Highly efficient O-glycosylations with p-tolyl thioribosides and p-TolSOTf.

A wide variety of p-tolyl thioriboside donors are examined for O-ribosylations of primary and secondary alcohols. p-Tolylsulfenyl trifluoromethanesulfonate (p-TolSOTf) is very effective in promoting O-ribosylations with p-tolyl thioriboside; all reactions are completed within 1-15 min to provide the desired products in good yield with reliable alpha/beta selectivity. A wide range of functional groups are tolerated under these conditions. The described O-ribosylation conditions are very useful for the generation of ribosaminouridine library molecules in solution or on polymer support.