptor of hydrogen gas. Alcohols with diverse functionality and structure undergo oxidative dehydroxymethylation to access the corresponding olefins. Our catalyst protocol enables a two-step semisynthesis of (+)-yohimbenone and dehomologation of feedstock olefins.
- Wu, Xuesong,Cruz, Faben A.,Lu, Alexander,Dong, Vy M.
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supporting information
p. 10126 - 10130
(2018/08/23)
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- Pd-Catalyzed Vinylation of Aryl Halides with Inexpensive Organosilicon Reagents Under Mild Conditions
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Pd-catalyzed Hiyama vinylation reaction of non-activated aryl chlorides and bromides under mild conditions was developed. The use of efficient vinyl donors and electron-rich sterically hindered phosphine ligands was critical for the success of the reaction. The products of this transformation can be used for Am/Cm separation, an important challenge in nuclear fuel reprocessing. The substituent effect on Am/Cm separating selectivity was also achieved, which could contribute to the development of new chromatographic materials for the separation of Am and Cm.
- Yang, Chu-Ting,Han, Jun,Liu, Jun,Li, Yi,Zhang, Fan,Yu, Hai-Zhu,Hu, Sheng,Wang, Xiaolin
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supporting information
p. 10324 - 10328
(2018/07/31)
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- Synthesis and utility of dihydropyridine boronic esters
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When activated by an acylating agent, pyridine boronic esters react with organometallic reagents to form a dihydropyridine boronic ester. This intermediate allows access to a number of valuable substituted pyridine, dihydropyridine, and piperidine products.
- Panda, Santanu,Coffin, Aaron,Nguyen, Q. Nhu,Tantillo, Dean J.,Ready, Joseph M.
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supporting information
p. 2205 - 2209
(2016/02/18)
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- A transition-metal-free Heck-type reaction between alkenes and alkyl iodides enabled by light in water
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A transition-metal-free coupling protocol between various alkenes and non-activated alkyl iodides has been developed by using photoenergy in water for the first time. Under UV irradiation and basic aqueous conditions, various alkenes efficiently couple with a wide range of non-activated alkyl iodides. A tentative mechanism, which involves an atom transfer radical addition process, for the coupling is proposed.
- Liu, Wenbo,Li, Lu,Chen, Zhengwang,Li, Chao-Jun
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supporting information
p. 6170 - 6174
(2015/06/08)
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- Organocatalytic enantioselective direct additions of aldehydes to 4-vinylpyridines and electron-deficient vinylarenes and their synthetic applications
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We describe a synergistic catalysis strategy for the asymmetric direct addition of simple aldehydes to 4-vinylpyridines. By means of independent activation of weakly electrophilic 4-vinylpyridines by the Bronsted acid CF3SO3H (TfOH) and aldehydes by chiral diphenylprolinol tert-butyldimethylsilyl (TBDMS) ether-catalyzed formation of nucleophilic enamines in a cooperative manner, the previously unattainable highly enantioselective addition process has been realized for the first time. Notably, the power of the addition process is fueled by its high efficiency in the production of synthetically valued chiral pyridines. 1H NMR studies of the process suggested that the nucleophilic enamine formed in situ from the chiral amine catalyst and the aldehyde is directly added to the trimeric 4-vinylpyridinium-derived species as a highly active electrophile generated from the 4-vinylpyridine in the presence of TfOH. Moreover, inspired by the similar electronic natures of pyridine and nitrobenzene, we have achieved an unprecedented chiral diphenylprolinol TBDMS ether-promoted, highly enantioselective direct addition of aldehydes to 2-nitrostyrenes without the use of TfOH as a cocatalyst. In this approach, introducing a strong electron-withdrawing group such as NO2, CF3, SO2Me, etc. on the 2-nitrostyrene creates a highly electrophilic vinyl moiety, which enables the direct addition of the in situ-formed enamine derived from the chiral amine promoter and the aldehyde. This method significantly expands the scope of the enantioselective addition process. While the electron-withdrawing nitro group is essential for activation of the vinyl group, we have demonstrated that it can be readily transformed to diverse functionalities. Furthermore, as shown, a chiral pyridine adduct serves as a key building block in the synthesis of the potent fibrinogen receptor antagonist L-734,217.
