Reducción de enlaces N‒O con glicoles catalizada por complejos de dioxomolibdeno(VI): síntesis de compuestos nitrogenados a partir de nitroarenos

El desarrollo de nuevos sistemas catalíticos tiene gran relevancia dentro de la Química actual por presentar beneficios tanto económicos como medioambientales. Este trabajo se centra en el desarrollo de nuevas metodologías en Síntesis Orgánica basadas en reacciones de desoxigenación de compuestos que presentan enlaces N–O catalizadas por complejos de dioxomolibdeno(VI), empleando glicoles como agentes reductores y, especialmente, en las aplicaciones sintéticas de la reducción del grupo nitro. Se describen diversos procesos catalíticos que emplean pinacol como agente reductor medioambientalmente benigno para la reducción de compuestos nitroaromáticos a anilinas, y para la desoxigenación N-óxidos heteroaromáticos y N-hidroxibenzotriazoles. Aplicando este sistema catalítico, también se han desarrollo nuevas estrategias de síntesis empleando como materiales de partida compuestos nitroaromáticos y glicoles, que permiten obtener una amplia variedad de compuestos nitrogenados con potencial actividad biológica, tales como N-bencilanilinas, α-aminofosfonatos y heterocíclicos nitrogenados (quinolinas y quinoxalinas

Molybdenum-Catalyzed Synthesis of Nitrogenated Polyheterocycles from Nitroarenes and Glycols with Reuse of Waste Reduction By-product

A novel domino reduction/imine formation/intramolecular cyclization/oxidation for the efficient synthesis of pyrrolo(indolo)[1,2-a]quinoxalines and pyrrolo(indolo)[3,2-c]-quinolines from readily available nitrobenzenes and glycols is reported. The process utilizes the carbonyl byproduct of the initial dioxomolybdenum(VI)-catalyzed reduction of nitroaromatics with glycols as a reagent for the imine generation. This method represents the first sustainable domino reaction for the preparation of biologically relevant heterocycles that internally incorporates the waste formed in the first step to the final product.Junta de Castilla y León and FEDER (BU076U16) and Ministerio de Economía y Competitividad (MINECO) (CTQ2015-70371-REDT and CTQ2016-75023- C2-1-P

Mo–Catalyzed One-Pot Synthesis of N-Polyheterocycles from Nitroarenes and Glycols with Recycling of the Waste Reduction Byproduct. Substituent-Tuned Photophysical Properties

A catalytic domino reduction–imine formation– intramolecular cyclization–oxidation for the general synthesis of a wide variety of biologically relevant N-polyheterocycles, such as quinoxaline- and quinoline-fused derivatives, and phenanthridines, is reported. A simple, easily available, and environmentally friendly dioxomolybdenum(VI) complex has proven to be a highly efficient and versatile catalyst for transforming a broad range of starting nitroarenes involving several redox processes. Not only is this a sustainable, stepeconomical as well as air- and moisture-tolerant method, but also it is worth highlighting that the waste byproduct generated in the first step of the sequence is recycled and incorporated in the final target molecule, improving the overall synthetic efficiency. Moreover, selected indoloquinoxalines have been photophysically characterized in cyclohexane and toluene with exceptional fluorescence quantum yields above 0.7 for the alkyl derivatives.Junta de Castilla y León and FEDER (BU291P18 and BU049P20) and Ministerio de Economía y Competitividad (MINECO) and FEDER (CTQ2016-75023-C2-1P) for financial support. The project leading to these results has also received funding from “la Caixa” Foundation, under the agreement (LCF/PR/PR18/51130007) (CAIXA-UBU001). R.H.-R. thanks Ministerio de Educación for a FPU predoctoral contract. S.S P. thanks Junta de Castilla y León and FSE and FEDER for a postdoctoral contract

On the Tunability of Toxicity for Viologen‐Derivatives as Anolyte for Neutral Aqueous Organic Redox Flow Batteries

Viologen-derivatives are the most widely used redox organic molecules for neutral pH negative electrolyte of redox flow batteries. However, the long-established toxicity of the herbicide methyl-viologen raises concern for deployment of viologen-derivatives at large scale in flow batteries. Herein, we demonstrate the radically different cytotoxicity and toxicology of a series of viologen-derivatives in in vitro assays using model organisms representative of human and environmental exposure, namely human lung carcinoma epithelial cell line (A549) and the yeast Saccharomyces cerevisiae. The results show that safe viologen derivatives can be molecularly engineered, representing a promising family of negolyte materials for neutral redox flow batteries.The authors acknowledge financial support by the Spanish Government (Ministerio de Ciencia e Innovacion, Grants PID2021-124974OB-C22 and PID2020-115789GB-C21) and Ramon y Cajal award (RYC2018-026086-I) as well as the MeBattery project. MeBattery has received funding from the European Innovation Council of the European Union under Grant Agreement no. 101046742. This work was supported by the Regional Government of Castilla y Leon (Junta de Castilla y Leon) and by the Ministry of Science and Innovation MICIN and the European Union NextGenerationEU/PRTR. We also gratefully acknowledge Junta de Castilla y Leon (BU049P20) and FEDER for financial support

A Selective, Efficient and Environmentally Friendly Method for the Oxidative Cleavage of Glycols

A catalytic methodology for the oxidative cleavage of vicinal diols is described as an advantageous alternative in terms of the environmental impact on classical methods involving toxic oxidants. The novel strategy is based on the use of dioxomolybdenum(VI) complexes as catalysts and dimethyl sulfoxide (DMSO) as an oxidant and displays high selectivity and a broad scope for glycol cleavage. In addition, the developed system is also useful for the oxidation of acyloins to diketones.Ministerio de Economía y Competitividad (MINECO) and FEDER (CTQ2013-48937-C2-1-P) and Junta de Castilla y León (BU237U13

Computer-aided design of membrane-free batteries using conductor-like screening model for real solvents

The use of renewable energy sources for electricity generation is increasing, and effective energy storage solutions are needed to manage the mismatch between energy production and demand. Redox Flow Batteries (RFBs), particularly Membrane-Free Flow Batteries based on Aqueous Biphasic Systems (ABSs), are a promising technology for stationary energy storage. However, to prevent the crossover of species, the redox-active compounds used in the catholyte and anolyte must be selectively dissolved, which is currently achieved using expensive physical barriers. In this study, an approach was developed to predict the partition coefficient of redox-active compounds in ABSs formed by ionic liquids or polymers, salt, and water using the Conductor-like Screening Model for Real Solvents (COSMO-RS). Experimental data from literature was used to validate the model, resulting in a good correspondence between predicted and experimental data. Furthermore, the method was used to design viologen derivatives and predict their partition coefficients, nine of which were synthesized and validated experimentally. It was found that derivatives containing amine groups have the highest partition coefficients to the salt-rich phase. COSMO-RS proved to be a powerful tool to accelerate the development of advanced biphasic membrane-free flow batteries by designing and finding combinations of redox species with suitable partition coefficients