- A simple, direct synthesis of 3-vinylindoles from the carbocation-catalysed dehydrative cross-coupling of ketones and indoles. A combined experimental and computational study
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A straightforward synthesis of a library of largely new 3-vinylindoles via a clean dehydrative coupling reaction between ketones and indoles has been developed. Highly stable, non-nucleophilic aryl(2-methylindol-3-yl)methylium salts have been used as effi
- Barbero, Margherita,Dughera, Stefano,Alberti, Sara,Ghigo, Giovanni
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p. 363 - 373
(2018/12/13)
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- Rearrangement of Hydroxylated Pinene Derivatives to Fenchone-Type Frameworks: Computational Evidence for Dynamically-Controlled Selectivity
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An acid-catalyzed Prins/semipinacol rearrangement cascade reaction of hydroxylated pinene derivatives that leads to tricyclic fenchone-type scaffolds in very high yields and diastereoselectivity has been developed. Quantum chemical analysis of the selecti
- Blümel, Marcus,Nagasawa, Shota,Blackford, Katherine,Hare, Stephanie R.,Tantillo, Dean J.,Sarpong, Richmond
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supporting information
p. 9291 - 9298
(2018/07/15)
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- Green synthesis method of acetal-type or ketal-type compound
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The invention discloses a green synthesis method of an acetal-type or ketal-type compound. A carbonyl compound is used as a raw material, a hydrogen-loaded compound is used as a catalyst, then an alcohol substance is added, a reaction is performed to generate the acetal-type or ketal-type compound. The synthesis method is simple and convenient, is high in conversion rate and yield, is safe and stable, has low toxicity and is easy to operate; the used catalyst is simple to prepare, and is cheap and easy to obtain; the reaction process is mild and efficient; the product is easy to separate and purify; the green synthesis method has a wide substrate application range, can be used for synthesizing acetal and ketal spices, and has potential industrial application value.
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Paragraph 0081-0086
(2017/05/26)
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- For detecting imaging agent of neurological disorders
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Imaging agents of formulas (I)-(V) and methods for detecting neurological disorders comprising administering to a patient in need compounds of formulas (I)-(V) capable of binding to tau proteins and β-amyloid peptides are presented herein. The invention also relates to methods of imaging Aβ and tau aggregates comprising introducing a detectable quantity of pharmaceutical formulation comprising a radiolabeled compound of formulas (I)-(V) and detecting the labeled compound associated with amyloid deposits and/or tau proteins in a patient. These methods and compositions enable preclinical diagnosis and monitoring progression of AD and other neurological disorders.
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Paragraph 1317-1318
(2016/10/08)
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- Efficient syntheses of ethyl 2-methylthio-and ethyl 2-benzylthio-6-methyl(aryl)pyrimidine-4-carboxylates and their carboxylic acid derivatives
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A simple and efficient procedure for the synthesis of ethyl 2-methylthio-and ethyl 2-benzylthio-6-methyl(aryl)-pyrimidine-4-carboxylates and their corresponding acid derivatives is reported. The products are obtained in good yields via the cyclocondensation reaction of ethyl 4-alkoxy-2-oxo-4-methyl(aryl)-but-3-enoates with 2-methylisothiourea sulfate or 2-benzylisothiourea hydrochloride, under mild, basic, aqueous conditions.
- Zanatta, Nilo,Fortes, Andressa S.,Bencke, Carlos E.,Marangoni, Mário A.,Camargo, Adriano F.,Fantinel, Cassio A.,Bonacorso, Helio G.,Martins, Marcos A. P.
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p. 827 - 835
(2015/03/14)
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- A new generation of aprotic yet Bronsted acidic imidazolium salts: Low toxicity, high recyclability and greatly improved activity
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Catalysts which have low antimicrobial toxicity and are aprotic, yet which can act as Bronsted acidic catalysts in the presence of protic additives have been developed. The catalysts are recyclable, considerably more active (i.e. can be used at 10-50 times lower loadings) and of broader scope than their antecedent generation.
