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Three novel lanthanide complexes with the ligand 4,4-difluoro-1-(1,5-dimethyl-1H-pyrazol-4-yl)butane-1,3-dione (HL), namely [LnL3(H2O)2], Ln = Eu, Gd and Tb, were synthesized, and, according to single-crystal X-ray diffraction, are isostructural. The photoluminescent properties of these compounds, as well as of three series of mixed metal complexes [EuxTb1-xL3(H2O)2] (EuxTb1-xL3), [EuxGd1-xL3(H2O)2] (EuxGd1-xL3), and [GdxTb1-xL3(H2O)2] (GdxTb1-xL3), were studied. The EuxTb1-xL3 complexes exhibit the simultaneous emission of both Eu3+ and Tb3+ ions, and the luminescence color rapidly changes from green to red upon introducing even a small fraction of Eu3+. A detailed analysis of the luminescence decay made it possible to determine the observed radiative lifetimes of Tb3+ and Eu3+ and estimate the rate of excitation energy transfer between these ions. For this task, a simple approximation function was proposed. The values of the energy transfer rates determined independently from the luminescence decays of terbium(III) and europium(III) ions show a good correlation.

A Knoevenagel based redox-reaction promoted by intramolecular phosphine sources is presented for the first time. The influence of different diketones, aldehydes, bases and acids was investigated. The effects of different substituents were evaluated based on their electronical influence on the diketone structure. With the obtained results a mechanism is proposed, giving information about transition states formed during the reaction, which can lead to different products. This type of an internal redox transformation with a phosphine oxide moiety remaining in the molecule after the redox reaction represents a new type of reaction.

Tesis-CEINDO, Universidad San Pablo CEU, Programa en Medicina Traslacional, leida el 1 de julio de 2020 El estrés oxidativo celular ha sido reconocido en los últimos años como un jugador clave en diferentes enfermedades, entre ellas las neurodegenerativas. Debido a que el cerebro es un órgano metabólicamente hiperactivo y con menor capacidad para la regeneración celular en comparación con otros órganos, es extremadamente vulnerable a este daño. Dentro de los compuestos estudiados en los últimos años como posibles metabolitos reguladores del estrés oxidativo, la curcumina ha sido objeto de numerosos estudios como posible terapia frente al daño oxidativo. Debido a sus características farmacocinéticas y farmacodinámicas tales como su baja solubilidad en agua, su baja biodisponibilidad, su alta inestabilidad química y su mala absorción digestiva, esta molécula presenta dificultades a la hora de llegar a sus dianas fisiológicas. Por ello, en este trabajo se han evaluado las propiedades antioxidantes de catorce derivados asimétricos de la curcumina, con la finalidad de caracterizar aquellos derivados con mejor perfil antioxidante, de tal manera que pudiéramos seleccionar aquellos que además presentaran mejores características para actuar a nivel neuronal. Los ensayos realizados para estudiar la capacidad antioxidante han sido ABTS, FRAP y DPPH habiéndose encontrado que todos los compuestos presentan propiedades antioxidantes similares a la curcumina. Los estudios de viabilidad celular realizados en las líneas celulares SH-SY5Y, HT-22 y HepG2, han demostrado que estos derivados tienen menor citotoxicidad que la curcumina. De todos los quimiotipos la selecion de 6b y 7b ha evidenciado que estos dos derivados presentan excelente solubilidad y estabilidad química en medios biorrelevantes, que tienen comportamiento de quelación frente a Fe2+ similar a la curcumina, y que además, ambos han proporcionado una buena actividad neuroprotectora contra el estrés oxidativo inducido tanto por generadores de radicales libres (H2O2) , como por inhibidores de la cadena de transporte electrónico mitocondrial, o como excitotoxicidad inducida por glutamato. Teniendo en cuenta estos resultados, se ha evidenciado que los compuestos 6b y 7b poseen un prometedor perfil antioxidante, con baja actividad citotóxica y buena actividad neuroprotectora, lo que les hace candidatos para ser una nueva clase química interesante con alto potencial farmacológico como nuevos agentes terapéuticos contra enfermedades neurodegenerativas. Oxidative stress has been recognized in recent years as a key player in different diseases, including neurodegenerative diseases. Because the brain is a metabolically hyperactive organ with less capacity of cell regeneration compared with other organs, therefore is extremely vulnerable to this damage. In the last years a lot of compunds has been studied as a metabolite like anti-oxidative regulator. In fact, curcumin has been object of numerous quimical studies to determine its use against oxidative damage. Due to its pharmacokinetic and pharmacodynamic characteristics such as low solubility in water, low bioavailability, high chemical instability and poor digestive absorption, this molecule presents difficulties to reaching its physiological targets. Therefore, in this work the antioxidant properties of fourteen asymmetric derivatives of curcumin have been evaluated, in order to characterize those derivatives wich present a better antioxidant profile. Then we selected those that also presented better characteristics to act at the neuronal level. The tests carried out to study the antioxidant capacity have been ABTS, FRAP and DPPH. The results have shown that all the compounds had antioxidant properties similars to curcumin. Cell viability studies on the cell lines SH-SY5Y, HT-22 and HepG2 have shown that these derivatives compared with curcumin had low cytotoxicity. After these assays, 6b and 7b compudns had been selected through their excellent solubility and chemical stability in biorelevant media, their chelation behavior against Fe2+, and in addition, about their neuroprotective activity against oxidative stress. Acording to these results, it has been shown that compounds 6b and 7b had a favorable antioxidant profile, with low cytotoxic and neuroprotective activity, which makes them the best eligible candidates as therapeutic agents against neurodegenerative diseases.