- Wang, Sinan,Li, Xiangmin,Liu, Hongwei,Xu, Li,Zhuang, Jinchen,Li, Jian,Li, Hao,Wang, Wei
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supporting information
p. 2303 - 2310
(2015/03/04)
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- Room temperature hydrophosphination using a simple iron salen pre-catalyst
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Phosphines are fundamentally important to the fine chemicals, pharmaceutical and agrochemical industries. Reported is the first example of alkene hydrophosphination using a designed iron pre-catalyst which yields the anti-Markovnikov products in high yield at room temperature. The phosphine products are excellent pro-ligands for Fe-catalyzed Negishi cross-coupling. This journal is
- Gallagher,Webster
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supporting information
p. 12109 - 12111
(2015/01/08)
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- Stereoselective nitration of olefins with tBuONO and TEMPO: Direct access to nitroolefins under metal-free conditions
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Nitroolefins are essential elements for both synthetic chemistry and medicinal research. Despite significant improvements in nitration of olefin an efficient metal-free synthesis remains elusive so far. Herein, we disclose a new set of reagents to access nitroolefins in a single step under metal-free conditions. A wide range of olefins with diverse functionalities has been nitrated in synthetically useful yields. This transformation is operationally simple and exhibits excellent E-selectivity. Furthermore, site selective nitration in a complex setup makes this method advantageous.
- Maity, Soham,Naveen, Togati,Sharma, Upendra,Maiti, Debabrata
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supporting information
p. 3384 - 3387
(2013/07/26)
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- Separating material
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The present invention provides a separating material producable by a) providing a solid substrate, having amino-functional groups coupled to the substrate surface, b) covalently coupling of the amino-functional groups with a thermally labile radical initiator, c) contacting the substrate surface with a solution of polymerizable monomers under conditions, where thermally initiated graft copolymerization of the monomers takes place, to form a structure of adjacent functional polymer chains on the surface of the substrate. The present invention further provides a method for the production of a separating material by a) providing a solid substrate, having amino-functional groups coupled to the substrate surface, b) covalently coupling of the amino-functional groups with a thermally labile radical initiator, c) contacting the substrate surface with a solution of polymerizable monomers under conditions, where thermally initiated graft copolymerization of the monomers takes place, to form a structure of adjacent functional polymer chains on the surface of the substrate.
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- PROCESS FOR THE PREPARATION OF VINYLPYRIDINE FROM PICOLINE OVER MODIFIED ZEOLITES
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The present invention relates to an improved eco-friendly process for the preparation of vinylpyridine from corresponding picoline over modified zeolite catalyst in vapour phase which comprises reacting picoline with formaldehyde with a molar ratio of formaldehyde to picoline in the range of 1:1 to 4:1, at a temperature ranging between 200°C to 450°C, at a weight hourly space velocity in the range of 0.25 hr?-1? - 1.00 hr?-1? over a modified commercial zeolite catalyst to obtain a high yield and selectivity of the desired product.
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- Process for the preparation of vinylpyridine from picoline over modified zeolites
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The present invention relates to an improved eco-friendly process for the preparation of vinylpyridine from corresponding picoline over modified zeolite catalyst in vapour phase which comprises reacting picoline with formaldehyde with a molar ratio of formaldehyde to picoline in the range of 1:1 to 4:1, at a temperature ranging between 200° C. to 450° C., at a weight hourly in the range of 0.25 hr?1-1.00 hr?1over a modified commercial zeotlite catalyst to obtain a high yield and selectivity of the desired product.
