Ketamine derivatives and compositions thereof

A compound of Formula (1):

• or a pharmaceutically acceptable salt thereof, wherein,
• R1 is selected from hydrogen and C1-6 alkyl;
• and
• R2 is selected from a moiety of Formula (2), a moiety of Formula (3), a moiety of Formula (4), and a moiety of Formula (5):
• wherein,
• R3 is selected from hydrogen, C1-6 alkyl, C7-12 alkylarene, and substituted C7-12 alkylarene;
• R4 is selected from hydrogen and C1-6 alkyl;
• R5 is selected from hydrogen, C1-6 alkyl, —C(═O)R10, and —C(═O)—OR10,
• wherein R10 is selected from C1-6 alkyl, C3-6 cycloalkyl, and —CF3;
• R6 is selected from C1-6 alkyl and C1-6 alkoxy;
• n is an integer from 0 to 3;
• R7 is selected from C1-6 alkyl, —C(═O)—R11 and —C(═O)—O—R10,
• wherein,
• R10 is selected from C1-6 alkyl and C3-6 cycloalkyl;
• and
• R11 is selected from —NH2, —CF3, C1-6 alkyl, and C3-6 cycloalkyl;
• and
• R9 is selected from hydrogen and C1-3 alkyl.