Compounds

A compound of formula I, or a salt or isomer thereof:

• wherein, R1 is selected from C1 to C20 alkyl, C2 to C20 alkenyl, C2 to C20 alkynyl, aryl, heteroaryl, aroyl, C5 to C7 cycloalkenyl and/or heterocyclic, each of which groups may be substituted or unsubstituted;
• R2 is selected from hydrogen, C1 to C12 alkyl, C2 to C12 alkenyl, aryl, heteroaryl, aroyl, C5 to C7 cycloalkenyl and/or heterocyclic, each of which groups may be substituted or unsubstituted;
• R3 and R4 are independently selected from C1 to C20 alkyl, C2 to C20 alkenyl, C2 to C20 alkynyl, C1 to C20 alkylamine, aryl, heteroaryl, aroyl, C5 to C7 cycloalkyl, C3 to C8 cycloalkenyl, C2 to C12 alkanoyloxy, haloalkyl, or heterocyclic, all of which groups may be substituted or unsubstituted, or R3 and R4 may together form a cyclic structure which includes the nitrogen atom to which they are attached, said cyclic structure being optionally substituted;
• and
• R5 is selected from C1 to C20 haloalkyl, C1 to C20 haloalkenyl, a fluorine-containing group, C1 to C20 alkyl, C2 to C20 alkenyl, C1 to C20 alkoxy, ester, amide, C1 to C20 alkanoyl, C1 to C20 alkenoyl, aryl, C5 to C7 cycloalkenyl or heterocyclic, each of which groups may be substituted or unsubstituted.