An efficient convergent synthesis of adenosine-5′-N-alkyluronamides

Herein we report an efficient synthesis of adenosine-5′-N-alkyluronamides in which an enzyme-mediated deacetylation reaction is a key to the selective modification of the 5′-N-position, prior to coupling the ribose and purine components via a microwave-assisted Vorbrüggen coupling. This approach provides access to highly functionalised adenosines with 2- and N6-substitutents, which can be incorporated before or after the ribose-coupling step. In all cases the microwave-assisted Vorbrüggen coupling conditions afforded anomerically pure purine ribosides in good to excellent yields.