Prodrugs of 6-diazo-5-oxo-l-norleucine

A compound of Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• R1 is selected from the group consisting of —OR2 and —NR3aR3b;
• R2 is selected from the group consisting of hydrogen, C1-C6 alkyl, C1-C6 haloalkyl C1-C6 alkenyl, C3-C20 heteroalkyl, and C3-C6 cycloalkyl;
• R3a and R3b are independently selected from the group consisting of hydrogen and C1-C4 alkyl;
• or
• R3a and R3b taken together with the nitrogen atom to which they are attached from a 4- to 8-membered heterocyclo;
• R4 is selected from the group consisting of C1-C6 alkyl, C1-C6 haloalkyl, (amino)C1-C6 alkyl, (amino)(aryl)C1-C6 alkyl, optionally substituted heteroaryl, —CH(R5a)N(R6a)C(═O)R7a, —(CH2)m—N(R6c)C(═O)R7c, and —OR8;
• R5a is selected from the group consisting of hydrogen, optionally substituted C1-C6 alkyl, optionally substituted aryl, (heterocyclo)C1-C4 alkyl, (aryl)C1-C4 alkyl, and (heteroaryl)C1-C4 alkyl;
• R6a is selected from the group consisting of hydrogen and C1-C4 alkyl;
• R7a is selected from the group consisting of C1-C6 alkyl, C1-C6 haloalkyl, optionally substituted C3-C8 cycloalkyl, optionally substituted 4- to 10-membered heterocyclo, optionally substituted heteroaryl, (amino)C1-C4 alkyl, (heterocyclo)C1-C4 alkyl, and —CH(R5b)N(R6b)C(═O)R7b,
• R8 is optionally substituted 4- to 10-membered heterocyclo;
• R5b is selected from the group consisting of hydrogen, optionally substituted C1-C6 alkyl, (aryl)C1-C4 alkyl, and (heteroaryl)C1-C4 alkyl,
• R6b is selected from the group consisting of hydrogen and C1-C4 alkyl;
• R7b is selected from the group consisting of C1-C6 alkyl, C1-C6 haloalkyl, optionally substituted C3-C8 cycloalkyl, optionally substituted 4- to 10-membered heterocyclo, optionally substituted heteroaryl, (amino)C1-C4 alkyl, and (heterocyclo)C1-C4 alkyl;
• R6c is selected from the group consisting of hydrogen and C1-C4 alkyl;
• R7c is selected from the group consisting of C1-C6 alkyl, C1-C6 haloalkyl, optionally substituted C3-C8 cycloalkyl, optionally substituted 4- to 10-membered heterocyclo, optionally substituted heteroaryl, (amino)C1-C4 alkyl, and (heterocyclo)C1-C4 alkyl;
• and
• m is 2, 3, 4, or 5,
• with the proviso that the compound of Formula I is not a compound of Table 1.