Antiviral activity is exhibited by compounds having the formula ##STR1## and its pharmaceutically acceptable salts wherein R.sub.1 is ##STR2## R.sub.6 is hydrogen, alkyl, substituted alkyl, or aryl; and R.sub.7 and R.sub.8 are independently hydrogen, ##STR3##
具有以下式子的化合物及其药学上可接受的盐具有抗病毒活性:##
STR1## 其中R.sub.1是##
STR2## R.sub.6是
氢,烷基,取代烷基或芳基;R.sub.7和R.sub.8独立地是
氢,##
STR3##