Polynucleotide molecules and uses thereof

A polynucleotide comprising at least one backbone moiety of Formula III:

• wherein the dotted line represents an optional double bond;
• B is a nucleobase;
• m and n are independently an integer from 0 to 3;
• X is S, CH2, SO2, O, or NR7;
• R1 is hydrogen or fluorine;
• R2 is hydrogen, fluorine, cyano, azido, or optionally substituted C1-C6 alkyl;
• R3 and R4 are independently hydrogen, optionally substituted hydroxyl, or fluorine;
• R5 and R6 are independently hydrogen or optionally substituted C1-C6 alkyl, or R5 and R6 are combined to form an optionally substituted C3-C6 cycloalkyl, provided that one of R5 and R6 is absent when the dotted line is a double bond;
• R7 is hydrogen or optionally substituted C1-C6 alkyl;
• each Y2 is independently hydroxyl or optionally substituted C1-C6 heteroalkyl;
• each Y3 is independently absent, O, or S;
• each Y5 is independently O, NH, or CR8R9;
• each Y6 is independently O or S;
• each Y7 is independently O or NH;
• and
• each R8 and R9 is independently hydrogen, fluorine, or optionally substituted C1-C6 alkyl, or R8 and R9 are combined to form an optionally substituted C3-C6 cycloalkyl, provided that one of R8 and R9 is absent when the dotted line is a double bond;
• wherein if X is O and R1, R2, R4, R5, and R6 are hydrogen, then at least one of Y5 and Y7 is NH or Y5 is CR8R9;
• provided that m and n are both 1 when the backbone moiety is not a 3′ or 5′ terminal moiety;
• or a salt thereof.

A compound of Formula IA:

• wherein the dotted line represents an optional double bond;
• B is a nucleobase;
• m and n are independently an integer from 0 to 3;
• X is S, CH2, SO2, O, or NR7;
• R1 is hydrogen or fluorine;
• R2 is hydrogen, fluorine, cyano, azido, or optionally substituted C1-C6 alkyl;
• R3 and R4 are independently hydrogen, optionally substituted hydroxyl, or fluorine;
• R5 and R6 are independently hydrogen or optionally substituted C1-C6 alkyl, or R5 and R6 are combined to form an optionally substituted C3-C6 cycloalkyl, provided that one of R5 and R6 is absent when the dotted line is a double bond;
• R7 is hydrogen or optionally substituted C1-C6 alkyl;
• Y1 and Y4 are independently hydroxyl, protected hydroxyl, or optionally substituted amino;
• each Y2 is independently hydroxyl or optionally substituted C1-C6 heteroalkyl;
• each Y3 is independently absent, O, or S;
• each Y5 is independently O, NH, or CR8R9;
• each Y6 is O or S;
• each Y7 is O or NH;
• and
• each R8 and R9 is independently hydrogen, fluorine, or optionally substituted C1-C6 alkyl, or R8 and R9 are combined to form an optionally substituted C3-C6 cycloalkyl, provided that one of R8 and R9 is absent when the dotted line is a double bond;
• or a salt thereof.

A polynucleotide comprising at least one backbone moiety of Formula IIA:

• wherein the dotted line represents an optional double bond;
• B is a nucleobase;
• m and n are independently an integer from 0 to 3;
• X is S, CH2, SO2, O, or NR7;
• R1 is hydrogen or fluorine;
• R2 is hydrogen, fluorine, cyano, azido, or optionally substituted C1-C6 alkyl;
• R3 and R4 are independently hydrogen, optionally substituted hydroxyl, or fluorine;
• R5 and R6 are independently hydrogen or optionally substituted C1-C6 alkyl, or R5 and R6 are combined to form an optionally substituted C3-C6 cycloalkyl, provided that one of R5 and R6 is absent when the dotted line is a double bond;
• R7 is hydrogen or optionally substituted C1-C6 alkyl;
• each Y2 is independently hydroxyl or optionally substituted C1-C6 heteroalkyl;
• each Y3 is independently absent, O, or S;
• each Y5 is independently O, NH, or CR8R9;
• each Y6 is independently O or S;
• each Y7 is independently O or NH;
• and
• each R8 and R9 is independently hydrogen, fluorine, or optionally substituted C1-C6 alkyl, or R8 and R9 are combined to form an optionally substituted C3-C6 cycloalkyl, provided that one of R8 and R9 is absent when the dotted line is a double bond;
• provided that m and n are both 1 when the backbone moiety is not a 3′ or 5′ terminal moiety;
• or a salt thereof.