Tetrahydropyridopyrazines modulators of gpr6

The compound of formula I

• wherein
• R1 is selected from the group consisting of optionally substituted C3-8 cycloalkyl, optionally substituted C3-6 heterocyclyl, optionally substituted C6-10 aryl, and optionally substituted C1-10 heteroaryl;
• X1 is N and X2 is CH;
• or
• X1 is CH and X2 is N;
• or
• X1 is N and X2 is N;
• when X1 is N, Z is selected from the group consisting of C1-6 alkylene, C1-6 haloalkylene, —C(O)—, and —S(O)2—;
• when X1 is CH, Z is selected from the group consisting of C1-6 alkylene, C1-6 haloalkylene, —O—, —C(O)—, —NH—, —S—, —S(O)—, and —S(O)2—;
• q is 0, 1, or 2;
• s is 0, 1, or 2;
• R2 is —OR5 or —NR6R7;
• R3, each time taken, is independently selected from the group consisting of C1-6 alkyl, C3-8 cycloalkyl, and trifluoromethyl;
• p is 0, 1, or 2;
• R4, each time taken, is independently selected from the group consisting of C1-6 alkyl, hydroxy, and halo;
• r is 0 or 1;
• R5 is selected from the group consisting of C1-6 alkyl and C3-8 cycloalkyl;
• R6 is selected from the group consisting of hydrogen and C1-6 alkyl;
• R7 is selected from the group consisting of optionally substituted C1-6 alkyl, C3-8 cycloalkyl, optionally substituted C6-10 aryl, optionally substituted C1-10 heteroaryl, and optionally substituted C3-6 heterocyclyl;
• X3 is selected from the group consisting of CH and CR4 and X4 is NR8;
• or
• X3 is NR8 and X4 is selected from the group consisting of CH and CR4;
• R8 is selected from the group consisting of C1-6 alkyl, C1-6 haloalkyl, C3-8 cycloalkyl, —S(O)2—R9, —C(O)—R10, —C(O)—N(R11)(R12), and —C(O)—OR13;
• R9 is selected from the group consisting of C1-6 alkyl, C3-8 cycloalkyl, and optionally substituted phenyl;
• R10 is selected from the group consisting of hydrogen, optionally substituted C1-6 alkyl, C3-8 cycloalkyl, optionally substituted C6-10 aryl, optionally substituted C1-10 heteroaryl, and optionally substituted C3-6 heterocyclyl;
• R11 is selected from the group consisting of hydrogen and C1-6 alkyl;
• R12 is selected from the group consisting of hydrogen, C1-6 alkyl and C3-8 cycloalkyl;
• or
• R11 and R12 are taken together with the nitrogen to which they are attached form a 4 to 7 membered, saturated, ring optionally having 1 additional ring heteroatom selected from the group N, O, and S and optionally substituted on any of the ring carbon atoms with 1 to 5 substituents independently selected from the group consisting of cyano, halo, hydroxy, amino, optionally substituted C3-6 heterocyclyl, C1-9 amide, optionally substituted C1-6 alkyl, and C1-4 alkoxy and substituted on any additional ring nitrogen by a substituent selected from the group consisting of hydrogen, C3-8 cycloalkyl, and optionally substituted C1-6 alkyl;
• R13 is selected from the group consisting of C1-6 alkyl and C3-8 cycloalkyl;
• or a pharmaceutically acceptable salt thereof.