Avances Recientes en la Síntesis de 3,4-Dihidropiran-2-Ones Organocatalizada por N-Carbenos Heterocíclicos

En los últimos años, los carbenos N-heterocíclicos (NHC) han ganado reconocimiento como moléculas versátiles capaces de actuar como organocatalizadores en diversas reacciones, en particular mediante la activación de aldehídos a través de aductos de tipo Breslow. Esta activación organocatalítica ha permitido la producción de numerosas 3,4-dihidropiran-2-onas y derivados relacionados. En esta revisión, ofrecemos una visión general de la producción de 3,4-dihidropiran-2-onas y derivados mediante procesos organocatalíticos con NHCs en los últimos ocho años. Estos procesos implican el uso de una diversa gama de sustratos, catalizadores y condiciones de reacción, que pueden clasificarse en cicloadiciones de tipo [4+2]-y [3+3]-, principalmente dirigidas a sintetizar este esqueleto debido a su actividad biológica y múltiples estereocentros. Estos procesos se escalan hasta la escala del gramo, y los productos resultantes se dirigen a menudo hacia la epimerización y funcionalización para producir moléculas más complejas con potenciales aplicaciones en el campo biológico. Por último, ofrecemos una perspectiva y las direcciones futuras de este tema en la síntesis orgánica.In recent years, N-heterocyclic carbenes (NHC) have gained recognition as versatile molecules capable of acting as organocatalysts in various reactions, particularly through the activation of aldehydes via Breslow-type adducts. This organocatalytic activation has enabled the production of numerous 3,4-dihydropyran-2-ones and related derivatives. In this review, we provide an overview of the production of 3,4-dihydropyran-2-ones and derivatives via organocatalytic processes involving NHCs over the past eight years. These processes involve the use of a diverse range of substrates, catalysts, and reaction conditions, which can be classified into [4+2]-and [3+3]-type cycloadditions, primarily aimed at synthesizing this skeleton due to its biological activity and multiple stereocenters. These processes are scaled up to the gram scale, and the resulting products are often directed towards epimerization and functionalization to produce more complex molecules with potential applications in the biological field. Finally, we provide a perspective and the future directions of this topic in organic synthesis

Importancia del conocimiento de la entomología en la formación del médico en Risaralda, Colombia

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Importancia del conocimiento de la entomología en la formación del médico en Risaralda, Colombia

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Importancia del conocimiento de la entomología en la formación del médico en Risaralda, Colombia

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Caracterización entomológica del dengue en el Departamento de Risaralda, Colombia, 2011 – 2012

El dengue es una enfermedad metaxénica, endemoepidémica en diferentes regiones de Colombia. Sin embargo, pocos estudios entomológicos se realizan, por lo cual es importante la caracterización del vector por diferentes indicadores.Dengue is a metaxenic disease, endemoepidemic in different regions of Colombia. However, few entomological studies has been made, then is of utmost importance to make characterization of its vector by different indexes

Indicadores Bibliométricos, Redes de Coautorias e Colaboração Institucional em Revistas Colombianas de Psicologia

