Hydrogen sulfide precursors and conjugates thereof

A compound according to Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• R1 and R2 are taken together to form C6-C10 aryl, C3-C6 cycloalkyl, 3- to 10-membered heterocyclyl, or 5- to 10-membered heteroaryl, each of which is optionally substituted with 1-3 R4;
• each R1a and R2a, when present, is independently selected from the group consisting of H and C1-6 alkyl;
• each R4 is independently selected from the group consisting of C1-C6 alkyl, C1-C6 alkoxy, C1-C6 haloalkyl, C1-C6 haloalkoxy, C1-C6 aminoalkyl, C1-C6 aminoalkoxy, C1-C6 thioalkyl, C1-C6 thioalkoxy, C3-C6 cycloalkyl, C6-C10 aryl, 6-10 membered heterocyclyl, —C(═O)R5, —C(═O)OR5, —NR5C(═O)OR5, —C(═O)NR5, halo, —CN, —NO2, —N3, and —NHR5;
• L1 and L2 are independently selected from the group consisting of a bond, —(CH2)x—, —SO2—, —CO—, —NR5—, —NR5CO—, and —NR5SO2—, wherein each subscript x is independently 0, 1, 2, 3, or 4;
• R3 is selected from the group consisting of O, S, and NH;
• W is selected from the group consisting of O, S, and NH;
• Z is selected from the group consisting of —C(═O)R6, —R6, —C(═O)OR6, —(CH2)xOR6, —(CH2)xC(═O)OR6, —(CH2)xOC(═O)R6, —(CH2)xOP(═O)(OR6)x, —OP(═O)(OR6)x, —P(═O)(OR6)x, and R7, wherein each subscript x is independently 0, 1, 2, 3, or 4;
• each R8 is independently selected from the group consisting of H, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 haloalkyl, C1-C6 haloalkoxy, C1-C6 aminoalkyl, C1-C6 aminoalkoxy, C1-C6 thioalkyl, C1-C6 thioalkoxy, C3-C6 cycloalkyl, C6-C10 aryl, —C(═O)R5, —C(═O)OR5, —C(═O)NR5, halo, CN, NO2, N3, and —NHR5,
• each R9 is independently selected from the group consisting of C1-C6 alkyl, H, C1-C6 alkoxy, C1-C6 haloalkyl, C1-C6 haloalkoxy, C1-C6 aminoalkyl, C1-C6 aminoalkoxy, C1-C6 thioalkyl, C1-C6 thioalkoxy, C3-C6 cycloalkyl, C6-C10 aryl, —C(═O)R5, —C(═O)OR5, —C(═O)NR5, halo, CN, NO2, N3, and —NHR5,
• wherein one R8 is optionally taken together with one R9 to form a double bond;
• Y is selected from the group consisting of a bond, —S—, —C(O)S—, and —NH—;
• R10 is selected from the group consisting of H, C1-C6 alkyl, C6-C10 aryl, (C6-C10 aryl)-(C1-C6 alkyl), C3-C6 cycloalkyl and 5- to 10-membered heteroaryl, wherein C1-C6 alkyl, C6-C10 aryl, (C6-C10 aryl)-(C1-C6 alkyl), C3-C6 cycloalkyl, and 5- to 10-membered heteroaryl are optionally substituted with 1-5 R10a;
• each R10a is independently selected from the group consisting of C1-C6 alkyl, —C(═O)OR5, —NR5C(═O)OR5, and a moiety —W—Z;
• each R5 is independently selected from the group consisting of H and C1-C4 alkyl;
• each R6 is independently selected from the group consisting of H, C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, and C3-C4 cycloalkyl;
• R7 is a sugar or a drug moiety;
• subscripts a and b are independently 0, 1, 2, or 3;
• each subscript c is 0 when R1 and R2 form aryl or heteroaryl;
• and
• each subscript c is 1 when R1 and R2 form cycloalkyl or heterocyclyl.