Abstract: The present invention is directed to compounds of formula (I), ##STR1## wherein R.sup.1 is OH, NH.sub.2 ; R.sup.2 is a heteroaromatic or aromatic substituent; R.sup.3 is H, OH, F, OCH.sub.3 ; R.sup.4 is H, F, OH or an ether or ester residue thereof, OCH.sub.3, CN, C.dbd.CH, N.sub.3 ; R.sup.5 is OH or an ether or ester residue thereof including mono, di- and triphosphate esters (.alpha.), wherein n is 0 or 1 and M is hydrogen or a pharmaceutically acceptable counterion such as sodium, potassium, ammonium or alkylammonium; and pharmaceutically acceptable salts thereof; and pharmaceutical compositions comprising said compounds can be used for therapeutic treatment of virus infections. The present invention is also directed to compounds of formula (I'), ##STR2## wherein R.sup.1 and R.sup.2 are as defined above, as intermediates.