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Page column 6
(2008/06/13)
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- Enantiospecific and regioselective opening of 2-alkyl nosylaziridines by indoles mediated by boron trifluoride. Application to a practical synthesis of a GnRH antagonist
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An efficient, high yield process for the synthesis of a GnRH antagonist has been developed. We have demonstrated that under boron trifluoride mediation, nosyl aziridines will react with 2-arylindole derivatives to afford β-substituted tryptamines in an enantiospecific process with remarkably high regioselectivity. The scope of the reaction was explored with several 2-substituted nosyl aziridines. The key reaction was developed expressly for the GnRH antagonist program and has been demonstrated on 40 kilogram scale.
- Farr, Roger N.,Alabaster, Ramon J.,Chung, John Y.L.,Craig, Bridgette,Edwards, John S.,Gibson, Andrew W.,Ho, Guo-Jie,Humphrey, Guy R.,Johnson, Simon A.,Grabowski
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p. 3503 - 3515
(2007/10/03)
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- Inhibitors of cell proliferation, angiogenesis, fertility, and muscle contraction
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The invention concerns inhibitors of cell proliferation, angiogenesis, fertility, and muscle contraction, characterized by formula I wherein, X, Y and Z independently represent C or N; ------ is an optional double bond; n is 0 or 1; R1, R2, and R4 independently represent hydrogen, a chemical bond, C1-10 alkyl; C2-10 alkenyl; C2-10 alkinyl; aryl; aryl-C1-10 alkyl; C3-10 heterocyclyl; C5-10 heteroaryl; halo, CF3; NO2; NHC(O)R*, OR, said alkyl, alkenyl, alkinyl, aryl, arylalkyl, heterocyclyl, or heteroaryl being optionally substituted; R3, R5, and R6 independently represent hydrogen, C1-10alkyl; C2-10 alkenyl; C2-10 alkinyl; aryl; aryl-C1-10alkyl; C3-10 heterocyclyl; C5-10 heteroaryl; halo, CF3; NO2; NHC(O)R*, OR, said alkyl, alkenyl, alkinyl, aryl, heterocyclyl, or heteroaryl being optionally substituted; or R5 and R6 together form a 5- or 6-member aryl, heterocyclyl or heteroaryl group; R is hydrogen or C1-6 alkyl; R* is hydrogen, or C1-6 alkyl, or OH, wherein the optional substituents are preferably selected from the group of one to three OH, C1-6 alkyl, halo, NO2, C1-6 alkoxy, and CF3, or a pharmaceutically acceptable salt thereof.
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- Polymeric transition metal complexes and uses thereof
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Novel polymeric transition metal complexes of iron, cobalt, ruthenium, osmium, and vanadium are described. The polymeric transition metal complexes can be electron transfer mediators in enzyme-based electrochemical sensors. In such instances, transition metal complexes accept electrons from, or transfer electrons to, enzymes at a high rate and also exchange electrons rapidly with the sensor.
