| abstract |
A compound of formula (I) or a salt thereof: ** Formula ** in formula R1, R2 and R3 are the same or different from each other, and are H, halogen, lower alkyl or haloalkyl lower; R4 is H, halogen, lower alkyl or haloalkyl lower; R5 is H; R6 is phenyl which may be substituted; or R5 and R6 can form a benzene ring that can be substituted, along with carbon atoms to which they are attached; and ----- is a single bond or a double bond; and the term "lower" refers to 1 to 6 carbon atoms. |