- Zirconium tetrachloride (ZrCl4) catalyzed highly chemoselective and efficient acetalization of carbonyl compounds
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Zirconium tetrachloride (ZrCl4) is a highly efficient and chemoselective catalyst for the acetalization, and in-situ transacetalization of carbonyl compounds under mild reaction conditions.
- Firouzabadi, Habib,Iranpoor, Nasser,Karimi, Babak
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- Robust acidic pseudo-ionic liquid catalyst with self-separation ability for esterification and acetalization
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The novel acidic pseudo-ionic liquid catalyst with self-separation ability has been synthesized through the quaternization of triphenylphosphine and the acidification with silicotungstic acid. The pseudo-IL showed high activities for the esterification with average conversions over 90%. The pseudo-IL showed even higher activities for acetalization than traditional sulfuric acid. The homogeneous catalytic process benefited the mass transfer efficiency. The pseudo-IL separated from the reaction mixture automatically after reactions, which was superior to other IL catalysts. The high catalytic activities, easy reusability and high stability were the key properties of the novel catalyst, which hold great potential for green chemical processes.
- Shi, Yingxia,Liang, Xuezheng
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p. 1413 - 1421
(2019/05/04)
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- Potent α-amino-β-lactam carbamic acid ester as NAAA inhibitors. Synthesis and structure-activity relationship (SAR) studies
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4-Cyclohexylbutyl-N-[(S)-2-oxoazetidin-3-yl]carbamate (3b) is a potent, selective and systemically active inhibitor of intracellular NAAA activity, which produces profound anti-inflammatory effects in animal models. In the present work, we describe structure-activity relationship (SAR) studies on 3-aminoazetidin-2-one derivatives, which have led to the identification of 3b, and expand these studies to elucidate the principal structural and stereochemical features needed to achieve effective NAAA inhibition. Investigations on the influence of the substitution at the β-position of the 2-oxo-3-azetidinyl ring as well as on the effect of size and shape of the carbamic acid ester side chain led to the discovery of 3ak, a novel inhibitor of human NAAA that shows an improved physicochemical and drug-like profile relative to 3b. This favourable profile, along with the structural diversity of the carbamic acid chain of 3b, identify this compound as a promising new tool to investigate the potential of NAAA inhibitors as therapeutic agents for the treatment of pain and inflammation.
- Nuzzi, Andrea,Fiasella, Annalisa,Ortega, Jose Antonio,Pagliuca, Chiara,Ponzano, Stefano,Pizzirani, Daniela,Bertozzi, Sine Mandrup,Ottonello, Giuliana,Tarozzo, Glauco,Reggiani, Angelo,Bandiera, Tiziano,Bertozzi, Fabio,Piomelli, Daniele
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supporting information
p. 138 - 159
(2016/02/18)
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- Driving an equilibrium acetalization to completion in the presence of water
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Formation of an acetal from a carbonyl substrate by condensation with an alcohol is a classical reversible equilibrium reaction in which the water formed must be removed to drive the reaction to completion. A new method has been developed for acetalization of carbonyl substrates by diols in the presence of water. Complexation of poly(4-styrenesulfonic acid) with poly(4-vinylpyridine) generates a catalytic membrane of polymeric acid at the interface between two parallel laminar flows in a microchannel of a microflow reactor. The catalytic membrane provides a permeable barrier between the organic layer and water-containing layer in the reaction, and permits discharge of water to the outlet of the microreactor to complete the acetalization. Condensation of a variety of carbonyl substrates with diols proceeded in the presence of water in the microflow device to give the corresponding acetals in yields of up to 97% for residence times of 19 to 38 s. the Partner Organisations 2014.
- Minakawa, Maki,Yamada, Yoichi M. A.,Uozumi, Yasuhiro
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p. 36864 - 36867
(2014/11/08)
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- CARBAMATE DERIVATIVES OF LACTAM BASED N-ACYLETHANOLAMINE ACID AMIDASE (NAAA) INHIBITORS
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Described herein are compounds and pharmaceutical compositions which inhibit N-acylethanolamine acid amidase (NAAA). Described herein are methods for synthesizing the compounds set forth herein and methods for formulating these compounds as pharmaceutical compositions which include these compounds. Also described herein are methods of inhibiting NAAA in order to sustain the levels of palmitoylethanolamide (PEA) and other N-acylethanolamines (NAE) that are substrates for NAAA, in conditions characterized by reduced concentrations of NAE. Also, described here are methods of treating and ameliorating pain, inflammation, inflammatory diseases, and other disorders in which modulation of fatty acid ethanolamides is clinically or therapeutically relevant or in which decreased levels of NAE are associated with the disorder.
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Paragraph 0637; 0638
(2014/09/29)
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- Indium(III) triflate catalysed transacetalisation reactions of diols and triols under solvent-free conditions
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Acyclic acetals and ketals undergo transacetalisation in the presence of catalytic quantities of indium(III) triflate (In(OTf)3) and diols or triols under solvent-free conditions to generate the corresponding cyclic acetals and ketals in excellent yield. The methodology has been further developed to encompass a tandem acetalisation-acetal exchange protocol, which provides a facile and high yielding route to cyclic ketals from unreactive ketones under very mild reaction conditions.
- Smith, Brendan M.,Kubczyk, Tomasz M.,Graham, Andrew E.
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experimental part
p. 7775 - 7781
(2012/09/21)
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- Synthesis of a novel multi-SO3H functionalized ionic liquid and its catalytic activities
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A novel multi-SO3H functionalized ionic liquid is synthesized and a detailed account of its cata- lytic activities in acetalization and acetylation is given. The results showed that the ionic liquid is very efficient in the conventional acid-catalyzed reactions with good to excellent yields within a short reaction time. Oper- ational simplicity, small amounts required, low cost of the catalyst, high yields, scalability and reusability are the key features of this methodology, which indicates the high potentialities of the novel ionic liquid to be used in environmentally friendly processes. Pleiades Publishing, Ltd., 2012.
- Xudong, Sun,Huiquan, Xiao,Yijun, Du,Jingjing, Zhang,Xuezheng, Liang,Chenze, Qi
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p. 301 - 305
(2012/10/29)
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- Indium triflate mediated tandem acetalisation-acetal exchange reactions under solvent-free conditions
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Acyclic acetals and ketals undergo exchange reactions in the presence of catalytic quantities of indium(III) triflate and diols to generate the corresponding cyclic acetals and ketals in excellent yield. The protocol is rapid, employs mild conditions and can be adapted to employ solvent-free reaction conditions. We have further developed this methodology to encompass a tandem acetalisation-acetal exchange protocol which provides facile access to cyclic ketals from unreactive ketones also under very mild, solvent-free reaction conditions.
- Smith, Brendan M.,Graham, Andrew E.
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experimental part
p. 6281 - 6283
(2011/12/14)
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- Acetalization of carbonyl compounds catalyzed by bismuth triflate under solvent-free conditions
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Carbonyl compounds were converted to the corresponding 1,3-dioxolanes and 1,3-dioxanes with ethylene glycol and 1,3-propandiol in the presence of bismuth triflate under solvent-free conditions. In addition, high chemoselective protection of aldehydes in the presence of ketones has been achieved.
- Aliyan, Hamid,Fazaeli, Razieh,Massah, Ahmad Reza,Momeni, Ahmad Reza,Naghash, Hamid Javaherian,Moeinifard, Behzad
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experimental part
p. 873 - 876
(2012/04/05)
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- Highly efficient and chemoselective acetalization of carbonyl compounds catalyzed by new and reusab e zirconyl triflate, zr0(0tf)2
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Various types of aromatic aldehydes were efficiently converted to their corresponding 1,3-dioxanes and 1,3-dioxolane with 1,3-propanediol and ethylene glycol, respectively, in the presence of catalytic amount of ZrO(OTf) 2 in acetonitrile at room temperature. The catalyst can be reused several times without loss of its catalytic activity. Very short reaction times, selective acetalization of aromatic aldehydes in the presence of aliphatic aldehydes and ketones, very mild reaction conditions, reusability of the catalyst, and easy workup are noteworthy advantages of this method.
- Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah,Yazdani, Parvin,Ghorjipoor, Saeedeh
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experimental part
p. 131 - 135
(2009/09/30)
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- Correlation between 13C and 17O chemical shifts and torsional strain in spiroacetals
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The relationship between the 13C and 17O NMR chemical shifts and the dihedral energies (non-bonding interactions) of 1,4-dioxaspiro[4.4]nonane, 1,4-dioxa- and 6,10-dioxaspiro[4.5]decane, 1,4-dioxa- and 6,11-dioxaspiro[4.6]undecane, 1,5-dioxaspiro[5.5]undecane, 1,5-dioxa and 7,12-dioxaspiro[5.6]dodecane and 1,6-dioxaspiro[6.6]tridecane were analyzed. These data showed correlation of the non-bonding interactions with the chemical shift of the spiranic carbon, as well as a linear relationship between 13C and 17O.
- Guerrero-Alvarez, Jorge Antonio,Ariza-Castolo, Armando
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p. 795 - 798
(2007/10/03)
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- Highly efficient and chemoselective interchange of 1,3-oxathioacetals and dithioacetals to acetals promoted by N-halosuccinimide
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Highly efficient interconversion of a range of 1,3-oxathiolanes, 1,3-dithiolanes and 1,3-dithianes to their acetals at ambient temperature using N-bromosuccinimide or N-chlorosuccinimide and different types of alcohols and diols was investigated.
