Exploiting boron-fluorine bonds for fluorination and synthesis of potential bi-modal imaging agents / Omar Sadek  

Public ISBD Titre : Exploiting boron-fluorine bonds for fluorination and synthesis of potential bi-modal imaging agents Type de document : texte imprimé Auteurs : Omar Sadek, Auteur ; Gras, Emmanuel, Directeur de thèse ; David Perrin, Directeur de thèse Langues : Anglais (eng) Tags : ORGANOFLUOROBORATES  FLUORATION  FLUOROPHORES Résumé : "The B-F bond has an expansive and rich history in chemical transformations and the versatility of the B-F bond has also shown immense utility in fields as far reaching as Positron Emission Tomography (PET) and fluorescence imaging. The application of B-F bonds for nucleophilic Carbon-Fluorine (C-F) bond formation and the development of novel fluorophores with potential applications in PET/fluorescence bi-modal imaging is reported in this document. Organotrifluoroborates are well known as indispensable synthetic tools for the elaboration of organic molecules. However, the trifluoroborate functionality is generally regarded as an auxiliary group, and its potential as a nucleophilic fluoride (F-) source has remained untested. In this context, the ability of organotrifluoroborates to serve as competent sources of F- was investigated. In an update to the historic Balz-Schiemann reaction, that traditionally uses BF4- as a source of F-, organotrifluoroborates were shown to mediate the fluorodediazoniation of in situ generated aryl diazonium salts under mild reaction conditions. In reactions with an analogous substrate class, unsymmetrical diaryliodonium salts could also be fluorinated using phenyltrifluoroborate via thermal decomposition of the ion pair. Finally, the ability of the trifluoroborate moiety to mediate intramolecular fluorination reactions was investigated through the synthesis of various trifluoroborate-containing molecular scaffolds. We also investigated novel fluoroborate (B-Fn) complexes of the 2-aryl-benzothiazole scaffold, known for its interaction with Aß aggregates, as fluorescent probes. Three complexes were isolated, characterized and their photophysical properties are reported. A 2,4-diaryl-benzothiazole monofluoroborate complex displaying the most promising photophysical properties, was shown to be stable to aqueous conditions. Fluoride abstraction from this complex was also demonstrated, providing promising preliminary results towards the viability of radiolabelling via 19F-18F isotope exchange. The monofluoroborate complex also showed interesting structural properties given the asymmetric boron centre. Enantiomers of the complex were successfully resolved by chiral chromatography from the racemic mixture, characterized by Circular Dichroism and their stability to inversion investigated." Document : Thèse de Doctorat Etablissement_delivrance : université de Toulouse 3 en cotutelle avec University of British Columbia. Library Date_soutenance : 04/10/2018 Ecole_doctorale : Sciences de la Matière (SdM) (Toulouse) Domaine : Chimie moléculaire En ligne : https://theses.hal.science/tel-02146608 Exploiting boron-fluorine bonds for fluorination and synthesis of potential bi-modal imaging agents [texte imprimé] / Omar Sadek, Auteur ; Gras, Emmanuel, Directeur de thèse ; David Perrin, Directeur de thèse . - [s.d.]. Langues : Anglais (eng) Tags : ORGANOFLUOROBORATES  FLUORATION  FLUOROPHORES Résumé : "The B-F bond has an expansive and rich history in chemical transformations and the versatility of the B-F bond has also shown immense utility in fields as far reaching as Positron Emission Tomography (PET) and fluorescence imaging. The application of B-F bonds for nucleophilic Carbon-Fluorine (C-F) bond formation and the development of novel fluorophores with potential applications in PET/fluorescence bi-modal imaging is reported in this document. Organotrifluoroborates are well known as indispensable synthetic tools for the elaboration of organic molecules. However, the trifluoroborate functionality is generally regarded as an auxiliary group, and its potential as a nucleophilic fluoride (F-) source has remained untested. In this context, the ability of organotrifluoroborates to serve as competent sources of F- was investigated. In an update to the historic Balz-Schiemann reaction, that traditionally uses BF4- as a source of F-, organotrifluoroborates were shown to mediate the fluorodediazoniation of in situ generated aryl diazonium salts under mild reaction conditions. In reactions with an analogous substrate class, unsymmetrical diaryliodonium salts could also be fluorinated using phenyltrifluoroborate via thermal decomposition of the ion pair. Finally, the ability of the trifluoroborate moiety to mediate intramolecular fluorination reactions was investigated through the synthesis of various trifluoroborate-containing molecular scaffolds. We also investigated novel fluoroborate (B-Fn) complexes of the 2-aryl-benzothiazole scaffold, known for its interaction with Aß aggregates, as fluorescent probes. Three complexes were isolated, characterized and their photophysical properties are reported. A 2,4-diaryl-benzothiazole monofluoroborate complex displaying the most promising photophysical properties, was shown to be stable to aqueous conditions. Fluoride abstraction from this complex was also demonstrated, providing promising preliminary results towards the viability of radiolabelling via 19F-18F isotope exchange. The monofluoroborate complex also showed interesting structural properties given the asymmetric boron centre. Enantiomers of the complex were successfully resolved by chiral chromatography from the racemic mixture, characterized by Circular Dichroism and their stability to inversion investigated." Document : Thèse de Doctorat Etablissement_delivrance : université de Toulouse 3 en cotutelle avec University of British Columbia. Library Date_soutenance : 04/10/2018 Ecole_doctorale : Sciences de la Matière (SdM) (Toulouse) Domaine : Chimie moléculaire En ligne : https://theses.hal.science/tel-02146608

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