The present invention provides a compound having a superior acid secretioninhibitory effect and showing an antiulcer activity and the like. The presentinvention provides a compound represented by the formula (I) wherein R1 is anitrogen-containing monocyclic heterocyclic group optionally condensed with abenzene ring or a heterocycle, the nitrogen-containing monocyclic heterocyclicgroup optionally condensed with a benzene ring or a heterocycle optionally hassubstituent(s), R2 is an optionally substituted C6-14 aryl group, anoptionally substituted thienyl group or an optionally substituted pyridylgroup, R3 and R4 are each a hydrogen atom, or one of R3 and R4 is a hydrogenatom and the other is an optionally substituted lower alkyl group, an acylgroup, a halogen atom, a cyano group or a nitro group, and R5 is an alkylgroup or a salt thereof.
