Abstract: Tri-substituted phenyl derivatives and processes for their preparation. In a preferred embodiment, the compounds have the general formula (1) ##STR1## wherein L may be --OR; Z may be --C(R.sup.3)(R.sup.4)--C(R.sup.5)(R.sup.6)(R.sup.7); R may be an optionally substituted cycloalkyl group; R.sup.3, R.sup.6 and R.sup.7 may be hydrogen; R.sup.4 may be --(CH.sub.2).sub.t --Ar--(L.sup.1).sub.n --Ar'; R.sup.5 may be --(CH.sub.2).sub.t Ar; Ar may be a monocyclic or bicyclic aryl or heteroaryl group; L.sup.1 may be a divalent linking group; and Ar' is Ar or an Ar containing group. Compounds of the invention may be potent and selective phosphodiesterase type IV inhibitors and are useful in the prophylaxis and treatment of various diseases, such as asthma, which are associated with an unwanted inflammatory response or muscular spasm.