1,2-FUSED PYRIMIDINES .6. SUBSTITUTED 2-AMINO-4H-PYRIDO[1,2-A]PYRIMIDIN-4-ONES WITH ANTIPLATELET ACTIVITY

The N-substituted 2-amino-4H-pyrido[1,2-a]pyrimidin-4-ones 2 d,g-i,l-p ,r,s and derivatives 4,5 b,6 a,b, 7 a,b were prepared. Both these nove l compounds (except the insoluble 7a) and compounds 2 a-c,e,f,k,q, 5 a , previously prepared by us, were tested in vitro for their inhibitory activity on human platelet aggregation induced by ADP, collagen, or A 23187. On the whole, the compounds tested proved to be more active tow ards collagen than towards ADP and A23187. The 2-(4-methyl-1-piperazin yl)derivative 2 g was the most active compound both towards ADP and co llagen, whereas the 2-(diethylamino)derivative 2 b proved to be the mo st active one towards A23187.