Catalytic action of azolium salts. IX. Synthesis of 6-aroyl-9H-purines and their analogues by nucleophilic aroylation catalyzed by imidazolium or benzimidazolium salt

Abstract

In the presence of 1,3-dimethylimidazolium iodide (1), 6-chloro-9- phenyl-9H-purine (7) and 4-chloro-5,6-dimethylpyrrolo[2,3-d]pyrimidines 40- 42 underwent nucleophilic aroylation with arenecarbaldehydes (5) to give the corresponding fused aroylpyrimidines 8 and 43-45. 1,3-Dimethylbenzimidazolium iodide (2) was an effective catalyst for the similar synthesis of 7-aroyl-3- phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidines 16-21. In the synthesis of 4- aroyl-1H-pyrazolo[3,4-d]pyrimidines 26-32, both azolium salts 1 and 2 were effective as catalysts. Moreover, 4-aroyl-7H-pyrrolo[2,3-d]pyrimidines 42-45 were obtained in good yields via the 4-tosyl derivatives, in the presence of catalytic amounts of sodium p-toluenesulfinate (46) and the imidazolium salt 1. This catalytic aroylation was found to be a facile and useful method for the synthesis of 6-aroyl-9H-purines and their analogues.