- The benzyl can be selectively removed by visible light or near visible light. Method for protecting allyl and propargyl group
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The invention provides a method for selectively removing benzyl, allyl and propargyl protecting groups by visible light or near visible light, namely a substrate containing benzyl, allyl or propargyl protecting groups. The method has the advantages of simple operation, safe and clean visible light or near visible light as excitation conditions, cheap and easily available reagents, high reaction yield, high reaction chemistry and regional selectivity, and is suitable for selective removal of benzyl, allyl and propargyl protecting groups in various substrates.
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Paragraph 0019
(2021/10/16)
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- Sulfoxylate Anion Radical-Induced Aryl Radical Generation and Intramolecular Arylation for the Synthesis of Biarylsultams
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Aryl radical generation from the corresponding aryl halides using an electron donor and subsequent intramolecular cyclization with arenes could be an important advancement in contemporary biaryl synthesis. A green and practically useful synthetic protocol to access diverse six- and seven-membered biarylsultams especially with a free NH group including demonstration of a gram-scale synthesis is reported herein. The sulfoxylate anion radical (SO2-?), generated in situ from the reagents rongalite or sodium dithionite (Na2S2O4), was found to be the key single electron transfer agent forming aryl radicals from aryl halides, which upon intramolecular arylation gives biarylsultams with good to excellent yields. The approach features generation of aryl radicals that remained underexplored, use of a cheap and readily available industrial reagents, and transition metal-free, mild, and green reaction conditions.
- Gupta, Pankaj,Laha, Joydev K.
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supporting information
(2022/03/16)
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- Metal-Free Directed C?H Borylation of Pyrroles
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Robust strategies to enable the rapid construction of complex organoboronates in selective, practical, low-cost, and environmentally friendly modes remain conspicuously underdeveloped. Here, we develop a general strategy for the site-selective C?H borylation of pyrroles by using only BBr3 directed by pivaloyl groups, avoiding the use of any metal. The site-selectivity is generally dominated by chelation and electronic effects, thus forming diverse C2-borylated pyrroles against the steric effect. The formed products can readily engage in downstream transformations, enabling a step-economic process to access drugs such as Lipitor. DFT calculations (wB97X-D) demonstrate the preferred positional selectivity of this reaction.
- Wang, Zheng-Jun,Chen, Xiangyang,Wu, Lei,Wong, Jonathan J.,Liang, Yong,Zhao, Yue,Houk, Kendall N.,Shi, Zhuangzhi
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supporting information
p. 8500 - 8504
(2021/03/16)
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- Rearrangement and cyclisation reactions on the 1-Arylpyrrol-2-iminyl-2-Aryliminopyrrol-1-yl radical energy surface
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Independent generation of the iminyl (X = N) and pyrrol-1-yl (X = N) radicals by flash vacuum pyrolysis of the corresponding oxime ether and N-(dimethylamino) compound, respectively, provides two regioisomeric pyrrolo1,2-A]quinoxalines compounds. This shows that the radical species interconvert via the spirodienyl moeity at high temperatures. Corresponding generation of the pyrrol-1-yl (X = CH) radical gives the pyrrolo[1,2-A]quinoline as the only cyclised product. In this case, DFT calculations suggest that direct cyclisation of the pyrrol-1-yl takes place, rather than formation of the spirodienyl species and exclusive migration of the C-N bond.
- Borthwick, Scott,Foot, Jonathan,Ieva, Maria,McNab, Hamish,McNab, Lilian,Rozgowska, Emma J.,Wright, Andrew
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supporting information
p. 161 - 175
(2021/02/02)
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- Transition-Metal-Free and Visible-Light-Mediated Desulfonylation and Dehalogenation Reactions: Hantzsch Ester Anion as Electron and Hydrogen Atom Donor
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Novel approaches for N- and O-desulfonylation under room temperature (rt) and transition-metal-free conditions have been developed. The first methodology involves the transformation of a variety of N-sulfonyl heterocycles and phenyl benzenesulfonates to the corresponding desulfonylated products in good to excellent yields using only KOtBu in dimethyl sulfoxide (DMSO) at rt. Alternately, a visible light method has been used for deprotection of N-methyl-N-arylsulfonamides with Hantzsch ester (HE) anion serving as the visible-light-absorbing reagent and electron and hydrogen atom donor to promote the desulfonylation reaction. The HE anion can be easily prepared in situ by reaction of the corresponding HE with KOtBu in DMSO at rt. Both protocols were further explored in terms of synthetic scope as well as mechanistic aspects to rationalize key features of desulfonylation processes. Furthermore, the HE anion induces reductive dehalogenation reaction of aryl halides under visible light irradiation.
- Heredia, Micaela D.,Guerra, Walter D.,Barolo, Silvia M.,Fornasier, Santiago J.,Rossi, Roberto A.,Budén, Mariá E.
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supporting information
p. 13481 - 13494
(2020/12/15)
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- Discovery and characterization of an acridine radical photoreductant
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Photoinduced electron transfer (PET) is a phenomenon whereby the absorption of light by a chemical species provides an energetic driving force for an electron-transfer reaction1–4. This mechanism is relevant in many areas of chemistry, including the study of natural and artificial photosynthesis, photovoltaics and photosensitive materials. In recent years, research in the area of photoredox catalysis has enabled the use of PET for the catalytic generation of both neutral and charged organic free-radical species. These technologies have enabled previously inaccessible chemical transformations and have been widely used in both academic and industrial settings. Such reactions are often catalysed by visible-light-absorbing organic molecules or transition-metal complexes of ruthenium, iridium, chromium or copper5,6. Although various closed-shell organic molecules have been shown to behave as competent electron-transfer catalysts in photoredox reactions, there are only limited reports of PET reactions involving neutral organic radicals as excited-state donors or acceptors. This is unsurprising because the lifetimes of doublet excited states of neutral organic radicals are typically several orders of magnitude shorter than the singlet lifetimes of known transition-metal photoredox catalysts7–11. Here we document the discovery, characterization and reactivity of a neutral acridine radical with a maximum excited-state oxidation potential of ?3.36 volts versus a saturated calomel electrode, which is similarly reducing to elemental lithium, making this radical one of the most potent chemical reductants reported12. Spectroscopic, computational and chemical studies indicate that the formation of a twisted intramolecular charge-transfer species enables the population of higher-energy doublet excited states, leading to the observed potent photoreducing behaviour. We demonstrate that this catalytically generated PET catalyst facilitates several chemical reactions that typically require alkali metal reductants and can be used in other organic transformations that require dissolving metal reductants.
