Search results for "Alcohol"
showing 10 items of 1798 documents
A Hybrid Cavitand Made by Capping Permethylated α-Cyclodextrin with Cyclotriveratrylene
2012
A hybrid C 3 -symmetric cavitand 1, in which permethylated α-cyclodextrin (PM α-CDX) is capped with cyclotriveratrylene (CTV), has been prepared in 8 % yield by intramolecular cyclization of a vanillyl alcohol derivative attached to the primary rim of the CDX platform. The reaction proceeds diastereoselectively (dr ≈ 6:1), the chirality of the α-glucopyranosyl units controlling the chirality of the CTV component. Interestingly, in polar solvents, 1 shows self-complexation properties as the primary methoxy groups of the CDX component are directed towards the CTV cavity.
Unexpected formation of chroman-4-ones during the synthesis of 4-hydroxymethyl-2H-chromenes from 4-aryloxybut-2-yn-1-ols
1986
Abstract The unexpected formation of chroman-4-ones by refluxing 4-aryloxybut-2-yn-1-ols in diethylaniline has been studied, 4-hydroxymethyl-2H-chromene and chroman-4-carboxaldehyde derivatives being established as intennediates.
Influence of the nature of the substrate and of operative parameters in the electrocarboxylation of halogenated acetophenones and benzophenones
2005
Abstract The electrocarboxylation of halogenated acetophenones and benzophenones to the corresponding hydroxycarboxylic acids has been carried out in undivided cell equipped with aluminium sacrificial anode and using 1-methyl-2-pyrrolidinone (NMP) as the solvent. The radical anion generated by the electro-reduction of the aromatic ketone is involved in several competitive reactions which lead to the formation of the target hydroxycarboxylic acid, the corresponding alcohol and pinacol and the de-halogenated parent ketone. If sufficiently negative working potentials are imposed, the latter is reduced to the corresponding carboxylate, pinacol and alcohol. Very different results in terms of sel…
An improved method for the asymmetric protonation of enolates with chiral α-sulfinyl alcohols/trifluoroethanol
2001
Abstract Enantioselective protonation of 2-methyl tetralone enolate using a stoichiometric amount of 2-sulfinyl alcohol ( S , R s )- 1 as a chiral proton donor yields the corresponding chiral ketone with a high level of enantioselectivity, provided that the chiral proton donor (CPD) is regenerated with an achiral proton source (APS). In contrast, stereoselectivity was only moderate if catalytic CPD (0.2 equiv.) and an APS are used.
The Creolophins: A Family of Linear Triquinanes fromCreolophus cirrhatus (Basidiomycete)
2007
Complicatic acid and five novel linear triquinanes were isolated from mycelial cultures of Creolophus cirrhatus. The creolophins A, C, D, and E represent a novel type of highly oxidized triquinane sesquiterpenoids. Whereas those compounds with a secondary alcohol moiety in ring A are stable, the exomethylene ketone creolophin E (5) partly dimerized during workup to form the decacyclic 1,4-dioxepin-6-one neocreolophin (6). Compounds 5 and 6 display cytotoxic activities against several tumor cell lines.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis of Optically Active N-(4-Hydroxynon-2-enyl)pyrrolidines: Key Building Blocks in the Total Synthesis of Streptomyces coelicolor Butanolide 5…
2021
AbstractStarting from 5-methylhexanal and (S)-configured N-propargylprolinol ethers, coupling delivered N-(4-hydroxynon-2-ynyl)prolinol derivatives as mixtures of C4 diastereomers. Resolution of the epimers succeeded after introduction of an (R)-mandelic ester derivative and subsequent HPLC separation. Alternatively, suitable oxidation gave the corresponding alkynyl ketone. Midland reagent controlled diastereoselective reduction afforded a defined configured propargyl alcohol with high selectivity. LiAlH4 reduction and Mosher analyses of the allyl alcohols enabled structure elucidation. The suitably protected products are used as key intermediates in enantioselective Streptomyces γ-butyrola…
Synthesis, Structure and Catalytic Properties of Dinuclear Mo-VI Complexes with Ditopic Diaminotetraphenols
2013
MoVI complexes with novel ditopic diaminotetraphenol ligands have been prepared by using a one-pot procedure in methanol or DMSO with [MoO2(acac)2] (acac = acetylacetonate) as the molybdenum source. The complexes were characterised with X-ray diffraction, NMR spectroscopic studies, elemental analysis and IR spectroscopy. In the solid state, the compounds represent either a rodlike molecular or oxido-bridged polymeric structure. The catalytic activity of the complexes was investigated by oxidising benzyl alcohol and 1-phenylethanol with hydrogen peroxide to the corresponding aldehyde and ketone, respectively. Furthermore, the catalytic activity was surveyed also in epoxidation of cyclooctene.
Structural modifications in an irradiated ethylene-vinyl alcohol copolymer
1982
Extraction experiments and calorimetric measurements have been performed, on a commercial ethylene-vinyl alcohol copolymer irradiated in the dose range 0–20 Mrad.
A novel approach to polymer-template mesoporous molecular sieves
2000
A novel synthesis route was developed to produce spherical silica particles. The synthesis is based on a modified Stoeber method and the room-temperature synthesis of MCM 41S-materials applying tetraethoxysilane, alcohol, water, ammonia and homopolymers as template. The specific surface area, the specific pore volume and the average pore diameter were varied in the following ranges: 5 – 1,000 m2/g; 0.1 – 1.0 cm3/g and 2-50 nm. With respect to catalytic applications hetero-atoms e.g. Al were incorporated into the silica framework.
Effect of over the counter mouthwashes with and without alcohol on sorption and solubility of bulk fill resins
2020
Background Composites sorption and solubility can be precursors of several chemical and physical processes, which lead to deleterious effects on the polymer structure. This study evaluated the effect of mouthwashes with and without alcohol on the sorption and solubility of conventional and low viscosity bulk fill resins. Material and Methods Four types of Bulk Fill resins (Filtek™ Bulk Fill, X-tra Fil, Filtek™ Bulk Fill Flow and X-tra Base) were submitted to the following mouthwashes: Listerine Cool Mint and Periogard (containing alcohol) and Listerine Zero and Periogard (alcohol-free). The specimens were stored in the mouthwashes for seven days. Solubility and sorption tests were performed…