- Catalysis of the acylation of aromatic derivatives by metallic tosylates
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A series of metallic tosylates were prepared by ultrasonic metal activation and were further used as efficient catalysts for the acylation of aromatic derivatives.
- Morizur, Vincent,Szafranek, Jessica,Bonhomme, Dominique,Olivero, Sandra,Desmurs, Jean Roger,Du?ach, Elisabet
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p. 6813 - 6817
(2015/08/24)
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- Opening or closing the lock? when reactivity is the key to biological activity
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Thiol-mediated processes play a key role to induce or inhibit inflammation proteins. Tailoring the reactivity of electrophiles can enhance the selectivity to address only certain surface cysteines. Fourteen 2',3,4,4'- tetramethoxychalcones with different α-X substituents (X=H, F, Cl, Br, I, CN, Me, p-NO2-C6H4, Ph, p-OMe-C 6H4, NO2, CF3, COOEt, COOH) were synthesized, containing the potentially electrophilic α,β-unsaturated carbonyl unit. The assessment of their reactivity as electrophiles in thia-Michael additions with cysteamine shows a change in the reactivity of more than six orders of magnitude. Moreover, a clear correlation between their reactivity and an influence on the inflammation proteins heme oxygenase-1 (HO-1) and the inducible NO synthase (iNOS) is demonstrated. As the biologically most active compound, the α-CF3-chalcone is shown to inhibit the NO production in RAW264.7 mouse macrophages in the nanomolar range. More than a million by only one substituent: The direct manipulation of the chemical reactivity of electrophilic agents could be proven for chalcones by simply exchanging the α-hydrogen atom of the α,β-unsaturated carbonyl unit with different substituents (X), leading to a change in reactivity of more than six orders of magnitude for thia-Michael additions with cysteamine, which correlates very well with two electrophile-sensitive biological readouts (see scheme).
- Al-Rifai, Nafisah,Ruecker, Hannelore,Amslinger, Sabine
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supporting information
p. 15384 - 15395
(2013/11/06)
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- Acylation of aromatic ethers using different carboxylic acid anhydrides as acylating agents in the presence of nontoxic, noncorrosive resin amberlyst 15 as a solid acid catalyst
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Friedel-Crafts acylation of aromatic ethers, anisole, 2-methoxynaphthalene, and dimethoxybenzenes with different acid anhydrides is carried out in the presence of an inexpensive and nonhazardous solid acid, Amberlyst 15. The catalyst is reusable, thus making the process environmentally friendly.
- Pande, Manoj A.,Samant, Shriniwas D.
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experimental part
p. 754 - 761
(2011/04/12)
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- Studies towards the stereoselective α-hydroxylation of flavanones. Biosynthetic significance
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The enolates of various propiophenones, chromanones, and also analogues of naturally occurring flavanones were stereoselectively hydroxylated at the ?-position, by employing commercially available enantiopure oxaziridines, to afford the desired ?-hydroxylated target molecules in good to exceptional stereoselectivities and in moderate to good chemical yields. A mechanistic rationale is presented to account for the stereoselectivities achieved. These in vitro results were tentatively related to the stereoselective biosynthesis of enantio-enriched dihydroflavonols while questions were raised about the authenticity of certain natural compounds. CSIRO 2008.
- Border, Zola-Michele,Marais, Charlene,Bezuidenhoudt, Barend C. B.,Steenkamp, Jacobus A.
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p. 122 - 130
(2008/04/11)
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- Catalytic Friedel-Crafts acylation of aromatic ethers using Sml3
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10% mol Sml3 catalysed the Friedel-Crafts acylation of aromatic ethers by acyl chlorides in acetonitrile with the yields of 48-82%. Reactions of various substituted aromatic ethers with acyl chloride were studied. The structures of compounds were established by IR and 1H NMR. The main product obtained with anisole is the para-substituted compound with only a trace (3, a pattern repeated with the other aromatic ethers used.
- Chen, Xiaohang,Yu, Mingxin,Wang, Meijun
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- Phase-vanishing method: Friedel-Crafts acylation of thiophene with tin tetrachloride and its application to convenient parallel synthesis
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Phase-vanishing (PV) method was applied to Friedel-Crafts acylations of aromatic compounds with tin tetrachloride as a Lewis acid. The reaction proceeded smoothly and acylation products were obtained in good yield. Parallel, four different Friedel-Crafts acylation reactions were carried out successfully based on the present PV method.
