Pyrazolo[3,4-d]pyrimidines: C4, C6 substitution leads to adenosine A1 receptor selectivity

Following the demonstration that substitution of 1-phenylpyrazolo[3,4-d]pyrimidines at C6 with thioethers containing amide moieties could effect adenosine A1 and A2a receptor selectivity, two compounds with high A1 selectivity have been obtained by a combined C4, C6 substitution. This further demonstrates that distal moieties at C6 can effect selectivity and that C4 substitutents have an important role.