- Myles, Lauren,Gore, Rohitkumar G.,Gathergood, Nicholas,Connon, Stephen J.
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supporting information
p. 2740 - 2746
(2013/10/08)
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- The catalytic versatility of low toxicity dialkyltriazolium salts: In situ modification facilitates diametrically opposed catalysis modes in one pot
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The ability of triazolium salts to serve as a precatalyst for both an acid and a powerful base/nucleophile (controlled by additives) has been exploited in a process characterised by a unique in situ catalyst modification strategy. The Royal Society of Chemistry 2013.
- Myles, Lauren,Gathergood, Nicholas,Connon, Stephen J.
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supporting information
p. 5316 - 5318
(2013/06/27)
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- ClickEnam. 1. Synthesis of novel 1,4-disubsituted-[1,2,3]-triazole-derived β-aminovinyl trifluoromethylated ketones and their copper(II) complexes
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The copper(I) catalyzed cycloaddition reaction of N-Boc propargyl amine (dipolarophile) 1 with benzyl azide (1,3-dipole) 2 was found to proceed smoothly in t-BuOH/H2O at room temperature, to furnish the corresponding 1,4-disubstituted-[1,2,3]-triazole-derived N-Boc amine 3 in good yield. Deprotection of 3 with trifluoroacetic acid and addition of the trifluoroacetate salt 4 in the presence of triethylamine, with a series of methoxyvinyl(trifluoromethyl)ketones 10-14, gave the corresponding β-aminovinyl trifluoromethylated ketones 15-19 in moderate to good yields. Two copper(II) complexes, one monomer and one dimer with chlorine double bridge, 20 and 21, respectively, were also prepared and their crystal structure determined. β-Aminovinyl trifluoromethylated ketones 15-17 and complexes 20 and 21 have been screened as potential antifungal agents and the antimalarial activity of 15 and 16 were tested against two Plasmodium falciparum strains (3D7 and W2).
- Chopin, Nicolas,Decamps, Sophie,Gouger, Aude,Médebielle, Maurice,Picot, Stéphane,Bienvenu, Anne-Lise,Pilet, Guillaume
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experimental part
p. 850 - 857
(2011/10/04)
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- Pyridinium ion catalysis of carbonyl protection reactions
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Aprotic pyridinium ions incorporating electron-withdrawing substituents on the aromatic ring are powerful catalysts for the acetalization of aldehydes and the formation of dithianes, dithiolanes, dioxanes, and dioxolanes. Under optimum conditions the best catalyst can be used at a loading as low as 0.1 mol% and can outperform a Bronsted acid catalyst with a pka of 2.2. Georg Thieme Verlag Stuttgart.
- Procuranti, Barbara,Myles, Lauren,Gathergood, Nicholas,Connon, Stephen J.
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experimental part
p. 4082 - 4086
(2010/03/05)
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- Unexpected catalysis: Aprotic pyridinium ions as active and recyclable Bronsted acid catalysts in protic media
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(Chemical Equation Presented) Simple pyridinium salt derivatives have been (rather unexpectedly) shown to promote highly efficient acetalization reactions of both aldehydes and ketones at ambient temperature. The optimum catalyst is aprotic, yet it can promote the formation of benzaldehyde dimethyl acetal at 0.1 mol % loading more efficiently than a protic Bronsted acid catalyst with a pKa of 2.2. The process is of wide scope with respect to both the nucleophilic and electrophilic components, and the ionic catalyst can be readily recovered by precipitation and reused without loss of activity.
- Procuranti, Barbara,Connon, Stephen J.
