Radical Scavenging Mechanisms of 1-Arylhydrazone Benzimidazole Hybrids with Neuroprotective Activity.

Benzimidazole-arylhydrazone hybrids showed promising potential as multifunctional drugs for the treatment of neurodegenerative disorders. The neuroprotection studies conducted using an model of HO-induced oxidative stress on the SH-SY5Y cell line revealed a remarkable activity of the compound possessing a vanilloid structural fragment. The cell viability was preserved up to 84% and this effect was significantly higher than the one exerted by the reference compounds melatonin and rasagiline.

New 1-benzimidazole-2-yl hydrazones with combined antiparasitic and antioxidant activity.

Parasitic infections, caused mainly by the species (), are widespread around the world and lead to morbidity and mortality in the population. Meanwhile, some studies have showed that these parasites induce oxidative stress in the infected host. With the aim of developing a class of compounds combining anthelmintic with antioxidant properties, a series of new benzimidazolyl-2-hydrazones 5a-l, bearing hydroxyl- and methoxy-groups, were synthesized.

Directed electrostatic activation in enantioselective organocatalytic cyclopropanation reactions: a computational study.

Cyclopropane rings are versatile building blocks in organic chemistry. Their synthesis, by the reaction of sulfur ylides with α,β-unsaturated carbonyl compounds, has recently aroused renewed interest after the discovery of efficient catalysis by using (S)-indoline-2-carboxylic acid. In order to rationalize the behavior of this catalyst, MacMillan proposed a directed electrostatic activation (DEA) mechanism, in which the negative carboxylate group interacts with the positive thionium moiety, thus reducing the activation energy and increasing the reaction rate.

A computational study on Lewis acid-catalyzed diastereoselective acyclic radical allylation reactions with unusual selectivity dependence on temperature and epimer precursor.

In stereoselective radical reactions, it is accepted that the configuration of the radical precursor has no impact on the levels of stereoinduction, as a prochiral radical intermediate is planar, with two identical faces, independently of its origin. However, Sibi and Rheault (J. Am.

Catalytic asymmetric 5-enolexo aldolizations. A computational study.

The diastereo- and enantioselectivity obtained experimentally by Enders et all. (Enders, D.; Niemeier, O.

An alternative mechanism for Diels-Alder reactions of Evans auxiliary derivatives.

The mechanism proposed by Evans for the dialkylaluminum chloride promoted Diels-Alder reaction of cyclopentadiene with alpha,beta-unsaturated N-acyloxazolidinones has been widely used as a basis for the rationalization of the experimental selectivities observed in many different types of reactions in which oxazolidinones or imidazolidinones are used as chiral auxiliaries. In this manuscript we introduce a new and more general model based on molecular modeling and NMR spectroscopy data that avoids several ambiguous concepts raised by the Evans model and fully explains all available experimental data. While the Evans proposal relies on the formation of high-energetic ionic chelates that promote the rotation of the amide bond in the N-acyloxazolidinone molecule, our model is based on the catalysis by means of low-energetic mono- or bicomplexes at the chain and the ring carbonyl groups that are easily observed by NMR spectroscopy measurements.

Spectrochemical, ab initio and density functional studies on the conversion of 2-hydroxybenzonitrile (o-cyanophenol) into the oxyanion.

The spectral and structural changes caused by the conversion of 2-hydroxybenzonitrile (o-cyanophenol) into the corresponding oxyanion have been followed by IR spectra, ab initio and density functional force field calculations. In agreement between theory and experiment, the conversion is accompanied by a 29 cm(-1) frequency decrease of the cyano stretching band, 2.7-fold increase in its integrated intensity, 5.

The conversion of phenylpropanedinitrile (phenylmalononitrile) into the carbanion, followed by IR spectra, ab initio and DFT force field calculations.

The spectral and structural changes, caused by the conversion of phenylpropanedinitrile (phenylmalononitrile) into the carbanion, have been followed by IR spectra, ab initio HF, MP2 and DFT BLYP force field calculations. In agreement between theory and experiment, the conversion is accompanied with strong frequency decreases (with 114 cm(-1), mean value) of the cyano stretching bands nu(C triple bond N), dramatic increases in the corresponding integrated intensities (136-fold, total value), strong enhancement of the nu(C triple bond N) vibrational coupling and other essential spectral changes. According to the calculations, the strongest structural changes take place at the carbanionic center: (i) shortenings of the Cz-Ph and Cz-CN bonds with 0.