phosphoramidite and nebularine

This article describes high-yield procedures for protection of purine ribonucleosides based on a reaction that allows highly regioselective 2'-silylation. Each protocol makes use of two transient protection steps. In the case of tritylation of the 5' hydroxyl, the 2',3'-diol is protected by reaction with N,N-dimethylformamide dimethylacetal (Zemlicka, 1963) to prevent the small, but potentially troublesome, tritylation of the 2'-hydroxyl that otherwise accompanies tritylation of the 5'-hydroxyl (Zhang et al., 1997). The phenoxyacetylation of the amino group is carried out after transient hydroxyl and guanine O

Topics: Organophosphorus Compounds; Ribonucleosides; RNA