Stereoselective synthesis of dithymidine phosphorothioates using d-xylose derived chiral auxiliaries

Abstract Different sized catalysts 1 , 2 , 5 and 7 were prepared and used as the activators in the coupling reactions of phosphoramidites with nucleosides. d -Xylose derived chiral auxiliary 22a has been synthesized and applied for the stereoselective synthesis of dithymidine phosphorothioates 27 . The mechanisms of the coupling reactions are discussed.