The invention relates to compounds of the formula 1 ##STR00001## and to pharmaceutically acceptable salts, solvates, prodrugs and metabolites thereof, wherein W, Z, R.sup.1 and R.sup.2, are as defined herein. The invention also relates to methods of treating Hepatitis C virus in mammals by administering the compounds of formula 1, and to pharmaceutical compositions for treating such disorders, which contain the compounds of formula 1. The invention also relates to methods of preparing the compounds of formula 1.