Readily available phenylsulfenyl 2,3,5-tri-O-benzoyl-beta-D-ribofuranoside glycosylates silylated nucleobases in a fast, high-yielding and stereoselective reaction promoted by trimethylsilyl trifluoromethanesulfonate. The method has been applied to the synthesis of [1'-C-13] labelled nucleosides further transformed to building blocks ready for oligodeoxynucleotide construction.