Compounds of formula I : including any possible stereoisomers thereof, wherein: R
1 is hydrogen, -C(=O)R
6 or -C(=O)CHR
7 -NH
2 ; R
2 is hydrogen; or C
1 -C
6 alkyl or phenyl, either of which is optionally substituted with 1, 2 or 3 substituents each independently selected from halo, C
1 -C
6 alkyl, C
2 -C
6 -alkenyl and C
1 -C
6 alkoxy, hydroxy or amino, or R
2 is naphtyl; or R
2 is indolyl, R
3 is hydrogen, Ci-C6alkyl, benzyl; R
4 is hydrogen, Ci-C6alkyl, benzyl; or R
3 and R
4 together with the carbon atom to which they are attached form C
3 -C
7 Cyclo- alkyl; R
5 is C
1 -C
10 alkyl, C
3 -C
7 -cycloalkyl, benzyl, or phenyl, any of which being optionally substituted with 1, 2 or 3 substituents each independently selected from hydroxy, C
1 -C
6 alkoxy, amino, mono- and diC
1 -C
6 alkylamino; R
6 is C
1 -C
6 alkyl; R
7 is C
1 -C
6 alkyl; R
8 is hydrogen or halogen; or a pharmaceutically acceptable salt or solvate thereof are useful in the prophylaxis or treatment of HCV infections.