Repositori URV

Identificador: TDX:789

Handle: https://hdl.handle.net/20.500.11797/TDX789

Autors:
Arnés Novau, Xavier

Resum:
2-Deoxy and 2,6-dideoxy glycosides are frequently found as single structural elements or, more frequently, as components of oligosaccharides, in antibiotics and anticancer agents such as antracyclines (cyclamicine 0), active antibiotics (erytromicines, angucyclines) and pharmacological compounds used in cardiac insufficiency treatment (cardiac glycosides such as digitoxine), etc.Therefore, methods for the efficient and stereoselective construction of deoxyglycosidic linkages will have useful applications in medicinal and bioorganic chemistry by allowing to understand biological mechanisms and elaborate new and less toxic drugs.On the other hand, in the nucleoside field, some 2'-deoxy and 2',3'-dideoxy-nucleosides are inhibitors of inverse transcriptase of AIDS virus, and they are often used in its treatment.In two cases, the lack of a stereodirecting neighbouring group adjacent to the anomeric center makes 2-deoxyglycoside synthesis a particular challenge. Moreover, the absence of electron-withdrawing substituent at C-2 makes the glycosidic bond much more acid labile, giving rise to easy hydrolysis or anomerization.In this context, the goal of this work is develop new synthetic methods for the stereoselective synthesis of 2-deoxy-oligosaccharides and nucleosides starting from 2-deoxy-2-iodo-pyranosides and furanosides. These glycosil donors are trying to obtain by intramolecular and stereoselective cyclization induced by electrophilic iodine and starting from polihydroxi-pentenylsulfides and polihydroxi-hexenylsulfides as substrates. This method would allow to prepare glycosil donors with iodine at position 2 by means of a procedure that does not require the use of glycals.It has been prepared different polihydroxi-alkenylsulfides following two different synthetic strat