Synthesis and pregnancy terminating activity of 2-arylimidazo [2,1-a]isoquinolines and isoindoles.
A series of 2-arylimidazo[2,1-a]isoquinolines (1-21), some 5,6-dihydro derivatives (22-28) and 2-phenyl-5H-imidazol[2,1]isoindole (29) were synthesized and tested for the pregnancy terminating activity in hamsters and rats. An efficient preparation of 2-arylimidazo[2,1-a]isoquinolines was devised. The isoquinolines having a 4-chlorophenyl (8), 4-bromophenyl (9), or a biphenylyl group (12) in the 2-position were the most potent compounds after subcutaneous administration. Compound 12 also showed good oral activity. The data obtained with the title compounds are compared with those of the corresponding triazolo [5,1-1]isoquinolines and isoindoles. The structure-activity relationships are discussed.