[en] In the present work, a complete study for the synthesis of 2-deoxy-glycosides is described, applyinga strategy previously developed in our group for the preparation of 2-deoxy-2-iodo-pyranoses. Thisstrategy, that involves Wittig¨CHorner olefination from fully protected furanoses to give alkenyl sulfides,electrophilic¨Cinduced cyclization to furnish 2-deoxy-2-iodo-pyranosyl thioglycosides, gives access to anew type of glycosyl donor that can be used in glycosylation reactions of the desired glycosyl acceptors togive 2-deoxy-2-iodo-glycosides.This method is based, on one hand, in the availability of sulfanylmethylphosphine oxides to performthe olefination reaction over the furanoses. The usual access to these reagents is the Arbuzov reaction,that requires chloro derivatives as starting materials that are not easy to prepare and in many cases areunstable. Furthermore, the efficiency of the cyclization is limited by the obtaintion of E/Z alkene mixturesin the olefination step, because Z alkenes were proved to be reluctant to cyclization.To increase the efficiency of the whole process, two implementations were studied in this work.First, a new approach for the preparation of sulfanylmethylphosphine oxides was investigated startingfrom (tosyloxymethyl)phosphine oxide. The method was also extended to heteroatomic substitutedmethylphosphine oxides (X, Se, Te, NR2, etc).Application of these novel sulfanylmethylphosphine oxides in the olefination of ribo- andarabinofuranoses resulted in the formation of the corresponding sulfanyl alkenes with increased E/Zstereoselectivity.The sulfanyl ribo and arabino alkenes were investigated in the iodonium¨Cinduced cyclizationreaction. The effect of the bulkiness of the substituent at sulfur was studied and the results of cyclizationcompared

[es] En este trabajo se describe un estudio completo para la s¨ªntesis de 2-desoxyglicosidos, aplicando laestrategia desarrollada anteriormente en nuestro grupo de investigaci¨®n para la preparaci¨®n de 2-desoxi-2-yodo-piranosidos. Este estrategia incluye la olefinaci¨®n de Wittig¨CHorner de furanosas protegidascompletamente para obtener alquenil sulfidos, las ciclaciones inducidas electrofilicamente para conseguir2-desoxi-2-yodo-piranisil tioglicosidos y permite el acceso a nuevo tipos de glicosil donores que puedenser utilizados en glicosilaci¨®n reacciones con aceptores deseados para suministrar 2-desoxi-2-yodoglicosidos.Esto m¨¦todo se basa, por un lado, en la disponibilidad de sulfanilmetil oxido fosfinas para llevar acabo la reacci¨®n de olefinaci¨®n empezando por furanosas. La preparaci¨®n corriente de estos reactivos es atrav¨¦s de la reacci¨®n de Arbuzov, que requiere derivados cloratos para materiales de partida cuyaobtenci¨®n, en muchas ocasiones, es complicada o no son estables en condiciones est¨¢ndar. Adem¨¢s, laeficacia de la ciclaci¨®n est¨¢ limitada a la obtenci¨®n de una mezcla de alquenes en una mezcla de E/Z en laetapa de olefinaci¨®n, porque los Z alquenos resultan de ciclar m¨¢s lento o no ciclan.Para mejorar la eficacia de todo el proceso se ha investigado el desarrollo para la obtenci¨®n desulfanilmetil oxido fosfinas a partir de tosiloximetil oxido fosfina. Este m¨¦todo se podr¨ªa ampliar para las¨ªntesis de otras metil oxido fosfinas ¦Á-sustituidas por heteroatomo (X, Se, Te, NR2, etc).De la aplicaci¨®n de estas nuevas sulfanilmetil oxido fosfinas en reacciones de olefinaci¨®n con riboyarabinofuranosas result¨® la formaci¨®n de las sulfanil alquenos correspondientes de estereoselectividadmejorada con una relaci¨®n de E/Z m¨¢s alta.Los sulfanil alque