Radical Fluoroalkylation Reactions

Recent protocols and reactions for catalytic radical perfluoroalkylations will be described. The production of perfluoroalkyl radicals (RF = CnF2n+1, n ≥ 2), which effect both addition and substitution reactions on organic substrates, can be realized through a range of diverse methods such as the well-established visible-light transition-metal-mediated photocatalysis, organic-dye-photocatalyzed reactions, electron donor-acceptor complexes, and more recently frustrated Lewis pairs. Thus, perfluoroalkylation reactions of carbon-carbon multiple bonds, isocyanides, nitrones, hydrazones, β-keto esters, α-cyano arylacetates, sulfides, and (hetero)arenes will be described. Special emphasis will be placed on examples published after 2015, where higher fluorinated series of fluoroalkylating reagents are studied.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: Cooke, María Victoria. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Postigo, A.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentin

Photocatalytic Difluoromethylation Reactions of Aromatic Compounds and Aliphatic Multiple C-C Bonds

Among the realm of visible light photocatalytic transformations, late-stagedifluoromethylation reactions (introduction of difluoromethyl groups in the last stages of syntheticprotocols) have played relevant roles as the CF2X group substitutions exert positive impacts on thephysical properties of organic compounds including solubility, metabolic stability, andlipophilicity, which are tenets of considerable importance in pharmaceutical, agrochemical, andmaterials science. Visible-light-photocatalyzed difluoromethylation reactions are shown to beaccomplished on (hetero)aromatic and carbon?carbon unsaturated aliphatic substrates under mildand environmentally benign conditions.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. Oficina de Coordinación Administrativa Houssay; 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. Oficina de Coordinación Administrativa Houssay; Argentin

Combined Raman and IR spectroscopic study on the radical-based modifications of methionine

Among damages reported to occur on proteins, radical-based changes of methionine (Met) residues are one of the most important convalent post-translational modifications. The combined application of Raman and infrared (IR) spectroscopies for the characterisation of the radical-induced modifications of Met is described here. Gamma-irradiation was used to simulate the endogenous formation of reactive species such as hydrogen atoms ( •H), hydroxyl radicals ( •OH) and hydrogen peroxide (H 2O 2). These spectroscopic techniques coupled to mass experiments are suitable tools in detecting almost all the main radical-induced degradation products of Met that depend on the nature of the reactive species. In particular, Raman spectroscopy is useful in revealing the radical-induced modifications in the sulphur-containing moiety, whereas the IR spectra allow decarboxylation and deamination processes to be detected, as well as the formation of other degradation products. Thus, some band patterns useful for building a library of spectra-structure correlation for radical-based degradation of Met were identified. In particular, the bands due to the formation of methionine sulfoxide, the main oxidation product of Met, have been identified. All together, these results combine to produce a set of spectroscopic markers of the main processes occurring as a consequence of radical stress exposure, which can be used in a spectroscopic protocol for providing a first assessment of Met modifications in more complex systems such as peptides and proteins, and monitoring their impact on protein structure.Fil: Torreggiani, A.. Consiglio Nazionale delle Ricerche; ItaliaFil: Barata Vallejo, Sebastian. Consiglio Nazionale delle Ricerche; Italia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Chatgilialoglu, C.. Consiglio Nazionale delle Ricerche; Itali

