Compounds of general formula (1) are described wherein =W- is (1) =C(Y)- where Y is a halogen atom, or an alkyl or -XRa group where X is -O-, -S(O)¿m?-[where m is zero or an integer of value 1 or 2], or -N(R?b¿)- where Rb is a hydrogen atom or an optionally substituted alkyl group or, (2) =N; L is a -XR, [where R is an optionally substituted alkyl, alkenyl, cycloalkyl or cycloalkenyl group], -C(R?11)=C(R1)(R2¿) or [-CH(R11)]nCH(R1)(R2) group where R11 is a hydrogen or a fluorine atom or a methyl group, and R?1 and R2¿, which may be the same or different, is each a hydrogen or fluorine atom or an optionally substituted alkyl, alkenyl, alkynyl, alkoxy, alkylthio, -CO¿2 R?8, [where R8 is a hydrogen atom or an optionally substituted alkyl, aralkyl, or aryl group], -CONR9R10 [where R?9 and R10¿, which may be the same or different are as defined for R8], -CSNR9R10, -CN or -NO¿2?group, or R?1 and R2¿ together with the C atom to which they are attached are linked to form an optionally substituted cycloalkyl or cycloalkenyl group and n is zero or the integer 1; Z is (1) a group -C(R?3)(R4)C(R5)(R6)(R7) or -C(R?4)=C(R5)(R6¿) where R3 is a hydrogen or a fluorine atom or an optionally substituted straight or branched alkyl group; R4 is a group selected from -XaL1R12 [where Xa is as defined above for X, L1 is a linker group and R12 is a hydrogen atom or a cycloaliphatic, heterocycloaliphatic, or monocyclic or bicyclic aryl group optionally containing one or more heteroatoms selected from oxygen, sulphur or nitrogen atoms], -Alk1R12 [where Alk1 is an optionally substituted straight or branched alkenyl or alkynyl chain optionally containing one or more -O- or -S- atoms or -N(Rb)-, carbocyclic or heteroatom-containing groups], -CH¿2L?1R12a [where R12a is as defined for R12 but is not a hydrogen atom]; -XaR12a; or -C(Xb)R12a [where Xb is an oxygen or sulphur atom]; R5 is a -(CH¿2?)pAr group where p is zero or an integer 1, 2 or 3 and Ar is a monocyclic or bicyclic aryl group optionally containing one or more heteroatoms selected from oxygen, sulphur or nitrogen atoms; R?6¿ is a hydrogen or a fluorine atom or an optionally substituted alkyl group; R7 is a hydrogen or a fluorine atom or an ORc group where Rc is a hydrogen atom or an optionally substituted alkyl or alkenyl group, or an alkoxyalkyl, alkanoyl, formyl, carboxamido or thiocarboxamido group; or Z is (2) a group -C(R?4)C(R5)(R6)(R7¿) where R4 is a group =CH¿2?, or =CH(L?1)¿n-R12; and the salts, solvates, hydrates, prodrugs and N-oxides thereof. Compounds according to the invention are phosphodiesterase type IV inhibitors and are useful in the prophylaxis and treatment of disease such as asthma where an unwanted inflammatory response or muscular spasm is present.