4906-24-5Relevant articles and documents
A multicatalyst system for the one-pot desymmetrization/oxidation of meso-1,2-alkane diols
Mueller, Christian E.,Hrdina, Radim,Wende, Raffael C.,Schreiner, Peter R.
supporting information; experimental part, p. 6309 - 6314 (2011/08/07)
Two is better than one: We demonstrate the viability of an organocatalytic reaction sequence along a short peptide backbone that carries two independent catalytic functionalities, which allow the rapid, one-pot acylative desymmetrization and oxidation of meso-alkane-1,2-diols to the corresponding acetylated acetoins with good yields and enantioselectivities (see scheme). Copyright
Ruthenium-catalyzed addition of carboxylic acids or cyclic 1,3-dicarbonyl compounds to propargyl alcohols
Berger, Stefanie,Haak, Edgar
experimental part, p. 6630 - 6634 (2011/02/21)
Monomeric ruthenium(O) complexes containing redox-coupled dienone ligands were found to catalyze the regio-selective addition of carboxylic acids or cyclic 1,3-dicarbonyl compounds to propargyl alcohols.
One-Pot desymmetrization of meso-l,2-hydrocarbon diols through acylation and oxidation
Mueller, Christian E.,Zell, Daniela,Schreiner, Peter R.
supporting information; experimental part, p. 9647 - 9650 (2010/04/28)
Avoid racemization! Short lipophilic oligopeptides utilizing nucleophilic N-jt-methyl histidine residues catalyze the desymmetrization of wieso-l,2-diols with enantiomeric ratios of up to 94:6. Direct one-pot oxidation, which avoids the well-known racemiz
Products, kinetic regularities, and mechanism of thermal decomposition of ethyl(methyl)dioxirane
Grabovskiy,Markov,Ryzhkov,Kabal'nova
, p. 1780 - 1787 (2008/02/10)
The products and kinetic regularities of thermal decomposition of ethyl(methyl)dioxirane (EMD) were studied. The consumption of EMD occurs via four parallel pathways: two isomerizations to ethyl acetate and methyl propionate, solvent oxidation via insertion of the oxygen atom into the C-H bond of a solvent molecule (butanone), and hydrogen atom abstraction from the solvent by dioxirane with radical escape from the cage. The contribution of the latter route to the oxidation of butan-2-one at 35°C is 43%. Alkyl radicals initiate EMD decomposition in an inert atmosphere. The activation parameters of EMD isomerization to esters and the reaction of EMD with butanone were determined. The isomerization of EMD was studied by the DFT method. The geometric parameters were optimized at the UB3LYP level using the 6-31G**and/or 6-311+G**basis sets. The calculated energies were corrected taking into account zero-point vibrations. The theoretical results are in good agreement with experimental data. The mechanism of EMD thermolysis is considered.
Asymmetric Reduction of 1-Acetoxy-2-alkanones with Baker's Yeast: Purification and Characterization of α-Acetoxy Ketone Reductase
Ishihara, Kohji,Nakajima, Nobuyoshi,Tsuboi, Sadao,Utaka, Masanori
, p. 3314 - 3319 (2007/10/02)
An α-acetoxy ketone reducing enzyme has been purified and characterized from the cell-free extract of bakers' yeast (Saccharomyces cerevisiae). Only one NADPH-dependent dehydrogenase that catalyzed the reduction of α-acetoxy ketone was found in bakers' yeast. The molecular weight of the enzyme was estimated to be 36 kDa by SDS-polyacrylamide gel electrophoresis. The enzyme was composed of a single polypeptide chain. The enzyme had reducing activity for both aliphatic and aromatic α-acetoxy ketones, although no reducing activity toward α-chloro ketones and α-hydroxy ketones was found. The enzyme catalyzed the reduction of not only α-acetoxy ketones, but also β-keto esters. Studies on the chromatographic behavior and stereospecificity indicated that the enzyme was identical with one of the β-keto ester reductases purified from bakers' yeast.
Chemistry of Dioxiranes. 21. Thermal Reactions of Dioxiranes
Singh, Megh,Murray, Robert W.
, p. 4263 - 4270 (2007/10/02)
Thermolysis of dioxiranes in solutions of their parent ketones or in mixtures of the parent ketone and a foreign ketone leads to the formation of esters.The results are explained by postulating a free-radical mechanism involving H atom abstraction from the ketones.The resulting radicals are converted to the observed esters by reaction with acyloxy radicals derived from homolysis of the dioxiranes.Autodecomposition of dimethyldioxirane in acetone solution at room temperature gives methyl acetate at a very slow rate.When catalyzed by BF3 etherate the same decomposition proceeds much more rapidly and is accompanied by acetol formation.
Regiospecific Synthesis of a Terminal, Oxyfunctionalized Methyl Ketone Enamines via Catalytic Aminomercuriation of Prop-2-ynyl Esters and Ethers
Barluenga, Jose,Aznar, Fernando,Liz, Ramon,Postigo, Carmen
, p. 1465 - 1467 (2007/10/02)
Catalytic aminomercuriation of 1-substituted prop-2-ynyl esters and ethers (5) provides a mild, simple, and regiospecific route to the terminal functionalized enamines (6) despite the fact that they are potentially isomerisable to their internal form; hyd
Thermolytic reactions of esters. Part XIII. The effect of electron-attracting α-substituents in alkyl acetates
Louw, Robert,Tinkelenberg, Arie,Werner, Erik S. E.
, p. 519 - 522 (2007/10/02)
α-Alkylation of esters, e.g.AcO-iPr -> AcO-tBu, results in a large rate increase for β-elimination of acetic acid, indicating that in the transition state Cα is positively charged.Replacement of α-H by electron-attracting groups Z, such as COOMe, also enhances the rate of formation of alkene.Neither differences in product stability nor steric acceleration appear to play a significant role.A major factor is dipolar destabilization of starting compounds containing two electronegative groups, such as AcOCMeZ compared with AcO-tBu.The free energies of the transition states are found to parallel those of the fully ionized species, AcO(-) + R(+).At elevated temperatures, esters such as AcOCMe(CN)Ph will give rise to O-C bond homolysis rather than to molecular elimination of acetic acid.
Reactions with Umpolung via Radicals: CC-Bond Formation between Ketones and Alkenes
Giese, Bernd,Erfort, Ulrich
, p. 1240 - 1251 (2007/10/02)
The hydrazones 1 - 11 from ketones react in a general synthetic procedure with alkenes 33a - m to yield products 34 - 44 (table 2 and 3).Important intermediates of these reactions with umpolung are 1-acetoxyalkyl radicals 49 that are formed from organomercuric salts 14 - 24 by reduction with NaBH4.This new CC-bond formation reaction can be carried out in a one-pot synthesis without isolation of the metalorganic compounds (table 4). - In side reactions the reduction products 50 are formed, if bulky starting compounds or less reactive alkenes are used (table 5 and 6).
