Mild, efficient, selective and "green" benzoylation of nucleosides using benzoyl cyanide in ionic liquid.

Use of benzoyl cyanide (BzCN) for benzoylation of nucleosides has been studied, both in pyridine and in ionic liquid BzCN in 1-methoxyethyl-3-methylimidazolium methanesulfonate as ionic liquid has been found to be a "green "alternative compared to the pyridine-BzCN system. An efficient and selective benzoylation of nucleosides of both, the 2'-deoxy- and the ribo-series at ambient temperature was accomplished.