Phd Thesis Tese De Doutoramento NM Xavier

Universidade de Lisboa Institut National des Faculdade de Ciências Sciences Appliquées de Lyon Departamento de Química e Bioquímica Synthesis of New Sugar Derivatives Containing an α,β-Unsaturated Carbonyl System in Their Structure and Biological Evaluation Nuno Manuel Ribeiro Martins Xavier Doutoramento em Química Doctorat en Chimie (Química Orgânica) (Spécialité Chimie) 2010 Universidade de Lisboa Institut National des Faculdade de Ciências Sciences Appliquées de Lyon Departamento de Química e Bioquímica Synthesis of New Sugar Derivatives Containing an α,β-Unsaturated Carbonyl System in Their Structure and Biological Evaluation Nuno Manuel Ribeiro Martins Xavier Doutoramento em Química Doctorat en Chimie (Química Orgânica) (Spécialité Chimie) Supervised by: Amélia Pilar Rauter , Professora Associada com Agregação Yves Queneau , Directeur de Recherche au CNRS 2010 Acknowledgements During the last three years as a PhD student I had the opportunity to benefit from the contribution of many people. Here I would like to thank all of them. First, I wish to express my respect and gratitude to my two supervisors: Prof. Dr. Amélia Pilar Rauter from the Faculdade de Ciências da Universidade de Lisboa (FCUL) and Dr. Yves Queneau from the Institut National des Sciences Appliquées de Lyon (INSA-Lyon). Prof. Rauter first taught me carbohydrate chemistry during my undergraduate studies, and motivated me to undertake doctoral studies in this field. I thank her for receiving me in a pleasant scientific environment, providing me guidance, encouragement and freedom to develop my ideas. Dr. Queneau has received me in his laboratory in July 2007 under a collaborative Luso-French project co-supervised by Prof. Rauter and encouraged the continuation of such collaboration in a PhD program. I acknowledge his active supervision and his invaluable enthusiasm which resulted in many excellent suggestions for my subject. I would like to thank Prof. Dr. Joachim Thiem from the Universität Hamburg, who has kindly given me the opportunity to join his group, for helpful advice and fruitful discussions. I gratefully acknowledge Prof. Dr. Alain Doutheau, director of the Laboratoire de Chimie Organique de l’INSA Lyon (LCO-INSA) for having received me in the team. I am grateful to Dr. Stéphane Chambert, Maître de Conferences at INSA-Lyon for his collaboration in part of the work developed during the research program in Lyon. I would like to thank Prof. Jorge Justino and his research team at the Escola Superior Agrária de Santarém , especially Dr. Ana Neves, Dr. Margarida Goulart and Dr. Filipa Silva for the biological activity assays performed with our compounds. Within the Centro de Química e Bioquímica of FCUL, I would like to express my gratitude to Prof. Helena Florêncio and to my colleague Paulo Madeira from the Environmental and Biological Mass Spectrometry Group for the mass spectrometry i analysis and their collaboration in investigating the ionization fragmentation mechanisms of some of our compounds. I would like to thank my dear lab colleagues at the Carbohydrate Chemistry Group of FCUL in Lisbon and at the Laboratory of Organic Chemistry of INSA-Lyon for their kindness, friendship and support all the time. In particular I thank Ana Rita Jesus, Madan Kumar Singh, Susana Dias Lucas and Sandrina Silva with whom I have shared the lab bench. Last but not least I would like to thank my parents and my sister for their unwavering care and support through these years, being there whenever I needed and giving me encouragement to reach my goals. ii Abstract This PhD research work was focused on the synthesis and uses of bicyclic carbohydrate lactones, in the context of the access to new sugar derivatives containing an α,β- unsaturated carbonyl function. These molecular targets, chosen for the intrinsic bioactivity associated to the conjugated carbonyl system, were synthesized and submitted to biological evaluation, particularly their effect towards fungi and bacteria. Moreover, the inclusion of conjugated carbonyl systems in carbohydrates provides suitable templates for further derivatization, to which a variety of reactions may be applied. Three types of bicyclic sugar lactones were investigated: furanose C-C-linked butenolides (compounds type I), pyranose-fused butenolides, including S- or NH - analogues (compounds type II −IV ), and carboxymethyl glycoside-derived lactones (CMGLs, compounds type V). The access to butenolide containing-sugars was explored. The synthetic methodology was based on the Wittig olefination of easily prepared 3- or 5-keto sugars and spontaneous intramolecular lactonization of the intermediate γ-hydroxy α,β-unsaturated esters. In the case of the bicyclic fused derivatives, furanos-3-uloses containing acid labile 5-O or 