Condensed thienopyrimidines. II. Synthesis and gastric antisecretory activity of thiazole and polymethylene condensed thienopyrimidine derivatives

Thiazolo3,2-a]thieno3,2-d]-, 3,4-d]- and 2,3-d]pyrimidin-5-one derivatives (6, 11 and 16), and polymethylene condensed thieno3,2-d]-, 3,4-d]- and 2,3-d]pyrimidin-5-one derivatives (19-21), in which the oxygen atom of the oxazolidine moiety in 3 was replaced by a sulfur atom or methylene groups, were synthesized and evaluated for gastric antisecretory activity in pylorus-ligated rats. The structure-activity relationships of these compounds are discussed.