Positive allosteric modulators of the muscarinic acetylcholine receptor m4

A compound of formula (I),

• or a pharmaceutically acceptable salt thereof, wherein:
• X is N or CR5;
• R5 is selected from hydrogen, halo, and cyano;
• R1 is selected from C1-C4-alkyl, C3-C6-cycloalkyl, hydrogen, halo, —ORa, and —NRbRc;
• R2 and R3 are each independently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, heteroalkyl, heterocycle, and —(CReRf)n—Y;
• or R2 and R3 are taken together with the nitrogen atom to which they are attached to form a heterocyclic ring;
• Y is selected from halo, —OR, —SR, —C(O)R, —C(O)OR, —S(O)R, —SO2R, —NR2, —C(O)NR2, —S(O)2NR2, aryl, heteroaryl, cycloalkyl, and heterocycle;
• n is 1, 2, 3, 4, 5, 6, 7, or 8;
• each Ra, Rb, and Rc is independently selected from hydrogen, C1-C4-alkyl, C1-C4-haloalkyl, aryl, heteroaryl, cycloalkyl, and heterocycle;
• each Re and Rf is independently selected from hydrogen, C1-C4-alkyl, C1-C4-haloalkyl, and halo;
• and
• each R is independently selected from hydrogen, alkyl, aryl, arylalkyl, cycloalkyl, cycloalkylalkyl, heterocycle, heterocyclealkyl, heteroaryl, heteroarylalkyl, and heteroalkyl;
• wherein each aryl, cycloalkyl, heterocycle, and heteroaryl is independently unsubstituted or substituted with 1, 2, or 3 substituents.