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- Catalysis of the β-elimination of HF from isomeric 2-fluoroethylpyridines and 1-methyl-2-fluoroethylpyridinium salts. Proton-activating factors and methyl-activating factors as a mechanistic test to distinguish between concerted E2 and E1cb irreversible mechanisms
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Second-order rate constants, kOHN, M-1 s-1, for the β-elimination reactions of HF with 2-(2-fluoroethyl)pyridine (2), 3-(2-fluoroethyl)pyridine (3), and 4-(2-fluoroethyl)pyridine (4) in OH-/H2O, at 50°C and μ = 1 M KCl, are kOHN = 0.646 × 10-4 M-1 s-1, kOHN = 2.97 × 10-6 M-1 s-1, and kOHN = 5.28 × 10-4 M-1 s-1, respectively. When compared with the second-order rate constants for the same processes with the nitrogen-methylated substrates 1-methyl-2-(2-fluoroethyl)pyridinium iodide (5), 1-methyl-3-(2-fluoroethyl)pyridinium iodide (6), and 1-methyl-4-(2-fluoroethyl)pyridinium iodide (7), the methyl-activating factor (MethylAF) can be calculated from the ratio kOHNCH3/kOHN, and a value of 8.7 × 105 is obtained with substrates 5/2, a value of 1.6 × 103 with 6/3, and a value of 2.1 × 104 with 7/4. The high values of MethylAF are in agreement with an irreversible E1cb mechanism (ANDE* + DN) for substrates 5 and 7 and with the high stability of the intermediate carbanion related to its enamine-type structure. In acetohydroxamate/acetohydroxamic acid buffers (pH 8.45-9.42) and acetate/acetic acid buffers (pH 4.13-5.13), the β-elimination reactions of HF, with substrates 2 and 4, occur at NH+, the substrates protonated at the nitrogen atom of the pyridine ring, even when the [NH+] is much lower than the [N], the unprotonated substrate, due to the high proton-activating factor (PAF) value observed: 3.6 × 105 for 2 and 6.5 × 104 for 4 with acetohydroxamate base. These high PAF values are indicative of an irreversible E1cb mechanism rather than a concerted E2 (ANDEDN) mechanism. Finally, the rate constant for carbanion formation from NH+ with 2 is kBNH+ = 0.35 M-1 s-1, which is lower than when chlorine is the leaving group (kBNH+ = 1.05 M-1 s-1; Alunni, S.; Busti, A. J. Chem. Soc., Perkin Trans. 2 2001, 778). This is direct experimental evidence that some lengthening of the carbon-leaving group bond can occur in the intermediate carbanion. This is a point of interest for interpreting a heavy-atom isotope effect.
- Alunni, Sergio,Laureti, Valeria,Ottavi, Laura,Ruzziconi, Renzo
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p. 718 - 725
(2007/10/03)
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- Product and process for making quaternized, water soluble vinylpyridine carboxylate polymers
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This invention relates to stable, quaternized vinlypyridine carboxylate home-, co- and ter-polymers, useful as dye transfer inhibitors and polymers complexable with active agrochemical, pharmaceutical or cosmetic agents for controlled release thereof, and
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- Cyclic amidino agents useful as nitric oxide synthase inhibitors
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The current invention discloses useful amidino derivative useful as nitric oxide synthase inhibitors.
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- Mechanism and proton activating factors in base-induced β-elimination reactions of N-[2-(4-pyridyl)ethyl]quinuclidinium and N-[2-(2-pyridyl)ethyl]quinuclidinium salts
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β-Elimination reactions of N-[2-(4-pyridyl)ethyl]quinuclidinium and N-[2-(2-pyridyl)ethyl]quinuclidinium salts (N) in acetohydroxamate-acetohydroxamic acid buffer, H2O, μ = 1 M KCl, 50°C, with the formation of 4- or 2-vinylpyridine, respectively, proceed by an Elcb mechanism with carbon deprotonation occurring in the substrates protonated at the pyridine ring (NH+). The formation of the intermediate carbanion has a high degree of reversibility. The systems consistently present H/D exchange. NH+ is much more reactive than N; this can be attributed to the strong stabilization of the intermediate carbanion formed from NH+ due to resonance.
