The invention provides compounds of the general formula ##STR1## and physiologically acceptable salts and solvates thereof, wherein Z represents the group ##STR2## where A represents a group selected from HOR.sup.3 --, R.sup.6 NH(CH.sub.2)p--, R.sup.10 R.sup.11 N--, R.sup.12 OCH.sub.2 --, CH.sub.3 SO.sub.2 CH.sub.2 -- or NCCH.sub.2 --;where R.sup.3 is a C.sub.1-3 alkylene group,R.sup.6 is a group selected from R.sup.7 CO--, R.sup.7 NHCO--, R.sup.7 R.sup.8 NSO.sub.2 -- orR.sup.9 SO.sub.2 --, and p is zero or 1,R.sup.7 and R.sup.8 each represent a hydrogen atom or a C.sub.1-3 alkyl group,R.sup.9 is a C.sub.1-3 alkyl group,R.sup.10 and R.sup.11 each represent a hydrogen atom or a C.sub.1-4 alkyl group or, when R.sup.10 is a hydrogen atom, R.sup.11 may also be a C.sub.1-4 alkoxycarbonyl group, andR.sup.12 is a C.sub.1-3 alkyl group; ##STR3## where one of R.sup.4 and R.sup.5 is a hydroxy group and the other is a hydrogen or halogen atom or a hydroxy group; ##STR4## where A.sup.1 is either a chlorine atom or a --CF.sub.3 group; ##STR5## X represents a bond or a C.sub.1-7 alkenylene or C.sub.2-7 alkynylene chain, andY represents a bond, or a C.sub.1-6 alkylene, C.sub.2-6 alkenylene or C.sub.2-6 alkynylene chain, with the proviso that the sum total of carbon atoms in X and Y is 2 to 10;R represents a hydrogen atom or a C.sub.1-3 alkyl group;R.sup.1 and R.sup.2 each represents a hydrogen atom or a C.sub.1-3 alkyl group; with the proviso that the sum total of carbon atoms inR.sup.1 and R.sup.2 is not more than 4;Q represents a pyridyl group optionally substituted by one or two substituents selected from halogen atoms or hydroxy, C.sub.1-3 alkyl or C.sub.1-3 alkoxy groups, or Q represents a phenyl group optionally substituted by one or more substituents selected from halogen atoms or the groups C.sub.1-6 alkyl, nitro, --(CH.sub.2).sub.q R.sup.13 or --O(CH.sub.2).sub.r R.sup.14, or Q represents a phenyl group substituted by an alkylenedioxy group of formula --O(CH.sub.2).sub.t O--; whereR.sup.13 represents hydroxy, C.sub.1-6 alkoxy, cyano, --NR.sup.15 R.sup.16, --NR.sup.17 COR.sup.18, --NR.sup.17 SO.sub.2 R.sup.19, --COR.sup.20, --SR.sup.21, --SOR.sup.22 or --SO.sub.2 R.sup.22 ;R.sup.14 represents hydroxy or C.sub.1-4 alkoxy;R.sup.15 and R.sup.16 each represent a hydrogen atom or a C.sub.1-4 alkyl group or --NR.sup.15 R.sup.16 forms a saturated heterocyclic amino group which has 5-7 ring members and optionally contains in the ring one or more atoms selected from --O-- or --S-- or a group --NH-- or --N(CH.sub.3)--;R.sup.17 represents a hydrogen atom or a C.sub.1-4 alkyl group;R.sup.18 represents a hydrogen atom or a C.sub.1-4 alkyl, C.sub.1-4 alkoxy, phenyl or --NR.sup.15 R.sup.16 group;R.sup.19 represents C.sub.1-4 alkyl, phenyl or --NR.sup.15 R.sup.16 ;R.sup.20 represents hydroxy, C.sub.1-4 alkoxy or --NR.sup.15 R.sup.16 ;R.sup.21 represents a hydrogen atom or a C.sub.1-4 alkyl or phenyl group;R.sup.22 represents a C.sub.1-4 alkyl or phenyl group;q represents an integer from 0 to 3;r represents 2 or 3; andt represents 1 or 2.The compounds have a stimulant action at .beta..sub.2 -adrenoreceptors and may be used in the treatment of diseases associated with reversible airways obstruction such as asthma and chronic bronchitis.