An alternative synthetic approach for the synthesis of biologically relevant 1,4-disubstituted pyrazolo[3,4-d]pyrimidines

A versatile approach for the synthesis of 1,4-disubstituted pyrazolo[3,4-d]pyrimidines has been developed. Starting from commercially available allopurinol, TBAF mediated N1-functionalization and subsequent C4 nucleophilic substitution, under microwave assisted- or standard heating conditions, granted access to highly functionalized pyrazolo[3,4-d]pyrimidines of potential biological interest.