The spatial relationships between the pharmacophore elements were investigated in the case of four different stereoisomeric forms of opioid tetrapeptide, endomorphin-2, taking into account the L-D and cis-trans isomerisms. On the basis of distances and angles measured between the pharmacophoric points, a comparative analysis of conformational distributions was performed, applying a variety of distance-angle maps. The results obtained by this theoretical study indicated that the stereoisomers of endomorphin-2 could be distinguished from one another, based on the comparative analysis of distance-angle maps. Nevertheless, it could be concluded that this method proved to be suitable to examine the effects of L-D and cis-trans isomerisms on the spatial relationships of the pharmacophores of tetrapeptide. [...]
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The synthesis and the stereochemistry of new 1,3,5-tris(1,3-dioxan-2-yl)-benzene derivatives are reported. The anancomeric structure and the axial orientation of the aryl group with respect to all 1,3-dioxane rings, and the cis-trans isomerism of some of the compounds are revealed. The data are supported by NMR investigations and by the molecular structure of one compound determined by single crystal X-ray diffractometry.
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The conformational analysis of rasagiline [N-propargyl-1(R)-aminoindan] was performed by the density functional theory (DFT) B3LYP method using the 6–31++G (d,p) basis set. A single point energy calculations based on the B3LYP optimized geometries were also performed at MP2/6-31++G (d, p) level. The vibrational frequencies of the most stable conformer of rasagiline was calculated at the B3LYP level and vibrational assignments were made for normal modes on the basis of scaled quantum mechanical force field (SQM) method. The influence of mesylate and ethanedisulfonate salts on the geometry of rasagiline free base and its normal modes are also discussed. [...]
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