Potent and selective adenosine A(2A) receptor antagonists: [1,2,4]-triazolo[4,3-c]pyrimidin-3-ones.

Antagonism of the adenosine A(2A) receptor affords a possible treatment of Parkinson's disease. In the course of investigating pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine A(2A) antagonists, we prepared [1,2,4]-triazolo[4,3-c]pyrimidin-3-ones with potent and selective (vs A(1)) A(2A) antagonist activity. Structure-activity relationships are described for this series.