Regioirregular and catalytic Mizoroki-Heck reactions

[EN] The palladium-catalysed cross-coupling reaction between alkenes and aryl halides (the Mizoroki-Heck reaction) is a powerful methodology to construct new carbon-carbon bonds. However, the success of this reaction is in part hampered by an extremely marked regioselectivity on the double bond, which dictates that electron-poor alkenes react exclusively on the beta-carbon. Here, we show that ligand-free, few-atom palladium clusters in solution catalyse the alpha-selective intramolecular Mizoroki-Heck coupling of iodoaryl cinnamates, and mechanistic studies support the formation of a sterically encumbered cinnamate-palladium cluster intermediate. Following this rationale, the alpha-selective intermolecular coupling of aryl iodides with styrenes is also achieved with palladium clusters encapsulated within fine-tuned and sterically restricted zeolite cavities to produce 1,1-bisarylethylenes, which are further engaged with aryl halides by a metal-free photoredox-catalysed coupling. These ligand-free methodologies significantly expand the chemical space of the Mizoroki-Heck coupling.This work was supported by MINECO (Spain, projects CTQ 2017-86735-P, PID2019-105391GB-C22 and MAT2017-82288-C2-1-P, Severo Ochoa programme SEV-2016-0683 and the Juan de la Cierva programme). F.G.-P. and R.G. thank ITQ for the concession of a contract. J.O.-M. acknowledges the Juan de la Cierva programme for the concession of a contract, and R.P.-R. and J.C.-S. thank the Plan GenT programme (CIDEGENT/2018/044) funded by Generalitat Valenciana. HR STEM measurements were performed at DME-UCA in Cadiz University, with financial support from FEDER/MINECO (PID2019-110018GA-I00 and PID2019-107578GA-I00). We acknowledge ALBA Synchrotron for allocating beamtime and CL AE SS beamline staff for their technical support during our experiment.Garnes-Portoles, F.; Greco, R.; Oliver-Meseguer, J.; Castellanos-Soriano, J.; Jiménez Molero, MC.; Lopez-Haro, M.; Hernández-Garrido, JC.... (2021). Regioirregular and catalytic Mizoroki-Heck reactions. Nature Catalysis. 4(4):293-303. https://doi.org/10.1038/s41929-021-00592-3S2933034

Evaluación del impacto del perfil del alumnado en la valoración de la actividad docente del profesorado

En este proyecto se analiza el perfil de los estudiantes de primer curso en tres Grados (Química, Biología y Óptica-Optometría) de las Facultades de Ciencias de la UCM, detectando las carencias que presentan los estudiantes en una materia básica como la Química. Se comparan los resultados con los obtenidos en el curso académico 2016-2017. Asimismo se analiza la relación del perfil del alumnado con la valoración de la actividad docente del profesorado que realizan los estudiantes dentro del programa DOCENTIA

Early Pliocene climatic optimum, cooling and early glaciation deduced by terrestrial and marine environmental changes in SW Spain

The Pliocene is a key period in Earth's climate evolution, as it records the transition from warm and stable conditions to the colder and more variable glaciated climate of the Pleistocene. Simultaneously, climate became more seasonal in the Mediterranean area, and Mediterranean-type seasonal precipitation rhythm with summer drought established. These climatic changes presumably had significant impacts on terrestrial environments. However, the response of terrestrial environments to such climate changes is still not fully understood due to the lack of detailed studies dealing with this period of time. In this study, multiproxy analyses of continuous core sampling from La Matilla (SW Spain) shows detailed and continuous record of pollen, sand content and abundance of benthic foraminifer Bolivina spathulata to describe paleoenvironmental and paleoclimate trends during the early Pliocene. This record shows warmest, most humid climate conditions and highest riverine nutrient supply at ~ 4.35 Ma, coinciding with the Pliocene climatic optimum and high global sea level. A climate cooling and aridity trend occurred subsequently and a significant glaciation occurred at ~ 4.1–4.0 Ma, during a period known by very little terrestrial evidence of glaciation. Our multiproxy data thus indicate that terrestrial and marine environments were significantly variable during the early Pliocene and that major glaciation-like cooling occurred before the intensification of northern hemisphere glaciation at the beginning of the Pleistocene (~2.7 Ma). This major climate cooling and aridity maxima between 4.1 and 4.0 Ma is independently validated by a coeval sea-level drop (third order Za2 sequence boundary). This sea level drawdown is supported by enhanced coarse sedimentation and minima in riverine nutrient supply, showing paired vegetation and sea-level changes and thus a strong land-ocean relationship. This study also shows that long-term climatic trends were interrupted by orbital-scale cyclic climatic variability, with eccentricity, obliquity and precession acting as the main triggers controlling climate and environmental change in the area.Peer ReviewedPostprint (author's final draft

Aprendizaje mentorizado en grupo y evaluación formativa metacognitiva centrados en el perfil preuniversitario del alumnado de primer curso de grado

Depto. de Química InorgánicaDepto. de Química OrgánicaFac. de Ciencias QuímicasFALSEVicerrectorado de Calidad de la Universidad Complutense de Madridsubmitte

Diseño y aplicación al aula de un modelo de asistente semi-automático para procesos de aprendizaje presenciales

Depto. de Arquitectura de Computadores y AutomáticaFac. de InformáticaFALSEsubmitte

Mentoría y aprendizaje significativo enfocado en estudiantes de primer curso de universidad: necesidades, expectativas y logros

Depto. de Química OrgánicaFac. de Ciencias QuímicasFALSEVicerrectorado de Calidad de la Universidad Complutense de Madridsubmitte

Comparative effects of overproducing the AraC-type transcriptional regulators MarA, SoxS, RarA and RamA on antimicrobial drug susceptibility in Klebsiella pneumoniae

OBJECTIVES: In Klebsiella pneumoniae, overproduction of RamA and RarA leads to increased MICs of various antibiotics; MarA and SoxS are predicted to perform a similar function. We have compared the relative effects of overproducing these four AraC-type regulators on envelope permeability (a combination of outer membrane permeability and efflux), efflux pump and porin production, and antibiotic susceptibility in K. pneumoniae. METHODS: Regulators were overproduced using a pBAD expression vector. Antibiotic susceptibility was measured using disc testing. Envelope permeability was estimated using a fluorescent dye accumulation assay. Porin and efflux pump production was quantified using proteomics and validated using real-time quantitative RT–PCR. RESULTS: Envelope permeability and antibiotic disc inhibition zone diameters both reduced during overproduction of RamA and to a lesser extent RarA or SoxS, but did not change following overproduction of MarA. These effects were associated with overproduction of the efflux pumps AcrAB (for RamA and SoxS) and OqxAB (for RamA and RarA) and the outer membrane protein TolC (for all regulators). Effects on porin production were strain specific. CONCLUSIONS: RamA is the most potent regulator of antibiotic permeability in K. pneumoniae, followed by RarA then SoxS, with MarA having very little effect. This observed relative potency correlates well with the frequency at which these regulators are reportedly overproduced in clinical isolates

Prediction of fluoroquinolone susceptibility directly from whole-genome sequence data by using liquid chromatography-tandem mass spectrometry to identify mutant genotypes

ABSTRACT Fluoroquinolone resistance in Gram-negative bacteria is multifactorial, involving target site mutations, reductions in fluoroquinolone entry due to reduced porin production, increased fluoroquinolone efflux, enzymes that modify fluoroquinolones, and Qnr, a DNA mimic that protects the drug target from fluoroquinolone binding. Here we report a comprehensive analysis, using transformation and in vitro mutant selection, of the relative importance of each of these mechanisms for fluoroquinolone nonsusceptibility using Klebsiella pneumoniae as a model system. Our improved biological understanding was then used to generate 47 rules that can predict fluoroquinolone susceptibility in K. pneumoniae clinical isolates. Key to the success of this predictive process was the use of liquid chromatography-tandem mass spectrometry to measure the abundance of proteins in extracts of cultured bacteria, identifying which sequence variants seen in the whole-genome sequence data were functionally important in the context of fluoroquinolone susceptibility. </jats:p