Molecular Squares, Coordination Polymers and Mononuclear Complexes Supported by 2,4-Dipyrazolyl-6H-1,3,5-triazine and 4,6-Dipyrazolylpyrimidine Ligands

The Fe[BF4]2 complex of 2,4-di(pyrazol-1-yl)-6H-1,3,5-triazine (L1) is a high-spin molecular square, [{Fe(L1)}4(μ-L1)4][BF4]8, whose crystals also contain the unusual HPzBF3 (HPz = pyrazole) adduct. Three other 2,4-di(pyrazol-1-yl)-6H-1,3,5-triazine derivatives with different pyrazole substituents (L2-L4) are unstable in the presence of first row transition ions, but form mononuclear, polymeric or molecular square complexes with silver(I). Most of these compounds involve bis-bidentate di(pyrazolyl)triazine coordination, which is unusual for that class of ligand, and the molecular squares encapsulate one or two BF4‒, ClO4‒ or SbF6‒ ions through combinations of anion...π, Ag...X and/or C‒H...X (X = O or F) interactions. Treatment of Fe[NCS]2 or Fe[NCSe]2 with 4,6-di(pyrazol-1-yl)-2H-pyrimidine (L5) or its 2-methyl and 2-amino derivatives L6 and L7) yields mononuclear [Fe(NCE)2L2] and/or the 1D coordination polymers catena-[Fe(NCE)2(μ-L)] (E = S or Se, L = L5-L7). Alcohol solvates of isomorphous [Fe(NCS)2L2] and [Fe(NCSe)2L2] compounds show different patterns of intermolecular hydrogen bonding, reflecting the acceptor properties of the anion ligands. These iron compounds are all high-spin, although annealing solvated crystals of [Fe(NCSe)2(L5)2] affords a new phase exhibiting an abrupt, low-temperature spin transition. Catena-[Fe(H2O)2(μ-L5)][ClO4]2 is a coordination polymer of alternating cis and trans iron centres

Cooperative learning as a tool for teaching Biology and Geology

Máster Universitario en Formación del Profesorado de Educación Secundaria Obligatoria, Bachillerato y Formación Profesional (Universidad de Oviedo, Facultad de Formación del Profesorado y Educación)Memoria de las experiencias adquiridas y de las observaciones realizadas durante el periodo formativo y en las prácticas docentes del Máster en Formación del Profesorado de Educación Secundaria Obligatoria, Bachillerato y Formación Profesional de la Universidad de Oviedo. Contiene una programación didáctica para Biología y Geología de 1º de Educación Secundaria Obligatoria (ESO) que incluye una propuesta de innovación pedagógica. Ambas han sido diseñadas tomando como referencia el centro educativo donde se realizaron las prácticas. Se ha propuesto como innovación el aprendizaje cooperativo como recurso y como contenido. El enfoque cooperativo contribuye a la adquisición de conocimientos. Favorece que los alumnos construyan su propio aprendizaje a través de la interacción con otros compañeros, promueve valores, mejora las relaciones interpersonales, facilita la atención a la diversidad y, a diferencia de otros métodos, el aprendizaje cooperativo se caracteriza por una doble función: además de cooperar para aprender, se aprende a cooperar.AsturiasES

Pd-catalyzed regio-, diastereo- and enantioselective cross-coupling reactions of dihydrofurans

The objective of this thesis was the development of new enantioselective intermolecular Pd-catalyzed cross-coupling transformations using 2,3-dihydrofuran derivatives and readily available electrophiles. In Chapter 2 the arylation of 5-alkyl-2,3-dihydrofurans is presented. The well established complementary reactivity of homo and heterotopic bidentate ligands in the Heck reaction allowed us to develop a single set of experimental reaction conditions. The use of a chiral (P,P) or (P,N) ligand afforded the corresponding 2-alkyl-2-aryl-2,3-dihydrofurans or 2-alkyl-2-aryl-2,5-dihydrofurans in good yield and high levels of regio- and enantiocontrol. In Chapter 3 and 4 the carboetherification and carboamination of 2,3-dihydrofuran derivatives by 2-bromophenol and mesyl protected 2-bromoanilines are disclosed. These fully intermolecular heterocarbofunctionalization methodologies give direct access to the highly valuable tetrahydrofurobenzofuran and tetrahydrofurofuroindoline scaffolds. In Chapter 5, the isolation and characterization of reactive intermediates allowed us to rationalize the factors that govern the regioselectivity of the arylation in these new transformations

Aprendizaje cooperativo como recurso para la enseñanza de biología y geología

El presente Trabajo Fin de Máster se estructura en dos partes. En la primera, se realiza una reflexión sobre el contenido del Máster asi como de las prácticas realizadas durante el mismo. A partir de esta información, se diseña una programación docente para Biología y Geología de 1º ESO constituyendo, por tanto, la segunda parte del trabajo.Además, dentro de la programación, se propone una innovación educativa relacionada con el aprendizaje cooperativo

Palladium-Catalyzed Enantioselective Intermolecular Carboetherification of Dihydrofurans

A novel enantioselective Pd-catalyzed intermolecular carboetherification of dihydrofurans is reported. The in situ generation of chiral bis-phosphine mono-oxide ligands is crucial, and a general catalytic system has been identified based on this approach. It provides access to a variety of fused tetrahydrofurobenzofurans in consistently high yield and enantiomeric excess

Direct Access to Furoindolines by Palladium-Catalyzed Intermolecular Carboamination

A versatile Pd-catalyzed intermolecular syn-carboamination of dihydrofurans giving access to the ubiquitous furoindoline motif is described. The efficiency of the process relies on the use of Buchwald-type biarylphosphines and the perfect control for site-selectivity of Pd insertion across the C═C bond. A catalytic sequence consisting of Heck and carboamination cross-coupling reactions from readily available dihydrofurans affords—in usually high chemical yields and high levels of diastereocontrol—poly(hetero)cyclic compounds that would be difficult to access by established methods. Encouraging preliminary results for the enantioselective carboamination of 2,3-dihydrofurans are also disclosed

Enantioselective Olefin Hydrocyanation Without Cyanide

The enantioselective hydrocyanation of olefins represents a conceptually straightforward approach to prepare enantiomerically enriched nitriles. These, in turn, comprise or are intermediates in the synthesis of many pharmaceuticals and their synthetic derivatives. Herein, we report a cyanide-free dual Pd/CuH-catalyzed protocol for the asymmetric Markovnikov hydrocyanation of vinyl arenes and the anti-Markovnikov hydrocyanation of terminal olefins in which oxazoles function as nitrile equivalents. After an initial hydroarylation process, the oxazole substructure was deconstructed using a [4+2]/retro-[4+2] sequence to afford the enantioenriched nitrile product under mild reaction conditions