abstract |
Compounds of the formula wherein: n is 2, 3 or 4; Ro is C1-C4 alkyl or C1-C3 haloalkyl; R1 and R2 which may be the same or different, are each selected from hydrogen, C1-C4 alkyl optionally substituted by one or more fluorine atoms, and C1-C4 alkoxy; X is a halogen atom; B is selected from: |