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Racemic Alcohols (racemic + alcohol)
Selected AbstractsChemInform Abstract: Immobilized Manihot esculenta Preparation as a Novel Biocatalyst in the Enantioselective Acetylation of Racemic Alcohols.CHEMINFORM, Issue 48 2008Luciana L. Machado Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Rational Design of an L-Histidine-Derived Minimal Artificial Acylase for the Kinetic Resolution of Racemic Alcohols.CHEMINFORM, Issue 5 2005Kazuaki Ishihara Abstract For Abstract see ChemInform Abstract in Full Text. [source] Cationic Carboxylato Complexes of Dirhodium(II) with Oxo Thioethers: Catalysts for Silane Alcoholysis under Homogeneous and Liquid-Liquid Biphasic ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2007Andrea Biffis Abstract A set of cationic dirhodium(II) complexes with oxo thioethers was prepared and employed as catalysts for the silane alcoholysis reaction. The complexes were found to be highly active under homogeneous conditions, both in the absence and in the presence of a solvent, including coordinating solvents such as N,N -dimethylformamide; the catalysts could be conveniently employed in concentrations as low as 0.01 mol,%, and a maximum TON of 30000 was recorded after 24,h. The same catalysts were also employed under liquid-liquid biphasic conditions with an ionic liquid as the catalyst-containing phase: comparable catalytic activity was observed under these conditions, and the catalyst-containing phase could be recovered and recycled. A chiral cationic dirhodium(II) complex was also prepared in the frame of this work; kinetic resolution of a racemic alcohol was attempted with this catalyst, unfortunately without success. [source] Synthetic Scope and Mechanistic Studies of Ru(OH)x/Al2O3 -Catalyzed Heterogeneous Hydrogen-Transfer ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2005Kazuya Yamaguchi Dr. Abstract Three kinds of hydrogen-transfer reactions, namely racemization of chiral secondary alcohols, reduction of carbonyl compounds to alcohols using 2-propanol as a hydrogen donor, and isomerization of allylic alcohols to saturated ketones, are efficiently promoted by the easily prepared and inexpensive supported ruthenium catalyst Ru(OH)x/Al2O3. A wide variety of substrates, such as aromatic, aliphatic, and heterocyclic alcohols or carbonyl compounds, can be converted into the desired products, under anaerobic conditions, in moderate to excellent yields and without the need for additives such as bases. A larger scale, solvent-free reaction is also demonstrated: the isomerization of 1-octen-3-ol with a substrate/catalyst ratio of 20,000/1 shows a very high turnover frequency (TOF) of 18,400 h,1, with a turnover number (TON) that reaches 17,200. The catalysis for these reactions is intrinsically heterogeneous in nature, and the Ru(OH)x/Al2O3 recovered after the reactions can be reused without appreciable loss of catalytic performance. The reaction mechanism of the present Ru(OH)x/Al2O3 -catalyzed hydrogen-transfer reactions were examined with monodeuterated substrates. After the racemization of (S)-1-deuterio-1-phenylethanol in the presence of acetophenone was complete, the deuterium content at the ,-position of the corresponding racemic alcohol was 91,%, whereas no deuterium was incorporated into the ,-position during the racemization of (S)-1-phenylethanol-OD. These results show that direct carbon-to-carbon hydrogen transfer occurs via a metal monohydride for the racemization of chiral secondary alcohols and reduction of carbonyl compounds to alcohols. For the isomerization, the ,-deuterium of 3-deuterio-1-octen-3-ol was selectively relocated at the ,-position of the corresponding ketones (99,% D at the ,-position), suggesting the involvement of a 1,4-addition of ruthenium monohydride species to the ,,,-unsaturated ketone intermediate. The ruthenium monohydride species and the ,,,-unsaturated ketone would be formed through alcoholate formation/,-elimination. Kinetic studies and kinetic isotope effects show that the RuH bond cleavage (hydride transfer) is included in the rate-determining step. [source] Kinetic Resolution of Racemic Secondary Alcohols Mediated by N -Methylimidazole in the Presence of Optically Active Acyl ChloridesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2010Loïc Leclercq Abstract N -Methylimidazole was used to promote the acylation of secondary racemic alcohols and to carry out their kinetic resolution through intermediate chiral acyl imidazolium chlorides. The kinetic resolution could be turned into a catalytic process in the presence of a catalytic amount of N -methylimidazole. [source] | ||||||||||