Substituted oxadiazolidinediones

A compound of the formula:

• or a pharmaceutically acceptable salt or ester form thereof,
• wherein:
• R1 is hydrogen, halogen, C1-C6 alkyl, C3-C8 cycloalkyl, C6-C10 aryl, or (C6-C10)aryl(C1-C6)alkyl;
• R2 is hydrogen, halogen, C1-C6 alkyl, C3-C8 cycloalkyl, C6-C10 aryl, C4-C10heteroaryl, (C6-C10)aryl(C1-C6)alkyl, or (C4-C10)heteroaryl(C1-C6)alkyl;
• R3 and R4 are independently hydrogen, C1-C6 alkyl, or C3-C8 cycloalkyl;
• X is O, S, or NR5;
• R5 is hydrogen, C1-C6 alkyl, C3-C8 cycloalkyl, C6-C10 aryl, or arylalkyl;
• and
• n is an integer of 1 to 3,
• wherein said alkyl, whether used alone or as part of another group, is unsubstituted or substituted with halogen, cyano, nitro, oxo, hydroxy, acyloxy, C1-C6 alkoxy, perhalo-(C1-C6)alkoxy, amino, amino substituted by one or two C1-C6 alkyl groups, aminoacyl, acylamino, thio(C1-C6)alkoxy, or trihalomethyl;
• wherein said aryl, whether used alone or as part of another group, is unsubstituted or substituted with from 1 to 5 substituents selected from acyloxy, hydroxy, acyl, C1-C6 alkyl, C1-C6 alkoxy, C2-C6 alkenyl, C2-C6 alkynyl, alkyl, perhalo-C1-C6 alkoxy, amino, amino substituted by one or two C1-C6 alkyl groups, aminoacyl, acylamino, azido, cyano, halo, nitro, thio(C1-C6)alkoxy, or trihalomethyl;
• and
• wherein said heteroaryl, whether used alone or as part of another group, is unsubstituted or substituted with from 1 to 5 substituents selected from acyloxy, hydroxy, acyl, C1-C6 alkyl, C1-C6 alkoxy, C2-C6 alkenyl, C2-C6 alkynyl, amino, amino substituted by one or two C1-C6 alkyl groups, aminoacyl, aclyamino, azido, cyano, halo, nitro, thio(C1-C6)alkoxy, or trihalomethyl.