[Synthesis and analgesic activity of 3-substituted derivatives of pyrido [3',2':4,5]thieno[3,2-d]pyrimidin-4(3H)-ones].

A series of Schiff bases of 3-amino-2,7,9-trimethylpyrido-[3',2',:4,5]thieno[3,2-d]pyrimidin- 4(3H)-one with aromatic aldehydes was synthesized. The compounds showed interesting analgesic activity without effects on the stomach even with oral doses of 200 mg/kg.