Piperazine Derivatives and Their Use in Controlling Pests

A method of combating and controlling insects, acarines, nematodes or molluscs which comprises applying to a pest, to a locus of a pest, or to a plant susceptible to attack by a pest an insecticidally, acaricidally, nematicidally or molluscicidally effective amount of a compound of formula I.

• Y is a single bond, C═O, C═S or S(O)m where m is 0, 1 or 2:
• the ring
• is a 6 membered aromatic ring or is a 5 or 6 membered heteroaromatic ring;
• R1 is hydrogen, optionally substituted alkyl, optionally substituted alkoxycarbonyl, optionally substituted alkylcarbonyl, aminocarbonyl, optionally substituted alkylaminocarbonyl, optionally substituted dialkylaminocarbonyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted heteroaryloxy, optionally substituted heterocyclyloxy, cyano, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted cycdloalkenyl, formyl, optionally substituted heterocyclyl, optionally substituted alkylthio, NO or NR13R14 where R13 and R14 are independently hydrogen, COR15, optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocyclyl or R13 and R14 together with the N atom to which they are attached form a group —N═C(R16)—NR17R18 or R13 and R14 together with the N atom to which they are attached form a five, six or seven-membered heterocyclic ring which may contain one or two further heteroatoms selected from O, N or S and which may be optionally substituted by one or two C1-6 alkyl groups, R15 is H, optionally substituted alkyl, optionally substituted alkoxy, optionally substituted aryl, optionally substituted aryloxy optionally substituted heteroaryl, optionally substituted heteroaryloxy or NR19R20;
• R16, R17 and R18 are each independently H or lower alkyl;
• R19 and R20 are independently optionally substituted alkyl, optionally substituted aryl or optionally substituted heteroaryl;
• R2 is H or optionally substituted alkyl;
• or R1 and R2 together with the groups Y and N form a 5- or 6-membered heterocyclic ring which may optionally contain one further heteroatom selected from O, N or S and which may be optionally substituted by C1-4 alkyl, C1-4 haloalkyl or halogen;
• each R4 is independently halogen, nitro, cyano, optionally substituted C1-8 alkyl, optionally substituted C2-6 alkenyl, optionally substituted C2-6 alkynyl, optionally substituted alkoxycarbonyl, optionally substituted alkylcarbonyl, optionally substituted alkylaminocarbonyl, optionally substituted dialkylaminocarbonyl, optionally substituted C3-7 cycloalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted heteroaryloxy, optionally substituted alkylthio or R21R22N where R21 and R22 are, independently, hydrogen, C1-8 alkyl, C3-7 cycloalkyl, C3-6 alkenyl, C3-6 alkynyl, C3-7 cycloakyl(C1-4)alkyl, C2-6 haloalkyl, C1-6 alkoxy(C1-6)alkyl, C1-6 alkoxycarbonyl or R21 and R22 together with the N atom to which they are attached form a five, six or seven-membered heterocyclic ring which may contain one or two further heteroatoms selected from O, N or S and which may be optionally substituted by one or two C1-6 alkyl groups, or 2 adjacent groups R4 together with the carbon atoms to which they are attached form a 4, 5, 6, or 7 membered carbocyclic or heterocyclic ring which may be optionally substituted by halogen;
• n is 0, 1, 2, 3 or 4;
• R8 is optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted alkoxycarbonyl, optionally substituted alkylcarbonyl or optionally substituted alkenylcarbonyl;
• each Ra is independently halogen, hydroxy, cyano, optionally substituted C1-8 alkyl, optionally substituted C2-6 alkenyl, optionally substituted C2-6 alkynyl, optionally substituted alkoxycarbonyl, optionally substituted alkylcarbonyl, optionally substituted alkylaminocarbonyl, optionally substituted dialkylaminocarbonyl, optionally substituted C3-7 cycloalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted heteroaryloxy, optionally substituted alkylthio, optionally substituted arylthio or R23R24N where R23 and R24 are, independently, hydrogen, C1-8 alkyl, C3-7 cycloalkyl, C3-6 alkenyl, C3-6 alkynyl, C3-7 cycloakyl(C1-4)alkyl, C2-6 haloalkyl, C1-6 alkoxy(C1-6)alkyl, C1-6 alkoxycarbonyl or R23 and R24 together with the N atom to which they are attached form a five, six or seven-membered heterocyclic ring which may contain one or two further heteroatoms selected from O, N or S and which may be optionally substituted by one or two C1-6 alkyl groups or two Ra groups attached to the same carbon atom are ═O, ═S, ═NRb, ═CRcRd where Rb, Rc and Rd are independently H or optionally substituted alkyl:
• p is 0, 1, 2, 3 or 4 or salts or N-oxides thereof.