Selective D3 dopamine receptor agonists and methods of their use

A compound of Formula I

• or a pharmaceutically acceptable salt thereof, wherein:
• W is O or S;
• R1 is pyridyl, or a phenyl which is fused to a 5-membered heterocyclic ring, and
• R2 is a phenyl, a 5 or 6-membered heteroaryl, having 1, 2, 3, or 4 heteroatoms independently chosen from N, O, and S or a 6,5-bicyclic heteroaryl group, having 1, 2, 3, 4, 5, or 6 heteroatoms independently chosen from N, O, and S, wherein the point of attachment in Formula I is in the 5-membered ring, and the 5-membered ring contains at least one heteroatom;
• where
• R1 and R2 are each optionally substituted with 1 or more substituents independently chosen from halogen, hydroxyl, cyano, nitro, oxo, —CONH2, amino, mono- and di-C1-C4alkylcarboxamide, (C3-C6cycloalkyl)C0-C2alkyl, and C1-C6hydrocarbyl, which C1-C6hydrocarbyl group is a hydrocarbon chain in which the carbon atoms are joined by single, double or triple bonds, and any one carbon atom can be replaced by O, NH, or N(C1-C4alkyl) and which hydrocarbyl group is optionally substituted with one or more substituents independently chosen from hydroxyl, oxo, halogen, and amino;
• and
• R3 and R4 are independently hydrogen or methyl.