- Esterification of Tertiary Amides by Alcohols Through C?N Bond Cleavage over CeO2
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CeO2 has been found to promote ester forming alcoholysis reactions of tertiary amides. The present catalytic system is operationally simple, recyclable, and it does not require additives. The esterification process displays a wide substrate scope (>45 examples; up to 93 % isolated yield). Results of a density functional theory (DFT) study combined with in situ FT-IR observations indicate that the process proceeds through rate limiting addition of a CeO2 lattice oxygen to the carbonyl group of the adsorbed acetamide species with energy barrier of 17.0 kcal/mol. This value matches well with experimental value (17.9 kcal/mol) obtained from analysis of the Arrhenius plot. Further studies by in situ FT-IR and temperature programmed desorption using probe molecules demonstrate that both acidic and basic properties are important, and consequently, CeO2 showed the best performance for the C?N bond cleavage reaction.
- Toyao, Takashi,Nurnobi Rashed, Md.,Morita, Yoshitsugu,Kamachi, Takashi,Hakim Siddiki,Ali, Md. A.,Touchy,Kon, Kenichi,Maeno, Zen,Yoshizawa, Kazunari,Shimizu, Ken-ichi
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p. 449 - 456
(2018/09/11)
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- Ionic liquids provide unique opportunities for oral drug delivery: Structure optimization and in vivo evidence of utility
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Ionic liquids (ILs) have been exploited to improve the absorption of poorly water-soluble drugs. Custom-made ILs solubilized very high quantities of the poorly water-soluble drugs, danazol and itraconazole, and maintained drug solubilization under simulated gastro-intestinal conditions. A danazol-containing self-emulsifying IL formulation gave rise to 4.3-fold higher exposure than the crystalline drug and prolonged exposure compared with a lipid formulation.
- Williams, Hywel D.,Sahbaz, Yasemin,Ford, Leigh,Nguyen, Tri-Hung,Scammells, Peter J.,Porter, Christopher J. H.
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supporting information
p. 1688 - 1690
(2014/02/14)
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- CeO2-catalysed one-pot selective synthesis of esters from nitriles and alcohols
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Thirteen kinds of metal oxides were tested for one-pot selective synthesis of esters from nitriles and alcohols. Ceria (CeO2) showed more than two orders of magnitude higher activity than the other oxides. CeO2 acted as a reusable and effective catalyst for the ester synthesis from various nitriles and alcohols under neutral and solvent-free conditions at 160 °C. This method provides a rare example for the synthesis of heteroaromatic esters, which have been difficult to synthesize by conventional catalytic esterification methods. Valuable esters such as picolinic acid alkyl esters and niacin benzyl esters were synthesized, demonstrating a practical aspect of the present method. Kinetic studies suggested the following reaction mechanism: (1) H2O and ROH dissociate on CeO2, (2) nucleophilic attack of hydroxyl species (OHδ-) to the adsorbed nitrile on CeO2, leading to the formation of the primary amide, (3) nucleophilic attack of alkoxide species (ORδ-) to the amide as the rate-limiting step.
- Tamura, Masazumi,Tonomura, Takuya,Shimizu, Ken-Ichi,Satsuma, Atsushi
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experimental part
p. 984 - 991
(2012/06/18)
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- Chemically-tagged Mitsunobu reagents for use in solution-phase chemical library synthesis
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A general method for high-throughput product purification of Mitsunobu reactions is described. Tagged phosphine and azodicarboxylate reagents are used to synthesize individual library members in solution-phase. Workup and purification are easily accomplished by post-reaction sequestration of the tagged reagents and reagent byproducts by a complementary functionalized ion exchange resin. The reagents are utilized in a 3 step library synthesis.
- Starkey, Gale W.,Parlow, John J.,Flynn, Daniel L.
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p. 2385 - 2390
(2007/10/03)
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- Mucor miehei lipase catalyzed transesterifications on aromatic and heteroaromatic substrates. A general survey
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An investigation on Mucor miehei lipase-catalyzed transesterifications of 16 aromatic and heteroaromatic esters in organic solvents is described. The points studied were the activity and regioselectivity of the enzyme-catalyzed reaction of either one or two ester groups situated in different positions on several heterocyclic systems with an aliphatic alcohol. The reactions took place in moderate to good yields and, in some cases, regioselectively.
- Martin-Munoz, Maria Gema,Fierros, Maria,Rodriguez-Franco, Maria Isabel,Conde, Santiago
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p. 6999 - 7008
(2007/10/02)
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- CONVENIENT SYNTHESIS OF ESTERS OF 2-PYRROLECARBOXYLIC ACID AND OF PYRIDINECARBOXYLIC ACIDS BY SOLID-LIQUID PHASE TRANSFER CATALYSIS WITHOUT ADDED SOLVENT
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By reaction of aromatic K-carboxylates having nucleophilic N-atom in solid-liquid phase transfer catalysis (PTC) conditions without added solvent (catalyst : tetraalkylammonium halide) with alkylating reagents, the corresponding esters are prepared.By a judicious choice of experimental conditions, the amounts of N-alkylated products can be lowered.From 2-pyrrolecarboxylic acid, the three isomers of pyridinecarboxylic acid and o-aminobenzoic acid, corresponding esters of ethyl, benzyl, n-octyl and n-cetyl, generally are obtained with good yields.
- Barry, Jean,Bram, Georges,Petit, Alain
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p. 875 - 880
(2007/10/02)
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