Microwave-assisted, divergent solution-phase synthesis of 1,3,6-trisubstituted pyrazolo[3,4-d]pyrimidines

A concise and highly divergent synthetic route has been developed to rapidly access 1,3,6-trisubstituted pyrazolopyrimidines. The synthesis features a microwave assisted one-pot N1-alkylation/Suzuki-Miyaura reaction as the key step. The sequence of the synthetic scheme can be varied to selectively modify the N1, C3, or C6 position at a late synthetic stage, thereby providing a highly efficient approach to explore the structure-activity relationships of pyrazolopyrimidine derivatives. The scope of these reactions has also been explored.