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Tautomeryzm i aktywność biologiczna β-diketonów, triketonów, β-ketoestrów i β-ketoamidów : mini przegląd

100%

Hansen P. E.

Wiadomości Chemiczne

2017

tom [Z] 71, 7-8

427--446

The review deals with β-diketones, β-ketoester, β-ketoamides, triketones, their tautomerism and biological activity. In addition, it covers briefly methods to detect tautomerism in particular NMR and deuterium isotope effects on chemical shifts, both primary and secondary. A number of typical systems are treated such as: usnic acid, tetracyclines, piroxicam, curcurmines, humulones, acyltetramic acids and quinolone 3-esters.

Modelowe obliczenia kwantowomechaniczne w chemii

63%

Abildgaard J. , Hansen P. E.

tom [Z] 54, 9-10

845-887

The paper reviews quantum chemical methods, ab initio as well as semiempirical methods based on the investigated molecules, salicylaldehede. The discussion is focused on determination of structure, calculation of vibrational frequencies, NMR chemical shifts and isotope effect on the latter. The various schemes, restricted Hartree-Fock (RHF), RHF including second order electron correlation and a series of old and new density functional theory (DFT) methods are compared with well known semiempirical methods like AM1, PM3, CNDO, etc. Add to this the multitude of basis sets. The comparisons are made with respect to time and space requirements, convergence and quality of results. A goal of the present paper is to find a molecular orbital method that in general will calculate both geometries and spectroslopic data as well.

Synthesis of the N-Allylthioamide Derivatives of Cyclic Oxo- and Dioxo- Acids and Their Cyclization to the Derivatives of 4,5-Dihydrothiazole

51%

Wesołowska A. , Jagodziński T. S. , Sośnicki J. G. , Hansen P. E.

tom Vol. 75, nr 3

387-400

The title N-allylthioamides (1a-f) were synthesized in the reaction of allyl isothiocyanate with enamines (1a-c) and 1,3-diketones (1d-f), respectively, carried out in an acetonitrile solution in the presence of DBU. When treated with the bromine-dioxane complex or with iodine, they underwent cyclization to the corresponding derivatives of 4,5-dihydrothiazole (2a-g). NMR spetroscopy made it possible to elucidate the tautomeric structures of the thioamides and thiazolines.