- MacKenzie, Ian A.,Wang, Leifeng,Onuska, Nicholas P. R.,Williams, Olivia F.,Begam, Khadiza,Moran, Andrew M.,Dunietz, Barry D.,Nicewicz, David A.
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- Integrating Biomass into the Organonitrogen Chemical Supply Chain: Production of Pyrrole and d-Proline from Furfural
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Production of renewable, high-value N-containing chemicals from lignocellulose will expand product diversity and increase the economic competitiveness of the biorefinery. Herein, we report a single-step conversion of furfural to pyrrole in 75 % yield as a key N-containing building block, achieved via tandem decarbonylation–amination reactions over tailor-designed Pd?S-1 and H-beta zeolite catalytic system. Pyrrole was further transformed into dl-proline in two steps following carboxylation with CO2 and hydrogenation over Rh/C catalyst. After treating with Escherichia coli, valuable d-proline was obtained in theoretically maximum yield (50 %) bearing 99 % ee. The report here establishes a route bridging commercial commodity feedstock from biomass with high-value organonitrogen chemicals through pyrrole as a hub molecule.
- Di, Lu,Fung Kin Yuen, Vincent,Song, Song,Sun, Qiming,Yan, Ning,Zhou, Kang
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supporting information
p. 19846 - 19850
(2020/09/02)
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- The Sn(IV)-tetra(4-sulfonatophenyl) porphyrin complexes with antioxidants: Synthesis, structure, properties
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Complexes of Sn(IV)-tetra(4-sulfophenyl)porphyrin with antioxidants (methoxydol and ionol) and their precursors (para-cresol and 3-hydroxypyridine) were synthesized. All four complexes were obtained by boiling in aqueous solutions of the p-sulfo substitut
- Mamardashvili, Galina M.,Lazovskiy, Dmitriy A.,Maltceva, Olga V.,Zh. Mamardashvili, Nugzar,Koifman, Oscar I.
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supporting information
p. 468 - 475
(2018/11/23)
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- Efficient acceptorless photo-dehydrogenation of alcohols and: N -heterocycles with binuclear platinum(ii) diphosphite complexes
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Although photoredox catalysis employing Ru(ii) and Ir(iii) complexes as photocatalysts has emerged as a versatile tool for oxidative C-H functionalization under mild conditions, the need for additional reagents acting as electron donor/scavenger for completing the catalytic cycle undermines the practicability of this approach. Herein we demonstrate that photo-induced oxidative C-H functionalization can be catalysed with high product yields under oxygen-free and acceptorless conditions via inner-sphere atom abstraction by binuclear platinum(ii) diphosphite complexes. Both alcohols (51 examples), particularly the aliphatic ones, and saturated N-heterocycles (24 examples) can be efficiently dehydrogenated under light irradiation at room temperature. Regeneration of the photocatalyst by means of reductive elimination of dihydrogen from the in situ formed platinum(iii)-hydride species represents an alternative paradigm to the current approach in photoredox catalysis.
- Zhong, Jian-Ji,To, Wai-Pong,Liu, Yungen,Lu, Wei,Che, Chi-Ming
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p. 4883 - 4889
(2019/05/16)
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- Accelerated decarbonylation of 5-hydroxymethylfurfural in compressed carbon dioxide: A facile approach
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Herein, decarbonylation of biomass-based 5-hydroxymethylfurfural (HMF) in compressed CO2 with an unexpected acceleration of the reaction rate and excellent catalytic activity is reported. Without any additive, CO surrogates, or any organic solvents, via the developed method, an excellent conversion of 99.8% and highest selectivity of furfuryl alcohol (99.6%) in 4 h at 145 °C were achieved using an alumina-supported Pd catalyst (Pd/Al2O3). The superior activity is due to the unique characteristics (miscibility of reactant gases and high diffusivity) of compressed CO2 and the synergy between CO2 and Pd/Al2O3, where CO2 plays an interesting role in accelerating the reaction by enhancing the diffusion of CO and furfuryl alcohol (both products have high solubilities in CO2), consequently shifting the equilibrium to the forward direction. Characterisation of the catalyst suggested its direct interaction with the substrate and provided an indication of the possible reaction path. Thus, a mechanism was outlined. Compared to the results obtained using organic solvents, the results obtained using compressed CO2 were superior in terms of activity, selectivity, and reaction rate. This strategy highlights easy product separation, improved catalyst life, and a simple sustainable process. The efficiency of this protocol is confirmed by its potential application to a series of aldehydes with various substituents to produce decarbonylated products in good to excellent yields.
- Chatterjee, Maya,Ishizaka, Takayuki,Kawanami, Hajime
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p. 2345 - 2355
(2018/06/01)
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- ELECTROLYTE SOLUTION AND ELECTROCHEMICAL DEVICE
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The present invention aims to provide an electrolyte solution containing a quaternary ammonium salt as an electrolyte salt and is capable of providing an electrochemical device having a high capacitance retention and reducing generation of gas. The electrolyte solution of the present invention contains a solvent, a quaternary ammonium salt, and a nitrogen-containing unsaturated cyclic compound. The unsaturated cyclic compound is a nitrogen-containing unsaturated heterocyclic compound. The unsaturated cyclic compound excludes salts of the unsaturated cyclic compound and ionic liquids obtainable from the unsaturated cyclic compound.