The excitation of the innermost carbonyl of nono‐2,3‐diulose derivatives by irradiation with visible‐light initiates a sequential Norrish type II photoelimination and aldol cyclization process that finally gives polyfunctionalized cyclopentitols. The rearrangement has been confirmed by the isolation of stable acyclic photoenol intermediates that can be independently cyclized by a thermal 5‐(enolexo)‐exo‐trig uncatalyzed aldol reaction with high diastereoselectivity. In this last step, the large deuterium kinetic isotope effect found for the 1,5‐hydrogen atom transfer seems to indicate that the aldol reaction runs through a concerted pericyclic mechanism. Owing to the ready availability of pyranose sugars of various configurations, this protocol has been used to study the influence of pyranose ring‐substituents on the diastereoselectivity of the aldol cyclization reaction. In contrast with other pyranose ring contraction methodologies no transition‐metal reagents are needed and the sequential rearrangement occurs simply by using visible light and moderate heating (0 to 60 °C)., This work was supported by the Investigation Programs (CTQ2010‐18244) of the Ministerio de Economía y Competitividad and (SolSub20081000192) of the Gobierno de Canarias. D.A.‐D. thanks the Ministerio de Economía y Competitividad for a fellowship. C.R.‐F. thanks the Programa I3P‐CSIC for a postdoctoral contract.

Due to the steric hindrance of the starting prochiral ketones, the preparation of chiral 1,4-diaryl-1,4-diols through the asymmetric hydrogen transfer reaction has been mainly restricted to the use of metal-based catalysts, oxazaborolidines, or organocatalysts. Herein, we demonstrated the versatility of oxidoreductases, finding overexpressed alcohol dehydrogenase from Ralstonia sp. (E. coli/RasADH) as the most active and stereoselective biocatalyst. Thus, the preparation of a set of 1,4-diaryl-1,4-diols bearing different pattern substitutions in the aromatic ring was achieved with complete diastereo- and enantioselectivity under mild reaction conditions. Ministerio de Economía y Competitividad CTQ2016-75752-R

A new method for the synthesis of substituted 4-amino-1-arylpyrazoles is described, starting from β-enaminones and variously substituted benzenediazonium tetrafluoroborates. The reaction proceeds under mild conditions, is very simple to perform, and is applicable to a relatively wide range of substituents, both at the β-enaminone and diazonium salt starting materials.

