Polycyclic N-heterocyclic compounds. XLI. Synthesis of 4-substituted 6,7-dihydro-5H-pyrimido[5,4-d][1]benzazepines, 1,2,5,6-tetrahydro-4H-imidazo[1′,2′:1,6]pyrimido[5,4-d][1]benzazepines and their related compounds as a series of potential blood platelet aggregation inhibitors

As a series of polyheterocyclic compounds for exploitation as anti-platelet agents, tricyclic heterocyclic compounds, 4-substituted 6,7-dihydro-5H-pyrimido5,4-d]1]benzazepines 3–6, 9, 12–14 , and 16–26 , having nitrogen, oxygen, or sulfur containing functional groups at the 4-position, were prepared. In addition, tetra-cyclic heterocyclic compounds, 3-methyl-1,2,5,6-tetrahydro-4H-imidazo1′,2′:1,6]pyrimido5,4-d]1]benzaze-pinium chloride ( 7 ), 1,2,5,6-tetrahydro-4H-imidazo1′,2′:1,6]pyrimido5,4-d]1]benzazepines 10a-e , 2,3,6,7-tetrahydro-1H 5H-pyrimido1′,2′:1,6]pyrimido5,4-d]1]benzazepine ( 11 ), and 1,2,5,6-tetrahydro-4H-thiazolo-3′,2′:1,6]pyrimido5,4-d]1]benzazepinium chloride ( 15 ) via ring closure of 4-(hydroxyalkylamino)- 6, 9a-e , and 3c , and 4-(2-hydroxyethylthio)-6,7-dihydro-5H-pyrimido5,4-d]1]benzazepine ( 14 ) with phosphoryl chloride or thionyl chloride, respectively, were also prepared. Their inhibitory activities against collagen-induced aggregation of rabbit blood platelets in vitro were investigated. Among them, compound 5 having a morpholino group at the 4-position on the tricyclic nucleus, which enhanced the activity more than 14-fold as compared with aspirin, was found to have the most satisfactory in inhibitory activity.