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- Pyrrole and preparation method thereof
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The invention provides pyrrole and a preparation method thereof, and relates to the field of chemical preparation. The preparation method of the pyrrole comprises the following step of under the existence of water steam, using solid superacid as a catalyst to enable furan and ammonia to react. The preparation method has the advantages that the under the condition of using the solid superacid as the catalyst, the furan with lower cost and wide source reacts with the ammonia to prepare the pyrrole; the technology process is simple, the reaction temperature is lowered, the yield rate is increased, and the batched production is realized. The pyrrole is prepared by the preparation method, and the purity is high.
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Page/Page column 5-8
(2017/08/29)
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- Reactivity of 7-Azanorbornenes in Bioorthogonal Inverse Electron-Demand Diels–Alder Reactions
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In the preparation of multicomponent compounds, the accumulation of components through sequential click reactions is an attractive strategy. In this work we examined the reactivity of various N-substituted 7-azanorbornenes in inverse electron-demand Diels–Alder (iEDDA) reactions with tetrazines to explore the potential of 7-azanorbornenes as clickable hub molecules. The iEDDA reaction of 7-azanorbornene is expected to proceed faster when the nitrogen atom at the 7-position is substituted with an electron-donating substituent. Contrary to this expectation, the electron-donating alkyl-bearing derivative reacted much more slowly than those bearing electron-withdrawing acyl groups. The results of DFT calculations indicate that the reaction rates correlate well with an increase in sp2 character of the 7-nitrogen atoms: The ease of conversion of the more stable exo conformer into the more reactive endo conformer may lower the activation energy of the first rate-determining hetero-Diels–Alder step. Indeed, the reaction rates of N-acylated 7-azanorbornenes, which have a more planar nitrogen atom, were found superior to those of other derivatives and comparable to those of norbornenes. Finally, we successfully labeled a tetrazine on a protein surface by fluorophore-conjugated 7-azanorbornene in the presence of other proteins.
- Karaki, Fumika,Ohgane, Kenji,Imai, Hirotaka,Itoh, Kennosuke,Fujii, Hideaki
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p. 3815 - 3829
(2017/07/22)
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- Palladium-Catalyzed Deformylation Reactions with Detailed Experimental and in Silico Mechanistic Studies
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A facile, efficient, and general deformylation reaction with a wide-ranging functional group compatibility has been developed with palladium acetate as a precatalyst under exogenous ligand-free conditions. The mechanistic details of the palladium-catalyzed deformylation reaction have been outlined on the basis of a combination of experimental and computational studies. The heterogeneous pathway is predominant for the deformylation, and homogeneous catalysis occurs to a lesser extent. This ligand-free catalytic cycle is proposed to undergo oxidative addition, migratory extrusion, and reductive elimination as the key steps. Kinetic studies reveal a first-order rate dependency with respect to the aldehyde. Furthermore, kinetic isotope effects, competition experiments, and Hammett studies suggest that the migratory extrusion step is the rate-determining step. For the homogeneous pathway, the experimental findings are also supported by DFT studies.
- Modak, Atanu,Rana, Sujoy,Phukan, Ashwini K.,Maiti, Debabrata
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supporting information
p. 4168 - 4174
(2017/08/07)
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- PdPb-Catalyzed decarboxylation of proline to pyrrolidine: Highly selective formation of a biobased amine in water
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Amino acids have huge potential as platform chemicals in the biobased industry. Pd-catalyzed decarboxylation is a very promising route for the valorization of these natural compounds derived from protein waste or fermentation. We report that the highly abundant and nonessential amino acid L-proline is very reactive in the Pd-catalyzed decarboxylation. Full conversions are obtained with Pd/C and different Pd/MeOx catalysts; this allowed the identification of the different side reactions and the mapping of the reaction network. Due to the high reactivity of pyrrolidine, the selectivity for pyrrolidine was initially low. By carefully modifying Pd/ZrO2 with Pb in a controlled mannervia two incipient wetness impregnation stepsthe selectivity increased remarkably. Finally, a thorough investigation of the reaction parameters resulted in an increased activity of this modified catalyst and an even further enhanced selectivity under a low H2 pressure of 4 bar at 235 °C in water. This results in a very selective and sustainable production route for the highly interesting pyrrolidine.
- Verduyckt, Jasper,Van Hoof, Maarten,De Schouwer, Free,Wolberg, Marike,Kurttepeli, Mert,Eloy, Pierre,Gaigneaux, Eric M.,Bals, Sara,Kirschhock, Christine E.A.,De Vos, Dirk E.
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p. 7303 - 7310
(2018/05/23)
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- Cyclopenta[d]pyrimidines And Substituted Cyclopenta[d]pyrimidines As Antitubulin and Microtubule Targeting Agents, Monocyclic Pyrimidines As Tubulin Inhibitors, And Pyrrolopyrimidines As Targeted Antifolates And Tubulin and Multiple Receptor Tyrosine Kinase Inhibition And Antitumor Agents
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The present invention provides a compound of Formula I, and salts thereof, and a pharmaceutical composition comprising a compound of Formula I: wherein R1 is selected from the group consisting of and R2 is an alkyl group having from one to ten carbon atoms, or wherein R2 is selected from the group consisting of R1 is an alkyl group having from one to ten carbon atoms; and R is H, or an alkyl group having from one to ten carbon atoms, and R3 is H, an alkyl group having from one to ten carbon atoms, or a halogen. Preferably the compound of Formula V includes wherein R3 is a halogen, and most preferably wherein the halogen is chlorine. Methods of treating a patient with cancer with these compounds are also provided.
