1,721,010 research outputs found
Ionic Liquid as a Suitable Phase for Multistep Parallel Synthesis of an Array of Isoxazolines
No full text(Equation presented) A parallel array of isoxazoline diamides was prepared using an ionic liquid [bmim][BF4] as the phase where a three-step procedure (Schotten-Baumann, 1,3-dipolar cycloaddition, ester amidation with Me3Al) was carried out. At the end, selective extraction of the final products with diethyl ether allowed simple isolation of the 16 components of the array (Syncore technology)
INFLUENCE OF THE REGIOCHEMISTRY AND STEREOCHEMISTRY ON THE FLORAL ODOR OF THP AND THF ETHERS
No full textThe relationships between chemical structure and the odor of white flowers in a new series of tetrahydropyranyl and tetrahydrofuranyl derivatives of substituted cyclohexanols and phenols was investigated, with particular reference to the stereochemistry of the odorants. Several of these compounds exhibit a pleasant floral odor, two of them being very similar in their odor profiles to hydroxycitronellal, taken as a reference for the odor of white flowers. They represent interesting alternatives to the currently used additives for cosmetics and detergents
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Sensible improvements induced by ionic liquids in the reaction of modified carbasugars with bases for the building of constrained carbanucleosides
No full textStarting from racemic 4-hydroxy-4-methyl-2-cyclopentenone, a family of enantiopure carbanucleosides locked in the northern conformation has been synthesized. The use of ionic liquids was determinant in the last step resulting in a tangible increase of the yields and dramatic reduction of reaction times and volumes of organic solvents. To our knowledge, this is the first example of the use of ionic liquids in the coupling of carbasugars with heterocyclic bases
ODOR PROPERTIES OF SOME TETRAHYDROPYRANYL ETHERS
No full textSeveral tetrahydropyranyl derivatives of phenols and alcohols have been prepared with the aim of reproducing the floral note of hydroxycitronellal in compounds of easier and cheaper synthesis. Some of the derivatives, particularly those prepared from cis-4-methylcyclohexanol and p-alkylphenols, present a pleasant floral character as the main note and could be used as detergent additives and in other products of pH above neutrality. This research also represents a contribution toward the understanding of the relationships between molecular structure and the odor of muguet
1H and 13C NMR Conformational Analysis of Adrenergic Drugs. Part 2. N-Isopropyl-N-{3-[4(4-Methoxybenzoylamino)Phenoxy]-2-Hydroxypropyl} Ammonium Chloride, a New β1-Blocking Agent
No full textDynamic and structural features of N-Isopropyl-N- {3-[4(4-Methoxybenzoylamino)Phenoxy]-2-Hydroxypropyl} Ammonium Chloride in [2H6]DMSO were investigated by measuring 13C and 1H spin-lattice relaxation rates and 13C- {1H} and 1H- {1H} n.O.e. Correlation times for main and internal reorientational motions were interpreted in terms of internal rotation around the two planal axes. Selective and double-selective 1H spin-lattice relaxation rates were measured, wherefrom relevant proton-proton intramolecular distances were calculated. It was shown that the β1− blocking agent assumes a preferred conformation where extensive intramolecular H-bonding prevents segmental motion along the quaternary ammonium sidechain
Measurements of Proton-carbon Internuclear Distances - Nmr-studies of Through-the-space C-13-h-1 Dipolar Couplings In Para-aminobenzoic Acid-derivatives
No full textMicrowave Assisted Paal-Knorr Reaction. Three step Regiocontrolled Synthesis of Polysubstituted Furans, Pyrroles and Thiophenes
No full textAn efficient and highly versatile synthesis of furans, pyrroles and thiophenes is described. Starting from commercially available or easily prepared P-keto esters, functional homologation provides differently substituted 1,4-diketones that can be transformed, through a microwave-assisted Paal-Knorr condensation, into the corresponding methoxycarbonyl heterocycles. The methoxycarbonyl moiety can be directly transformed into an NH2 group by hydrolysis to carboxylic acid and Curtius rearrangement or into an amide by reaction with a primary amine in the presence of Me3Al. The method is compatible with the presence of a CbzNH group so that the final heterocycle can be inserted into a peptide sequence as a turn inducer. By using this procedure, a collection of more than 60 different tetrasubstitued pyrroles or trisubstituted thiophenes has been prepared. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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