Compounds of formula (I): or a pharmaceutically acceptable derivative thereof, wherein R represents C.sub.1-6alkyl (optionally substituted by C.sub.1-6alkyloxy or Het) or C.sub.1-6alkyloxy; R.sup.1 and R.sup.2 independently represent hydrogen, halo or C.sub.1-6alkyl, ring A represents Het.sup.1; X represents O or NR.sup.3; R.sup.3 represents hydrogen or C.sub.1-6alkyl; ring B represents a phenyl group or Het.sup.2, either of which may be optionally substituted with one or more groups selected from halo, CN, C.sub.1-6alkyloxy, CF.sub.3, C.sub.1-6alkyl, NH.sub.2 and NO.sub.2; Het and Het.sup.1 independently represent a 5- or 6-membered saturated, partially unsaturated or aromatic heterocyclic group comprising either (a) 1 to 4 nitrogen atoms, (b) one oxygen or one sulphur atom or (c) 1 oxygen atom or 1 sulphur atoms and 1 or 2 nitrogen atoms are useful for treating anxiety, cardiovascular disease (including angina, atherosclerosis, hypertension, heart failure, edema, hypernatremia), dysmenorrhoea (primary and secondary), endometriosis, emesis (including motion sickness), intrauterine growth retardation, inflammation (including rheumatoid arthritis) mittlesmerchz, preclampsia, premature ejaculation, premature (preterm) labour and Raynaud's disease.