2,3-Dicyclohexylsuccinimide as a directing/protecting group for the regioselective glycosylation or alkylation of purines.

Here we describe the synthesis and application of a novel 2,3-dicyclohexylsuccinimide (Cy2SI) protecting group towards regioselective purine glycosylation and alkylation reactions. This bulky protecting group promotes high regioselectivity during the glycosylation (as well as diastereoselectivity) or alkylation of purines using Hoffer's chlorosugar or tert-butyl bromoacetate, respectively. Cy2SI offers the additional synthetic advantage that other base-labile protecting groups, such as toluoyl esters, can be selectively removed in its presence without affecting the imide.