Cyclohexanone monooxygenase from Acinetobacter calcoaceticus was employed for the Baeyer-Villiger oxidation of racemic bicyclic diketones such as the Wieland-Miescher and the Hajos-Parrish diketones and of some of their derivatives. The corresponding lactones were produced in a highly regio- and enantioselective manner. The reactions were carried out using a crude enzyme preparation in aqueous buffer, at room temperature, and the recycling of the expensive coenzyme NADPH was conducted with a second ancillary enzymatic system. The enzymatic process was simple and easy to handle, thus providing a very practical tool to access enantiopure lactones.

A series of four α‐diketones placed as 1α‐pyruvoyl tethers on D‐glucopyranose and D‐glucopyranosiduronic acid skeletons was prepared in order to determine the influence of captodative and stereoelectronic effects on the regioselectivity of the hydrogen atom transfer (HAT) in Norrish type II photochemical processes. We observed that the 1,5‐HAT regioselectivity can be switched between the two potentially abstractable syn‐1,3‐diaxial hydrogens at H6 and H8. Highly unusual photoproducts from Norrish type II photoelimination and Norrish–Yang photocyclization initiated by the excited internal carbonyl group were obtained, in some cases in excellent synthetic yield. The 1,5‐HAT transition state in the Norrish type II photoelimination was investigated by photochemical experiments in the crystalline state., This work was supported by the Investigation Programs of the Ministerio de Economía y Competitividad (CTQ2010‐18244) and of the Gobierno de Canarias (SolSub20081000192). D.A.‐D. thanks the Ministerio de Economía y Competitividad for a fellowship. C.R.‐F. thanks the Programa I3P‐CSIC for a postdoctoral contract.

Bis-adducts of 1,2,3,4-tetrahalo-5,5-dimethoxycyclopentadiene and 1,3-butadiene, generated in situ from 3-sulfolene, have been synthesized in excellent yield. Ruthenium catalyzed oxidation of the bis-adducts followed by a one-pot transformation of the resulting α-diketone furnished oxa-bridged compounds. Unambiguous stereochemical assignments of both diastereomeric series are reported.

The nickel(II) and copper(II) complexes of 2-substituted-4,4,4-trifluoro-1- (2-thienyl)butane-1,3-dione (R-TTAH) and their 2,2? -bipyridine and 1,10-phenanthroline adducts have been prepared and characterized by microanalysis, conductance, magnetic and spectral measurements. The conductance data in nitromethane indicate that the compounds are non-electrolytes except for [Cu(Phen)2TTA](TTA) and [Ni(Phen)3](TTA)2, which are 1:1 and 1:2 electrolytes respectively. The room temperature magnetic moments suggest that they are magnetically dilute compounds while the electronic spectral (solid and solution) bands of the ligands shifted upon chelation. The infrared spectra showed the different shifts of the carbonyl frequencies and a six-coordinate octahedral geometry formed by coordination of the nickel(II) ion through four oxygen atoms of the 4,4,4-trifluoro-1-(2-thienyl)butane-1,3-dione (TTAH) and two nitrogen atoms of the bipyridine was established for (2,2?-bipyridine)bis{4,4,4-trifluoro-1-(2-thienyl)butane-1,3-dionato} nickel(II) using X-ray crystallography.

A series of o-substituted benzophenones was prepared by efficient method involving the 3-substituted isocoumarins and phenylmagnesium bromide. The reaction was completed in presence of anhydrous ether under dry ice-solvent bath in few hours with modest to good yields.Key words: Isocoumarins, diketones, aryl, phenyl magnesium bromide, ether, dry ice.e-mail: nawaz_f@yahoo.co.in. INTRODUCTION Synthetic and naturally occurring isocoumarins possess important biological properties. They are useful intermediates in the synthesis of a variety of carbocyclic and heterocyclic compounds 1-6 .In continuous of our interest in carbon-carbon bond formation reaction 7-12 ,the present paper presents an efficient method to synthesize o-substituted benzophenones (2) from 3-substitued isocoumarins (1) and phenyl magnesium bromide in presence of anhydrous ether under dry ice-solvent bath. Benzophenone and its derivatives are important intermediates in dyes, pharmaceutical and other chemical industries

2,6-Diones on treatment with zeolite H-ZSM-5 yield dimethylphenols (DMPs) or alpha,beta-unsaturated cyclohexenones.