Studies on antiulcer drugs. I. Synthesis and antiulcer activities of imidazo[1,2-alpha]pyridinyl-2-oxobenzoxazolidines-3-oxo-2H-1,4-benzoxaz ines and related compounds.

A series of imidazo[1,2-alpha]pyridinyl-2-oxobenzoxazolidines (4a-i), -3-oxo-2H-1,4-benzoxazines (5a-q), their thio-analogues (4j-p and 5r-t) and 5,6,7,8-tetrahydroimidazo[1,2-alpha]pyridinyl derivatives (8 and 9) were synthesized and tested for anti-stress ulcer activity in rats. Several compounds were found to be more active than the reference compounds, zolimidine, cimetidine and sucralfate. Among them, compound 4e, 5i and 5l also exhibited potent protective activity against ethanol-induced gastric lesion. The synthesis and structure-activity relationships of these compounds are discussed.