Nucleotide analogs

A compound of the structure of Formula (I), or a pharmaceutically acceptable salt thereof:

• wherein:
• B1 is
• Z1 is O;
• Z2 is NRZ;
• RZ is hydrogen or C1-4 alkyl;
• R1 is aryl, or aryl(C1-4 alkyl);
• R2 is
• R3 is CHF2, CF3, or OCH3;
• each R9 and each R10 are independently hydrogen, C1-6alkyl, —CH2SH, —CH2(C═O)NH2, —CH2CH2(C═O)NH2, —CH2CH2S CH3, CH2—phenyl, —CH2OH, —CH(OH)CH3,
• —CH2(C═O)OH,
• —CH2CH2(C═O)OH, —(CH2)3NH(C═NH)NH2,
• or —(CH2)4NH2;
• each R11 is independently hydrogen, C1-8 alkyl, C2-8 alkenyl, alkynyl, cycloalkyl, cycloalkyl(C1-C4 alkyl)-, cycloalkenyl, cycloalkenyl(C1-C4 alkyl)-, aryl, aryl(C1-4 alkyl)-, heteroaryl, heteroaryl(C1-C4 alkyl)-, heterocyclyl, or heterocyclyl(C1-C4 alkyl)-;
• and
• R13 is unsubstituted C1-6 alkyl or an unsubstituted C3-6 cycloalkyl.