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- But-2-ene-1,4-diamine and But-2-ene-1,4-diol as Donors for Thermodynamically Favored Transaminase- and Alcohol Dehydrogenase-Catalyzed Processes
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Both cis- and trans-but-2-ene-1,4-diamines have been prepared and efficiently applied as sacrificial cosubstrates in enzymatic transamination reactions. The best results were obtained with the cis-diamine. The thermodynamic equilibrium of the stereoselective transamination process is shifted to the amine formation due to tautomerization of 5H-pyrrole into 1H-pyrrole, achieving high conversions (78–99%) and enantiomeric excess (up to >99%) by using a small excess of the amine donor. Furthermore, when the reaction proceeded, a strong coloration was observed due to polymerization of 1H-pyrrole. A structurally related compound, cis-but-2-ene-1,4-diol, has been utilized as cosubstrate in different alcohol dehydrogenase (ADH)-mediated bioreductions. In this case, high conversions (91–99%) were observed due to a lactonization process. Both strategies are convenient from both synthetic and atom economy points of view in the production of valuable optically active products. (Figure presented.).
- Martínez-Montero, Lía,Gotor, Vicente,Gotor-Fernández, Vicente,Lavandera, Iván
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supporting information
p. 1618 - 1624
(2016/10/13)
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- AZOLE DERIVATIVE, METHOD FOR PRODUCING AZOLE DERIVATIVE, AND INTERMEDIATE COMPOUND
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In order to provide a novel azole derivative, an azole derivative of the present invention is an azole derivative represented by a general formula (V'). (where R6 and R7 independently represent a hydrogen atom, a C1-C4 alkyl group, a phenyl group, or a benzyl group; X represents a halogen atom, a C1-C4 alkyl group, a haloalkyl group, an alkoxy group or a haloalkoxy group, a phenyl group, a cyano group, or a nitro group; m represents an integer of 0 to 5; and A represents a nitrogen atom or a methyne group.)
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Page/Page column
(2014/05/07)
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- Oxidant-free conversion of cyclic amines to lactams and H2 using water as the oxygen atom source
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Direct conversion of cyclic amines to lactams utilizing water as the only reagent is catalyzed by pincer complex 2. In contrast to previously known methods of amine-to-amide conversion, this reaction occurs in the absence of oxidants and is accompanied by liberation of H2, with water serving as a source of oxygen atom. Formation of a cyclic hemiaminal intermediate plays a key role in enabling such reactivity. This represents an unprecedented, conceptually new type of amide formation reaction directly from amines and water under oxidant-free conditions.
- Khusnutdinova, Julia R.,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 2998 - 3001
(2014/03/21)
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- Carbon kinetic isotope effects reveal variations in reactivity of intermediates in the formation of protonated carbonic acid
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Kinetic evidence suggests that acid-catalyzed decarboxylation reactions of aromatic carboxylic acids can occur by a hydrolytic process that generates protonated carbonic acid (PCA) as the precursor of CO2. Measurements of reaction rates and carbon kinetic isotope effects (CKIE) for decarboxylation of isomeric sets of heterocyclic carboxylic acids in acidic solutions reveal that C-C cleavage to form PCA is rate-determining with significant variation in the magnitude of the observed CKIE (1.018-1.043). Larger values are associated with the more reactive member in each isomeric pair. This variation is consistent with stepwise mechanisms in which C-C cleavage is competitive with C-O cleavage, leading to reversion to the protonated reactant to varying degrees with an invariant intrinsic CKIE for C-C cleavage. Thus, the relative barriers to reversion and formation of PCA control the magnitude of the observed CKIE in a predictable manner that correlates with reactivity. Application of the proposed overall mechanism reveals that carboxylation reactions in acidic solutions will proceed by way of initial formation of PCA.
- Vandersteen, Adelle A.,Mundle, Scott O. C.,Lacrampe-Couloume, Georges,Sherwood Lollar, Barbara,Kluger, Ronald
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p. 12176 - 12181
(2014/01/06)
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- Rhenium complexes of di-2-pyridyl ketone, 2-benzoylpyridine and 2-hydroxybenzophenone: A structural and theoretical study
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The reactions of di-2-pyridyl ketone (dpk), 2-benzoylpyridine (zpy) and 2-hydroxybenzophenone (Hbp) with [Re(CO)5Cl] (A) and trans-[ReOX 3(PPh3)2] (B, X = Cl, Br) were studied. The complexfac-[Re(CO)3 (dpk·OCH3)] was isolated from the reaction of A with dpk in methanol. The monoanionic tridentate chelate dpk·OCH3 was formed by the nucleophilic attack of methanol at the carbonylic carbon atom of dpk. A similar attack of water on dpk was observed in the compound cis-[ReOBr2(dpk·OH)]·2(dpkH +Br), which was formed from dpk and [ReOBr3(PPh 3)2] in acetone. The reaction of zpy with B in acetonitrile produced the complexes [ReIIIX3(zpy)(PPh 3)], but in methanol as solvent the compounds [ReOX 2(zpyH)(PPh3)] were isolated, where zpyH coordinates bidentately as the monoanionic ligand [C6H5(HC-O)C 5H4N]. With A as starting material the complexfac-[Re(CO)3(zpy)Cl] was isolated. The complexes cis-[ReOX2(bp)(PPh3)] were the products of the reaction of Hbp with B in acetonitrile; however, in methanol cis-[ReIIIBr 2 (bp)(PPh3)2] was isolated. All these complexes were characterized by conductance measurements, elemental analyses, UV-Vis, IR and NMR spectroscopy and by single crystal X-ray diffraction. DFT calculations regarding the electronic ground states show single states for all the complexes, except for the rhe-nium(III) complexes [ReIIIX 3(zpy)(PPh3)] and [ReBr2(bp)(PPh 3)2], in which the states are triplet. The DFT and experimental results are in agreement in all cases, especially the anisotropy of the Re-N bond length offac-[Re(CO)3(dpk·OCH3)] and exact O(1)-Re-O(3) angles for [ReOX2(bp)(PPh3)].
