Ketonucleosides nucleophilic additions

In contrast to nucleophilic additions to ketoses, which very often lead to diastereoisomeric products, additions to ketonucleosides have been found to be highly stereoselective, permitting ready synthesis of amino-, epimino-, triazolo-, and other rare-sugar nucleosides. 

A variety of nucleophiles could also be added to unsaturated ketonucleosides, to afford (by way of a 1,4-addition mechanism) amino-, azido-, aziridino-, and thio-ketonucleosides. The action of metal hydrides on ketonucleosides has been extensively discussed in Section V. 

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