Lewis Acid Triggered Regioselective Magnesiation and Zincation of Uracils, Uridines, and Cytidines

The Lewis acid MgCl2 allows control of the metalation regioselectivity of uracils and uridines. In the absence of the Lewis acid, metalation of uracil and uridine derivatives with TMPMgCl center dot LiCl occurs at the position C(5). In the presence of MgCl2, zincation using TMP2Zn center dot 2LiCl center dot 2MgCl(2) occurs at the position C(6). This metalation method provides easy access to functionalized uracils and uridines. Using TMP2Zn center dot 2LiCl center dot 2MgCl(2) also allows to functionalize cytidine derivatives at the position C(6).