- Alunni, Sergio,Conti, Annarita,Errico, Rosa Palmizio
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p. 453 - 457
(2007/10/03)
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- Photochemical ligand loss as a basis for imaging and microstructure formation in a thin polymeric film
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Ligand loss photochemistry occurs in thin polymeric films of poly[Ru(bpy)2(vpy)2]2+ (bpy is 2,2′-bipyridine, vpy is 4-vinylpyridine), poly[Ru(Me2bpy)2(vpy)2]2+ (Me2bpy is 4,4′-dimethyl-2,2′-bipyridine), and poly[Ru(Me4bpy)2(vpy)2]2+ (Me4bpy is 4,4′,5,5′-tetramethyl-2,2′-bipyridine). These films were formed by reductive electropolymerization of the corresponding 4-vinylpyridine complexes on Pt disk electrodes. Upon photolysis, the ruthenium-pyridyl bonds were cleaved and the polymer was lost, exposing the underlying substrate. The photochemical reaction was used to transfer an image to the films by using masking techniques. In a subsequent step, poly[Os(vbpy)3]2+ (vbpy is 4-methyl-4′-vinyl-2,2′-bipyridine), which is photochemically stable, was formed selectively in the exposed regions of the electrode by reductive electropolymerization. This procedure gave a laterally resolved, two-component, film-based structure in which there were discrete, spatially segregated regions of RuII and OsII. In a final step, the remaining film containing RuII was removed by photolysis. This procedure left an image of the original mask in the poly[Os(vbpy)3]2+ that remained.
- Gould, Sharon,O'Toole, Terrence R.,Meyer, Thomas J.
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p. 9490 - 9496
(2007/10/02)
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- A NOVEL APPROACH TO FUNCTIONALIZATION OF AZINES. OXIRANYL AND THIIRANYL DERIVATIVES OF PYRIDINE, QUINOLINE AND ISOQUINOLINE
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Convenient methods for synthesis of the oxiranyl and thiiranyl derivatives of pyridine, quinoline and isoquinoline have been elaborated.Oxiranes have been synthesized from corresponding aldehydes with dimethylsulfonium methylide in anhydrous medium.Exchange of the oxygen atom in the oxirane ring on sulfur with potassium thiocyanate gave thiiranylazines.
- Kloc, Krystian,Kubicz, Elzbieta,Mlochowski, Jacek
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p. 2517 - 2522
(2007/10/02)
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- Catalytic Reactions of Pyridines. IV. Heterogeneous Vapor-phase Side-chain Alkylation of Pyridines with Alcohols over Na+, K+, Rb+, and Cs+ Exchanged Zeolites
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The heterogeneous vapor-phase alkylation of pyridine with methanol over Na+, K+, Rb+, or Cs+ exchanged X- or Y-type zeolite in an atmophere of nitrogen resulted in the formation of 2- and 4-ethylpyridines and 2- and 4-vinylpyridines together with picolines and lutidines.Next, the alkylation of α-, β-, and γ-picolines with methanol was studied over alkali cation exchanged zeolites and was found to produce mainly the side-chain methylated derivatives: ethylpyridines and vinylpyridines.However, considerable amounts of ring-alkylated derivatives (lutidines) were formed simultaneously.In general, the catalytic activity became observable under reaction conditions involving both a high temperature and a small flow rate of carrier gas (N2).The yields of ethylpyridines were highest when the CsY catalyst was used at 450 deg C, whereas the yields of vinylpyridines were highest when the CsX catalyst was used at 425 deg C.This catalytic side-chain alkylation over alkali cation exchanged zeolites was successfully applied to a variety of picolines, lutidines, and ethylpyridines with either methanol or ethanol.
- Kashiwagi, Hiroshi,Enomoto, Saburo
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p. 404 - 411
(2007/10/02)
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- GROUP VIA METAL PENTACARBONYL COMPLEXES OF 2- AND 4-VINYLPYRIDINE AND THEIR COPOLYMERS. PREPARATION, SPECTROSCOPIC CHARACTERISATION AND PHOTOCHEMICAL PROPERTIES
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M(CO)5(4-VP) (M = Cr, Mo, or W) and M(CO)5(2-VP) (M = Cr, W), prepared from the reaction of M(CO)5(EtOH) and 2-vinylpyridine (2-VP) or 4-vinylpyridine (4-VP), have been characterised by IR, 1H NMR, and UV/visible absorption spectroscopy.Copolymers of M(CO
- Kelly, John M.,Long, Conor
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p. 315 - 326
(2007/10/02)
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