Compound of formula (I) are ligands of the CRTH2 receptor, useful inter alia for treatment of inflammatory conditions. Wherein X is —SO2— or *—SO2NR3— wherein the bond marked with an asterisk is attached to Ar1; R1 is hydrogen, fluoro, chloro, CN or CF3; R2 is hydrogen, fluoro or chloro; R3 is hydrogen, C1C8alkyl or C3-C7cycloalkyl; Ar1 is phenyl or a 5- or 6-membered heteroaryl group selected from furanyl, thienyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, pyridinyl, pyridazinyl, pyrimidinyl and pyrazinyl, wherein the phenyl or heteroaryl groups are optionally substituted by one or more substituents independently selected from fluoro, chloro, CN, C3-C7cycloalkyl, —O(C1-C4alkyl) or C1C6alkyl, the latter two groups being optionally substituted by one or more fluoro atoms; and Ar2 is phenyl or 5- or 6-membered heteroaryl group selected from pyrrolyl, furanyl, thienyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, pyridinyl, pyridazinyl, pyrimidinyl and pyrazinyl, wherein the phenyl or heteroaryl groups are optionally substituted by one or more substituents independently selected from fluoro, chloro, CN, C3-C3-C7cycloalkyl, —O(C1-C4alkyl) or C1C6alkyl, the latter two groups being optionally substituted by one or more fluoro atoms.