Carbocyclic derivatives and conjugated derivatives thereof, and their use in vaccines

An oligomer of Formula (Ia) or (Ib):

• wherein
• n is ≥6;
• R is H or —P(O)(OR″)2, wherein R″ is H or a pharmaceutically acceptable phosphate counterion;
• R′ is H or a pharmaceutically acceptable phosphate counterion;
• Rx is H or —C(O)CH3 and may be the same or different in each repeat unit;
• Ry is H or —C(O)CH3 and may be the same or different in each repeat unit;
• wherein at least one of Rx or Ry is —C(O)CH3 in at least one repeat unit, wherein both of Rx and Ry are —C(O)CH3 in at least one same repeat unit;
• and wherein taken together, about 50 to 90% of Rx and Ry in the oligomer is —C(O)CH3;
• Az is an aza substituent selected from the group consisting of —NH(CO)R1, —N(R1)2 and —N3, wherein R1 is independently selected from the group consisting of H, a linear or branched C1-C6-alkyl and a linear or branched C1-C6-haloalkyl;
• Z is (i) a protecting group,
• (ii) a functional linker for conjugation to a protein,
• or (iii) a linear or branched C1-C6 alkyl, optionally substituted phenyl, —C(O) Y, or a linear or branched C1-C6-alkyl-X,
• wherein Y is H, a linear or branched C1-C6-alkyl or a protecting group, and
• wherein X is —NH2, —N3, —C≡CH, —CH═CH2, —SH or —S—C≡N.