- Ketalization of ketones to 1,3-dioxolanes and concurring self-aldolization catalyzed by an amorphous, hydrophilic SiO2-SO3H catalyst under microwave irradiation
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The amorphous, mesoporous SiO2-SO3H catalyst with a surface area of 115 m2 g-1 and 1.32 mmol H+ per g was very efficient for the protonation of ketones on a 10percent (m/m) basis, and the catalyst-bound intermediates can be trapped by polyalcohols to produce ketals in high yields or suffer aldol condensations within minutes under low-power microwave irradiation. The same catalyst can easily reverse the ketalization reaction. Printed in Brazil-
- Barbosa, Sandro L.,Ottone, Myrlene,De Almeida, Mainara T.,Lage, Guilherme L.C.,Almeida, Melina A.R.,Nelson, David Lee,Dos Santos, Wallans T.P.,Clososki, Giuliano C.,Lopes, Norberto P.,Klein, Stanlei I.,Zanatta, Lucas D.
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p. 1663 - 1671
(2018/06/29)
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- PALLADIUM CATALYSED HECK ARYLATION OR VINYLATION OF 1-SUBSTITUTED OLEFINS
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The present invention relates to a process for preparing arylated or vinylated olefins.
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Page/Page column 13-14; 16-17
(2008/06/13)
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- Pd(II)-catalyzed conversion of styrene derivatives to acetals: Impact of (-)-sparteine on regioselectivity
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Pd[(-)-sparteine]Cl2 catalyzes the formation of dialkyl acetals from styrene derivatives with Markovnikov regioselectivity. The substrate scope of this reaction has been investigated, and initial mechanistic studies indicate that the reaction proceeds through an enol ether intermediate and a Pd-hydride.
- Balija, Amy M.,Stowers, Kara J.,Schultz, Mitchell J.,Sigman, Matthew S.
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p. 1121 - 1124
(2007/10/03)
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- The Heck reaction of electron-rich olefins with regiocontrol by hydrogen-bond donors
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No salt please: Halide scavengers AgOTf and TlOAc are not required for the Heck coupling of electron-rich olefins with aryl bromides and chlorides. Using ammonium additives, these reactions can be carried out in either an imidazolium ionic liquid or a common molecular solvent, thus furnishing 1,1′- disubstituted olefins in high yields with excellent regioselectivities. (Chemical Equation Presented).
- Mo, Jun,Xiao, Jianliang
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p. 4152 - 4157
(2007/10/03)
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- Palladium-catalysed direct regioselective synthesis of cyclic ketals from electron-rich olefins and aryl bromides in ionic liquids
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The Heck reaction comprises one of the most important carbon-carbon coupling reactions in organic synthesis. The popularity of the reaction is attributable to the broad availability of aryl halides and to the tolerance of the reaction for a wide variety o
- Hyder, Zeynab,Mo, Jun,Xiao, Jianliang
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p. 1699 - 1704
(2007/10/03)
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- NOVEL METHODS FOR THE TREATMENT OF INFLAMMATORY DISEASES
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Methods of inhibiting the cytokine or biological activity of Macrophage Migration Inhibitory Factor (MIF) comprising contacting MIF with a compound of formula (I) are provided. The invention also relates to methods of treating diseases or conditions where MIF cytokine or biological activity is implicated comprising administration of compounds of formula (I), either alone or as a part of combination therapy. Novel compounds of formula (I) are also provided for.
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- 2,4,4,6-Tetrabromo-2,5-cyclohexadienone (TABCO) as a versatile, efficient, and chemoselective catalyst for the acetalization and transacetalization of carbonyl compounds, the preparation of acetonides from epoxides and acylals (1,1-diacetates) from aldehydes
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The efficient and chemoselective preparation of acetals and ketals from carbonyl compounds, transacetalization reactions, the conversion of epoxides to acetonides, and the preparation of acylals from aldehydes in the presence of catalytic amounts of 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO) are described.
- Firouzabadi, Habib,Iranpoor, Nasser,Shaterian, Hamid Reza
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p. 2195 - 2205
(2007/10/03)
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- Tri-n-butylstannyl chloride-sodium cyanoborohydride mediated regioselective reductive demethoxylation of alkyl methyl ketals
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A regioselective reductive demethoxylation of alkyl methyl ketals employing sodium cyanoborohydride in the presence of a catalytic amount of tri-n-butyltin chloride as Lewis acid is described.
- Srikrishna,Viswajanani
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p. 621 - 625
(2007/10/03)
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- Dialkylation of acetophenones and acetophenone ethylene ketals with 1,8-bis(trimethylsilyl)-2,6-octadiene (BISTRO). Semi-empirical SCF studies of α-methoxy-α-methylbenzyl cations
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Titanium tetrachloride mediated dialkylation of acetophenones or acetophenone ethylene ketals by 1,8-bis(trimethylsilyl)-2,6-octadiene (BISTRO) leads to a mixture of dl and meso 1-alkyl-1-phenyl-2,5-divinylcyclopentane. Better yields are observed with p-b
- Burtin, Guillaume,Pellissier, Helene,Santelli, Maurice
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p. 2075 - 2086
(2007/10/03)
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- A mild and simple procedure for the reductive cleavage of acetals and ketals
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A convenient, mild and simple procedure, employing sodium cyanoborohydride in the presence of either catalytic or stoichiometric amount of boron trifluoride etherate in dry THF, for the reductive cleavage of the acetals and ketals is described.
- Srikrishna, Adusumilli,Viswajanani, Ranganathan
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p. 3339 - 3344
(2007/10/02)
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- 18O-Isotope Effect in 13C Nuclear Magnetic Resonance Spectroscopy. 5 - Substituent Group Electronic Effects in Substituted Acetophenones
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A series of para- and meta-substituted acetophenones were prpared which were highly labeled with 18O at the carbonyl function.The natural abundance 13C NMR spectra of the compounds were recorded and the 18O-isotope-induced shifts of the carbonyl carbon we
- Risley, John M.,DeFrees, Shawn A.,Etten, Robert L. Van
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- Free Radical Reactions in Solution. Part 6. Thermal Decomposition of Substituted Dibenzyl Mercurials in Solution. An improved ?. Scale
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The kinetics of the decomposition of ten substituted dibenzylmercury compounds in solution have been determined in the temperature range 126-156 deg C.From the relative rates at 140.2 deg C, a new scale of substituent constants ?. applicable to
- Dinctuerk, Suphi,Jackson, Richard A.,Townson, Michael,Agirbas, Hikmet,Billingham, Norman C.,March, Gary
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p. 1121 - 1126
(2007/10/02)
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