The invention provides compounds of general formula (I) wherein R.sup.1 is H or C.sub.1 -C.sub.6 alkyl; R.sup.2 and R.sup.3, together with the interconnecting atoms form a 4 to 8-membered saturated ring containing one or two heteroatoms (including the nitrogen to which R.sup.2 is attached) wherein a second heteroatom, if present, is selected from oxygen, nitrogen and sulfur, with the proviso that said ring cannot contain two adjacent heteroatoms; Z is CF.sub.3, OCF.sub.3, C.sub.1 -C.sub.6 alkylthio or C.sub.1 -C.sub.6 alkoxy; Y is hydrogen, halogen, --OR.sup.a, R.sup.a or C.sub.1 -C.sub.6 alkylthio, and wherein R.sup.a is C.sub.1 -C.sub.4 alkyl optionally substituted with fluorine atoms; or when Z and Y are attached para and meta to the ether linkage linking rings A and B, Z and Y are linked so that, together with the interconnecting atoms, Z and Y form a fused 5 to 7-membered carbocyclic or heterocyclic ring which may be saturated, unsaturated or aromatic, and wherein when Z and Y form a heterocyclic ring, in addition to carbon atoms, the linkage contains one or two heteroatoms independently selected from oxygen, sulfur and nitrogen; and Z and Y together do not form a fused phenyl ring; R.sup.4 and R.sup.5, which may be the same or different, are: A--X, wherein A=--CH.dbd.CH-- or --(CH.sub.2).sub.p -- where p is 0, 1 or 2; X is hydrogen, F, Cl, Br, I, CONR.sup.6 R.sup.7, SO.sub.2 NR.sup.6 R.sup.7, SO.sub.2 NHC(.dbd.O)R.sup.6, OH, C.sub.1-4 alkoxy, NR.sup.8 SO.sub.2 R.sup.9, NO.sub.2, NR.sup.6 R.sup.11, CN, CO.sub.2 R.sup.10, CHO, SR.sup.10, S(O)R.sup.9 or SO.sub.2 R.sup.10 ; or a 5- or 6-membered heterocyclic ring containing 1, 2 or 3 heteroatoms selected from N, S and O, optionally substituted independently by one or more R.sup.13 ; wherein R.sup.13 is hydroxy, C.sub.1 -C.sub.4 alkoxy, F, C.sub.1 -C.sub.6 alkyl, haloalkyl, haloalkoxy, --NH.sub.2, --NH(C.sub.1 -C.sub.6 alkyl) or --N(C.sub.1 -C.sub.6 alkyl).sub.2. ##STR1##