Herbicidal compounds

A method of controlling plants which comprises applying to the plants or to the locus thereof a herbicidally effective amount of a compound of formula (I)

• wherein
• A1, A2, A3 and A4 are independently C—R1 or N, provided at least one of A1, A2, A3 and A4 is N, and provided that if A1 and A4 are both N, A2 and A3 are not both C—R1;
• each R1 is independently hydrogen, C1-C4alkyl, C1-C4haloalkyl, halo, cyano, hydroxy, C1-C4alkoxy, C1-C4alkylthio, aryl or aryl substituted by one to five R6, which may be the same or different, or heteroaryl or heteroaryl substituted by one to five R6, which may be the same or different;
• R3 is hydrogen, C1-C10alkyl, C1-C4haloalkyl, C2-C10alkenyl, C2-C4haloalkenyl, C2-C10alkynyl, C2-C4haloalkynyl, C3-C10cycloalkyl, C3-C10cycloalkyl-C1-C6alkyl-, C1-C10alkoxy-C1-C6alkyl-, C1-C10cyanoalkyl-, C1-C10alkoxycarbonyl-C1-C6alkyl-, N—C1-C3alkyl-aminocarbonyl-C1-C6alkyl-, N,N-di-(C1-C3alkyl)-aminocarbonyl-C1-C6alkyl-, aryl-C1-C6alkyl- or aryl-C1-C6alkyl- wherein the aryl moiety is substituted by one to three R7, which may be the same or different, or heterocyclyl-C1-C6alkyl- or heterocyclyl-C1-C6alkyl- wherein the heterocyclyl moiety is substituted by one to three R7, which may be the same or different;
• R4 is aryl or aryl substituted by one to five R8, which may be the same or different, or heteroaryl or heteroaryl substituted by one to four R8, which may be the same or different;
• R5 is hydroxy or a group which can be metabolised to a hydroxy group;
• each R6, R7 and R8 is independently halo, cyano, nitro, C1-C10alkyl, C1-C4haloalkyl, C2-C10alkenyl, C2-C10alkynyl, hydroxy, C1-C10alkoxy, C1-C4haloalkoxy, C1-C10alkoxy-C1-C4alkyl-, C3-C7cycloalkyl, C3-C7cycloalkoxy, C3-C7cycloalkyl-C1-C4alkyl-, C3-C7cycloalkyl-C1-C4alkoxy-, C1-C6alkylcarbonyl-, formyl, C1-C4alkoxycarbonyl-, C1-C4alkylcarbonyloxy-, C1-C10alkylthio-, C1-C4haloalkylthio-, C1-C1-C4haloalkylsulfinyl-, C1-C10alkylsulfonyl-, C1-C4haloalkylsulfonyl-, amino, C1-C10alkylamino-, di-C1-C10alkylamino-, C1-C10alkylcarbonylamino-, aryl or aryl substituted by one to three R13, which may be the same or different, heteroaryl or heteroaryl substituted by one to three
• R13, which may be the same or different, aryl-C1-C4alkyl- or aryl-C1-C4alkyl- wherein the aryl moiety is substituted by one to three R13, which may be the same or different, heteroaryl-C1-C4alkyl- or heteroaryl-C1-C4alkyl- wherein the heteroaryl moiety is substituted by one to three R13, which may be the same or different, aryloxy- or aryloxy-substituted by one to three R13, which may be the same or different, heteroaryloxy- or heteroaryloxy-substituted by one to three R13, which may be the same or different, arylthio- or arylthio-substituted by one to three R13, which may be the same or different, or heteroarylthio- or heteroarylthio-substituted by one to three R13, which may be the same or different;
• and
• each R13 is independently halo, cyano, nitro, C1-C6alkyl, C1-C6haloalkyl or C1-C6alkoxy;
• or a salt or N-oxide thereof.