Abstract: A compound represented by the following formula (I): wherein R1 represents hydrogen, aryl which may have a substituent, a saturated or unsaturated 5- to 7-membered heterocyclic group which may have a substituent, etc.; R2 represents hydrogen, aryl which may have a substituent, a saturated or unsaturated 5- to 7-membered heterocyclic group which may have a substituent, etc.; R3 represents hydrogen, etc.; Ar represents a divalent group derived from aromatic hydrocarbon, etc.; X represents a single bond, linear or branched alkylene having from 1 to 3 carbon atoms which may have a substituent, etc.; and G represents halogen, a saturated or unsaturated 5- or 6-membered cyclic hydrocarbon group which may have a substituent, a saturated or unsaturated 5- to 7-membered heterocyclic group which may have a substituent, etc.

Abstract: Aminophenol derivatives represented by the following formula (1): ##STR1## wherein X is O or S; A is alkylene, R.sup.1 is phenyl, etc., R.sup.2 and R.sup.3 are H or alkyl; R.sup.4 is substituted carbamoylalkyl, etc.; R.sup.5 is substituted amino, etc.; their salts, and optical isomers of the derivatives and salts. Also disclosed are gastrin receptor antagonists, cholecystokinin receptor antagonists, and medicines for digestive diseases. The compounds have strong binding inhibition against gastrin receptor or CCK-A receptor and also they have higher selectivity to either group of CCK-A receptor or gastrin receptor, and therefore, the compounds are useful for preventing and treating gastrointestinal diseases including peptic ulcers as well as central nervous system diseases.