5,6-di-O-protecting groups were used as precursors and converted into the corresponding (Z)- or ( E)-3-C-(ethoxycarbonyl)methylene furanoses. Further acid- mediated hydrolysis made possible their isomerization to the pyranose ring and concomitant intramolecular transesterification leading directly to the target compounds in good overall yields. Such bicyclic systems featured the butenolide moiety annelated at C-2-C-3 (compounds type II ) or at C-3-C-4 of the sugar backbone, depending on the stereochemistry of the C3-C3’double bond. The introduction of a sulfur function at C-5 of the furanoid 3-C-α,β-unsaturated esters, widened the scope of this methodology to thiosugar analogues of type III . When this approach was applied to related 5-azido v furanoid esters aiming at imino sugar-based molecules of type IV , different carbohydrate derivatives comprising both an amide functionality and an α,β-unsaturated carbonyl system were obtained. The (E)- and (Z)-3-C-(ethoxycarbonyl)methylene 5- amino furanoses were converted to a furanose-fused α,β-unsaturated δ-lactam and to a butenolide-containing N-ethylformamide, respectively. Moreover, the hydrolysis of the 1,2-O-isopropylidene group of the ( Z)-5-azido furanose precursor, followed by azide reduction, provided a 2-keto iminopyranose, which led to the 1,2-dihydropyridin-3-one system upon acetylation. CMGLs (compounds type V) were used as precursors for 3-enopyranosid-2-uloses (compounds type VI ). The opening of the lactone moiety by amines provided tri-O- acylated 2-hydroxy pyranosides which by oxidation/elimination generated the enone system. Further Wittig olefination afforded 2-C-branched-chain conjugated dienepyranosides (compounds type VII ). Glycosides bearing a propargyl moiety were engaged in “click” chemistry reactions leading to the corresponding 1,2,3-triazoles (compounds type VIII −IX ). OAc OAc O O O O O O NHR NH AcO AcO X N N R X N VI X = O VIII X = O VII X = CHCO2Et IX X = CHCO2Et Among the molecular targets obtained, the furanose-linked butenolides, the pyranose- fused butenolides, the conjugated carbonyl sugar derivatives synthesized from CMGLs and the triazole-containing glycosides were submitted to antimicrobial activity assays. The butenolide-containing sugars did not show satisfactory antibacterial or antifungal activities. Such weak effect is probably due to the presence of a quaternary β-carbon in the conjugated system of these molecules, which is specially hindered in the fused systems, reducing their Michael acceptor ability. In contrast, significant efficacy was observed for 3-enopyranosid-2-uloses and conjugated diene pyranosides. In particular, (N-dodecylcarbamoyl)methyl enulosides vi displayed strong and very strong activities against some of the pathogen microbes tested, being in some cases similar to those of the standard antibiotics. The α-enuloside exhibited very strong effect towards Bacillus cereus and Bacillus subtillis and strong activity against Enterococcus faecalis and the fungal pathogen Penicillium aurantiogriseum . The β-anomer presented a very strong inhibitory effect against the fungi Aspergillus niger and Penicillium aurantiogriseum . Dienepyranosides exhibited a strong activity selectively towards Enterococcus faecalis . Triazole derivatives were virtually ineffective. Three of the bioactive compounds, including the most active one, i.e. the α-(N-dodecylcarbamoyl)methyl enuloside, showed low acute toxicity in eukaryotic hepatoma cells. vii Resumo O trabalho desenvolvido no âmbito deste Doutoramento centrou-se na síntese e no uso de biciclolactonas glicídicas com o objectivo de se obterem novos derivados de açúcares contendo um sistema carbonílico α,β-insaturado na sua estrutura. Estes alvos moleculares foram sintetizados no sentido de se avaliarem posteriormente as suas propriedades biológicas, nomeadamente a nível de actividade antifúngica e antibacteriana. O sistema carbonílico α,β-insaturado é frequentemente encontrado em produtos naturais e de síntese que possuem uma variedade de actividades biológicas. A bioactividade exibida por estes compostos está geralmente associada à capacidade da função conjugada para reagir segundo adição de Michael com nucleófilos existentes em proteínas. Em particular, derivados de açúcares contendo lactonas α,β-insaturadas foram descritos como fungicidas ou como insecticidas potentes. Por outro lado, a inclusão destas unidades em carbo-hidratos conduz a moléculas funcionalizadas que poderão ser úteis para posterior derivatização, devido à reactividade do sistema conjugado. As moléculas-alvo tiveram como base três tipos de lactonas bicíclicas (Fig. 1): butenolidas ligadas a anéis de furanose (compostos tipo I), butenolidas fundidas a anéis de pyranose, incluindo tio- e iminoaçúcares análogos

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