Le nombre de cancers et notamment de cancers photoinduits étant en augmentation, il est indispensable d’identifier de nouvelles molécules protectrices de type filtres UV, réparatrices vis-à-vis des altérations de l’ADN mais également favorisant la réponse pigmentaire. Les lichens sont des organismes originaux qui possèdent des qualités de résistance remarquables aux rayonnements solaires dues notamment à la production de métabolites photoprotecteurs tels que les mycosporines. A partir de ce motif structural original, nous avons synthétisé divers analogues par catalyse à l’or en utilisant un outil de la chimie théorique (TD-DFT) pour orienter les synthèses. Les premières évaluations de leurs propriétés physico-chimiques des molécules ont montré des activités prometteuses. / For several years, melanoma is the cancer with 84,000 new cases per year in Europe, including over 7000 cases in France, in 2010. One of the major causes of this cancer is the excessive exposure to UV radiations and it has been suggested that UV-A may be the primary cause of sunlight-induced melanoma. Hence, sunscreens with a good absorption in the UV-A spectral range need to be developed with a good efficacy and photostability. Lichens are original sources for the development of new UV filters because they possess ability to absorb UV due to the presence of metabolites such as mycosporines or MAAs (mycosporines like aminoacid). Based on the general structure of mycosporines, we have synthesized various analogues of mycosporines using a gold-catalyzed strategy. To orientate the synthesis, we used the method of the quantum chemistry: TD-DFT (Time-dependent density functional theory). These products were analyzed for their UV profiles and some of them showed good absorbing properties in UVA range. The cytotoxicity assay showed no toxicity of all products evaluated.

Boron trichloride, a cheap and commercially available Lewis acid, has been demonstrated to activate alkynes possessing appropriate nucleophiles, facilitating borylative cyclisation. This reaction furnishes polycyclic compounds possessing a new C(sp2)-B bond externally to the newly formed ring (through concomitant C-C and C-B bond formation). The RBCl2 intermediates generated from cyclisation were esterified with pinacol to furnish air/moisture stable boronic esters. This methodology has been applied to the following classes of starting materials: 1,4-disubstituted but-1-ynes (including N- and O- linked analogues), 2-alkynylanisoles, 2-alkynylthioanisoles and 1,2-bis(alkynyl)benzenes. Thus, borylated scaffolds such as dihydronaphthalenes, dihydroquinolines, 2H-chromenes, benzofurans, benzothiophenes, dibenzopentalenes and benzofulvenes have been synthesised. A variety of functionalities (e.g. amines, esters, nitriles) were tolerated by the reaction, with a number of substrates cyclised on either a gram scale, or under ambient conditions, demonstrating the robust nature of this methodology. An oxidation reaction with [Ph3C][BF4] was carried out on some of the borylated dihydronaphthalene compounds to obtain borylated naphthalenes. Suzuki-Miyaura cross-coupling reactions were carried out on certain borylated cycles to furnish new C-C bonds and generate analogues of established pharmaceuticals such as Nafoxidine or Raloxifene, demonstrating the synthetic value of these borylated cycles. Additionally, a one-pot borylative cyclisation/Suzuki-Miyaura cross-coupling reaction was also developed. Throughout this investigation, alternative reactivity has been observed when using BCl3 to activate certain alkynes, including intermolecular 1,2-trans-carboboration and a rare example of N- and O-directed 1,2-trans-haloboration. Additionally, multiple borylative cyclisations have been carried out on an appropriate alkyne to obtain a B-doped polyaromatic hydrocarbon (PAH), which has potential material-based applications.

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Thèse de doctorat : Chimie organique : Lille 1 : 2000. / Résumé en français et en anglais. Notes bibliogr.

Reproduction de : Thèse de doctorat : Sciences physiques : Metz : 1973. / Titre provenant de l'écran-titre. Notes bibliogr.

No description available.

Hohenheim, Univ., Diss., 2007. / Enthält u.a. drei Zeitschriftenaufsätze.

Thèses (Ph.D.)--Université de Sherbrooke (Canada), 2000. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.