Pharmaceutically active benzoquinazoline compounds

A compound of formula (I)

• or a salt thereof, wherein the dotted line represents a single or double bond,
• R1 is C1-4 alkyl or amino optionally substituted by a C1-4 alkyl, C1-5 alkanoyl or benzyl group;
• R2, R3, R4 and R5 are the same or different and each is selected from
• hydrogen, phenyl, halo, nitro, or
• a group S(O)nR8 wherein n is the integer 0, 1 or 2 and R8 is halo, C1-4 alkyl, a group NR9 R10 wherein R9 and R10 are both hydrogen, a group NR11R12 wherein R11 and R12 are the same or different and each is hydrogen or C1-4 alkyl, or
• a group OR13 wherein R13 is hydrogen or C1-4 alkyl optionally substituted by halo, or
• a C1-4 aliphatic group optionally substituted by a group OR14 or NR14 R15 wherein R14 and R15 are the same or different and each is hydrogen or C1-4 alkyl;
• or
• two of R2 to R5 are linked together to form a benzo group, or
• one of R2 to R5 is a group —X—Y—R16, wherein
• X is CH2, NR17, CO or S(O)m,
• m is 0, 1 or 2,
• R17 is hydrogen or a C1-4 aliphatic group,
• Y is CH2, NR17′,O, or S(O)m′,
• m′ is 0,1 or 2,
• R17′ is hydrogen or a C1-4 aliphatic group
• provided that X and Y are only the same when each is CH2, or —X—Y— is a group —O—, —NR17—, —CH═CH— or —N═N— wherein R17 is as hereinbefore defined,
• R16 is
• a C1-4 aliphatic group or
• a 5- or 6-membered aromatic ring optionally substituted by a group R18 at a position at least one carbon atom removed from that linked to Y, the 5- or 6-membered ring being optionally further substituted by a halo atom;
• R18 is halo, C1-4 alkoxy, nitro, nitrile, C1-4 alkyl optionally substituted by halo, halo or a group COR19,
• R19 is
• hydroxy, C1-4 alkoxy or C1-6 alkyl optionally substituted by one or two carboxyl groups or C1-12 esters thereof or
• a group NR20 R21 wherein R20 and R21 are the same or different and each is hydrogen or C1-4 alkyl optionally substituted by hydroxy or
• a C2-3 alkylene group linked to the 5- or 6-membered aromatic ring to form a further 5- or 6-membered ring, or
• when R18 is a C1-4 alkyl group substituted by COR19, R19 is an amino acid or an ester thereof in which the first nitrogen atom of the amino acid together with the carbons of the C1-4 alkyl and the carbonyl carbon COR19 may be linked to the 5- or 6-membered aromatic ring to form a further 5- or 6-membered heterocyclic ring;
• R6 and R7 are the same or different and each is hydrogen, C1-4 alkyl optionally substituted by hydroxy or C1-4 alkoxy, or methyl substituted by bromo, or together form a benzo group;
• provided that at least one of R2 to R7 is other than hydrogen or methyl and that R4 is not methoxy or ethoxy when R1 is hydroxy or methyl.