- Yumata,Habarurema,Mukiza,Gerber,Hosten,Taherkhani,Nahali
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- Molecular products from the thermal degradation of glutamic acid
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The thermal behavior of glutamic acid was investigated in N2 and 4% O2 in N2 under flow reactor conditions at a constant residence time of 0.2 s, within a total pyrolysis time of 3 min at 1 atm. The identification of the main pyrolysis products has been reported. Accordingly, the principal products for pyrolysis in order of decreasing abundance were succinimide, pyrrole, acetonitrile, and 2-pyrrolidone. For oxidative pyrolysis, the main products were succinimide, propiolactone, ethanol, and hydrogen cyanide. Whereas benzene, toluene, and a few low molecular weight hydrocarbons (propene, propane, 1-butene, and 2-butene) were detected during pyrolysis, no polycyclic aromatic hydrocarbons (PAHs) were detected. Oxidative pyrolysis yielded low molecular weight hydrocarbon products in trace amounts. The mechanistic channels describing the formation of the major product succinimide have been explored. The detection of succinimide (major product) and maleimide (minor product) from the thermal decomposition of glutamic acid has been reported for the first time in this study. Toxicological implications of some reaction products (HCN, acetonitrile, and acyrolnitrile), which are believed to form during heat treatment of food, tobacco burning, and drug processing, have been discussed in relation to the thermal degradation of glutamic acid.
- Kibet, Joshua K.,Khachatryan, Lavrent,Dellinger, Barry
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p. 7696 - 7704
(2013/09/02)
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- Unusual reactivity of N-tert-butylimines under FVT conditions
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Thermal reactions of N-tert-butyl-(E)-crotonaldimine (1a) and 1,4-di-(tert-butyl)-1,4-diazabuta-1,3-dien (glyoxal-bis-N-tert-butylimine) (1b) under FVT conditions have been studied. It has been found that at 800 °C compound 1a yielded pyrrole and crotonon
- Le?niak, Stanis?aw,Pasternak, Beata,Justyna, Katarzyna,Vu, Thien Y.,Huynh, Thi Kieu Xuan,Khayar, Sa?d,Dargelos, Alain,Chrostowska, Anna
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p. 722 - 729
(2013/07/27)
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- Flash flow pyrolysis: Mimicking flash vacuum pyrolysis in a high-temperature/high-pressure liquid-phase microreactor environment
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Flash vacuum pyrolysis (FVP) is a gas-phase continuous-flow technique where a substrate is sublimed through a hot quartz tube under high vacuum at temperatures of 400-1100 °C. Thermal activation occurs mainly by molecule-wall collisions with contact times in the region of milliseconds. As a preparative method, FVP is used mainly to induce intramolecular high-temperature transformations leading to products that cannot easily be obtained by other methods. It is demonstrated herein that liquid-phase high-temperature/high- pressure (high-T/p) microreactor conditions (160-350 °C, 90-180 bar) employing near- or supercritical fluids as reaction media can mimic the results obtained using preparative gas-phase FVP protocols. The high-T/p liquid-phase "flash flow pyrolysis" (FFP) technique was applied to the thermolysis of Meldrum's acid derivatives, pyrrole-2,3-diones, and pyrrole-2-carboxylic esters, producing the expected target heterocycles in high yields with residence times between 10 s and 10 min. The exact control over flow rate (and thus residence time) using the liquid-phase FFP method allows a tuning of reaction selectivities not easily achievable using FVP. Since the solution-phase FFP method does not require the substrate to be volatile any more -a major limitation in classical FVP-the transformations become readily scalable, allowing higher productivities and space-time yields compared with gas-phase protocols. Differential scanning calorimetry measurements and extensive DFT calculations provided essential information on pyrolysis energy barriers and the involved reaction mechanisms. A correlation between computed activation energies and experimental gas-phase FVP (molecule-wall collisions) and liquid-phase FFP (molecule-molecule collisions) pyrolysis temperatures was derived.
- Cantillo, David,Sheibani, Hassan,Kappe, C. Oliver
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experimental part
p. 2463 - 2473
(2012/05/20)
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- A general and efficient aldehyde decarbonylation reaction by using a palladium catalyst
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A facile decarbonylation reaction of aldehydes has been developed by employing Pd(OAc)2. A wide variety of substrates are decarbonylated, without using any exogenous ligand for palladium as well as CO-scavenger.
- Modak, Atanu,Deb, Arghya,Patra, Tuhin,Rana, Sujoy,Maity, Soham,Maiti, Debabrata
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supporting information; experimental part
p. 4253 - 4255
(2012/05/04)
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- Palladium-catalysed direct arylations of NH-free pyrrole and N-tosylpyrrole with aryl bromides
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The palladium-catalysed direct coupling of aryl halides with pyrroles provides a greener access to arylated pyrroles than more classical couplings such as Suzuki, Stille or Negishi reactions. However, so far, NH-free pyrrole and N-tosylpyrrole gave disappointing results for such couplings either in terms of regioselectivity of the arylation, catalyst loading or substrate scope. The reactivity of both NH-free pyrrole and N-tosylpyrrole was studied, and the tosylated pyrrole led to higher yields of coupling products due to better conversions of the aryl bromides. A range of aryl bromides undergo regioselective coupling at C2 of N-tosylpyrrole in moderate to good yields using 1 mol % [Pd(Cl(C3H5)]2 as the catalyst, KOAc as the base in DMAc.
