[en] Imino sugars are sugar mimics in which the oxygen in the ring is replaced by nitrogen. Imino sugars have a huge pharmacological potential as they are considered among the most potent inhibitors of glycosidases and glycosyltransferases, enzymes which are essential for survival. In this work several iminosugars, with either 5 or 6 members in the ring (belonging to the 2,5- dideoxy-2,5-iminohexitol or the 1,5-dideoxy-1,5-iminohexitol class, respectively) have been synthesized making use of aldol reactions between glycine derived anions and 2,3- or 2,4-O-alkylidene-derivatives of tetroses. Firstly, reactions of azaenolates derived from Schöllkopf´s bislactim ether with 2,3- or 2,4-alkylidenederivatives of tetroses have been studied. The stereoselectivity of these reactions was found determined by a double asymmetric induction process, which is dependent on the relative configuration of the reaction partners. The influence of the metallic counterion and the protecting group for the hydroxyaldehyde in the yield and the stereochemical outcome of the reaction has been analyzed, both for the matched and the mismatched pairs. Secondly, to increase the applicability of our aldol methodology for the synthesis of iminosugars in the industrial scale, the reactions between O´Donnell imine and 4-O-benzyl-2,3-O-isopropylidene-Lthreose catalyzed by ammonium salts derived from N-anthracenylmethylcinchoninium or cinchonidinium have been studied. In this case, we have analyzed the influence of the catalyst loading, the nature of the base, the temperature and the solvent in the yield and the stereoselectivity of the process. Finally, efficient methodologies for the conversion of the aldol products derived from glycine and 2,3- or 2,4-alkylidenetetroses into the imino sugars of pharmacological interest have been developed, making use of intramolecular alkylation process of the nitrogen to achieve cyclization, which were based on either nucleophilic substitutions or reductive aminations

[gl] Os iminoazúcares son análogos dos azucáres onde un átomo de nitróxeno substitúe ao osíxeno do anel. Os iminoazúcares son moléculas de grande interese farmacolóxico, pois se atopan entre os inhibidores máis potentes de enzimas de grande importancia biolóxica, como son as glicosidasas e as glicosiltransferasas. Neste traballo sintetizáronse varios iminoazúcares con aneis de 5 ou 6 membros, do tipo 2,5-didesoxi-2,5-iminohexitol e 1,5-didesoxi-1,5-iminohexitol, respectivamente, facendo uso dunha adición aldólica de anións derivados da glicina sobre 2,3- ou 2,4-O-alquilidén derivados das tetrosas. En primeiro lugar estudáronse as reaccións de azaenolatos derivados de éteres de bislactima de Schöllkopf con 2,3- ou 2,4-O-alquilidén derivados das tetrosas. A estereoselectividade destas reaccións determínase mediante un dobre proceso de indución asimétrica, que depende da configuración relativa dos compoñentes de reacción. Analizouse a influencia do contraión metálico do azaenolato e do grupo protector do hidroxialdehído no rendemento e o resultado estereoquímico da reacción, tanto nas situacións de configuración complementaria como non complementaria. Por outra banda, coa intención de potenciar a aplicabilidade a escala industrial da nosa metodoloxía aldólica para a síntese de iminoazúcares, estudáronse as reaccións da imina de O´Donnell e a 4-O-bencil-2,3-Oisopropilidén- L-treosa con catálisis por sales derivados de N-antracenilmetilcinconinio ou N-antracenilmetil-cinconidinio. Analizouse a influencia da carga do catalizador, a natureza da base, a temperatura e o disolvente no rendemento e a estereoselectividade do proceso. Para rematar desenvolvéronse metodoloxías eficientes para a transformación dos aminoaldoles derivados de glicina e as 2,3- ou 2,4-O-alquilidéntetrosas en iminoazúcares de interese farmacolóxico, facendo uso de procesos de alquilación intramolecular do grupo amino para alcanzar a ciclación, ben por substitución nucleófila ou por aminación redutora.