Antiviral therapeutic agents

A compound of formula I:

• wherein;
• B represents a 5, 6, 7 or 8 membered carbocyclic or heterocyclic ring comprising one or more double bonds, wherein B is optionally substituted with one or more oxo, thioxo, NRcRd, F, Cl, Br, I, ORz, SRz, alkyl, C≡N, C≡C—R, N3 or SO2R′;
• wherein:
• R is H, alkyl or aryl;
• R′ is OH, NH2 or alkyl;
• R1 is H, NRaRb, Cl, F, ORa, SRa, NHCORa, NHSO2Ra, NHCONHRa, CN, alkyl, aryl, ONRaRb, or NRaC(O)ORb;
• R2 is a nucleoside sugar group;
• W3 is absent, alkyl, or H;
• Ra and Rb are independently selected from the group consisting of H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl, heterocyclic, aryl, substituted aryl, acyl, substituted acyl, SO2-alkyl, amino, substituted amino, and NO;
• or Ra and Rb together with the nitrogen to which they are attached form a pyrrolidino, piperidino, piperazino, azetidino, morpholino, or thiomorpholino ring;
• Rc and Rd are independently selected from the group consisting of H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl, acyl, substituted acyl and SO2-alkyl;
• or Rc and Rd together with the nitrogen to which they are attached form a pyrrolidino, piperidino, piperazino, azetidino, morpholino, or thiomorpholino ring;
• and
• each Rz is independently selected from the group consisting of H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl, acyl and substituted acyl;
• or a pharmaceutically acceptable salt or prodrug thereof.