| 摘要 |
A compound of the formula <IMAGE> wherein X has the formula <IMAGE> wherein ring A is phenyl, naphthyl or heterocyclic; wherein R1 is hydrogen, alkyl, alkanoyl or aroyl; wherein R2, R3 and R4, which may be the same or different, each is an electron withdrawing substituent selected from halogeno, nitro, cyano, trifluoromethyl, alkylthio, alkylsulphinyl and alkylsulphonyl or each is hydrogen, alkyl, alkoxy or dialkylamino provided that when ring A is phenyl or naphthyl at least one of R2, R3 and R4 is an electron-withdrawing substituent; wherein R5 and R6, which may be the same or different, each is hydrogen, halogeno or alkyl; wherein R7 is alkyl or halogenoalkyl; and wherein R8 is carbamoyl, alkyl, cycloalkyl, alkenyl, alkynyl, halogenoalkyl, halogenoalkenyl, halogenoalkynyl, alkanoyl, alkylcarbamoyl, dialkylcarbamoyl or aroyl; or wherein R8 is alkyl or alkenyl which bears one or more substituents selected from cyano, carbamoyl, amino, hydroxy, alkanoyl, alkoxy, alkylthio, alkenylthio, alkylsulphinyl, alkenylsulphinyl, alkylsulphonyl, alkenylsulphonyl, alkanoylamino, alkoxycarbonylamino, alkylsulphonamido, alkylamino, dialkylamino, dialkylsulphamoyl, aroyl, aryl, arylthio, arylsulphinyl, arylsulphonyl, heterocyclylthio, heterocyclylsulphinyl and heterocyclylsulphonyl; or wherein R8 has the formula <IMAGE> wherein ring B is phenyl, naphthyl or heterocyclyl and wherein R2, R3 and R4 have any of the meanings stated above, provided that when R7 is methyl R8 is not also methyl.
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