Heslin & Rothenberg, P.C.
Nucleoside derivatives and process for preparing the same
 According to the present invention, provided are novel nucleoside derivatives having antiviral activity, in particular, anti-HBV (anti-Hepatitis-B Virus) activity, represented by general formula (I), wherein R.sub.1 represents hydrogen, phosphate, phosphonate, alkyl or acyl; R.sub.2 represents alkoxy or halogen; R.sub.3 represents substituted or non-substituted pyrimidine or purine base; and X represents O, S, SO or SO.sub.2 ; pharmaceutically acceptable salts thereof, and processes thereof. As the compound (I) has two or more asymmetric carbon atoms, all possible stereoisomers and mixtures thereof are included in the scope of the present invention. ##STR1## 
Chong Kun Dang Corp.
C C A C A
C07D C07D A61P C07D A61P
inventional inventional inventional inventional inventional
Byeong Seon Soon Kil Jung Woo Hoe Joo Koo Hun
Jeong Ahn Kim Son Chung