Photochemistry of N-(selenoalkyl)-phthalimides. Formation of N, Se-heterocyclic systems

A variety of N-(selenomethyl)alkyl-phthalimides (alkyl = -(CH2)n-; n = 2-5, 1a, b, d, e) and N-(selenobenzyl)propyl phthalimide (1c) were synthesized and their photochemistry was studied at λ = 300 nm. Steady-state photolysis and laser time-resolved spectroscopy studies confirmed that these reactions proceeded by direct or acetone-sensitized excitation followed by intramolecular electron transfer (ET) between Se atom and the phthalimide moiety. Two main pathways are possible after ET: proton transfer to the ketyl radical anion from the CH3Se+ or the -CH2Se+- moieties, yielding the corresponding biradicals. Collapse of these biradicals yields cyclization products with the respective endo or exo selenium-containing heterocycles. Competition between both proton transfer processes depends on the chain length of the alkyl spacer between the phthalimide and Se groups as well as the size of the cycle being formed.Fil: Oksdath Mansilla, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Heredia, Adrián Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Argüello, Juan Elias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Peñeñory, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Azide-alkyne cycloadditions in a vortex fluidic device: Enhanced "on water" effects and catalysis in flow

The Vortex Fluidic Device is a flow reactor that processes reactions in thin films. Running the metal-free azide-alkyne cycloaddition in this reactor revealed a dramatic enhancement of the "on water"effect. For the copper-catalyzed azide-alkyne cycloaddition, stainless steel or copper jet feeds were effective reservoirs of active copper catalyst.Fil: Oksdath Mansilla, Gabriela. Flinders University.; Australia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Kucera, Renata L.. Flinders University.; AustraliaFil: Chalker, Justin Mark. Flinders University.; AustraliaFil: Raston, Colin Llewellyn. Flinders University.; Australi

Deracemisation processes employing organocatalysis and enzyme catalysis

Deracemisation methods have demonstrated their importance in the preparation of chiral compounds in the last few years. In order to resolve a racemic mixture in a dynamic sense, one enantiomer of the starting material can be converted to the other through a deracemisation procedure, that can be achieved by different mechanisms based on stereoinversion or enantioconvergence, often involving two-opposite half reactions, with at least one of the reactions being enantioselective enough to finally obtain an enantioenriched chiral compound. The focus of this comprehensive review is on the application of deracemisation procedures in the present century in order to obtain optically active valuable compounds when employing non-metallic catalysts. Thus, the review will mainly focus on the use of different enzymatic preparations (purified enzymes, cell-free extracts or whole cell systems) and organocatalysts for the deracemisation of racemic mixtures. (Figure presented.).Fil: Aranda Álvarez, María del Carmen. Instituto de Recursos Naturales y Agrobiologia de Sevilla; EspañaFil: Oksdath Mansilla, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Bisogno, Fabricio Román. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: de Gonzalo, Gonzalo. Universidad de Sevilla; Españ

CH3CH2SCH3+OH radicals: Temperature-dependent rate coefficient and product identification under atmospheric pressure of air

Relative rate coefficients have been determined for the gas-phase reaction of hydroxyl (OH) radicals with ethyl methyl sulfide (EMS) using isobutene as a reference compound. The experiments were performed in a 1080 L quartz glass photoreactor in the temperature range of 286-313 K at a total pressure of 760W10 Torr synthetic air using in situ FTIR absorption spectroscopy to monitor the concentration-time behaviors of reactants and products. OH radicals were produced by the 254nm photolysis of hydrogen peroxide (H2O 2). The kinetic data obtained were used to derive the following Arrhenius expression valid in the temperature range of 286-313 K (in units of cm3 molecule-1 s-1): k = (3.0±0:6) × 10-15 exp [(2457 ± 65)/=T]The rate coefficient displays a negative temperature dependence and low pre-exponential factor which supports the existence of an addition mechanism for the reaction involving reversible OH-adduct formation. The results are compared with previous data of other sulfides from the literature and are rationalized in terms of structure-reactivity relationships. Additionally, product identification of the title reaction was performed for the first time by the FTIR technique under atmospheric conditions. Sulfur dioxide, formaldehyde, and formic acid were observed as degradation products in agreement with the two possible reaction channels (addition/abstraction). Copyright © 2010 John Wiley and Sons, Ltd.Fil: Oksdath Mansilla, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Peñeñory, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Albu, Mihaela. Bergische Universitaet Wuppertal. Physikalische Chemie/FBC; AlemaniaFil: Barnes, Ian. Bergische Universitaet Wuppertal. Physikalische Chemie/FBC; AlemaniaFil: Wiesen, Peter. Bergische Universitaet Wuppertal. Physikalische Chemie/FBC; Alemania; AlemaniaFil: Teruel, Mariano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Regioselective ohotocycloaddition of Saccharin Anion to π-Systems: Continuous-Flow synthesis of Benzosultams

