Prodrugs of glutamine analogs

A compound having formula (I):

• or a pharmaceutically acceptable salt thereof, wherein:
• X is —(CH2)n—, wherein n is an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8;
• R1 is selected from the group consisting of H, C1-6 alkyl, substituted C1-6 alkyl, C3-C10 cycloalkyl, substituted C3-C10 cycloalkyl, C1-C6 alkenyl, and substituted C1-C6 alkenyl;
• R2 is selected from the group consisting of —C(═O)—Ar, —C(═O)—Y—(CR3R4)m—Ar, —C(═O)—Y—(CR3R4)m—NR5R6, —P(═O)(OR7)(NHR9)o, —C(═O)—Y—(CR3R4)m—Ar—O—C(═O)—R8, —C(═O)—Y—(CR3R4)—Ar—O—R8, —C(═O)—O—R9, —C(═O)—Y—(CR3R4)m—Ar—O—C(═O)—Ar, and —C(═O)—Y—(CR3R4)m—Ar—NR5R6;
• Y is —O— or a bond;
• m is an integer selected from the group consisting of 0, 1, 2, 3, 4, 5, 6, 7, and 8;
• each n and o is an integer from 0 to 2 provided that the sum of n and o is 2;
• each R3 and R4 is independently H, C1-C6 alkyl or substituted C1-C6 alkyl, aryl or substituted aryl, —(CR3R4)m—NR5R6, or
• each R5 and R6 is independently H, alkyl, —C(═O)—(CR3R4)mH, —C(═O)—(NR5R6), or —C(═O)—(CR3R4)m—NR5R6;
• each R7 is independently selected from the group consisting of H, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heterocyclyl, substituted heterocyclyl, alkenyl, substituted alkenyl, cycloalkenyl, substituted cycloalkenyl, —(CR3R4)m—Z, and —(CR3R4)m-Q-Z;
• Q is a monosaccharide, aryl, substituted aryl, heteroaryl, or substituted heteroaryl;
• Z is
• or R7 together with the oxygen atom to which it is attached forms a purine or pyrimidine nucleoside;
• each R9 is independently selected from the group consisting of H, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heterocyclyl, substituted heterocyclyl, alkenyl, substituted alkenyl, cycloalkenyl, substituted cycloalkenyl, —(CR3R4)m—Z, aryl, substituted aryl, heteroaryl, substituted heteroaryl, and
• provided that R1 is not H;
• each R8 is independently alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, monosaccharide, acylated monosaccharide, aryl, substituted aryl, heteroaryl, substituted heteroaryl;
• and
• Ar is aryl, substituted aryl, heteroaryl, or substituted heteroaryl
• R2′ is selected from the group consisting of H, C1-C6 alkyl, and substituted C1-C6 alkyl.