| abstract |
Compounds of formula (I), and pharmaceutically acceptable salts thereof <CHEM> wherein R1 is hydroxy, amino, chloro or OR7 wherein R7 is C1-6 alkyl, phenyl or phenyl C1-2 alkyl either of which phenyl moieties may be substituted by one or two substituents selected from halo, C1-4 alkyl or C1-4 alkoxy; R2 is amino or, when R1 is hydroxy or amino, R2 may also be hydrogen; R3 is hydrogen, hydroxymethyl or acyloxymethyl; R4 is a group of formula: <CHEM> R5 and R6 are independently selected from hydrogen, C1-6 alkyl and optionally substituted phenyl; or R3 and R4 together are: <CHEM> wherein R6 is as defined above; having antiviral activity, to processes for their preparation and their use as pharmaceuticals. |