High-yielding two-step synthesis of 6,8-disubstituted N-9-unprotected purines.

We report herein a convenient method for the synthesis of libraries of 6,8-disubstituted-9-H-purines in two steps, including cyclization of 6-chloro-4,5-diaminopyrimidine with various arylcarboxylic acids or chlorides, followed by S(N)Ar with amines and alkoxides or Pd-catalyzed amidations at C-6. These reactions were highly efficient and allowed the synthesis of a 32-member library of 6,8-disubstituted purines.