Bleomycin-induced trans lipid formation in cell membranes and in liposome models

Cell cultures of NTera-2 cells incubated with bleomycin and liposomes as biomimetic models of cell membranes were used for examining some novel aspects of drug-metal induced reactivity with unsaturated lipids under oxidative conditions. In cell cultures, bleomycin was found for the first time to cause the formation of trans fatty acids. The chemical basis of this transformation was ascertained by liposome experiments, using bleomycin-iron complexes in the presence of thiol as a reducing agent that by incubation at 37 °C gave rise to the thiyl radical-catalysed double bond isomerisation of membrane phospholipids. The effect of oxygen and reagent concentrations on the reaction outcome was studied. An interesting scenario of free radical reactivity is proposed, which can be relevant for understanding the role of membrane lipids in antitumoral treatments and drug carrier interaction.Fil: Cort, Aysegul. Akdeniz University. Faculty of Medicine; Turquía. Consiglio Nazionale delle Ricerche; ItaliaFil: Ozben, Tomris. Akdeniz University. Faculty of Medicine; TurquíaFil: Sansone, Anna. Consiglio Nazionale delle Ricerche; ItaliaFil: Barata Vallejo, Sebastian. Consiglio Nazionale delle Ricerche; Italia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Chatgilialoglu, Chryssostomos. Demokritos National Centre For Scientific Research; GreciaFil: Ferreri, Carla. Consiglio Nazionale delle Ricerche; Itali

Photocatalytic fluoroalkylation reactions of organic compounds

Photocatalytic methods for fluoroalkyl-radical generation provide more convenient alternatives to the classical perfluoroalkyl-radical (Rf) production through chemical initiators, such as azo or peroxide compounds or the employment of transition metals through a thermal electron transfer (ET) initiation process. The mild photocatalytic reaction conditions tolerate a variety of functional groups and, thus, are handy to the late-stage modification of bioactive molecules. Transition metal-photocatalytic reactions for Rf radical generation profit from the redox properties of coordinatively saturated Ru or Ir organocomplexes to act as both electron donor and reductive species, thus allowing for the utilization of electron accepting and donating fluoroalkylating agents for Rf radical production. On the other hand, laboratory-available and inexpensive photoorgano catalysts (POC), in the absence of transition metals, can also act as electron exchange species upon excitation, resulting in ET reactions that produce Rf radicals. In this work, a critical account of transition metal and transition metal-free Rf radical production will be described with photoorgano catalysts, studying classical examples and the most recent investigations in the field.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: Bonesi, Sergio Mauricio. 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 Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; 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

Synthetic strategies for fluorosulfonylated compounds: application to click chemistry reactions

The syntheses and applications of fluorosulfonylated organic compounds have flourished in the last ten years due to their versatility to participate in click chemistry (SuFEx) reactions. Also, organic architectures that combine the SO2F group and other ancillary functional moieties such as olefins, alkynes, etc. (i.e.: bis-electrophiles) have augmented the applications and diversity of the end compounds. To this effect, the association of an alkyne functionality and the SuFExable group within one structure has been shown to encompass two-in-one click chemistry sequential protocols with the aim of building on the diversity of scaffolds by two consecutive click processes. We next examine the syntheses of (hetero)aromatic-, alkyl-, alkenyl-, and alkynyl-sulfonyl fluorides and β-keto-sulfonyl fluorides and the syntheses of compounds bearing N-SO2F and O-SO2F bonds through diverse catalytic methods, illustrating examples of their SuFEx click chemistry and other ancillary functional group reactivity.Fil: Barata Vallejo, Sebastian. 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. Cátedra de Química Orgánica I; Argentina. Consiglio Nazionale delle Ricerche. Istituto per la Sintesi Organica e la Fotoreattività; ItaliaFil: Yerien, Damián Emilio. 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. Cátedra de Química Orgánica I; ArgentinaFil: 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. Cátedra de Química Orgánica I; Argentin

Bioinspired Photocatalyzed Organic Synthetic Transformations. The Use of Natural Pigments and Vitamins in Photocatalysis

Due to the necessity for more environmentally benign processes in synthetic organic chemistry, and in particular in photocatalysis, a recourse to photocatalysts that are also found in nature and mimic natural processes to accomplish organic transformations is very appealing. Synthetic useful reactions such as oxidations, reductions, carbon-oxygen, carbon-carbon and carbon-sulfur bond formation reactions, and E-to-Z geometrical isomerization reactions photocatalyzed by biological natural pigments, vitamins, cofactors, and compounds with antiviral activity will be discussed in this account. Interestingly, due to the remarkable redox properties and triplet energies of some of these catalysts that are found in nature, both electron transfer (ET)- and energy transfer (EnT)-driven photocatalytic processes can be accomplished.Fil: Barata Vallejo, Sebastian. Consiglio Nazionale delle Ricerche; Italia. 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; ArgentinaFil: Yerien, Damián Emilio. 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; 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