Saccharin is a versatile scaffold to build up different heterocycles with relevance in asymmetric catalysis, agricultural chemistry, medicinal chemistry, and so forth. Here, we report a photochemical strategy to obtain seven-membered ring benzosultams in one step, using saccharin anion as starting material. The reaction can be improved in a photoflow reactor and its scope was evaluated. Furthermore, computational study at the CASPT2//CASSCF level of theory was also performed to rationalize the involved mechanism.Fil: Figueroa, Francisco Nicolas. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Heredia, Adrián Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Peñéñory, Alicia B.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Sampedro, Diego. Universidad de la Rioja; ArgentinaFil: Argüello, Juan Elias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Oksdath Mansilla, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Stronger bonds bring bigger challenges

For organic chemists, synthesizing complex molecules in a few steps without waste and with minimal energy has been a long-standing challenge. In many cases, synthetic methodology now enables the design of straightforward syntheses of molecules with different degrees of structural complexity and even their large-scale production. The starting materials are often derived ultimately fromhydrocarbons in petroleum after extensive processing. Is it possible to start with hydrocarbons directly? On page 92 of this issue, Laudadio et al. (1) use gas-phase hydrocarbons to form more complex chemical entities by irradiating them with light. This approach was efficiently achieved not in static batch chemistry but under flow conditions through capillary tubing. This challenge was met by their design of a continuous-flow platform for the regioselectiveactivation of gaseous hydrocarbons under mild conditions applied to carbon-carbonbond formation.Fil: Oksdath Mansilla, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Light on the horizon: Current research and future perspectives in flow photochemistry

Synthetic organic photochemistry is a powerful tool for creating both natural products and molecules with high structural complexity in a simple way and under mild conditions. However, because of the challenges in scaling-up, it has been difficult to apply a photochemical reaction in an industrial process. Flow chemistry provides an opportunity for better control over the conditions of the reaction and, additionally, improved reaction selectivity and enhanced reproducibility. Taking into account that significant interest has focused on the use of flow photochemistry as a method for the synthesis of heterocycles and its applications in target-oriented synthesis over the past few years, the aim of this review is to highlight recent efforts to apply flow photochemistry methodology to diverse reactions as a greener and more scalable process for the pharmaceutical and fine chemical industries. Additionally, the review highlights future perspectives in the development of scale-up strategies, combining photochemical reactions in the continuous-flow multistep synthesis of organic molecules, which is of interest for scientists and engineers alike.Fil: Politano, Fabrizio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Oksdath Mansilla, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Reactivity of 2-aryl-1,3-dithiane anions towards neopentyl, neophyl and phenyl iodides. New evidence for an SRN1 mechanism

The reactions of 2-(4-Z-phenyl)-1,3-dithiane anions (Z=H, OMe, Cl, CN) with neopentyl, neophyl and phenyl iodides were studied in DMSO, taking into consideration the effect of the Z substituent on the dithiane anions reactivity as well as on the product distribution. These substitution reactions proceed by an SRN1 mechanism with radicals and radical anions as intermediates. Two competitive pathways are possible for the radical anion of the substitution product, namely electron transfer (ET) to the substrate giving the substitution product and C-S bond fragmentation to yield a distonic radical anion. ET is the main pathway for the reactions between dithiane anions bearing electron-donor substituents and neopentyl or its analogue iodides affording the substitution products in moderate yields (41-53%). Copyright © 2011 John Wiley & Sons, Ltd.Fil: Oksdath Mansilla, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Peñeñory, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Oxidation of organosulfur compounds promoted by continuous-flow chemistry

Organosulfur compounds are important moieties found in several medicinal drugs used in the therapy of arthritis, cancer, depression, diabetes or immune deficiency syndrome. Furthermore, organosulfur compounds are intermediates in many organic reactions with a key role as ligands or chiral auxiliaries. Due to their importance in various areas as pharmaceutical chemistry, synthetic organic chemistry, as well as materials science, the development of new and more sustainable synthetic protocols to provide access to different organosulfur compounds, has a high impact on the broader chemistry community. Many interesting transformations of organosulfur compounds involve an oxidation reaction to access to organosulfur derivatives such as disulfide, sulfinyl or sulfones. Organosulfur oxidation is typically carried out using different oxidant agents such as peroxides, peracids or using atmosphere oxygen under photocatalysis. Despite the numerous procedures reported in the academia, the developments of oxidation of organosulfur compounds with an industrial interest has been limited in regard to the scaling-up, sustainable and safer process. In this context, the use of continuous-flow technology has allowed overcome the disadvantaged of batch approach and is a bridge to connect the academia with the industry. The aim of this review is to highlight the importance of applying flow chemistry methodology as a greener and scalable process in the oxidation of organosulfur compounds. Additionally, a critical view of the different developed methodologies and a future view in the employ of organosulfur oxidation are discussed.Fil: Colomer, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Traverssi, Miqueas Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Oksdath Mansilla, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin