Nucleosides with antiviral and anticancer activity

A compound of formula I:

• wherein:
• R1 is guanine, cytosine, thymine, 3-deazaadenine, or uracil, optionally substituted by 1, 2, or 3 U;
• wherein each U is independently halo, hydroxy, (C1-C6)alkyl, (C3-C6)cycloalkyl, (C1-C6)alkoxy, (C3-C6)cycloalkyloxy, (C1-C6)alkanoyl, (C1-C6)alkanoyloxy, trifluoromethyl, hydroxy(C1-C6)alkyl, —(CH2)1-4P(═O)(ORw)2, aryl, aryl(C1-C6)alkyl, or NRxRy;
• R2 is halo;
• R6 and R7 are independently H or (C1-C6)alkyl;
• R3 is hydroxy;
• R4 is hydrogen, (C1-C6)alkyl, (C3-C6)cycloalkyl, aryl, aryl(C1-C6)alkyl, or 2-cyanoethyl;
• R5 is an amino acid;
• X is oxy, thio, or methylene;
• each Rw is independently hydrogen or (C1-C6)alkyl;
• Rx and Ry are each independently hydrogen, (C1-C6)alkyl, (C3-C6)cycloalkyl, phenyl, benzyl, phenethyl, or (C1-C6)alkanoyl;
• or Rx and Ry together with the nitrogen to which they are attached are pyrrolidino, piperidino or morpholino;
• wherein any (C1-C6)alkyl of R1, R4-R7, Rw, Rx, and Ry is optionally substituted with one or more halo, hydroxy, (C1-C6)alkoxy, (C3-C6)cycloalkyloxy, (C1-C6)alkanoyl, (C1-C6)alkanoyloxy, trifluoromethyl, azido, cyano, oxo (═O), (C1-C6)alkyl, (C3-C6)cycloalkyl, (C3-C6)cycloalkyl(C1-C6)alkyl, (C1-C6)alkyl-S—(C1-C6)alkyl-, aryl, heteroaryl, alkyl(C1-C6)alkyl, or heteroary(C1-C6)alkyl, or NRajRak;
• wherein each Raj and Rak is independently hydrogen, (C1-C6)alkyl, (C3-C6)cycloalkyl, phenyl, benzyl, or phenethyl;
• and wherein any aryl or heteroaryl may optionally be substituted with one or more substituents selected from the group consisting of halo, hydroxy, (C1-C6)alkyl, (C3-C6)cycloalkyl, (C1-C6)alkoxy, (C3-C6)cycloalkyloxy, (C1-C6)alkanoyl, (C1-C6)alkanoyloxy, trifluoromethyl, trifluoromethoxy, nitro, cyano, and amino;
• or a pharmaceutically acceptable salt thereof.