Compounds of formula (I): or a pharmaceutically acceptable derivative thereof, wherein R represents C1-6alkyl (optionally substituted by C1-6alkyloxy or Het) or C1-6alkyloxy; R1 and R2 independently represent hydrogen, halo or C1-6alkyl, ring A represents Het1; X represents O or NR3; R3 represents hydrogen or C1-6alkyl; ring B represents a phenyl group or Het2, either of which may be optionally substituted with one or more groups selected from halo, CN, C1-6alkyloxy, CF3, C1-6alkyl, NH2 and NO2; Het and Het1 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.