- Matsubara, Hiroshi,Yasuda, Shinji,Ryu, Ilhyong
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p. 247 - 249
(2007/10/03)
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- Evidence that the availability of an allylic hydrogen governs the regioselectivity of the Wacker oxidation
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The allylic hydrogen is found to have a dramatic effect on the regioselectivity of the Wacker oxidation, leading to the postulation that an agostic hydrogen or enyl (σ + π) complex helps to stabilise the key intermediate.
- Gaunt,Yu,Spencer
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p. 1844 - 1845
(2007/10/03)
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- Modulation of lifetimes and diastereomeric discrimination in triplet- excited substituted butane-1,4-diones through intramolecular charge-transfer quenching
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Triplet lifetimes have been determined for the diastereomers of a broad set of butane-1,4-dione derivatives (1-3). A remarkable dependence of lifetimes on conformational preferences is revealed in that the lifetimes are shorter for the meso diastereomers of 1-3 than those for the racemic ones. The intramolecular β-phenyl quenching is promoted in the case of meso diastereomers by virtue of the gauche relationship between the excited carbonyl group and the β-aryl ring, while a distal arrangement in the lowest energy conformation (H-anti) in racemic diastereomers prevents such a deactivation. The involvement of charge transfer in the intramolecular β- phenyl quenching is suggested by the correlation of the triplet lifetimes of the meso diastereomers of compounds 2 with the nature of the substituent on the β-phenyl rings. In the case of racemic diastereomers, p-methoxy substitution on the β-phenyl ring (2-OCH3, 3-OCH3) also led to a decrease of the triplet lifetimes when compared to those of the nonsubstituted compounds (2-H, 3-H). This shortening is accounted for by the deactivation of a small proportion of the excited molecules through β-phenyl quenching. In addition to the above factors, the lifetimes in the case of meso diastereomers can further be controlled by increasing the energy spacing between the T1 and T2 states, since β-phenyl quenching occurs from the latter for compounds 2 and 3. Through a rational conformational control, a surprisingly long triplet lifetime (300 ns) has been measured for the first time for a purely n,π* triplet-excited β-phenylpropiophenone dimer (1- rac).
- Moorthy,Monahan,Sunoj,Chandrasekhar,Bohne
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p. 3093 - 3103
(2007/10/03)
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- Effects of Monoalkyl Phosphate Surfactants upon the Acid Hydrolysis of Dioxolanes
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The pseudophase ion-exchange (PPIE) model was tested in the presence and absence of buffer for the acid-catalyzed hydrolysis of 2-(p-methoxyphenyl)-1,3-dioxolane (p-MPD) and 2-(2,4-dimethoxyphenyl)-2-ethyl-1,3-dioxolane (2,4-DPED) in the presence of sodium monoalkyl phosphate surfactants.The maximum increase in the observed rate constant was about 10-fold for both substrates.The second-order rate constant for the acid hydrolysis of 2,4-DPED in the micellar phase of the phosphate surfactants (k2,m = 14.3 M-1 s-1) is similar to that observed in the bulk aqueous phase (k2,w = 12.7 M-1 s-1).When p-MPD was used as a substrate, a modest 3-fold enhancement in the second-order rate constant is found.The application of the PPIE model requires careful pH measurements, since the surfactant itself is a weak acid.
- Ruzza, Angelo A.,Walter, Maria Rosania K.,Nome, Faruk,Zanette, Dino
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p. 1463 - 1467
(2007/10/02)
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- The Synthesis of Indan-1-ones and Isocoumarins
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A flexible synthetic route leading via indan-1-ones to variously methylated and oxygenated isocoumarins is described.The indanones are prepared by alternative routes involving intramolecular Friedel-Crafts cyclisation of arylpropionic acids or pericyclic ring closure of acrylophenones.The influence of substitution on the rate of the pericyclic reaction is assessed.
- Carter, Rachel H.,Garson, Mary J.,Hill, Robert A.,Staunton, James,Sunter, David C.
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p. 471 - 479
(2007/10/02)
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