The emergence of Pd-mediated reversible oxidative addition in cross coupling, carbohalogenation and carbonylation reactions

Exploiting the reversibility of chemical processes is a long-standing tactic of organic chemists, and permeates most areas of the discipline. The notion that oxidative addition of Pd(0) to Ar–X bonds can be considered an irreversible process has been challenged, periodically, over the last 30 years. Recent examples of methodologies that harness the reversibility of oxidative addition reactions in catalytic processes have enabled access to challenging carbocyclic and heterocyclic scaffolds. This Perspective seeks to describe the development of these processes from the early proof-of-principle findings, and highlight key challenges that remain in this avenue of research. In particular, we draw attention to significant deficiencies that remain in the choice of suitable ligands and additives for these transformations. We conclude by describing how the concept of reversible oxidative addition has recently been exploited in the development of novel carbonylation reactions

Visible-Light-Mediated Deaminative Three-Component Dicarbofunctionalization of Styrenes with Benzylic Radicals

The visible-light-mediated three-component dicarbofunctionalization of styrenes using simple benzylic radicals is described. Notably, this work describes a rare example of undirected dicarbofunctionalization using unsubstituted benzyl radicals. Key to the success of this strategy was the rational design and use of benzylic pyridinium salts as radical precursors. Using this approach, abundant styrenes, electron-rich heterocycles, and benzylic amines were combined to rapidly afford a number of densely functionalized 1,1-diarylalkanes. A dipeptide-derived pyridinium salt was applied in this transformation, which resembles a visible-light-mediated deaminative generation of radicals from peptides

Visible-Light-Mediated Deaminative Three-Component Dicarbofunctionalization of Styrenes with Benzylic Radicals

The visible-light-mediated three-component dicarbofunctionalization of styrenes using simple benzylic radicals is described. Notably, this work describes a rare example of undirected dicarbofunctionalization using unsubstituted benzyl radicals. Key to the success of this strategy was the rational design and use of benzylic pyridinium salts as radical precursors. Using this approach, abundant styrenes, electron-rich heterocycles, and benzylic amines were combined to rapidly afford a number of densely functionalized 1,1-diarylalkanes. A dipeptide-derived pyridinium salt was applied in this transformation, which resembles a visible-light-mediated deaminative generation of radicals from peptides

Comprensión lectora: baterías y técnicas para su evaluación

Treball Final de Grau en Mestre o Mestra d'Educació Primària. Codi: MP1040. Curs acadèmic: 2016/2017En la actualidad, la lectura es el proceso por el cual, el ser humano adquiere conocimiento, contrasta información o plasma sus propios pensamientos. Por ello, la competencia lectora es la capacidad para dar sentido a los textos y para usarlos con diferentes finalidades. Para dicha adquisición de conocimientos mediante los diferentes tipos de textos, el ser humano tiene que tener una desarrollada competencia lectora, puesto que, si existen deficiencias en algún proceso de la competencia: descifrado de letras, comprensión o en el procesamiento. El lector tendrá dificultades para exprimir toda la información posible de un texto. Para evitar esas deficiencias, es muy importante, no pasar por alto la enseñanza de todos los procesos cognitivos que intervienen en la lectura. Estando pendientes para prevenir cualquier dificultad y corregirla antes de que el alumno/a se incorpore a la educación secundaria. Puesto que, en un centro secundario no se presta atención a la potenciación de la competencia lectora. La existencia de pruebas estandarizadas a nivel mundial como PIRLS y PISA focaliza más el valor de la competencia lectora en el mundo, porque consideran que saber leer es mucho más que saber reconocer grafías y palabras. Como plasmó Cassany, Luna y Sanz (1994:193) “la lectura es uno de los aprendizajes más importantes, indiscutidos e indiscutibles… ¡Son tantas las cosas obligatorias que solamente se pueden hacer leyendo y escribiendo! Burocracia, leyes, trabajo, ocio o vivienda”

Enantioselective Catalytic Ring Expansion of Methylenecyclopropane Carboxamides Promoted by a Chiral Magnesium Lewis Acid

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