Synthesis and hypocholesterolemic activity of 6,7-dihydro-4H-pyrazolo[1,5-a]pyrrolo[3,4-d]pyrimidine-5,8-diones, novel inhibitors of acylCoA:cholesterol O-acyltransferase.

A novel series of 6,7-dihydro-4H-pyrazolo[1,5-a]pyrrolo[3,4-d]pyrimidine-5,8-dione inhibitors of the enzyme acyl-CoA:cholesterol O-acyltransferase is described. A number of these derivatives were found to be potent modulators of serum lipoprotein levels in cholesterol-fed rats. Further evaluation of one of the most effective analogues confirmed that it was significantly blocking the absorption of cholesterol from the gut.