Patent ID: 7396487

Claim:
A compound of formula (I) where R 1 is alkyl or alkenyl, Y 1 and Y 2 are independently selected from oxygen or sulphur, n is an integer of from 1 to 5, A is an optionally substituted phenyl or an optionally substituted cycloalkyl ring, X is a direct bond, a C 1-4 alkylene, a C 2-4 alkenylene, an acetylene, —CO(O)— or a group of sub-formula (i) where X 1 and X 2 are independently selected from a direct bond, a C 1-4 alkylene, a C 2-4 alkenylene, an acetylene or —CO(O)— and R 2 , R 3 and R 4 are independently selected from hydrogen, halo or cyano, provided that no more than one of R 2 , R 3 and R 4 is hydrogen and that where A is unsubstituted phenyl and Y 1 and Y 2 are both oxygen, then: (a) where X is a direct bond, R 2 —R 4 together represent other than either two cyano groups or two halogen atoms when R 1 is alkyl; (b) where X is —CO(O)—, R 2 —R 4 together represent other than one halogen and one cyano group, and (c) where X is an acetylene group, R 2 —R 4 together represent other than one cyano group and two halogen atoms.