Visible Light-catalyzed Fluoroalkylation Reactions of Free Aniline Derivatives

The electron-rich nature of aminoaromatic compounds and the electrophilic characterof fluoroalkyl R F radicals allow for a special match in substitution reactions. Weherein present visible light-photocatalyzed fluoroalkylation reactions of anilinederivatives, with a study of the reaction mechanisms. The examples evaluated makeuse of different photocatalysts, such as polypyridyl complexes of Ir or Ru transitionmetals, organic dyes such as Rose Bengal, phthalocyanine-metal organocatalysts, orvisible-light activated complexes. Different visible light sources that span from the blueregion of the electromagnetic spectrum to low power red light irradiation sourcesdeliver the excited photocatalysts that ensue into the production of fluoroalkyl R Fradicals. In turn, many sources of R F radicals can be employed, such as fluoroalkylhalides, Togni s reagents, Umemoto s reagent, etc. All these protocol variantsdemonstrate the expansion of the methodology and the versatility of photocatalytictechniques applied to a special family of organic compounds such as aminoaromaticsubstrates, which has been studied by different groups. Contributions from our ownlaboratory will be given.Fil: Lantaño, Beatriz. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica. Cátedra de Química Orgánica I; ArgentinaFil: Yerien, Damián Emilio. 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; ArgentinaFil: Barata Vallejo, Sebastian. 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. 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. Oficina de Coordinación Administrativa Houssay; Argentin

Catalytic Fluoroalkylation Reactions of Alcoxy‐subtituted (Hetero)Arenes

Electron-rich alcoxy-substituted (hetero)arenes and electrophilic fluoroalkyl moieties represent advantageous partners for substitution reactions due to their electronic match. Fluoroalkylation strategies of alcoxy-substituted (hetero)arenes are herein presented which depict photocatalytic and thermal methods. Photocatalytic methods rely on the use of diverse photocatalysts such as Ru(bpy)3Cl2, tetrabutylammonium decatungstate TBADT, N-doped carbon nanodots NCNDs, and vitamin derivatives which can partner with the Langlois reagent NaSO2CF3, CF3CO2H, and perfluoroalkyl iodides RFI as fluoroalkylating reagents. Also, electrocatalytic methods that make use of the cathodic reduction of CF3SO2Cl to generate CF3 radicals can achieve trifluoromethylation reactions of alcoxysubstituted (hetero)arenes. On the other hand, thermal methodologies comprising Pd(OAc)2 catalysis and using CF3Br as trifluoromethylating source have been implemented.Fil: Yerien, Damián Emilio. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lantaño, Beatriz. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Barata Vallejo, Sebastian. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consiglio Nazionale delle Ricerche; ItaliaFil: Postigo, Jose Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentin

Revisiting the reaction of hydroxyl radicals with vicinal diols in water

The carbonyl products of the reactions of hydroxyl radicals with three vicinal diols (ethane-1,2-diol, propane-1,2-diol and butane-2,3-diol) have been identified and quantified. Hydroxyl radicals were produced by gamma-radiolysis of N2O-saturated aqueous solutions. The reactions result in the formation of alkoxyl radicals (15%) followed by beta-fragmentation, and alpha-hydroxyl alkyl radicals that undergo H2O elimination. The latter process is part of a radical chain reaction at higher diol concentrations.Fil: Jiang, Dong. University of Newcastle; Reino UnidoFil: Barata Vallejo, Sebastian. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica. Cátedra de Química Orgánica I; ArgentinaFil: Golding, Bernard T.. University of Newcastle; Reino UnidoFil: Ferreri, Carla. Consiglio Nazionale delle Ricerche; ItaliaFil: Chatgilialoglu, Chryssostomos. Consiglio Nazionale delle Ricerche; Itali