- Bheeter, Charles Beromeo,Bera, Jitendra K.,Doucet, Henri
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experimental part
p. 509 - 513
(2012/02/02)
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- CsF-Celite as an efficient heterogeneous catalyst for sulfonylation and desulfonylation of heteroatoms
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CsF-Celite is found to be as an efficient reusable catalyst for sulfonylation and desulfonylation of heteroatoms. Sulfonamides and N-acylsulfonamides deprotect efficiently in the presence of CsF-Celite under solvent free conditions to give the free amines or amides in good to excellent yields.
- Tamaddon, Fatemeh,Nasiri, Alireza,Farokhi, Somayeh
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experimental part
p. 1477 - 1482
(2012/06/18)
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- Photoinduced electron transfer in pentacoordinated complex of zinc tetraphenylporphyrin and isoquinoline N-oxide. Crystal structure, spectroscopy and DFT studies
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A novel, pentacoordinated complex of (1:1) zinc tetraphenylporphyrin and isoquinoline N-oxide (ZnTPP-IQNO) was synthesized and its crystal structure along with photophysical properties by experimental methods (absorption, steady state and time-resolved emission) in conjunction with DFT and TD DFT calculations were investigated. In ZnTPP-IQNO complex, the isoquinoline N-oxide ligand (IQNO) is directly coordinated to the central zinc atom of the ZnTPP unit through the oxygen atom of the NO group and crystallizes in centrosymmetric triclinic unit, in the space group P1. Particular contacts between the two monomeric units (hydrogen bonds, O...H-C interactions, ...etc.) lead to a supramolecular dimer which forms the layers propagating both along the a and the b-axis. The electronic locally excited and the charge-transfer states of the complex were calculated by TDDFT CAM-B3LYP/6-31G(d,p) method. A surprising presence of the charge transfer states between the Soret and the Q bands leads to excitation energy dissipation processes involving the opening of the radiationless channels of excited ZnTPP-IQNO complex. Emission from the S 1 state (Q band) in ethyl acetate decays accordingly to monoexponential function (1.92 ns) while a bi-exponential decay is found in n-propanol [(2.5 ns (87%); 14.4 ns (13%)] and in the solid state [1.36 ns (67.5%), 7.31 ns (32.5%)].
- Oberda,Deperasinska,Nizhnik,Jerzykiewicz,Szemik-Hojniak
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body text
p. 2391 - 2399
(2011/10/10)
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- NOVEL AROMATIC COMPOUND AND POLYARYLENE COPOLYMER HAVING NITROGEN-CONTAINING HETEROCYCLE INCLUDING SULFONIC ACID GROUP IN SIDE CHAIN
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Provided is a solid polymer electrolyte having increased heat resistance and high proton conductivity and a proton conductive membrane composed of the electrolyte. Also provided is a copolymer having a sulfonic acid group. The copolymer includes a repeating unit represented by Formula (1): (in the formula, Y denotes at least one kind of structure selected from the group consisting of —CO—, —SO2—, —SO—, —CONH—, —COO—, —(CF2)l— (l is an integer of 1 to 10), and —C(CF3)2—; W denotes at least one kind of structure selected from the group consisting of a direct bond, —CO—, —SO2—, —SO—, —CONH—, —COO—, —(CF2)l— (l is an integer of 1 to 10), —C(CF3)2—, —O—, and —S—; Z denotes a direct bond or at least one kind of structure selected from the group consisting of —(CH2)l—(l is an integer of 1 to 10), —C(CH3)2—, —O—, —S—, —CO—, and —SO2—; R30 denotes a nitrogen-containing aromatic ring having a substituent represented by —SO3H, —O(CH2)hSO3H, or —O(CF2)hSO3H (h is an integer of 1 to 12); p is an integer of 0 to 10; q is an integer of 0 to 10; r is an integer of 1 to 5; and k is an integer of 0 to 4).
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- Decarboxylation via addition of water to a carboxyl group: Acid catalysis of pyrrole-2-carboxylic acid
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(Chemical Equation Presented) The decarboxylation of pyrrole-2-carboxylic acid is subject to acid catalysis in strongly acidic solutions. Protonation of the pyrrole ring at C2 produces a potentially low-energy carbanion leaving group. Carbon dioxide forma
- Mundle, Scott O. C.,Kluger, Ronald
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p. 11674 - 11675
(2009/12/08)
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- Iron-catalyzed inexpensive and practical synthesis of N-substituted pyrroles in water
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An operationally simple, practical, and economical protocol for iron(III) chloride catalyzed Paal-Knorr pyrrole synthesis in water in good to excellent yields has been developed. Several N-substituted pyrroles are readily prepared from the reaction of 2,5-dimethoxytetrahydrofuran and aryl/alkyl, sulfonyl and acyl amines under very mild reaction conditions. Georg Thieme Verlag Stuttgart.
- Azizi, Najmedin,Khajeh-Amiri, Alireza,Ghafuri, Hossein,Bolourtchian, Mohammad,Saidi, Mohammad Reza
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experimental part
p. 2245 - 2248
(2009/12/03)
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- On-line analysis of gas-phase composition in the combustion chamber and particle emission characteristics during combustion of wood and waste in a small batch reactor
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The emission of participate matter and gaseous compounds during combustion of wood and refuse-derived fuel in a small batch reactor is investigated by laser mass-spectrometric on-line measurement techniques for gas-phase analysis and simultaneous registration of physical aerosol properties (number size distribution). The gas-phase composition is addressed by a laser-based mass spectrometric method, namely, vacuum-UV single-photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS). Particle-size distributions are measured with a scanning mobility particle sizer. Furthermore, a photoelectric aerosol sensor is applied for detection of particle-bound polycyclic aromatic hydrocarbons. The different phases of wood combustion are distinguishable by both the chemical profiles of gas-phase components (e.g., polycyclic aromatic hydrocarbons, PAH) and the particle-size distribution. Furthermore, short disturbances of the combustion process due to air supply shortages are investigated regarding their effect on particle-size distribution and gas-phase composition, respectively. It is shown that the combustion conditions strongly influence the particle-size distribution as well as on the emission of particle-bound polycyclic aromatic hydrocarbons.
