Stereochemical outcomes of C-F activation reactions of benzyl fluoride

NK and DOH acknowledge support from the University of St Andrews, Engineering and Physical Sciences Research Council (EPSRC, Grant No.: EP/L017911/1), and the EPSRC UK National Mass Spectrometry Facility at Swansea University. This work was also supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), the FRQNT Centre in Green Chemistry and Catalysis (CGCC), and the Université Laval.In recent years, the highly polar C-F bond has been utilised in activation chemistry despite its low reactivity to traditional nucleophiles, when compared to other C-X halogen bonds. Paquin's group has reported extensive studies on the C-F activation of benzylic fluorides for nucleophilic substitutions and Friedel-Crafts reactions, using a range of hydrogen bond donors such as water, triols or hexafluoroisopropanol (HFIP) as the activators. This study examines the stereointegrity of the C-F activation reaction through the use of an enantiopure isotopomer of benzyl fluoride to identify whether the reaction conditions favour a dissociative (SN1) or associative (SN2) pathway. [2H]-Isotopomer ratios in the reactions were assayed using the Courtieu 2H NMR method in a chiral liquid crystal (poly-γ-benzyl-L-glutamate) matrix and demonstrated that both associative and dissociative pathways operate to varying degrees, according to the nature of the nucleophile and the hydrogen bond donor.Publisher PDFPeer reviewe

Mode of action of antimicrobial peptides: long and short amphipathic alpha-helixes use different mechanisms

1 pag. -- 58th Annual Meeting of the Biophysical-Societ

Stereochemical outcomes of C-F activation reactions of benzyl fluoride

In recent years, the highly polar C-F bond has been utilised in activation chemistry despite its low reactivity to traditional nucleophiles, when compared to other C-X halogen bonds. Paquin's group has reported extensive studies on the C-F activation of benzylic fluorides for nucleophilic substitutions and Friedel-Crafts reactions, using a range of hydrogen bond donors such as water, triols or hexafluoroisopropanol (HFIP) as the activators. This study examines the stereointegrity of the C-F activation reaction through the use of an enantiopure isotopomer of benzyl fluoride to identify whether the reaction conditions favour a dissociative (SN1) or associative (SN2) pathway. [2H]-Isotopomer ratios in the reactions were assayed using the Courtieu 2H NMR method in a chiral liquid crystal (poly-γ-benzyl-L-glutamate) matrix and demonstrated that both associative and dissociative pathways operate to varying degrees, according to the nature of the nucleophile and the hydrogen bond donor.</p

Electrochemical Grafting of Aryl Diazonium Salts in Deep Eutectic Solvents

International audienceDeep eutectic solvents are seen as a new class of green and cheap solvents in electrochemical processes. Many electrochemical deposition techniques have been reported in the literature mainly focusing on metal electrodeposition and electro-polymerization. Here, we report for the first time the efficient electro-grafting of aryl diazonium salts on carbon surfaces using ethaline as an example of a natural and biodegradable deep eutectic solvent. Three different aryl diazonium salts have been tested, namely the 4-iodophenyldiazonium ion, 4-carboxymethylphenyl diazonium ion and 4-ethynylphenyldiazonium ion. Effect of concentration, deposition time and potential have been studied in relation to electrode blocking behavior toward redox probes in solution and deposited organic films thickness. Post-functionalization with redox active moieties is demonstrated on such electro-grafted organic layer to show their potential usefulness

Microwave Assisted Organic Synthesis (MAOS) of New Dispacamide A Derivatives Bearing a Thiazolinone Platform, Biological Assays on Inhibition of Protein Kinases and Cell Effects

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Profils : Onze artistes québécois à New York = Profils : Eleven Quebec Artists in New York

Paquin notes the attraction of New York for Quebec artists. Includes biographical notes as well as statements by 11 artists