Prodrugs of phosphonamide nucleotide analogues and their pharmaceutical use

A compound of formula (I):

• or a pharmaceutically acceptable salt thereof, wherein
• R1 and R2 are independently chosen from C1-12alkyl, aryl-C1-4alkylene, C3-7cycloalkyl, C3-7cycloalkyl-C1-4alkylene, aryl-C3-7cycloalkylene, C7-12spirocycloalkyl, C7-12spirocycloalkyl-C1-4alkylene, bridged C5-10bicycloalkyl, bridged C5-10bicycloalkyl-C1-4alkylene, fused C5-10bicycloalkyl, C10-16dispirocycloalkyl, C10-16dispirocycloalkyl-C1-4alkylene, bridged C9-12tricycloalkyl, bridged C9-12tricycloalkyl-C1-4alkylene, C3-7cycloalkyl-C3-7cycloalkylene, and 5- to 7-membered monocyclic heterocyclyl having from 1 to 3 heteroatoms chosen from N, O, and S, wherein each C1-12alkyl, aryl-C1-4alkylene, C3-7cycloalkyl, C3-7cycloalkyl-C1-4alkylene, aryl-C3-7cycloalkylene, C7-12spirocycloalkyl, and C7-12spirocycloalkyl-C1-4alkylene is optionally substituted with from one to three Ra;
• R3, R4, R5, and R6 are independently chosen from C1-4alkyl, C3-6cycloalkyl, and aryl-C1-4alkylene, wherein each C1-4alkyl, C3-6cycloalkyl, and aryl-C1-4alkylene is optionally substituted with from one to three Rb;
• or optionally:
• R3 and R4 together with the carbon atom to which they are attached form a 3- to 6-membered saturated or partially unsaturated carbocyclic ring optionally substituted with from one to three Rb;
• and R5 and R6 are independently chosen from C1-4alkyl, C3-6cycloalkyl, and aryl-C1-4alkylene, wherein each C1-4alkyl, C3-6cycloalkyl, and aryl-C1-4alkylene is optionally substituted with from one to three Rb;
• or
• R3 and R4 are independently chosen from C1-4alkyl, C3-6cycloalkyl, and aryl-C1-4alkylene, wherein each C1-4alkyl, C3-6cycloalkyl, and aryl-C1-4alkylene is optionally substituted with from one to three Rb;
• and R5 and R6 together with the carbon atom to which they are attached form a 3- to 6-membered saturated or partially unsaturated carbocyclic ring optionally substituted with from one to three Rb;
• or
• R3 and R4 together with the carbon atom to which they are attached form a 3- to 6-membered saturated or partially unsaturated carbocyclic ring optionally substituted with from one to three Rb;
• and R5 and R6 together with the carbon atom to which they are attached form a 3- to 6-membered saturated or partially unsaturated carbocyclic ring optionally substituted with from one to three Rb;
• B is
• R7 is hydrogen or R8;
• R8 is -L1-(L2)m-(L3)n-R8a;
• L1 is chosen from a bond, —C(O)—, and —C(O)O—;
• L2 is C1-6alkylene;
• L3 is —C(O)O— or
• R8a is chosen from C1-12alkyl, aryl, —C(O)-aryl, —C(O)—C1-4alkyl, —S—C(O)—C1-4alkyl,
• wherein aryl and —C(O)-aryl are optionally substituted with one or two Rc;
• each Ra is independently chosen from C1-4alkyl, halo, C1-4haloalkyl, and —O—C1-4alkyl;
• each Rb is independently C1-4alkyl;
• each Rc is independently C1-4alkyl or —OC(O)—C1-4alkyl;
• m and n are independently 0 or 1;
• and
• p is 0, 1, or 2.