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supporting information; experimental part
p. 4935 - 4938
(2009/05/07)
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- A marcus treatment of rate constants for protonation of ring-substituted α-methoxystyrenes: Intrinsic reaction barriers and the shape of the reaction coordinate
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Rate and equilibrium constants were determined for protonation of ring-substituted α-methoxystyrenes by hydronium ion and by carboxylic acids to form the corresponding ring-substituted α-methyl α-methoxybenzyl carbocations at 25°C and I = 1.0 (KCl). The thermodynamic barrier to carbocation formation increases by 14.5 kcal/mol as the phenyl ring substituent(s) is changed from 4-MeO- to 3,5-di-NO2-, and as the carboxylic acid is changed from dichloroacetic to acetic acid. The Bronsted coefficient a for protonation by carboxylic acids increases from 0.67 to 0.77 over this range of phenyl ring substituents, and the Bronsted coefficient β for proton transfer increases from 0.63 to 0.69 as the carboxylic acid is changed from dichloroacetic to acetic acid. The change in these Bronsted coefficients with changing reaction driving force, ?α/?ΔG°av = ?β/ ?ΔG°av = 1/8Λ = 0.011, is used to calculate a Marcus intrinsic reaction barrier of Λ = 11 kcal/mol which is close to the barrier of 13 kcal/mol for thermoneutral proton transfer between this series of acids and bases. The value of α = 0.66 for thermoneutral proton transfer is greater than α = 0.50 required by a reaction that follows the Marcus equation. This elevated value of β may be due to an asymmetry in the reaction coordinate that arises from the difference in the intrinsic barriers for proton transfer at the oxygen acid reactant and resonance-stabilized carbon acid product.
- Richard, John P.,Williams, Kathleen B.
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p. 6952 - 6961
(2008/02/09)
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- Antimalarial activity of 4-(5-trifluoromethyl-1H-pyrazol-1-yl)-chloroquine analogues
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The antimalarial activity of chloroquine-pyrazole analogues, synthesized from the reaction of 1,1,1-trifluoro-4-methoxy-3-alken-2-ones with 4-hydrazino-7-chloroquinoline, has been evaluated in vitro against a chloroquine resistant Plasmodium falciparum clone. Parasite growth in the presence of the test drugs was measured by incorporation of [3H]hypoxanthine in comparison to controls with no drugs. All but one of the eight (4,5-dihydropyrazol-1-yl) chloroquine 2 derivatives tested showed a significant activity in vitro, thus, are a promising new class of antimalarials. The three most active ones were also tested in vivo against Plasmodium berghei in mice. However, the (pyrazol-1-yl) chloroquine 3 derivatives were mostly inactive, suggesting that the aromatic functionality of the pyrazole ring was critical.
- Cunico, Wilson,Cechinel, Cleber A.,Bonacorso, Helio G.,Martins, Marcos A. P.,Zanatta, Nilo,De Souza, Marcus V.N.,Freitas, Isabela O.,Soares, Rodrigo P. P.,Krettli, Antoniana U.
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p. 649 - 653
(2007/10/03)
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- Kinetics and Mechanism of Acid-catalysed Addition of Methanol to α-Methoxystyrenes
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A kinetic study of the complex behaviour of ring-substituted α-methoxystyrenes in acidic (HBr) methanol is reported.The reaction yields the corresponding acetals as the only kinetic products; these are subsequently partly hydrolysed into acetophenones with rates only a little lower than those of their formation.The rate-limiting step for methanol addition corresponds to proton attachement to the double bond, yielding an oxocarbenium ion which is trapped by methanol with a rate constant 10E4 higher than that of ion deprotonation.The rate constants for proton transfer from CH3OH2+ are in the same range of magnitude as those for proton transfer from H3O+ in water.The lyonium ion catalytic constants fit a good Young-Jencks equation with ρn-2.86 and ρr-1.28
- Toullec, Jean,El-Alaoui, Mohiedine,Bertrand, Roland
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p. 1517 - 1522
(2007/10/02)
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- Solvolysis of α-Arylvinyl Ethyl Phosphates in Aqueous and Methanolic Solutions: Intramolecular Participation by the oxy Group
