Expanding the diversity of purine libraries

In recent years, there has been a resurgence of interest in the synthesis of purine derivatives due to the discovery of purine-derived ligands for a variety of nucleotide dependent enzymes. The majority of chemistry has focused on substitution of the purine core structure by alkylation at N9 and nucleophilic-aromatic substitution reactions at C2 and C6. Here we report the syntheses of aryl, N-aryl, O-aryl substituted purine libraries by the palladium-mediated coupling of boronic acids, anilines or phenols at the C2 position, and copper(II)-mediated N-arylation with boronic acids at the N9 position. The chemistry described here greatly expands our ability to introduce different functionality and create new purine scaffolds. (C) 2001 Published by Elsevier Science Ltd.