This study was carried out with the objective of analyzing the bibliometric production indicators in six psychology journals in Colombia during the 2009-2011period, defining the properties of the scientific collaboration networks between the authors and institutions. With that purpose in mind we carried out the standardization of the information related to the articles published in each one of the journals defining the production indexes in accordance with bibliometric criteria (number of articles and authors, areas of publication, type of production, among others); we calculated structural indicators of the networks and we designed visualizations of the scientific cooperation networks. What stands out is an extensive production in countries such as Colombia, Spain and Mexico, essentially in Spanish, within the field of applied research. We observed a high level of collaboration between authorsEste estudio fue desarrollado con el objetivo de analizar los indicadores bibliométricos de producción de seis revistas de psicología en Colombia durante el período 2009-2011, para lo que se definieron las propiedades de las redes de colaboración científica entre los autores e instituciones. Para ello, se realizó la estandarización de la información relacionada con los artículos publicados en cada una de las revistas, se definieron los índices de producción de acuerdo con criterios bibliométricos (nú- mero de artículos y autores, áreas de publicación, tipo de producción, entre otros), se calcularon indicadores estructurales de las redes y se diseñaron visualizaciones de las redes de cooperación científica. Se destaca una producción amplia en países como Colombia, España y México, esencialmente en español, con resultados de investigación aplicada. Se observó un nivel elevado de colaboración entre autoresEste estudo foi desenvolvido com o objetivo de analisar os indicadores bibliométricos de produção em seis revistas de psicologia na Colômbia durante o período 2009-2011, definindo as propriedades das redes de colaboração científica entre os autores e instituições. Para isso, realizou-se a estandardização da informação relacionada com os artigos publicados em cada uma das revistas definindo os índices de produção conforme a critérios bibliométricos (número de artigos e autores, áreas de publicação, tipo de produção, entre outros); calcularam-se indicadores estruturais das redes e se criaram visualizações das redes de cooperação cientí- fica. Destaca-se uma produção ampla em países como a Colômbia, a Espanha e o México, essencialmente em espanhol, com resultados de pesquisa aplicada. Observou-se um nível elevado de colaboração entre autores

Conceptos y herramientas para transitar hacia la sostenibilidad : avances a 2020

En este contexto institucional, desde las líneas de investigación de sostenibilidad en paisajes urbano-rurales, gestión ambiental sectorial y conflictos socioecológicos, los autores de esta publicación se plantearon el reto de generar una serie de documentos denominada “Conceptos y herramientas para transitar hacia la sostenibilidad” que recoja el conocimiento y la experiencia del Instituto entorno a los cambios transformacionales necesarios a nivel nacional para lograr el establecimiento de unos sistemas socioecológicos sostenibles en el país. En el caso de este primer documento de la serie, se busca recoger los avances conceptuales y las herramientas generadas por el Instituto hasta 2020 para apalancar TSS planteadas.Bogotá D.C

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p&lt;0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p&lt;0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Self-Condensation Of α, β -Unsaturated Aldehydes Organocatalyzed By N-Heterocyclic Carbenes

