Dibutyltin oxide--phenyl isocyanate system for regioselective phenylcarbamoylation of the hydroxy-groups of ribonucleosides.

For partial phenylcarbamoylation of the hydroxy-groups of ribonucleosides, dibutyltin oxide--phenyl isocyanate system was found to be surperior to the bis(tributyltin) oxide--phenyl isocyanate system from the standpoint of reaction procedures including isolation of the products; the reaction was proved to occur with similar regioselectivity and to give the corresponding 5'-, 3'-, and 2'-O-phenylcarbamoyl derivatives in good yields, respectively, due to the conditions used.