This paper describes a combined synthesis of b-hydroxy-sesquiterpen eudesmane derivative using a microbiological hydroxylation sesquiterpen eudesmane derivative as the key reaction. The stereochemistry of the biohydroxylation was identified using mono and bi-dimensional ¹H-NMR experiments

A new synthesis of 9a-hydroxy-a-agarofuran (6a) is described, using a microbiological hydroxylation a-agarofuran (5) as the key reaction. The stereochemistry of the biohydroxylation was determined on the basis of a NOESY-experiment and GIAO calculations at the B3LYP/cc-pVDZ level. A strong g-effect was observed at C15 of the agarofuran ring which was correctly predicted by the GIAO-B3LYP calculations

Inclusion complexes and physical mixtures were prepared with isomeric mixture of E/Z (50:50) of 3-(4'-bromo-[1,1'-biphenyl]-4-yl)-3-(4-bromophenyl)-N,N-dimethyl-2-propen-1-amine (BBAP) and b-cyclodextrin (b-CD) in different proportions. In this study, theoretical calculations using Molecular Mechanics MM+ force field were applied to predict the structures of the inclusion complexes formed by interaction of BBAP and b-cyclodextrin. Circular dichroism, differential thermal analysis (DTA), X-ray diffraction and 13C CP/MAS NMRmethods were used to characterize the inclusion complexes and provide information about the stoichiometry of the inclusion complexes. The combined spectroscopy techniques indicate the formation of a complex of BBAP/b-CD in the molar proportion of 1:1 and 1:2 by co-evaporation and no complexation was detected in the physical mixture of the compounds

1-(n-Hexil)-3-metil-2-pirazolin-5-ona foi acilada com cloretos de acidos e a condensação com aminas primárias forneceu uma série de enaminas. De acordo com os dados de RMN de ¹H e 13C, os derivados acilas têm principamente uma estrutura 4-acilpirazol-5-ol com ligação de hidrogênio intramolecular e os derivados 4-aminometilenos existem predominantemente na forma de enamina estabilizada também por este tipo de interação.

1-(n-Hexyl)-3-methyl-2-pyrazolin-5-one was acylated with acid chlorides. Condensation of acyl derivatives with primary amines afforded enamines. According to the ¹H and 13C NMR data, the acyl derivatives have mainly a 4-acylpyrazol-5-ol structure with intramolecular hydrogen bond, and the 4-aminomethylene derivatives exist predominantly in the enamine form stabilized by the same type of interaction.

The preparation of copper (II) and palladium (II) complexes derived from ligands of Schiff’s bases (L¹, L², L³, L4) incorporating 1,3,4-oxadiazole and 1,3,4-thiadiazole rings are reported. The thermal behaviour of the complexes was characterized by DSC, TGA and polarizing optical microscopy. Only the complexes derived from Schiff`s base L¹ display liquid crystalline properties. The complexes Ic and IIc, exhibit an enantiotropic smectic C phase, whereas the complexes IIa and IIb display dimorphism smectic C-nematic

Complexation between acyclovir (ACV), an antiviral drug used for the treatment of herpes simplex virus infection, and beta-cyclodextrin (beta-CD) was studied in solution and in solid states. Complexation in solution was evaluated using solubility studies and nuclear magnetic resonance spectroscopy (¹H-NMR). In the solid state, X-ray diffraction, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and dissolution studies were used. Solubility studies suggested the existence of a 1:1 complex between ACV and beta-CD. ¹H-NMR spectroscopy studies showed that the complex formed occurs with a stoichiometry ratio of 1:1. Powder X-ray diffraction indicated that ACV exists in a semicrystalline state in the complexed form with beta-CD. DSC studies showed the existence of a complex of ACV with beta-CD. The TGA studies confirmed the DSC results of the complex. Solubility of ACV in solid complexes was studied by the dissolution method and it was found to be much more soluble than the uncomplexed drug.

ABSTRACT The syn-anti conformational equilibrium for a series of nine cyclic nucleotides was studied at semiempirical AM1 level. The AM1 results indicate that for guanosine cyclic 3',5'-monophosphate and their derivatives substituted at 8-position, the syn-conformers are more stable than the anti ones. For purine derivatives without an amino group at position 2, which participate in a hydrogen bonding with the axial oxygen of the phosphate group, the anti conformation is preferred. The AM1 results suggest that syn-anti equilibruim is a dominant factor for the binding of cyclic nucleotides to cyclic phosphodiesterases. Reinterpretation of experimental results for the competitive inhibition of c-GMP-stimulated phosphodiesterase was performed.

Se estudió el equilibrio syn-anti de una serie de nueve nucleótidos cíclicos utilizando el método AM1. Los resultados indican que para el 3',5'-monofosfato cíclico de guanosina y sus derivados sustituídos en la posición 8, el isómero syn es más estable que el isómero anti. Los derivados de purina que no poseen un grupo amino en la posición 2, el cual puede participar en enlace de hidrógeno con el oxígeno axial del grupo fosfato, prefieren la conformación anti. Los resultados obtenidos por el método AM1 sugieren que el equilibrio syn-anti es un factor dominante para la union de nucleótidos cíclicos a fosfodiesterasas. Según esto se hizo un nuevo análisis de los resultados de la inhibición competitiva de la fosfosdiesterasa cíclica estimulada por c-GMP

The prototropic tautomerism of 3-methyl-5-pyrazolone was studied byusing Density Functional Theory along with 1H, 13Cand 15N-NMR. The results show that for the isolated moleculeand low polarity solvent the 5PYR-1 tautomer, a keto form, is the predominant species. In DMSO solution the predominant tautomeric form is 5PYR3, a hydroxytautomeric species. For almost every atom an excellent agreement was foundbetween the experimental and calculated NMR spectra using GIAO method at DFT/B3LYP/6-311+G (2p,d) level

El tautomerismo prototrópico de la 3-metil-5-pirazolona fue estudiadopor medio de 1H, 13C y 15N-RMN en conjuntocon cálculos DFT. Para la molécula aislada y en solventede baja polaridad los resultados indicaron que el tautómero 5PYR1,una forma ceto, es la especie predominante. En DMSO la especie predominantees un hidroxi tautómero, 5PYR3. Una excelente correlación fue encontrada entre los espectros de RMN experimentales y los calculadosa nivel GIAO-DFT/B3LYP/6-311+G (2p,d)