Carlos M. Meléndez Gómez

Recent Progress in the Synthesis of Quinolines

New developments in the chemistry of quinoline derivatives are reviewed. Two general synthetic routes based on the utilization of mono-substituted or ortho-substituted anilines are discussed. Their major methods and modifications are analyzed. syntheses. These classical syntheses are well-known and still frequently used for the preparation of pharmaceutical agents, ligands and functional materials bearing a quinoline backbone. However, current methods for quinoline synthesis often do not allow for adequate diversity and substitution on the quinoline ring system (19). Recent developments in the chemistry of quinoline derivatives have demonstrated that new metal-catalyzed coupling cyclizations or acid catalyzed cycloaddition of appropriate precursors could compete with classical syntheses in the efficacy and rapidity of the quinoline construction. These new developments have prompted us to review and analyze their major methods and modifications.

In vitro antifungal activity of polyfunctionalized 2-(hetero)arylquinolines prepared through imino Diels-Alder reactions.

Diverse polyfunctionalized quinolines, easily prepared using Lewis acid-catalyzed imino Diels-Alder reactions between corresponding aldimines, were tested for antifungal properties against standardized as well as clinical isolates of clinically important fungi. Among them, 4-pyridyl derivatives displayed the best activities mainly against dermatophytes. The activity appears not to be related neither to the lipophilicity nor to the basicity of compounds.

Synthesis and antifungal activity of diverse C-2 pyridinyl and pyridinylvinyl substituted quinolines

Diverse 2-pyridinyl quinolines 6-12 and 2-pyridinilvinyl quinolines 13-17 were prepared using a straightforward synthesis based on the BiCl(3)-catalyzed multicomponent imino Diels-Alder (imino DA) reaction or a novel tandem imino DA/catalytic tetrahydroquinoline ring oxidation/Perkin condensation sequential process. All members of the series showed activities against dermatophytes and some of them possessed a broad spectrum of action. 2-(Pyridin-4-yl)quinoline 9 and 2-(2-pyridin-4-yl)vinyl)quinoline 16 showed the best MIC(80) and MIC(50) against the clinically important fungi Candida albicans and non-albicans Candida species. In turn, 6-ethyl-2-(pyridin-2-yl)quinoline 6 showed the best properties against standardized as well as clinical strains of Cryptococcus neoformans.

Anti-leishmanial evaluation of C2-aryl quinolines: Mechanistic insight on bioenergetics and sterol biosynthetic pathway of Leishmania braziliensis

A series of diverse simple C2-aryl quinolines was synthesized de novo via a straightforward synthesis based on the acid-catalyzed multicomponent imino Diels-Alder reactions. Seven selected quinolines were evaluated at different stages of Leishmania braziliensis parasite. Among them, the 6-ethyl-2-phenylquinoline 5f was able to inhibit the growth of promastigotes of this parasite without affecting the mammalian cells viability and decreasing the number of intracellular L. braziliensis amastigotes on BMDM macrophages. The mechanism of action studied for the selected compound consisted in: (1) alteration of parasite bioenergetics, by disrupting mitochondrial electrochemical potential and alkalinization of acidocalcisomes, and (2) inhibition of ergosterol biosynthetic pathway in promastigote forms. These results validate the efficiency of quinoline molecules as leishmanicide compounds.

Optimization Methodology to Distributed Generation Location in Distribution Networks Assessing Protections Coordination

In this paper the results from the behavior analysis of the electrical protections from a distribution grid to include distributed generation are presented. For that purpose IEEE 37 nodes test grid was modeled, and distributed resources were included by two technologies: synchronous machine and static generator. Changes produced both in load currents and short-circuit are established and cases for which the coordination of protection devices holds are classified. Optimization methodology is used to classify the cases either coordination holds or coordination lost, to involve distributed source location in a node changing its location in each of the nodes of the grid. In the same way, capacity of distributed generation was changed from 100 kW to 1200 kW. Based on the results a change in the setting time of the protections is proposed to reduce the cases for which the protections coordination is lost.

Efficient synthesis and free-radical scavenging capacity of new 2,4-substituted tetrahydroquinolines prepared via BiCl3-catalyzed three-component Povarov reaction, using N-vinylamides

Efficient synthesis of new structurally different 2-(het)aryl-4-amidyl-substituted tetrahydroquinolines 8–29 is reported. The synthesis based on BiCl3-catalyzed three-component Povarov reaction between anilines, (het)aryl aldehydes and enamides offers a fast, safe, and cheap way for efficient tetrahydroquinoline libraries construction. Using N-vinylamides (N-vinylpyrrolidin-2-one and N-vinylacetamide) in this reaction, it was possible to obtain two series of different cis tetrahydroquinolines with antioxidant properties. Among 14 tested compounds, 7 tetrahydroquinolines revealed a prominent anti-radical capacity, equal or higher than that of the commercial antioxidants. Being the most active molecule, the N-[2-(α-furanyl)-6-methoxy-1,2,3,4-tetrahydroquinolin-4-yl] acetamide 21 was ca. 2.2-fold more potent than the well-known antioxidant, vitamin E (α-tocopherol).

Northernmost new records of Enyalioides touzeti Torres-Carvajal, Almendáriz, Valencia, Yánez-Muñoz & Reyes, 2008 (Sauria: Hoplo­cercidae) from Ecuador: altitudinal and latitudinal distribution extension, new provincial and biogeographical record

In this note, we present new locality records and extend the known geographical distribution and elevation range of the dwarf iguana Enyalioides touzeti in southern Ecuador. Presence of E. touzeti in heavily deforested coastal regions of southwestern Ecuador suggests an urgent need for research to evaluate its conservation status.

Efectos de la operación en isla de generación distribuida en redes de distribución

In this paper the effects and issues due to islanding operation with distributed generation in a distribution network are shown.Two specific conditionsare assessed (intentional island and unintentional island) by analyzing the main influence on load currents, voltage profiles and frequency of the system.Whence, the IEEE 37 nodes test grid was modeled and distributed resources locations were varied along the network whilst its capacity is changed from 100 kW to 1200 kW.

Simple Preparation of New Potential Bioactive Nitrogen-Containing Molecules and Their Spectroscopy Analysis

The impact of research on the small molecules chemistry is difficult to quantify and currently, it is still one of the most active areas of organic chemistry, medicinal chemistry and lately chemical biology. In recent years, a lot of interest has been shown in the preparation of nitrogen-containing compounds due to their numerous biologically significant activities. But it is the separation and purification process of the new synthetized organic molecules, the ones that take a key role in drug design and development.