Oxygen containing heterocycles as glycine transporter inhibiting compounds

A compound of formula (I) or a salt or solvate thereof:

• wherein:
• R1 is a group selected from:
• and wherein
• Each Z is independently selected from hydrogen, halogen, C3-7cycloalkyl, C1-4alkyl, haloC1-4alkyl, C1-4alkoxyC1-4alkyl, C1-4alkoxy, haloC1-4alkoxy, C1-4alkylthio, haloC1-4alkylthio, C3-7cycloalkylC1-4alkoxy, C1-4alkylsulphoxy, C1-4 alkylsulphonyl, and cyano;
• and each Z′ is independently selected from hydrogen, fluoro or C1-4alkyl;
• R2 is selected from the group consisting of halogen, cyano, C1-4alkoxy, C1-4alkyl, Alkyl, haloC1-4alkoxy, C3-7cycloalkyl, C(O)NR9R10, (where each of R9 and R10 is independently hydrogen or C1-4alkyl, or R9 and R10 together with the nitrogen atom to which they are attached form a 4-, 5-, 6- or 7-membered saturated carbocyclic ring, the 4-, 5-, 6- or 7-membered saturated ring optionally further comprising an additional heteroatom group selected from O, N and S(O)m (where m is 0, 1, or 2)), C3-7cycloalkylC1-4alkoxy, C1-4alkylthio, and haloC1-4alkylthio;
• n is 0, 1 or 2.
• R3 and R4 are independently selected from hydrogen, C1-4alkyl, optionally substituted with one or more groups Y;
• or R3 and R4 together with the nitrogen atom to which they are attached form a saturated or partially unsaturated carbocyclic 4-, 5- 6- or 7-membered ring optionally substituted with a group Y′;
• Y is selected from the group consisting of C1-4alkoxy, hydroxy, haloC1-4alkoxy and C3-5cycloalkyl and C5-10 aryl;
• Y′ is selected from the group consisting of C1-4alkyl, C1-4alkoxy, halogen, hydroxy, haloC1-4alkoxy, C3-5cycloalkyl and C5-10aryl or Y′ forms a —CH2— or —CH2—CH2— bridge between two atoms on the 4-, 5- or 6-membered ring;
• R5 and R6 are independently C1-4alkyl, optionally substituted with one or more groups X;
• or R5 and R6 together with the carbon atom to which they are attached form a saturated 5- or 6-membered carbocyclic ring optionally substituted with one or more groups X′, in the case of R5 and R6 together with the carbon atom to which they are attached forming a 5-membered saturated carbocyclic ring, that ring may optionally further comprise an additional heteroatom group selected from O, N and S(O)m;
• where m=0, 1 or 2.
• X is selected from the group consisting of halogen, hydroxy, C1-4alkoxy, haloC1-4alkyl, haloC1-4alkoxy and C5-10aryl;
• and
• X′ is selected from the group consisting of halogen, hydroxy, C1-4alkoxy, haloC1-4alkyl, haloC1-4alkoxy and C5-10aryl.