- Ferge,Maguhn,Hafner,Muehlberger,Davidovic,Warnecke,Zimmermann
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p. 1393 - 1402
(2007/10/03)
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- Allylic amination via decarboxylative C-N bond formation
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This manuscript details the development of a palladium-catalyzed allylic amination that proceeds via decarboxylation of allylic carbamates. Both saturated and aromatic heterocycles undergo decarboxylative rearrangement in good yields. The mechanism of allylation of heteroaromatic amines involves the formation of π-allyl palladium complexes followed by decarboxylation of the carbamate. Finally, the heteroaromatic anion equivalent is allylated to provide allylic amines. Georg Thieme Verlag Stuttgart.
- Mellegaard-Waetzig, Shelli R.,Rayabarapu, Dinesh Kumar,Tunge, Jon A.
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p. 2759 - 2762
(2007/10/03)
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- ortho-anisylsulfonyl as a protecting group for secondary amines: Mild Ni0-catalyzed hydrodesulfonylation
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A potentially good alternative to the tosyl group (Ts) as a protecting group for amines is N-ortho-anisylsulfonyl (Ans), which is readily cleaved under mild, Ni0-catalyzed reductive conditions (see scheme, acac = acetylacetonate). N-Anisylation of primary amines followed by alkylation and deprotection provides a route to a range of secondary amines.
- Milburn, Robert R.,Snieckus, Victor
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p. 892 - 894
(2007/10/03)
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- Method for making a biochip and biochip
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The present invention relates to a method to produce a biochip and to a biochip, said biochip being composed particularly of biological probes grafted onto a conductive polymer. The method according to the invention comprises the following steps: a) structuring of a substrate so as to obtain on said substrate microtroughs comprising in their base a layer of a material capable of initiating and promoting the adhesion onto said layer of a film of a pyrrole and functionalised pyrrole copolymer by electropolymerisation, b) collective electropolymerisation, so as to form an electropolymerised film of a pyrrole and functionalised pyrrole copolymer on the base of said microtroughs, c) direct or indirect fixation of functionalised oligonucleotides by microdeposition or a liquid jet printing technique.
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- A New Chemoselective Base-Mediated Protection/Deprotection Method for Aldehydes
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A wide range of aldehydes was efficiently protected as pyrrole carbinol derivatives by direct addition of lithium pyrrolate in THF at -78°C. The protection is chemoselective towards aldehydes over ketones and the O-lithiated, O-protonated or O-silylated carbinols may be used to block the aldehyde from nucleophilic and basic reagents at low temperatures. Mild, basic deprotection using DBU, NaOMe or TBAF allows for in situ trapping-reactions (such as Wadsworth-Horner-Emmons olefination) of the released aldehyde.
- Dixon, Darren J.,Scott, Mark S.,Luckhurst, Chris A.
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p. 2317 - 2320
(2007/10/03)
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- Antidiabetic agents
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The present invention provides compounds of Formula (I): wherein A, X, Q, Y, B, D, Z, and E have any of the values defined in the specification, and pharmaceutically acceptable salt thereof, that are useful as antidiabetic agents. Also disclosed are pharmaceutical compositions comprising one or more compounds of Formula I, processes for preparing compounds of Formula I, and intermediates useful for preparing compounds of Formula I.
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- Novel aminophenyl ketone derivatives
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Novel heteroaryl aminophenyl ketone derivatives which are inhibitors of MAP kinases, in particular the p38 MAP kinase, are useful as anti-inflammatory agents in the prophylaxis or treatment of inflammatory diseases or conditions.
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- Bile-acid derived compounds for enhancing oral absorption and systemic bioavailability of drugs
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Disclosed are compounds that exhibit high transport across the intestinal wall of an animal. The compounds may optionally be linked to drugs that are poorly absorbed or poorly transported across the intestinal wall after oral administration to provide for enhanced therapeutic, and optionally prolonged therapeutic, systemic blood concentrations of the drugs upon oral administration of the drug-compound conjugate. Also disclosed are pharmaceutical compositions containing and methods of using such compounds.
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- Heterocycle substituted purine derivatives as potent antiproliferative agents
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The compounds of the present invention are 2,6,9-trisubstituted purine derivatives which are inhibitors of cyclin/cdk complexes. The compounds of the current invention also are potent inhibitors of human cellular proliferation. As such, the compounds of the present invention constitute pharmaceutical compositions with a pharmaceutically acceptable carrier. Such compounds are useful in treating a disorder mediated by elevated levels of cell proliferation in a mammal compared to a healthy mammal by administering to such mammal an effective amount of the compound. Examples of the compounds of the present invention are represented by the following chemical structures: with Y, V, A, R1, R2, R3, R4, R7, and n1 defined herein.
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- Spiro(2h-1-benzopyran-2,4-piperidine)derivatives as glycine transport inhibitors
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The present invention relates to spiro[2H-1-benzopyran-2,4′-piperidine] derivatives having general formula (I), wherein the substituents R1, R2, X and Y are ase defined in the claims or a pharmaceutically acceptable salt thereof. The invention also relates to pharmaceutical compositions comprising said derivatives, as well as to the use of these spiro[2H-1-benzopyran-2,4′-piperidine] derivatives in therapy, more specifically for the treatment of CNS disorders.
