Much recent efforts have been devoted to the development of synthetic oligonucleotides for various therapeutic and diagnostic applications because of their capability to cause selective inhibition of gene expression by bonding to the target DNA/RNA sequences through antigen, antisense and RNA interference. The easy formation of well-defined structures like alpha-, béta-, gamma-turns or helical structures of N-oxy peptides promoted us to design new modified oligonucleotides so as to study their physico-chemical and biological properties. During this work, synthesis of different nucleosides aminoxy acids as well as their oligomers has been investigated. In the first part, aminoxy, carboxylic acid and aldehyde functions were introduced into the sugar ring of thymidine and different monofunctionalized nucleosides were obtained thanks to Mitsunobu, O-allylation and oxidation reactions. Different nucleoside monomers were then linked together, leading to novel dinucleosides with N-oxy amide, oxime or aminoxy linkage. In the second part, preparation of different uridines aminoxy acids was studied by using uridine, 2,2’-anhydro and 2,3’-anhydro uridines as starting materials. An uridine aminoxy ester was obtained from 3’-oxo uridine, through homologation with Wittig reaction and introduction of the oxyamine function by nucleophilic substitution of the 5’-iodo derivative. In parallel, as a continuing program in the laboratory on the glycoamino acids synthesis, we have synthesized novel C-glycosyl aminoxy acids in order to generate new mimes of glycopeptides. From perbenzylated C-allyl glucopyranoside, two diastereomeric C-glucosyl aminoxy acids have been successfully prepared.
