Carlos Bustos

FACILE SYNTHESIS OF ISOXAZOLES AND PYRAZOLES FROM ß-DIKETOHYDRAZONES

New 3,5-dimethyl-4-[(E)-4-(R1-phenyl)diazenyl]isoxazoles and 3,5-dimethyl-1-(R2-phenyl)-4-[(E)-(R1-phenyl)diazenyl]-1H-pyrazoles may be obtained by reaction of 3-[2-(R1-phenyl)hydrazono)]pentane-2,4-dione with H2NOH-HCl and R2-4-C6H4-NHNH2, respectively. The reactions were performed in ethanol as solvent and catalyzed by glacial acetic acid.

(E)-3,5-Dimethyl-1-p-tolyl-4-(p-tolyl­diazen­yl)-1H-pyrazole

There are two independent molecules, A and B, in the asymmetric unit of the title compound, C19H20N4, in each of which the N=N double bond has an E conformation. The dihedral angles between the pyrazole ring and the p-tolyl rings in the 1- and 4-positions are 22.54 (8) and 35.73 (7)°, respectively, in molecule A. The corresponding dihedral angles in molecule B are 28.13 (8) and 22.18 (8)°. In the crystal, the A and B molecules are linked by weak C—H⋯π interactions, leading to inversion dimers in each case.

A family of substituted hydrazonoisoxazolones with potential biological properties

The synthesis, characterization and biological study of a new 3,4,5-trisubstituted isoxazolones have been reported, whereby a series of (Z)-3-methyl-4-(2-(R-phenyl)hydrazinylidene)isoxazol-5(4H)-ones were prepared by the reaction of a β-diketohydrazone with hydroxylammonium chloride. All the products were characterized using EA, UV-Vis, FT-IR, 1H-NMR, 13C-NMR spectroscopy and HMBC. The crystalline and molecular structures of three compounds were solved by X-ray diffraction methods. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations were performed to obtain a better explanation of the observed experimental behaviour of these newly synthetized compounds. Furthermore, the reports of cytotoxicity and an antiproliferative effect in human promyelocytic leukaemia cells, HL-60, was tested by the MTT reduction method, showing that most of the newly synthetized compounds had important antineoplastic activity. The most active isoxazolones were used in reverse transcription polymerase chain reaction (RT-PCR) experiments to determine the effect on the expression levels on mRNA encoding using the anti-apoptotic, Bcl 2, pro-apoptotic, Bax, and the proliferation inhibition, p21WAF-1, proteins. Therefore, it was possible to fully characterize the complete library of 15 isoxazolones and to show that most of them are antineoplastic trough an apoptotic pathway.

Dimers linked by type-I C—F...F—C contacts in (Z)-3-methyl-4-[2-(4-methylphenyl)hydrazinylidene]-1-(pentafluorophenyl)-1H-pyrazol-5(4H)-one

The title compound, C17H11F5N4O, is described and compared with two closely related analogues in the literature. There are two independent molecules in the asymmetric unit, linked by N-H···O hydrogen bonds and π-π interactions into dimeric entities, presenting a noticeable noncrystallographic C2 symmetry. These dimers are in turn linked by a medium-strength type-I C-F···F-C interaction into elongated tetramers. Much weaker C-H···F contacts link the tetramers into broad two-dimensional substructures parallel to (101).

Paleontología social: una esperiencia educativa sobre ciencia, patrimonio e identidad

This paper aims to present an educational experience with children and young people in Southern Chile. They learned about heritage using the scientific method as a vehicle of knowledge and appreciation. Our work is based on researches on paleontological and archaeological findings in Pilauco and Monte Verde. We have oriented both experiences to the so-called Social Palaeontology, understood as integrated to the archaeology of early settlers and based on concepts of heritage and identity.

On substituted pyrazole derivatives. I. 3-Methyl-4-[(Z)-2-(4-methylphenyl)hydrazin-1-ylidene]-1-(3-nitrophenyl)-1H-pyrazol-5(4H)-one and 3-methyl-4-[(Z)-2-(4-methylphenyl)hydrazin-1-ylidene]-1-[4-(trifluoromethyl)phenyl]-1H-pyrazol-5(4H)-one.