ilustraciones, diagramas, fotografíasLos carbenos N-heterocíclicos (NHCs) son moléculas que suelen emplearse junto a metales de transición como catalizadores organometálicos. A pesar de sus grandes virtudes como catalizadores, los complejos organometálicos suelen ser rechazados en muchos procesos industriales debido a la presencia de trazas de metales pesados en los productos finales y la dificultad de su eliminación. Es por esta razón que desde hace algunos años los NHCs han sido objeto de estudios que buscan su implementación como organocatalizadores. Estos procesos han demostrado ser menos selectivos que sus competidores organometálicos. Sin embargo, el fácil acceso a estos catalizadores (muchos se extraen de fuentes naturales o se sintetizan de una manera sencilla) hace que los procesos sean menos costosos y por supuesto, menos tóxicos porque se evita la presencia de metales. Tanto así que, en el último tiempo, múltiples reacciones que involucraban procesos organometálicos, han sido ensayados en presencia de organocatalizadores encontrando rendimientos, relaciones diastereoméricas y excesos enantioméricos favorables. Este último aspecto es fundamental en la síntesis total y en la química medicinal, pues muchos compuestos empleados como fármacos suelen ser ópticamente activos y administrados en muchos casos en sus formas enantioméricamente puras por lo que desarrollar procesos catalíticos enantioselectivos resulta muy atractivo para estas dos áreas. En este sentido, nosotros presentamos aquí el empleo de NHCs como activadores de aldehídos α, β insaturados a partir de adiciones 1,2. Nosotros encontramos que posterior a dicha adición los aldehídos experimentan transformaciones electrónicas que varían el comportamiento electrofílico/nucleofílico típico de sus diversas posiciones y que, dadas estas circunstancias no es necesario agregar compuestos adicionales para que estos interaccionen, generando reacciones de autocondensación del aldehído inicial a través de la formación de enlaces C-C y C-O. De esta forma y empleando cinamaldehído, crotonaldehído y furfural, tres compuestos sencillos y económicos, se lograron obtener γ-butirolactonas (moléculas bloques de construcción de muchos compuestos con actividad biológica) y α-hidroxicetonas (moléculas muy reactivas que suelen ser útiles en química orgánica como precursores). En el caso de la reacción con cinamaldehído, se pudo obtener buenas relaciones diastereoméricas (86:14 cis:trans) y un exceso enantiomérico resaltable (70% en el producto mayoritario, cis) cuando se evaluó un organocatalizador quiral. Adicionalmente, en la reacción con cinamaldehído, se buscó dar una explicación a la reactividad mostrada por esta molécula a partir de un estudio computacional basado en cálculos DFT que permitió esbozar su mecanismo de reacción y entender los requerimientos energéticos que este proceso demanda. Mediante estos cálculos se encontró también el doble rol de la base empleada (Cs2CO3) en la reacción ya que además de deprotonar la sal de imidazolio para generar la especie catalíticamente activa, ayuda el proceso de transferencia de protón de uno de los intermediarios disminuyendo la energía del proceso en 27.7 kcal/mol comparado a una transferencia típica de protón intramolecular. (Texto tomado de la fuente)N-heterocyclic carbenes (NHCs) are molecules that are often used together with transition metals as organometallic catalysts. Despite their great performances as catalysts, organometallic complexes are often rejected in many industrial processes due to the presence of traces of heavy metals in the final products and the difficulty of their removal. This is why since some years ago, NHCs have been studied as organocatalysts. These processes have proven to be less selective than their organometallic analogs. However, the easy access to these catalysts (many are extracted from natural sources or synthesized in a simple way) makes the processes less expensive and, of course, less toxic because the presence of metals is avoided. Thus, multiple reactions involving organometallic processes have been tested in the presence of organocatalysts, finding favorable yields, diastereomeric ratios and enantiomeric excesses. The latter is fundamental in total synthesis and medicinal chemistry, since many compounds used as drugs are usually optically active and administered in many cases in their enantiomerically pure forms, making the development of enantioselective catalytic processes very attractive for these two areas. In this regard, we present here the use of NHCs as activators of α, β-unsaturated aldehydes from 1,2-additions. We find that after such addition the aldehydes undergo electronic transformations that vary the typical electrophilic/nucleophilic behavior of their various positions and that, given these circumstances, it is not necessary to add additional compounds for them to interact, generating self-condensation reactions of the initial aldehyde through the formation of C-C and C-O bonds. In this way, by using cinnamaldehyde, crotonaldehyde, and furfural, three simple and cheap compounds, it was possible to obtain γ-butyrolactones (building block molecules of many compounds with biological activity) and α-hydroxyketones (very reactive molecules that are usually useful in organic chemistry as precursors). Regarding the condensation of cinnamaldehyde, it was possible to obtain a good diastereomeric ratio (86:14 cis:trans) and a remarkable enantiomeric excess (70% of the major product, cis) when a chiral organocatalyst was tested in the reaction. Additionally, in the reaction with cinnamaldehyde, we tried to explain the reactivity shown by this compound from a computational study based on DFT calculations that allowed us to outline its reaction mechanism and understand the energetic requirements this process requires. By performing these calculations, we were able to uncover the dual role of the base used (Cs2CO3) in the reaction. It not only deprotonates the imidazolium salt to generate the catalytically active species, but it also facilitates the proton transfer process of one of the intermediates by reducing the energy required for the process by 27.7 kcal/mol compared to the common intramolecular proton transferMaestríaMagíster en Ciencias - QuímicaOrganocatálisi