Condensed thienopyrimidines. IV. Synthesis and gastric antisecretory activity of 2,3-dihydro-5H-oxazolothienopyrimidine derivatives

2,3-Dihydro-5H-oxazolo[3,2-a]thieno[3,2-d]-(2a--d), [3,4-d]-(2e--h), and [2,3-d]pyrimidine derivatives (2i,j) were synthesized and evaluated for gastric antisecretory activity. These analogues (2) were prepared stepwise starting from formylthiophenecarbamates (4). The structure-activity relationships of these compounds are discussed.