Metal-Catalyzed Carbon-Carbon Bond Forming Reactions for the Synthesis of Significant Chiral Building Blocks

Morita Baylis-Hillman (MBH) reaction a carbon-carbon bond forming reaction between an α,β-unsaturated carbonyl and aldehydes or activated ketones in the presence of a nucleophilic catalyst. The MBH reaction is an atom-economical method of rapid increase of molecular complexity. The development of this process has received considerable attention in recent years. This dissertation presents the development of a new catalytic system for the symmetric and asymmetric MBH reaction. The new system for the racemic version of this reaction was accomplished employing a 1:1:1 ratio of catalytic amounts (10 mol%) of MgI2, TMEDA and DMAP and proved to be highly effective. For the asymmetric version was developed a highly enantio-selective system based on Fu’s planar chiral DMAP derivative (II) with ee´s up to 98%. Abnormal MBH adducts are obtained employing either ethyl 2,3-butadienoate or ethyl propiolate in good yields, in the presence if MgI2 and either a tertiary amine or phosphine as the nucleophile. The α,β-unsaturated carbonyls where prepared by a modified direct α- methylenation using paraformaldehyde, diisopropylammonium trifluoroacetate, and catalytic acid or base with excellent yields for several carbonyls compounds. The Negishi cross-coupling reaction is the Pd or Ni-catalyzed stereoselective cross-coupling or organozincs and aryl-, alkenyl-, or alkynyl halides. Enantioselective Negishi cross-coupling of aryl zincs and α-bromo ketones was accomplished employing a NCN Pincer complex as the catalyst with ee´s up 99%. The required pincer complexes have been prepared by the oxidative addition of pincer ligands with palladium or nickel. Additionally, It has been developed a direct and highly active, (NCN)-Pd catalytic system for the α-arylation of ketones with a variety of aryl bromides using the air and moisture stable [t-BuPheBox-Me2]PdBr (XVI) as the catalyst. The adducts are obtained in excellent yields (92% average for 20 examples) in only 1 hour using 1 mol% of catalyst loading. Perhaps more importantly, the work described here shows that XVI is highly reactive, highly selective, even on substrates bearing challenging functional groups such alkenes

Stellar energy loss rates beyond the standard model

It is known that the dipolemoments of the neutrino lead to important astrophysical and cosmological effects. In this regard, within the context of a U(1)B−L model, we develop and present novel analytical formulas to assess the effects of the anomalous magnetic moment and electric dipole moment of the neutrino on the stellar energy loss rates through some common physical process of pair-annihilation e+e− → (γ, Z, Z ) → ν¯ν. Our results show that the stellar energy loss rates strongly depend on the effective magnetic moment of the neutrino, but also on the parameters which characterize the adopted U(1)B−L mode

Genotoxic Effect of Chronic Exposure to DDT on Lymphocytes, Oral Mucosa and Breast Cells of Female Rats

The genotoxicity of some environmental contaminants may affect human health directly by damaging genetic material and thus plays an important role in cancer development. Xenoestrogens are one kind of environmental pollutants that may alter hormonal routes or directly affect DNA. The number of available biomarkers used to assess genetic risk and cancer is very extensive. The present study evaluated genotoxicity produced by the pesticide DDT on systemic and mammary gland cells obtained from adult female Wistar rats. Oral mucosa cells micronuclei were assessed; the comet assay in peripheral blood-isolated lymphocytes and mammary epithelial cells was also carried out. Additionally, oxidative stress was studied in mammary tissue through a lipid peroxidation assay. Our data showed an increase in lipid peroxidation, product of an increase in free oxygen radical levels, which leads to an oxidative stress status. Our results suggest that DDT is genotoxic, not only for lymphocytes but also to mammary epithelial cells

Microwave-assisted solid-phase reactions of Dötz benzannulation of naphthoquinones and “click chemistry” of azide-acetylene cycloaddition-efficient formation of water disperse micelles

Solid-phase organic chemistry offers an efficient route to construct large libraries of lead compounds for combinatorial chemistry. 2,3-disubstituted naphthoquinone derivatives exhibit a broad spectrum of biological activities that may be attenuated by the incorporation of protein recognition elements, amphiphilic properties and active groups for future incorporation of bioactive compounds. The Dötz benzannulation is a powerful method to construct naphthoquinones that could easily incorporate of the properties mentioned above. The required disubstituted alkynes precursors have been prepared by the palladium-catalyzed Sonogashira coupling of mono or di-protected propargylamine with iodo alkyl benzoates in good to excellent yields. The microwave-assisted Dötz benzannulation of the resultant alkynes with solid supported phenyl Fischer chromium carbene complex and subsequent cleavage of the beads afforded (3-aminomethyl-2-benzoyl alkyl ester)-1,4-naphthoquinones in moderate to good yields. The presence of an amino group and a carboxyl group in the 1,4-naphthoquinone moiety could be an ideal candidate for the incorporation of polypeptides. Click Chemistry ([3+2] cycloaddition) of azides and acetylenes has been extremely used in organic chemistry due to its practical and reliability. (Abstract shortened by UMI.

