Cyclopentyl nucleoside analogs as anti-virals

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

• wherein:
• B1 is an optionally substituted C-linked heterocyclic base or an optionally substituted N-linked heterocyclic base;
• R1 is selected from the group consisting of hydrogen, halogen, cyano, an optionally substituted C1-6 alkyl, an unsubstituted C2-6 alkenyl and an unsubstituted C2-6 alkynyl, wherein when the C1-6 alkyl is substituted, the C1-6 alkyl is substituted with at least one halogen;
• R2 is hydrogen or fluoro;
• R3 is hydrogen or fluoro;
• R4 is selected from the group consisting of hydrogen, halogen, hydroxy, cyano and an optionally substituted C1-4 alkyl, wherein when the C1-4 alkyl is substituted, the C1-4 alkyl is substituted with a hydroxy or at least one halogen;
• R5 is hydrogen or hydroxy;
• R6 is selected from the group consisting of hydrogen, halogen, cyano, an optionally substituted C1-4 alkyl, an optionally substituted C2-4 alkenyl and an unsubstituted C2-4 alkynyl, wherein when the C1-4 alkyl or the C2-4 alkenyl are substituted, the C1-4 alkyl and C2-4 alkenyl are independently substituted with at least one halogen;
• R7 is selected from the group consisting of hydrogen, an optionally substituted acyl, an optionally substituted O-linked α-amino acid,
• and
• R10 and R11 are independently selected from the group consisting of absent, hydrogen,
• and
• or
• R10 is
• and R11 is absent or hydrogen;
• R12 is absent, hydrogen, an optionally substituted aryl or an optionally substituted heteroaryl;
• R13 is an optionally substituted N-linked α-amino acid or an optionally substituted N-linked α-amino acid ester derivative;
• R14 and R15 are independently an optionally substituted N-linked α-amino acid or an optionally substituted N-linked α-amino acid ester derivative;
• R16, R17, R19 and R20 are independently selected from the group consisting of hydrogen, an optionally substituted C1-24 alkyl and an optionally substituted aryl;
• R18 and R21 are 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 and an optionally substituted —O-aryl;
• R22 is selected from the group consisting of hydrogen, an optionally substituted C1-24 alkyl and an optionally substituted aryl;
• R23, R24 and R25 are independently absent or hydrogen;
• R8 and R9 are independently hydrogen or halogen;
• and
• m is 0 or 1;
• and
• provided that a compound of Formula (I), or a pharmaceutically acceptable salt thereof, is not a compound of (i), (ii) or (iii), or a pharmaceutically acceptable salt thereof:
• (i) when R1 is hydrogen;
• R2 is hydrogen or fluoro;
• R3 is hydrogen or fluoro;
• R4 is hydroxy;
• R5 is hydrogen;
• R6 is hydrogen or fluoro;
• R8 and R9 are each hydrogen and B1 is selected from the group consisting of
• then R7 is not selected from the group consisting of:
• (a) hydrogen;
• (b)
• wherein R10 and R11 are each hydrogen or each absent;
• (c)
• wherein R10 is
• R11, R23, R24 or R25 are independently absent or hydrogen, and m is 0 or 1;
• and (d)
• wherein R12 is an unsubstituted phenyl or an unsubstituted naphthyl, and R13 is alanine isopropyl ester, alanine isobutyl ester or alanine neopentyl ester;
• (ii) when R1 is hydrogen;
• R4 is hydroxy;
• R5 is hydrogen;
• R6 is hydrogen;
• R8 and R9 are each hydrogen;
• B1 is selected from the group consisting of
• R7 is selected from the group consisting of:
• (a)
• wherein R10 is
• R11, R23, R24 or R25 are independently absent or hydrogen, and m is 1;
• and (b)
• wherein R12 is an unsubstituted phenyl, and R13 is alanine isopropyl ester, then (a) R2 is not hydrogen when R3 are fluoro;
• and (b) R2 is not fluoro when R3 are hydrogen;
• and
• (iii) when R1 is hydrogen;
• R4 is hydroxy;
• R5 is hydrogen;
• R6 is hydrogen;
• R7 is hydrogen and R8 and R9 are each hydrogen;
• then B1 is not selected from the group consisting of