Abstract: Compounds of formula I: wherein R1, R2, R3, R4, m, R5, R6, n and Y are as defined in claim 1; or N-oxides, salts and optical isomers thereof. Furthermore, the present invention relates to processes for preparing compounds of formula (I), to herbicidal compositions comprising them and to methods of using them to control plants or to inhibit plant growth.

Abstract: A process for the synthesis of a compound of general formula II: ##STR1## wherein: R.sup.2 and R.sup.3 are each independently hydrogen or C.sub.1 -C.sub.4 alkyl;A is an aromatic or heteroaromatic ring system optionally substituted with one or more substituents as defined herein; and in which any ring nitrogen atom may be quaternised or oxidised;alternatively, any two substituents of the group A may combine to form a fused 5- or 6-membered saturated or partially saturated carbocyclic or heterocyclic ring in which any carbon or quaternised nitrogen atom may be substituted with any of the groups defined herein for A or in which a ring carbon atom may be oxidised;the process comprising cyclising a compound of general formula VII: ##STR2## wherein A, R.sup.2 and R.sup.3 are as defined for general formula II, R.sup.20 is hydrogen, benzyl or benzyl substituted with up to five substituents selected from halo, C.sub.1 -C.sub.6 alkyl, O(C.sub.1 -C.sub.6 alkyl) or nitro and R.sub.21 is C.sub.1 -C.sub.