| abstract |
Heterotricyclic derivatives of formula (I) wherein R1 is hydrogen, lower alkyl, lower alkoxy, lower alkylthio, halogen, nitro, amino or protected amino, R2 is hydroxy, protected hydroxy, halogen, amino or protected amino, R3 is hydrogen or an organic group, R4 is hydrogen or lower alkyl, R8 is hydrogen or lower alkyl, and -Z- is -O- or a group of formula (II) (in which n is 0, 1 or 2), and pharmaceutically acceptable salts thereof which are useful as a medicament. |