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- Polymerization of olefinic compounds
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Certain complexes containing ligands having a phosphino group, amino group or an imino group, and a second functional group such as amide, ester or ketone, when complexed to transition metals, catalyze the (co)polymerization of olefinic compounds such as ethylene, α-olefins and/or acrylates. A newly recognized class of ligands for making copolymer containing polar monomers using late transition metal complexes is described.
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- Kinetics of elimination of several heterocyclic carbamates in the gas phase
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The kinetics of the gas-phase elimination of several heterocyctic carbamates were determined in a static system over the temperature range 190.0-409.7°C and the pressure range 26.5-125 Torr (1 Torr = 133.3 Pa). The reactions in seasoned vessels, with the free radical inhibitor cyciohexene and/or toluene always present, are homogeneous and unimolecular and obey a first-order rate law. The observed rate coefficients are represented by the following Arrhenius equations: for tert-butyl-1-pyrrolidine carboxylate, log k1 (s-1) = (11.36 ± 0.31) - (145.4 ± 3.1) kJ mol-1 (2.303RT)-1; for 1-(tert-butoxycarbonyl)-2-pyrrolidinone, log k1 (s-1) = (11.54 ± 0.29) - (140.8 ± 2.8) kJ mol-1 (2.303RT)-1; for tert-butyl-1-pyrrole carboxylate, log k1 (s-1): (12.12 ± 0.05) - (145.2 ± 1.0) kJ mol-1 (2.303RT)-1; and for 1-ethylpiperazine carboxylate, log k1 (s-1): (12.05 ± 0.19) - (188.2 ± 4.6) kJ mol-1 (2.303RT)-1 The saturated heterocyclic carbamates show a decrease in rates of elimination due to electronic factors. Heterocyclic carbamates with a nitrogen atom able to delocalize its electrons with π-bonds present in the ring were found to enhance the rates due to resonance interactions. Copyright
- Brusco, Yannely,Dominguez, Rosa M.,Rotinov, Alexandra,Herize, Armando,Cordova, Mary,Chuchani, Gabriel
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p. 796 - 800
(2007/10/03)
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- Lactam inhibitors of matrix metalloproteinases, TNF-α and aggrecanase
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The present application describes novel lactams and derivatives thereof of formula I: or pharmaceutically acceptable salt forms thereof, wherein ring B is a 4-8 membered lactam containing from 0-3 additional heteroatoms selected from N, O, and S, which are useful as inhibitors of matrix metalloproteinases, TNF-α, and aggrecanase.
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- TETRAHYDROINDOLONE DERIVATIVES AS GABAAALPHA5 LIGANDS FOR ENHANCING COGNITION
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Compounds according to Formula (I) or a pharmaceutically acceptable salt thereof are GABA-A Alpha 5 ligands useful for enhancing cognition: where A is C 1-6alkyl, C 2-6alkenyl, C 2-6alkynyl, C 3-6cycloalkyl, arylC 1-6alkyl, or aryl wherein the aryl group is optionally substituted by halogen, C 1-6alkyl, CF 3, CN, NO 2 or NH 2, NR 1R 10, S(O) pR 1, heteroarylC 1-6alkyl or heteroaryl where heteroaryl is a 5-or 6-membered heteroaromatic ring as defined for B; and B is phenyl or a 5-membered ring having one or two unsaturations containing 1, 2, 3, or 4 heteroatoms chosen from O, N and S provided that not more than one heteroatom is other than N, a 6-membered heteroaromatic ring containing 1, 2, 3 or 4 nitrogen atoms, each of which rings is optionally substituted by one or more substituents.
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- Novel substituted calix (4) pyrroles and process for the synthesis of calix (4) pyrroles over molecular sieve catalysts
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The present invention relates to novel calix pyrroles and a process for synthesis of calix (4) pyrroles by reacting pyrrole with cyclic or acyclic ketones in dichloro methane (DCM) solvent over molecular sieve catalysts which provides an eco-friendly, more economical and selective heterogeneous method.
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- Combination therapy for the treatment of migraine
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The present invention relates to a method of treating migraine in a mammal, including a human, by administering to the mammal a 5HT1receptor agonist in combination with caffeine and a cyclooxygenase-2 (COX-2) inhibitor. It also relates to pharmaceutical compositions containing a pharmaceutically acceptable carrier, a 5HT1receptor agonist with caffeine and a cyclooxygenase-2 (COX-2) inhibitor.
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- Fragrance precursors
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The invention relates to fragrance precursors, In particular, the invention relates to the use of several classes of compounds which may act as fragrance precursors, e,g., in cosmetic products such as deodorants and antiperspirants and in laundry products such as detergents and fabric softners. These compounds are odorless, but upon contacting the skin as example, in skin care compositions or in personal care compositions, produce fragrances. The compounds also produce fragrances when used in the presence of lipases, e.g. as used in (laundry) detergents, thus providing a prolongation of the fabric scenting effect. The compounds under consideration are compounds of the formula I: The substituents are defined in the specification.
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- Substituted thiadiazolesulfonamides
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Compounds of the formula (I): are suitable for the preparation of pharmaceuticals for prophylaxis and treatment of all those diseases where an increased concentration of interleukin-1β participates in their course, for example septic shock, leukemia, hepatitis, muscular degeneration, HIV infections or degenerative joint diseases (such as osteoarthrosis, spondylosis, chondrolysis following joint trauma or prolonged immobilization of joints following meniscus or patella injuries, or torn ligaments), diseases of the connective tissue (such as collagenosis, periodontal diseases, or wound-healing disturbances), and chronic diseases of the locomotor system (such as inflammatory or immunologically or metabolism-related acute and chronic arthritis, arthropathies, rheumatoid arthritis, myalgias and disturbances in bone metabolism).
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