1,721,017 research outputs found
Aromatic radical perfluoroalkylation reactions
Full text linkThis account intends to cover recent literature on radical perfluoroalkylation reactions of aromatic nuclei in organic and aqueous media. Emphasis will be placed on radical aromatic perfluoroalkylation reactions in water or aqueous media, with the aim of exploring aromatic radical reactivity in a benign environment. © 2012 Published by NRC Research Press.Fil: Postigo, Jose Alberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Radical fluorination reactions by thermal and photoinduced methods
Full text linkThe radical or radical ion-based fluorination reactions of organic compounds will be presented. These methodologies include fluorination processes accomplished through thermal or photoinduced radical/electron transfer methods. In doing so, the fluorination reactions of diverse families of organic compounds such as aliphatic and aromatic substrates will be presented. Recently summarized or reviewed articles will be mentioned but not discussed.Fil: Lantaño, Beatriz. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica. Cátedra de Química Orgánica I; ArgentinaFil: Postigo, Jose Alberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica. Cátedra de Química Orgánica I; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Homolytic aromatic radical perfluoroalkyl-group substitution of arenes in water
Full text linkThe substitution reaction of aromatic nuclei, such as N,N-dialkylated aromatic amines and methoxysubstituted arenes with perfluoroalkyl Rf groups was acomplished in water by a photoinduced method to yield the substitution products resulting from replacement of aromatic H’s with the Rf moiety in good yields (57-88%). Mechanistic aspects are discussed giving support for a photoinduced electron transfer substitution (PET) reaction. A radical chain mechanism superimposed with a redox process is proposed to account for product formation, as evidenced by the observation of the UV-vis transient spectra of the radical cation species generated from electron-rich aromatic compounds in the presence of perfluoroalkyl halides by Nanosecond Laser Flash Photolysis (NLFP) techniques.Fil: Postigo, Jose Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentin
Photoinduced perfluorobutylation of organic substrates in aqueous media
Full text linkHydroperfluorobutylation of a series of electron-deficient and electron-rich alkenes through consecutive radical reactions employing perfluorobutyl iodide, n-C4F9I, and (Me3Si)3SiH as chain carrier/hydrogen atom donor is described. The photoinduced Halogen Atom Transfer (HAT) reactions of both olefins and alkynes with n-C4F9I are also shown to be achieved efficiently in aqueous mixtures. On the other hand, aromatic and heteroaromatic substrates can be perfluorobutylated with high efficiency in a photoinduced fashion by means of a Homolytic Aromatic Substitution (SHA) process which involves an Electron Transfer (ET) and a Proton Transfer (PT) step.Fil: Postigo, Jose Alberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Perfluoroalkylation of organic compounds by photoredox catalysis with organic dyes
No full textThe generation of perfluoroalkyl radicals (RF) by means of photocatalysis is a more suitable route than the established perfluoroalkyl radical production through chemical initiators, like azo or peroxide compounds or the employment of transition metals through thermal electron transfer (ET) initiation processes. The photocatlytic reaction conditions withstand an array of functional groups and, therefore, can be applied to the late-stage modification of bioactive molecules. Photoorgano catalysts (POC), in the absence of transition metals, can function, upon excitation, as electron exchange species, triggering ET reactions that yield RF radicals. RF radical production without the assistance of transition metals through the employment of POC will be described, studying classical examples and the most recent investigations in the field.Fil: Postigo, Jose Alberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin
Propagation chains in photocatalyzed radical nucleophilic substitutions of thiolates with perfluoroalkyl groups
No full textQuantum yields and radical chain lengths have been investigated in photocatalyzed radical nucleophilic perfluorobutyl group substitution reactions of 2-mercaptothiolate anion under three different photocatalytic systemsoperating in reductive and quenching manners. Important propagation chain lengths have been uncovered with photocatalysts under both scenarios, reductive and oxidative. The different overall quantum yields and chain lengths observed demonstrate the balance between the efficiency of the photoinitiation events, propagation and termination steps. Theoretical calculations provide a better understanding and throw light into whether a closed or an open catalytic cycle is operating in photoinitiated perfluoroalkyl group- thiolate coupling reaction.Fil: Postigo, Jose Alberto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin
A facile one-pot synthesis of 8-oxo-7,8-dihydro-(2′-deoxy)adenosine in water
Full text linkReaction of 2-mercaptoethanol with 8-bromo-2′-deoxyadenosine and 8-bromo-adenosine in aqueous solution and in the presence of triethylamine gave the 8-oxo-adenine derivatives in very good yields. Some mechanistic details are reported.Fil: Chatgilialoglu, Chryssostomos. Consiglio Nazionale delle Ricerche; ItaliaFil: Navacchia, Maria Luisa. Consiglio Nazionale delle Ricerche; ItaliaFil: Postigo, Jose Alberto. Universidad de Belgrano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Electron Donor-Acceptor Complexes in Perfluoroalkylation Reactions
No full textElectron-donor-acceptor complexes (EDA) can be established through halogen-bonding interactions between the N lone electron pair from organic bases (or N-/O-centered anions) and perfluoroalkyl iodides RF–I. These EDA complexes can be activated thermally or photochemically, and will be shown to be responsible for new C–RF bond formation reactions, bypassing the use of visible-light photocatalysts (either organic or organometallic) or harsh reaction conditions, thus simplifying reaction protocols, work-up and analysis. Through this strategy, diverse reaction types can be realized, such as atom transfer radical additions, homolytic aromatic substitutions, and multicomponent reactions.Fil: Postigo, Jose Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica. Cátedra de Química Orgánica I; Argentin
Late-stage fluorination of bioactive molecules and biologically-relevant substrates
No full textLate Stage Fluorination of Bioactive Molecules and Biologically-Relevant Substrates reviews how the use of these techniques on compounds with already known and relevant biological activity can provide new pharmaceutical leads with improved medicinal properties. The fluorination strategies discussed take into account both conventional and novel reagents, including nucleophilic, electrophilic, those of a radical nature, and diverse families of organic compounds, such as (hetero) aromatic rings and aliphatic substrates. Drawing on the author's expert knowledge, this book provides researchers with a broad set of applicable methods to use in their work.Key FeaturesHighlights the latest developments in the field in a concise volumeProvides details of key fluorinating reagents across diverse families of organic compoundsExplores the current applications and future potential of fluorine in drug development.Fil: Postigo, Jose Alberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica. Cátedra de Química Orgánica I; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin
Reactivity of fluorinated organic radicals in aqueous media
Full text linkFluorinated radicals in water are shown to enable a useful array of synthetic organic transformations, reflecting these intermediates' distinct behavior in water or aqueous media. The enhanced reactivities of perfluroalkyl radicals in water facilitate their addition reactions to carbon–carbon and carbon–heteroatom multiple bonds. Activated and unactivated unsaturated substrates are equally reactive candidates for radical perfluoroalkylation reactions in aqueous systems. Parallel behavior of perfluorinated radicals in organic solvents and in water is presented, demonstrating the scope of reactions based on fluorinated radicals in aqueous media, as well as the ease of carbocyclic construction.Fil: Barata Vallejo, Sebastian. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Postigo, Jose Alberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
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