- Highly efficient and green esterification of carboxylic acids in deep eutectic solvents without any other additives
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A protocol that carboxylic acids esterifies with the quaternary ammonium salt of deep eutectic solvent (DES) is presented, which opens a new access to ester using DES as alkylating agent, solvent, and catalyst. The reaction runs smoothly in DES without any other additives. Substituted cinnamic acids, aromatic acids, and aliphatic acids can be esterified in moderate to good yields. The advantages of this reaction include excellent functional group compatibility and simple reaction procedure.
- Yasmin, Sumera,Sheng, Wen-Bing,Peng, Cai-Yun,Rahman, Atta-ur,Liao, Duan-Fang,Choudhary, M. Iqbal,Wanga, Wei
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supporting information
p. 68 - 75
(2017/12/26)
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- Tuning the interactions between electron spins in fullerene-based triad systems
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A series of six fullerene-linker-fullerene triads have been prepared by the stepwise addition of the fullerene cages to bridging moieties thus allowing the systematic variation of fullerene cage (C60 or C70) and linker (oxalate, acetate or terephthalate) and enabling precise control over the inter-fullerene separation. The fullerene triads exhibit good solubility in common organic solvents, have linear geometries and are diastereomerically pure. Cyclic voltammetric measurements demonstrate the excellent electron accepting capacity of all triads, with up to 6 electrons taken up per molecule in the potential range between -2.3 and 0.2 V (vs Fc+/Fc). No significant electronic interactions between fullerene cages are observed in the ground state indicating that the individual properties of each C60 or C 70 cage are retained within the triads. The electron-electron interactions in the electrochemically generated dianions of these triads, with one electron per fullerene cage were studied by EPR spectroscopy. The nature of electron-electron coupling observed at 77 K can be described as an equilibrium between doublet and triplet state biradicals which depends on the inter-fullerene spacing. The shorter oxalate-bridged triads exhibit stronger spin-spin coupling with triplet character, while in the longer terephthalate-bridged triads the intramolecular spin-spin coupling is significantly reduced.
- Lebedeva, Maria A.,Chamberlain, Thomas W.,Davies, E. Stephen,Thomas, Bradley E.,Schroeder, Martin,Khlobystov, Andrei N.
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p. 332 - 343
(2014/03/21)
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- Catalytic phosphorus(V)-mediated nucleophilic substitution reactions: Development of a catalytic appel reaction
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Catalytic phosphorus(V)-mediated chlorination and bromination reactions of alcohols have been developed. The new reactions constitute a catalytic version of the classical Appel halogenation reaction. In these new reactions oxalyl chloride is used as a consumable stoichiometric reagent to generate the halophosphonium salts responsible for halogenation from catalytic phosphine oxides. Thus, phosphine oxides have been transformed from stoichiometric waste products into catalysts and a new concept for catalytic phosphorus-based activation and nucleophilic substitution of alcohols has been validated. The present study has focused on a full exploration of the scope and limitations of phosphine oxide catalyzed chlorination reactions as well as the development of the analogous bromination reactions. Further mechanistic studies, including density functional theory calculations on proposed intermediates of the catalytic cycle, are consistent with a catalytic cycle involving halo- and alkoxyphosphonium salts as intermediates.
- Denton, Ross M.,An, Jie,Adeniran, Beatrice,Blake, Alexander J.,Lewis, William,Poulton, Andrew M.
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experimental part
p. 6749 - 6767
(2011/10/02)
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- Modulators of LXR
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Compounds of the invention, such as compounds of formula (I): where n, m, A, B, R1, R2, R3, R4 and R5 are defined herein, are useful as modulators of the activity of liver X receptors. Pharmaceutical compositions containing the compounds and methods of using the compounds are also disclosed.
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- Alkylation with Oxalic Esters. Scope and Mechanism.
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Alkyl oxalates are well suited for use as standard synthetic reagents in N-, O-, or S-alkylations and often display an interesting regioselectivity.The mechanism seems to be a direct alkylation of the substrate anion.
- Bergman, Jan,Norrby, Per-Ola,Sand, Peter
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p. 6113 - 6124
(2007/10/02)
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- Electro-organic reactions. Part 27. The mechanism of cathodic cleavage of activated esters; oxalates, squarates and oxamates
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Esters of oxalic acid, 3,4-dihydroxy-3-cyclobutene-1,2-dione (squaric acid), and oxamic acid, are reduced cathodically at modest potentials. In aprotic solvent, and on the cyclic voltammetric time scale, the esters are cleaved to the corresponding alkane. For oxalates, the mechanism of cathodic cleavage was investigated thoroughly by voltammetry, coulometry, and detailed product analysis. On the time scale of controlled potential electrolysis the rapid electrogenerated base-catalysed hydrolysis of the esters by adventitious water competes with cathodic cleavage. Similarly, rapid base-catalysed transesterification involving oxalates and added alcohols is observed which provides a practical method of reductively cleaving alcohols to alkanes by co-electrolysis of a mixture of alcohol and readily available oxalate (e.g. diethyloxalate). The leaving group in such cathodic fragmentation is the half-ester anion and the efficiency of reaction depends on the stability of the other, radical, fragment.
- Islam, Nazar-ul,Sopher, David W.,Utley, James H.P.
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p. 959 - 970
(2007/10/02)
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- Preparing oxalic acid esters
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A method for the preparation of organic esters of oxalic acid by reaction of carbon monoxide under pressure with the corresponding alcohol is disclosed, the improvement consisting in the use of a quite particular catalyst system. The catalyst is a binary system in which the principal member is a palladium complex and the co-catalyst is a compound, preferably an organic compound having an acidic nature, no matter how weak.
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- N,N'(Cyano-phenylene)dioxamic acids and esters
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It has now been discovered that novel compounds of FIG. 1 SPC1 are useful in the prophylactic treatment of sensitized humans and animals for allergy and all anaphylactic reactions of a reagin or non-reagin mediated nature. Additionally, these compounds are intermediates to the acids and physiologically acceptable salts which also have the same biological utility. The compounds of the invention are formulated with pharmaceutical carriers for oral, parenteral, inhalation or rectal means of administration.
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