The title substituted pyrazole derivatives, C17H15N5O3 and C18H15F3N4O, share most of their molecular features, in particular the hydrazinylidene (-HN-N=) rather than the diazene (-N=N-) tautomeric form, and differ only in the substituents (NO2 and CF3) on one of the outer phenyl rings. The molecular units are basically planar, with the rotation of the phenyl rings being hindered by the presence of two intramolecular hydrogen bonds having the keto O atom as acceptor. In both structures, the packing is governed by weak C-H...O, C-H...π and π-π interactions. The subtle way in which minor structural differences lead to rather different supramolecular structures is analysed.

2-[2-(3-Chlorophenyl)hydrazinylidene]-1,3-diphenylpropane-1,3-dione

The conformation of the title molecule, C21H15BrN2O2, is stabilized by a weak intramolecular C—H⋯N hydrogen bond and a strong resonance-assisted N—H⋯O intramolecular hydrogen bond. In the crystal, the molecules are linked by weak intermolecular C—H⋯O interactions, forming zigzag chains along the b axis.

Reactivity of [Mo(NHNRPh)(NNRPh)(acac)X2] (R=Ph, Me; X=Br, I) toward tertiary phosphines

The reactivity of mixed [organohydrazido(1-)][organohydrazido(2-)]molybdenum(VI) complexes [Mo(NHNRPh)(NNRPh)(acac)X2] {R = Ph, X = Br (1); R = Ph, X = I (2) and R = Me; X = I (3)} with tertiary phosphines as PPh3, PMePh2 and PMe2Ph are examined. The syntheses of [Mo(NNPh2)2Br2(PPh3)] (4), [Mo(NNPh2)2Br2(PMePh2)2] (5), [Mo(NNPh2)2Br2(PMe2Ph)2] (6), [Mo(NNPh2)2(acac)I(PPh3)] (7), [Mo(NNPh2)2(acac)(PMePh2)2]+I− (8) and [Mo(NNMePh)2(acac)(PMePh2)2]+I− (9) are reported. All complexes were characterized by elemental analysis, UV-visible, IR, 1H and 31P{H} NMR spectroscopy.

Quimioluminiscencia electrogenerada del luminol usando electrodos de bajo costo

The purpose of the study was to observe eletrogenerated chemiluminescence (ECL) of luminol using different materials as electrodes such as wires, nails, coins, razor blades, etc. Based on the experimental observations and the mechanisms proposed in the literature, students should be capable of analyzing their results in order to understand the phenomena studied. Students could then elaborate a mechanism of action consistent with the experimental results which could rationalize the formation of intermediates in the reaction and the dependence of ECL on solution pH in addition to other points of interest

New 3,4,5-trisubstituted isoxazole derivatives with potential biological properties

Synthesis of (E)-3,5-dimethyl-4-(R-phenyldiazenyl)isoxazoles was carried out by reacting β-diketohydrazones (R-C6H4-NHNC(COCH3)2) with hydroxylammonium chloride, where R = 4-N(CH3)2(1), 4-OH(2), 4-CH3(3), 4-OCH3(4), 4-H(5), 4-Cl(6) 4-Br(7), 4-CO2H(8), 4-CO2CH2CH3(9), 4-COCH3(10), 4-CN(11), 4-NO2(12), 4-CH2CO2CH2CH3(13), 3-Cl(14), 2-OH(15), 2-Cl(16), 2-NO2(17), 2-CO2H(18). All compounds were characterized by EA and spectroscopic methods. The crystalline structure of two of the compounds, (7) and (17), were solved by the X-ray diffraction method. DFT and TDDFT computations were performed in order to characterize the molecular geometry and the molecular orbitals involved in the transitions. Besides, a biological activity study was performed to evaluate the toxicity of the compounds towards human promyelocytic leukemia cell line, HL-60, using the MTT reduction method. The IC50 values are in a wide concentration range, 86–755 μM. Isoxazoles (3) and (6) were the most cytotoxic. Expression analysis in HL-60 cells was carried out with compounds (3) and (6) by RT-PCR, in order to determine the effect on the expression levels of mRNA that codify for the genes Bcl-2, Bax and p21WAF-1. Isoxazole (3) induced a decrease in the expression of Bcl-2, whereas isoxazole (6) showed an opposite behaviour. However, these isoxazoles had no effect on mRNA levels of Bax. On the other hand, both isoxazoles increased the levels of p21WAF-1. These results suggest that the cytotoxic activity of isoxazole (3) would be the sum of effects triggered by promotion of apoptosis and cell cycle arrest, whereas for isoxazole (6) it would be mainly through cell cycle arrest.