Synthesis and Evaluation of Novel Pyrazolo(1,5-a)pyrimidine Derivatives as Nonpeptide Angiotensin II Receptor Antagonists.

A novel series of 6-alkyl-7-oxo-4,7-dihydropyrazolo[1,5-alpha]pyrimidine-3-carboxyli c acid derivatives was prepared as angiotensin II (AII) receptor antagonists. When evaluated in an in vitro binding assay using COS cells transfected with a cDNA encoding a human AT1 angiotensin II receptor, the compounds in this series showed Ki values in the range of 0.4-4.0 nM. In anesthetized spontaneously hypertensive rats (SHRs), administration of the 6-propyl derivative 4d (1 mg/kg, i.v.) reduced the mean blood pressure (MBP) by a maximum of more than 30 mmHg from the normal value.