Abstract: A compound of formula (I) or a pharmaceutically acceptable salt thereof; ##STR1## wherein: R.sub.1 is hydrogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy or halogen;R.sub.2 and R.sub.3 are both hydrogen or together represent a bond;R.sub.4 is hydrogen and R.sub.5 is hydrogen or R.sub.4 and R.sub.5 together represent an oxo group;R.sub.6 is C.sub.1-7 alkyl substituted by NR.sub.8 R.sub.9 where R.sub.8 and R.sub.9 are independently hydrogen or C.sub.1-4 alkyl or together are C.sub.3-7 polymethylene optionally containing a further heteroatom which is oxygen, sulphur or nitrogen substituted by R.sub.10 where R.sub.10 is hydrogen, C.sub.1-4 alkyl or benzyl, and optionally substituted by one or two C.sub.1-4 alkyl, C.sub.2-5 alkanoyl, C.sub.1-4 alkoxycarbonyl, aminocarbonyl optionally substituted by one or two C.sub.1-6 alkyl groups or by a benzyl group, cyano, phenyl or benzyl and wherein any phenyl or benzyl group is optionally substituted in the phenyl ring by one or two halo, CF.sub.3, C.sub.1-4 alkyl, C.sub.

Abstract: A compound of formula (I) or a pharmaceutically acceptable salt thereof: ##STR1## wherein: R.sub.1 is hydrogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy or halogen;R.sub.2 and R.sub.3 are both hydrogen or together represent a bond;R.sub.4 is selected from C.sub.1-6 alkyl, phenyl, phenyl C.sub.1-4 alkyl, COR.sub.8 where R.sub.8 is hydroxy, C.sub.1-6 alkoxy or NR.sub.9 R.sub.10 where R.sub.9 and R.sub.10 are independently hydrogen or C.sub.1-4 alkyl and CH.sub.2 OR.sub.11 and R.sub.11 is hydrogen, C.sub.1-4 alkyl or C.sub.1-4 alkanoyl;R.sub.5 is hydrogen, C.sub.1-6 alkyl or phenyl C.sub.1-4 alkyl;R.sub.6 is phenyl C.sub.1-7 alkyl in which the phenyl moiety is optionally substituted by one or two of halogen, ortho-nitro, meta- or para-methoxy, methyl or NR.sub.12 R.sub.13 wherein R.sub.12 and R.sub.13 are independently hydrogen or C.sub.1-6 alkyl or R.sub.12 and R.sub.13 together are C.sub.2-6 polymethylene or the phenyl moiety is 3,4-disubstituted by methylenedioxy or ethylenedioxy; andR.sub.7 is hydrogen or C.sub.

Abstract: A pharmaceutical composition comprising a compound of formula (I) or a pharmaceutically acceptable salt thereof: ##STR1## wherein: R.sub.1 is hydrogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy or halogen;R.sub.2 and R.sub.3 are both hydrogen or together represent a bond;R.sub.4 is hydrogen and R.sub.5 is hydrogen or R.sub.4 and R.sub.5 together represent an oxo group;R.sub.6 is phenyl C.sub.1-7 alkanoyl in which the phenyl moiety is optionally substituted by one or two of halogen, nitro, meta- or para-methoxy, methyl or NR.sub.8 R.sub.9 wherein R.sub.8 and R.sub.9 are independently hydrogen or C.sub.1-6 alkyl or R.sub.8 and R.sub.9 together are C.sub.2-6 polymethylene, or 3,4-disubstituted by methylenedioxy or ethylenedioxy; or C.sub.1-7 alkanoyl substituted by NR.sub.10 R.sub.11 where R.sub.10 and R.sub.11 are independently hydrogen or C.sub.1-4 alkyl or together are C.sub.3-7 polymethylene optionally containing a further heteroatom which is oxygen, sulphur or nitrogen substituted by R.sub.12 where R.sub.

Abstract: A compound of formula (I) or a pharmaceutically acceptable salt thereof: ##STR1## wherein: R.sub.1 is hydrogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy or halogen;R.sub.2 and R.sub.3 are both hydrogen or together represent a bond;R.sub.4 is hydrogen and R.sub.5 is hydrogen or R.sub.4 and R.sub.5 together represent an oxo group;R.sub.6 is phenyl, phenyl C.sub.1-7 alkyl or phenyl C.sub.1 -7 alkanoyl, in which the phenyl moiety is substituted by NR.sub.8 R.sub.9 wherein R.sub.8 is C.sub.1-6 alkyl substituted by a group R.sub.10 selected from hydroxy, halo, CF.sub.3 or COR.sub.11 where R.sub.11 is hydroxy, C.sub.1-4 alkoxy or amino optionally substituted by one or two C.sub.1-4 alkyl groups, and R.sub.9 is hydrogen, C.sub.1-6 alkyl or R.sub.8 ; andR.sub.7 is hydrogen or C.sub.1-4 alkyl.

Abstract: A compound of the formula (I) or a pharmaceutically acceptable salt thereof: ##STR1## wherein: R.sub.1 is hydrogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy or halogen;R.sub.2 and R.sub.3 are both hydrogen or together represent a bond;R.sub.4 is hydrogen and R.sub.5 is hydrogen or R.sub.4 and R.sub.5 together represent an oxo group;R.sub.6 is C.sub.1-7 alkyl substituted by NR.sub.8 R.sub.9 where R.sub.8 and R.sub.9 are independently hydrogen or C.sub.1-4 alkyl or together are C.sub.3-7 polymethylene optionally containing a further hetereoatom which is oxygen, sulphur or nitrogen substituted by R.sub.10 where R.sub.10 is hydrogen, C.sub.1-4 alkyl or benzyl, and optionally substituted by one or two C.sub.1-4 alkyl, C.sub.2-5 alkanoyl, C.sub.1-4 alkoxycarbonyl, aminocarbonyl optionally substituted by one or two C.sub.1-6 alkyl groups or by a benzyl group, cyano, phenyl or benzyl and wherein any phenyl or benzyl group is optionally substituted in the phenyl ring by one or two halo, CF.sub.3, C.sub.1-4 alkyl, C.sub.