Catalysis of nucleophilic aromatic substitutions in the 2,6,8-trisubstituted purines and application in the synthesis of combinatorial libraries

The following paper summarizes our work on compound libraries of 2,6,8-trisubstituted purines. This synthesis route on a polystyrene support begins with 2,6-dichloro purine making extensive use of catalysis. During the synthesis the polymer bound purines were brominated selectively on C8. The substitution reaction of C6-Cl by amines was found to be acid catalyzed. The substitution of C2-Cl by amines and aryls, as well as the substitution of a C8-Br by aryls, alkenyl and alkynyl groups can be catalyzed by transition metals. Under some bromination conditions novel selective oxidative transformations of 2-amino groups in 2,6-diamino purines have been found.