Synthesis of Natural and Sugar-Modified Nucleosides Using the Iodine/Triethylsilane System as N-Glycosidation Promoter

The reagent system based on the combined use of Et₃SiH/I₂ acts as an efficient N-glycosidation promoter for the synthesis of natural and sugar-modified nucleosides. An analysis of reaction stereoselectivity in the absence of C2-positioned stereodirecting groups revealed high selectivity with six-membered substrates, depending on the nucleophilic character of the nucleobase or based on anomerization reactions. The synthetic utility of the Et₃SiH/I₂-mediated N-glycosidation reaction was highlighted by its use in the synthesis of the investigational drug apricitabine.