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The α-arylvinyl ethyl phosphates 2a-c were synthesized and their solvolysis reactions were studied in acidic aqueous solution and methanol.In aqueous solution both the anionic and neutral diesters are subject to acid-catalyzed hydrolysis.Solvent deuterium isotope effects, the observation of general acid catalysis by formic acid, and comparison with the reaction characteristics of the acid-catalized hydrolysis of other vinyl esters and ethers indicate that the anionic diesters hydrolyze via an ASE2 mechanism.The ratio of the rate constants for hydronium ion catalyzed hydrolysis of anionic and protonated 2c, k-/k0, is 14.1 +/- 0.3.This modest acceleration is consistent with weak electrostatic stabilization of the developping cation by the anionic site, although an inductive effect must also contribute.A previously reported correlation of log kH+ for a series of alkenes of the type R1R2C=CH2 with the sum of the ?P+ parameters for R1 and R2 and k- for 2a at 25 deg C were used to calculate a value of -0.52 for the ?P+ parameter of the anionic oxy group.The estimated ?P+ of the protonated group is -0.43.These parameters and direct comparisons of hydrolysis rates of 2a-c with the hydrolysis rates of the corresponding triesters 1a-c and the α-arylvinyl methyl ethers confirm that the oxy group, in both of its ionization states, is intermediate between a oxy group and an alkoxy group in its ability to stabilize a cation.The solvolysis of 2a-c in methanol/HCl proceeds via two routes.An HCl-catalyzed pathway has characteristics very similar to the acid-catalyzed hydrolysis reactions.Another path, the rate of which is independent of HCl concentration, apparently involves intramolecular general acid catalysis of methanolysis by the prot onated oxy group.Differences in the ionization caonstants of the diesters in the two solvents apparently account for the divergent solvolysis behavior.
- Novak, Michael,Roy, Kalpana R.
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p. 4584 - 4590
(2007/10/02)
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- Ring Substituent Effects on Acetophenone Dimethyl Acetal Formation. 1. Dual-Parameter Treatment of Equilibrium Data in Methanol, Water, and Dodecane
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For substituted acetophenones, the ketone to acetal equilibrium constants, Kx, measured by a water concentration jump method, are reported.Ketone and acetal partition coefficients, P, for the water-dodecane and methanol-dodecane solvent systems provide Gibbs free energies of transfer from methanol to dodecane and from methanol to water.Both sets of results make it possible to calculate Kx values in water and dodecane; these values are compared with those directly measured in methanol and with equilibrium constants reported for other reactions involving the trigonal to tetrahedral conversion of the carbonyl carbon atom.Substituent effects tor the three solvents are examined by means of the usual dual-parameter Gibbs free energy relationships.The Young-Jencks modified Yukawa-Tsuno equation, log Kx = ρn?n + ρr(?+-?n) + i, gives ρn = 1.73, 1.81, and 0.99 for methanol, dodecane, and water, respectively, but ρr ca. 1 whatever the solvent.It is concluded that the through-ring conjugation effects are solvent independent.In contrast, the Taft-Lewis equation, log Kx = ρI?I + ρ+R?+R + i, gives ρI and ρ+R values that are both solvent dependent.The substituent effects on relative solubilities in methanol, dodecane, and water are examined by means of the equation ΠX(Y) = log PX(Y) - log PH(Y) where Y is the carbonyl or the acetal group and X is the substituent.It is shown that log PX(Y) deviates from additivity (ΠX(Y) ΠX(H) and is Y dependent) because of the effects of X on carbonyl and acetal solvation.These effects are particularly large for solvation of acetals by water molecules.Therefore, substituent effects on Kx are interpreted as being mainly due to (a) an inductive effects of the sustituted ring on ketone stability, (b) a solvent-independent through-ring conjugation effect within the ketone, and (c) a specific inhibition of acetal solvation by water molecules.
- Toullec, Jean,El-Alaoui, Mohiedine,Kleffert, Pascal
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p. 4808 - 4816
(2007/10/02)
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