Highly Efficient Catalysis of Retro-Claisen Reactions: From a Quinone Derivative to Functionalized Imidazolium Salts

A new and efficient method for the preparation of several imidazolium salts containing an ester group in the C4 position of the aromatic ring through a retro-Claisen reaction pathway between a quinone derivative and several alcohols is described. This new organic transformation proceeds in the absence of a catalyst, but it is greatly catalyzed by different Lewis acids, especially with AgOAc at a very low catalyst loading and in very short reaction times. The process takes place by the nucleophilic attack of the carbonyl groups by the alcohol functionality, thus promoting a double C-C bond cleavage and C-H and C-O bond formation. This reaction represents the first example of this type between a quinone derivative and alcohols. A new and efficient method for the preparation of several imidazolium salts containing an ester group in the C4 position of the aromatic ring through a retro-Claisen reaction pathway is described. This new organic transformation takes place by the nucleophilic attack of an alcohol functionality over the carbonyl groups, thus promoting a double C-C bond activation (see scheme; Mes=mesityl)

Gold Catalyzed Multicomponent Reactions Beyond A3 Coupling

The preparation of complex architectures has inspired the search for new methods and new processes in organic synthesis. Multicomponent reactions have become an interesting approach to achieve such molecular diversity and complexity. This review intends to illustrate important gold-catalyzed examples for the past ten years leading to interesting skeletons involved in biologically active compounds

Cytotoxicity and biodistribution studies of luminescent Au(i) and Ag(i) N-heterocyclic carbenes. Searching for new biological targets

A range of fluorescent and biologically compatible gold(i)-N-heterocyclic carbenes bearing acridine as a wingtip group and either a 2-mercaptopyridine or a tetra-O-acetyl-1-thio-β-d-glucopyranoside as an ancillary ligand has been synthesised. Their luminescence, cytotoxicity and biodistribution have been investigated together with those of analogous gold(i) and silver(i) chloride- and bis-NHC complexes. All complexes displayed emissions based on IL transitions centred on the acridine moiety. The cytotoxic activity measured in lung, A549, and pancreatic, MiaPaca2, carcinoma cell lines revealed a general cytotoxicity pattern (thiolate > biscarbene > chloride derivatives) and flow cytometry assays pointed towards apoptosis as the cell death mechanism. Moreover, fluorescence cell microscopy disclosed an unusual biodistribution behavior, being mainly localised in lysosomes and to a lesser extent in the nucleus. Preliminary DNA interaction experiments suggested the metal fragment and not the acridine moiety as responsible for such biodistribution, which widen the scope for new biological targets

Desarrollo de análisis fisicoquímicos y participación en la acreditación de algunos métodos de ensayo en la sección de aguas de la coordinación de inspección de calidad de Ecopetrol S.A. Refinería de Cartagena

Tesis (Químico) -- Universidad de Cartagena. Facultad de Ciencias Exactas y Naturales. Programa de Química, 2008Este documento describe criterios y pasos a tener en cuenta para la determinación de agua en crudos por titulación, incluidos todos los análisis que estaban en proceso de acreditació

Application of the taboo search in solving the qualified problem of lotification in multilevel production systems: a state of the art

In this work, a study of the application of the taboo search for the resolution of the problem of production planning in multilevel systems with capacity restrictions is approached from the literature. This family of problems is classified in the literature as Np-Hard. Relaxation and search strategies, especially Taboo Search, have played a decisive role in the development of alternative solutions for this type of problem, allowing to obtain solutions close to the optimal minimum cost value, in operationally acceptable times. The purpose of this article is to collect, describe and analyze the use and application of taboo search in the solution of the problem of lotification in multilevel production systems. Contemplating the large number of variations of the problem and emphasizing the methodology used and the configuration of the search, it is intended to establish the baseline for the development of new solution algorithms for the lotification problem.En este trabajo, se aborda desde la literatura, un estudio de la aplicación de la búsqueda tabú para la resolución del problema de planificación de la producción en sistemas multinivel con restricciones de capacidad. Esta familia de problemas está clasificada dentro de la literatura como Np-Hard. Las estrategias de relajación y búsqueda, especialmente la búsqueda tabú, han jugado un papel determinante en el desarrollo de alternativas de solución de este tipo de problemas, permitiendo obtener de soluciones cercanas al valor óptimo de mínimo costo, en tiempos operativamente aceptables. El presente artículo tiene por objetivo recopilar, describir y analizar el uso y aplicación de la búsqueda tabú en la solución del problema de lotificación en sistemas de producción multinivel. Contemplando la gran cantidad de variaciones del problema y haciendo énfasis en la metodología utilizada y la configuración de la búsqueda, se pretende establecer la línea base para el desarrollo de nuevos algoritmos de solución para el problema de lotificación