Toll-like receptor 7 (tlr7) agonists having a pyridine or pyrazine moiety, conjugates thereof, and methods and uses therefor

A compound having a structure according to formula (I)

• wherein
• Ar is
• R1— is (C1-C5 alkyl)O, (C1-C2 alkyl)O(CH2)2-3O, (C1-C5 alkyl)C(═O)O, (C1-C5 alkyl)NH, (C1-C2 alkyl)O(CH2)2-3NH, or (C1-C5 alkyl)C(═O)NH;
• R2 is, independently for each occurrence thereof, H, C1-C3 alkyl, halo, O(C1-C3 alkyl), CN, or NO2;
• and
• R3 and R4 are independently H;
• C1-C6 alkyl;
• (CH2)2-4OH;
• (CH2)2-4O(C1-C3 alkyl);
• (CH2)2-4NH2;
• (CH2)2-4NH(C1-C3 alkyl);
• (CH2)2-4N(C1-C3 alkyl)2;
• (CH2)1-3(aryl);
• (CH2)1-3(heteroaryl);
• (CH2)2-4(OCH2CH2)2-8(CH2)2-4NHBoc;
• wherein a CH2 group in the cycloaliphatic ring may be replaced by O, S, NH, or N(C1-C3 alkyl) and the cycloaliphatic ring may be substituted with C1-C3 alkyl, OH, O(C1-C3 alkyl), halo, (CH2)0-3NH2, or (CH2)0-3NH(C1-C3 alkyl);
• or R3 and R4 combine with the nitrogen to which they are bonded to form a cyclic amine of the structure
• wherein a CH2 group in the cycloaliphatic ring that is separated from the amine nitrogen by at least two CH2 groups may be replaced by O, S, NH, or N(C1-C3 alkyl) and the cyclic amine may be substituted with C1-C3 alkyl, OH, O(C1-C3 alkyl), halo, (CH2)0-3NH2, or (CH2)0-3NH(C1-C3 alkyl).