A compound represented by one of the following formulae: wherein each x is independently 1 or 2; each R 1 is independently selected from the group consisting of H; halogen; C 1-4 alkyl; C 1-4 alkenyl; C 1-4 alkynyl; -COR 4 where R 4 is H, C 1-4 alkyl or C 1-4 alkoxy; C 3-6 cycloalkyl; aryl; heteroaryl; cyano; nitro; trihalomethyl; oxo; or -(CH 2) n -X-(CH 2) m -(R 5) o where X is O, S or N, n is 0-3, m is 0-3, o is 0-1, and R 5 is methyl or H 1-2; each R 2 and each R 3 are independently selected from the group consisting of H; C 1-4 alkyl; C 1-4 alkenyl; C 1-4 alkynyl; halide; trihalomethyl; cycloalkyl; (CH 2) n -X- (CH 2) m -(R 5) o, where X is O, S or N, n is 0-3, m is 0-3, o is 0-1, and R 5 is methyl or H 1-2; or an R 2 and an R 3 together condense to form a saturated, partly saturated, or unsaturated ring structure having the formula -(C(R 6) p) q -X s -(C(R 6) p) r -X t -(C(R 6) p) u where each R 6 is independently selected from the group consisting of H; halogen; C 1-4 alkyl; C 1-4 alkenyl; C 1-4 alkynyl; -COR 4 where R 4 is H, C 1-4 alkyl or C 1-4 alkoxy; C 3-6 cycloalkyl; aryl; heteroaryl; cyano; nitro; trihalomethyl; and oxo where each p is independently 1 or 2, q is 0-4, r is 0-4, u is 0-4; each X is independently O, S, or N, s is O or 1, and q+s+r+t+u = 3 or 4; Y is selected from the group consisting of O; S; N; -Y 1 =CH- and -Y 1 CH 2 - where Y 1 is O, N or S; the ring including Y has either a single double bond or no double bond, except that when an R 2 and an R 3 condense together to form a saturated, unsaturated or partly saturated ring structure said Y-including ring may share an additional double bond with said condensed ring, provided Y is not S, O, or N; with the proviso that if the ring including Y is a heterocyclic 5-membered ring, said ring contains a single double bond; wherein each x is independently 1 or 2; each R 1 is independently selected from the group consisting of H; halogen; C 1-4 alkyl; C 1-4 alkenyl; C 1-4 alkynyl; -COR 4 where R 4 is H, C 1-4 alkyl or C 1-4 alkoxy; C 3-6 cycloalkyl; aryl; heteroaryl; cyano; nitro; trihalomethyl; oxo; or -(CH 2) n -X-(CH 2) m -(R 5) o where X is O, S or N, n is 0-3, m is 0-3, o is 0-1, and R 5 is methyl or H 1-2; each R 2 and each R 3 are independently selected from the group consisting of H; C 1-4 alkyl; C 1-4 alkenyl; C 1-4 alkynyl; halide; trihalomethyl; cycloalkyl; (CH 2) n -X- (CH 2) m -(R 5) o, where X is O, S or N, n is 0-3, m is 0-3, o is 0-1, and R 5 is methyl or H 1-2; or an R 2 and an R 3 together condense to form a saturated, partly saturated, or unsaturated ring structure having the formula -(C(R 6) p) q -X s -(C(R 6) p) r -X t -(C(R 6) p) u where each R 6 is independently selected from the group consisting of H; halogen; C 1-4 alkyl; C 1-4 alkenyl; C 1-4 alkynyl; -COR 4 where R 4 is H, C 1-4 alkyl or C 1-4 alkoxy; C 3-6 cycloalkyl; aryl; heteroaryl; cyano; nitro; trihalomethyl; and oxo where each p is independently 1 or 2, q is 0-4, r is 0-4, u is 0-4; each X is independently O, S, or N, s is O or 1, and q+s+r+t+u = 3 or 4; Y is selected from the group consisting of O; S; N; -Y 1 =CH- and -Y 1 CH 2 - where Y 1 is O, N or S; the ring including Y has either a single double bond or no double bond, except that when an R 2 and an R 3 condense together to form a saturated, unsaturated or partly saturated ring structure said Y-including ring may share an additional double bond with said condensed ring, provided Y is not S, O, or N; with the proviso that if the ring including Y is a heterocyclic 5-membered ring, said ring contains a single double bond;