Thienyl compounds for the treatment of a central nervous system disease or disorder

A compound of Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• X is S, Y is CR5, and Z is CR6;
• or X is CR4, Y is S, and Z is CR6;
• or X is CR4, Y is CR5, and Z is S;
• A is chosen from a single bond, —CH2—, —O—, —CH2—CH2—, and —CH═CH—;
• R1 is chosen from H, methyl, and ethyl, and R2 is chosen from H, C1-C3 alkyl optionally substituted by one C3-C5 saturated cycloalkyl, 3-5 membered saturated heterocycloalkyl, and C3-C5 saturated cycloalkyl optionally substituted by one or more halogen, or R1 and R2, taken together with the intervening nitrogen atom, form a 3-7 membered saturated heterocyclic ring;
• R3 is H or C1-C3 alkyl;
• R4, R5, and R6 are independently chosen from H, C1-C4 alkyl optionally substituted by one NR10R11, C1-C4 haloalkyl, halogen, CN, phenyl, and C3-C5 saturated cycloalkyl;
• and
• R10 and R11 are independently chosen from H and C1-C4 alkyl;
• provided that:
• a) R2 is H only if R1 is H;
• b) if A is —CH2—, X is S, and R1, R2, R3 and R5 are H, then R6 is not H, methyl, CN, cyclopentyl, isobutyl, t-butyl, phenyl, CF3, or CH2CH2N(CH3)2;
• c) if A is —CH2—, Y is S, and R1, R2, R3 and R6 are H, then R4 is not H or Br;
• d) if A is —CH2—, Z is S, and R1, R2, R3 and R4 are H, then R5 is not H, CN, Cl, or Br;
• e) if A is —CH2—, Z is S, and R1, R3 and R4 are H, and R5 is H, Cl, or Br, then R2 is not methyl;
• and
• f) the compound of Formula I is not