Acyclic antivirals

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

• wherein:
• B1 is an optionally substituted C-linked bicyclic heteroaryl containing 9 atoms in the rings and 3, 4 or 5 nitrogens or an optionally substituted C-linked bicyclic heterocyclyl containing 9 atoms in the rings and 3, 4 or 5 nitrogens;
• R1 and R2 are each independently selected from the group consisting of O−, —OH, an optionally substituted —O—C1-24 alkyl, an optionally substituted —O—C2-24 alkenyl, an optionally substituted —O—C2-24 alkynyl, an optionally substituted —O—C3-6 cycloalkyl, an optionally substituted —O—C3-6 cycloalkenyl, an optionally substituted —O-aryl, an optionally substituted —O-heteroaryl, an optionally substituted —O-aryl(C1-6 alkyl), an optionally substituted *—O—(CR4R5)p—O—C1-24 alkyl, an optionally substituted *—O—(CR6R7)q—O—C1-24 alkenyl,
• an optionally substituted N-linked amino acid and an optionally substituted N-linked amino acid ester derivative;
• or
• R1 is
• and R2 is O− or OH;
• or
• R1 and R2 are taken together to form a moiety selected from the group consisting of an optionally substituted
• and an optionally substituted
• wherein the phosphorus and the moiety form a six-membered to ten-membered ring system;
• R3a and R3b are each independently selected from the group consisting of hydrogen, halogen, an unsubstituted C1-4 alkyl, an unsubstituted C3-6 cycloalkyl, cyano, halogen(C1-4 alkyl), hydroxy(C1-4 alkyl), alkoxy(C1-4 alkyl), acyl(C1-4 alkyl) and cyano(C1-4 alkyl);
• or
• R3a and R3b are taken together with the carbon to which they are connected to form an optionally substituted C3-6 cycloalkyl;
• each R4, each R5, each R6 and each R7 are independently hydrogen, an optionally substituted C1-24 alkyl or alkoxy;
• R8, R9, R11 and R12 are each independently selected from the group consisting of hydrogen, an optionally substituted C1-24 alkyl and an optionally substituted aryl;
• R10 and R13 are each independently selected from the group consisting of hydrogen, an optionally substituted C1-24 alkyl, an optionally substituted aryl, an optionally substituted —O—C1-24 alkyl, an optionally substituted —O-aryl, an optionally substituted —O-heteroaryl and an optionally substituted —O-monocyclic heterocyclyl;
• R14 is selected from the group consisting of hydrogen, an optionally substituted C1-24 alkyl and an optionally substituted aryl;
• R15 and R16 are each independently selected from the group consisting of —C≡N, an optionally substituted C2-8 organylcarbonyl, an optionally substituted C2-8 alkoxycarbonyl and an optionally substituted C2-8 organylaminocarbonyl;
• R17 is selected from the group consisting of hydrogen, an optionally substituted C1-24-alkyl, an optionally substituted C2-24 alkenyl, an optionally substituted C2-24 alkynyl, an optionally substituted C3-6 cycloalkyl and an optionally substituted C3-6 cycloalkenyl;
• R19, R20 and R21 are each independently absent or hydrogen;
• m is 0 or 1;
• n is 1 or 2;
• p and q are each independently selected from the group consisting of 1, 2 and 3;
• r is 1 or 2;
• s is 0 or 1;
• Z1 is oxygen (O) or sulfur (S).