Xanthones or xanthen-9-ones (dibenzo-g-pirone) comprise an important class ofoxygenated heterocycles whose role is well-known in Medicinal Chemistry. The biological activities of this class of compounds are associated with their tricyclic scaffold but vary depending on the nature and/or position of the different substituents. To obtain more structural diversity and quantities for biological assays, suitable and efficient synthetic processes are necessary.Different synthetic methodologies, “classical” and “non-classical”, namely microwaveassisted organic synthesis, heterogeneous catalysis and a combination of heterogeneous catalysis with microwave irradiation, were applied to obtain new xanthone derivatives.Thus, this thesis reports the synthesis and structure elucidation of seven new compounds:1,3-dihydroxy-5-methoxyxanthone (X1), 1-hydroxy-3-mesyloxy-5-methoxyxanthone (X2), 1-hydroxy-5-methoxy-3-(3-methylbut-2-enyloxy)xanthone (P1), 1-hydroxy-5-methoxy-4-(3-methylbut-2-enyl)-3-(3-methylbut-2-enyloxy)xanthone (P2), 1-hydroxy-5-methoxy-4-(3-methylbut-2-enyl)-6’,6’-dimethyl-’,5’-dihydropyran(2’,3’:3,2) xanthone (P3), 1-hydroxy-5-methoxy-6’,6’-dimethyl-’,5’-dihydropyran(2’,3’:3,2)xanthone (P4) and 1-hydroxy-5-methoxy-6’,6’-dimethyl-’,5’-dihydropyran(2’,3’:3,4)xanthone (P5), as well as the evaluation of theirantitumor activity.The synthesized xanthones and respective derivatives with prenyl units were structurallyelucidated by spectroscopic methods including IR, NMR (1H, 13C, HSQC and HMBC) and HRMS.Their biological activity was evaluated by a screening assay for inhibition of growth of human tumor cell lines.
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