Crystal structure of (E)-1,3-dimethyl-2-[3-(3-nitrophenyl)triaz-2-en-1-ylidene]-2,3-dihydro-1H-imidazole

The title compound, C11H12N6O2, a π-conjugated triazene, crystallized with two independent molecules (A and B) in the asymmetric unit. Both molecules have an E conformation about the –N=N– bond and have slightly twisted overall conformations. In molecule A, the imidazole ring is inclined to the benzene ring by 8.12 (4)°, while in molecule B the two rings are inclined to one another by 7.73 (4)°. In the crystal, the independent molecules are linked to each other by C—H...O hydrogen bonds, forming –A–A–A– and –B–B–B– chains along [100]. The chains are linked by C—H...O and C—H...N hydrogen bonds, forming sheets lying parallel to (001). The sheets are linked by further C—H...N hydrogen bonds and π–π interactions [centroid–centroid distance = 3.5243 (5) Å; involving the imidazole ring of molecule A and the benzene ring of molecule B], forming a three-dimensional framework structure

Synthesis of a New α-Azidomethyl Styrene from Safrole via a Dearomative Rearrangement

There is a growing interest in developing more efficient synthetic alternatives for the synthesis of nitrogen-containing allylic compounds. This article presents a straightforward two-step protocol to produce 5-(3-azidoprop-1-en-2-yl)benzo[d][1,3]dioxole 4 from the natural product safrole. The method yielded the expected α-azidomethyl styrene 4, in good yield, via a dearomative rearrangement

π‑Conjugated Triazenes: Intermediates That Undergo Oxidation and Substitution Reactions

Novel reactivity for π-conjugated triazenes is herein reported. This observed and unprecedented triazene reactivity gave access to oxidation and substitution reactions. These transformations include successful synthesis of aldehydes, ketones, ethers, and sulfides from readily available organic azides via π-conjugated triazene intermediates. Notably, the afforded adducts were obtained in good yields, at room temperature, and in the absence of added metal catalysts

Programación Orientada A Objetos-IS148-201300

El curso imparte los conocimientos fundamentales de la Programación Orientada a Objetos los elementos básicos principios (encapsulación herencia polimorfismo) uso de librerías y manejo de excepciones

Fundamentos De Programación-IS147-201300

El presente curso imparte los fundamentos de la programación conceptos y elementos básicos estructuras de control y control de flujo para el desarrollo de programas y algoritmos. Se hace énfasis en el análisis del problema diseño del algoritmo diseño del juego de datos de prueba codificación y depuración. Estos conceptos permitirán la elaboración de procesos algorítmicos tanto para la elaboración de programas de computadora que resuelvan tareas simples como para la elaboración de procesos para ser ejecutados directamente por personas de forma estandarizada y precisa para la obtención de los resultados esperados

Desarrollo Para Entorno Web-IS211-201602

El presente es un curso de especialidad de la carrera de Ingeniería de Sistemas EPE de carácter teórico-práctico dirigido a los estudiantes del tercer nivel que busca desarrollar la competencia general de pensamiento Crítico. Nivel 1 y la competencia específica: B - Diseña y conduce experimentos analizando e interpretando los datos obtenidos. Nivel 1El curso está orientado a desarrollar una aplicación web con una arquitectura dividida en capas usando bibliotecas de desarrollo y aplicando los principios de programación orientada a objetos así como también patrones de diseño aplicando prácticas ágiles de desarrollo de software. El curso proporciona una introducción a los conceptos metodología tecnologías relacionadas y patrones del desarrollo para aplicaciones en entorno web.El actual entorno de desarrollo y uso de aplicaciones web ha crecido de manera exponencial en los últimos años de tal manera que hoy en día ningún entorno profesional se puede desarrollar fuera de este entorno es por ello que se hace indispensable para todos los profesionales vinculados a la tecnología la necesidad de conocer a profundidad el uso y funcionamiento de aplicaciones vinculadas a Internet