Negative allosteric modulators of metabotropic glutamate receptor 2

A compound of formula (I), or a pharmaceutically acceptable salt thereof,

• wherein:
• L1 is a C1-6alkylene or C1-6fluoroalkylene, wherein optionally 1 or 2 methylene groups in the alkylene or fluoroalkylene of L1 are independently replaced with —O—, —S—, —SO—, —SO2—, —C(O)—, or —N(R)—, wherein 2 methylene groups replaced with —O—, —S—, —SO—, —SO2—, or —N(R)— are separated by two or more carbon atoms in the alkylene or fluoroalkylene;
• and/or optionally 1 methylene group in the alkylene or fluoroalkylene of L1 is replaced with -Cy-;
• Cy is a C3-6cycloalkylene or a 4- to 6-membered heterocyclylene, wherein Cy is optionally substituted with 1-6 substituents independently selected from the group consisting of C1-C4alkyl, C1-2fluoroalkyl, and halogen;
• R, at each occurrence, is independently hydrogen or C1-4alkyl;
• R1, at each occurrence, is independently hydrogen, fluorine, or C1-4alkyl;
• R2 is hydrogen or C1-6alkyl;
• R3 is a 6- to 12-membered aryl or 5- to 12-membered heteroaryl, wherein R3 is unsubstituted or substituted with 1, 2, 3, or 4 substituents independently selected from the group consisting of C1-4alkyl, halogen, cyano, C1-2haloalkyl, —OC1-4alkyl, —OC1-2haloalkyl, and G;
• G3 is a 5-membered heteroaryl containing 1-3 heteroatoms that are independently S, O, or N or a 4- to 6-membered heterocyclyl containing 1-2 heteroatoms that are independently S, O, or N;
• R1 is a 6- to 12-membered aryl or 5- to 12-membered heteroaryl, wherein R is unsubstituted or substituted with 1, 2, 3, or 4 substituents independently selected from the group consisting of C1-4alkyl, halogen, cyano, C1-2haloalkyl, —OC1-4alkyl, and —OC1-2haloalkyl;
• and
• R5 and R6 are each independently hydrogen, C1-4alkyl, halogen, cyano, C1-2haloalkyl, —OC1-4alkyl, or —OC1-2haloalkyl.