- Karimi, Babak,Seradj, Hassan,Maleki, Jafar
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p. 4513 - 4516
(2007/10/03)
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- An efficient procedure for the preparation of cyclic ketals and thioketals catalyzed by zirconium sulfophenyl phosphonate
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A convenient method for the preparation of cyclic ketals and thioketals using zirconium sulfophenyl phosphonate as catalyst is described.
- Curini,Epifano,Marcotullio,Rosati
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p. 1182 - 1184
(2007/10/03)
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- 5. Formation of cyclic ketals from hydroxyalkyl enol ethers, a stereoelectronically controlled endo-trig-cyclizatitm process
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Acid-catalyzed cyclic ketal formation vs. hydrolysis of a series of hydroxyalkyl cyclic enol ethers in the presence of 1 equiv. of H2O, and acid-catalyzed cyclic-ketal formation (same ketals as above) vs. methanolysis of a series of mixed pent-4-enyl hydroxyalkyl ketals with N-bromosuccinimide in the presence of 4 equiv. of MeOH led to the same result: the intramolecular cyclization processes occur at similar rates as the intermolecular H2O or MeOH attacks independently of the size of the rings formed (five-, six-, or seven-niembered), by cyclizations. These results can be explained by the facts that, due to stereoelectronic effects which impose a torsional strain to the sp2 hybridized O-atom, the cyclization activation enthalpy decreases, as the length of the hydroxyalkyl chain increase (ease of cyclization: 7 > 6 > 5), whereas the entropy factor favors the cyclization in the reverse fashion (ease of cyclization: 5 > 6 > 7). The various reaction pathways have been examined using the semi-empirical Hamiltonian AM1, and the results obtained confirm that large-ring formation is enthalpically much favored over the cyclization processes leading to small rings (ease of cyclization: 7 > 6 > 5).
- Deslongchamps, Pierre,Dory, Yves L.,Li, Shigui
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- Stereospecific annulation of hydroxy vinyl ethers. Synthetic application to polyfunctionalized cyclic compounds
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Stereospecific annulation of hydroxy vinyl ethers in the presence of triflic anhydride and tertiary amines and its synthetic application are described. Each 1-hydroxy-2-oxabicyclo(n.4.0)alkane, 2-oxabicyclo(n.4.0)alk-1(6)-ene and 2-oxabicyclo(n.4.0)alk-1(6+n)-ene is stereoselectivity synthesized from the same hydroxy vinyl ether depending on the choice of the reaction conditions (temperature, solvent and tertiary amine). These compounds lead to polyfunctionalized cyclic compounds and some natural product. We propose that this annulation reaction proceeds through a pure S(N)2-like mechanism.
- Hanaki, Naoyuki,Ishihara, Kazuaki,Kaino, Makoto,Naruse, Yuji,Yamamoto, Hisashi
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p. 7297 - 7320
(2007/10/03)
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- Synthese d'acetals cycliques dans des conditions douces; Applications a l'acetalisation du chloramphenicol
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Acetalization of 1-2 and 1-3 diols, even as sterically crowded as chloramphenicol, by carbonyl derivatives with substituents of various sizes has been performed at room temperature under mild conditions, by using heterogeneous catalysis (sulfonated polystyrene) in the presence of molecular sieves.Several new acetals of chloramphenicol have thus been obtained in good yields, isolated and characterized.
- Meslard, J. C.,Subira, F.,Vairon, J. P.,Guy, A.,Garreau, R.
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- Kinetic cyclohexylidenation and isopropylidenation of aldose diethyl dithioacetals
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Aldose diethyl dithioacetals react with 1.2 equivalents of 1-ethoxycyclohexene or 2-methoxypropene in N,N-dimethylformamide at 0° with p-toluenesulfonic acid as catalyst to give the five-membered ring acetal attached to the two terminal oxygen atoms as the major product in every case. In most instances, a small proportion of the terminal, six-membered ring acetal was also obtained, and in a few cases, terminal seven-membered ring acetals were also isolated. Cyclohexylidenation at room temperature gave the same products, but isopropyl-idenation at room temperature resulted in certain cases in partial rearrangement. Cyclohexylidenation reactions gave smaller proportions of the minor six- and seven-membered ring products. Structures were established from13C-n.m.r. and mass spectra. The13C-n.m.r. spectra of model cyclohexylidene derivatives were found very similar to those of isopropylidene derivatives previously studied. Two new features useful for structure determination were noted when the spectra of the precursor diols were compared with those of both types of derived acetals; the chemical shift of C-2 of a 1,3-propanediol derivative was shifted upfield by 6-9 p.p.m. on acetalation and the shifts of the diol carbon atoms attached to oxygen were affected according to the type of acetal and ring-size formed. Similar observations were made for methylene acetals.
- Grindley, T. Bruce,Cote, Christian J.P.,Wickramage, Chandra
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p. 215 - 238
(2007/10/02)
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