The present invention relates to novel compounds of formula (I) or a pharmaceutically acceptable salt thereof: [chemical expression included] wherein G is selected from a group consisting of: phenyl, pyridyl, benzothiazolyl and indazolyl; p is an integer ranging from 0 to 5; R1 is independently selected from a group consisting of: halogen, hydroxy, cyano, C1-4alkyl, haloC1-4alkyl, C1-4alkoxy, haloC1-4alkoxy, C1-4alkanoyl and SF5; or corresponds to a group R5; each R2 is independently hydrogen or C1-4alkyl; n is 2, 3, 4 or 5; R3 is C1-4alkyl; R4 is hydrogen, or a phenyl group, a heterocyclyl group, a 5- or 6-membered heteroaromatic group, or a 8- to 11-membered bicyclic group, any of which groups is optionally substituted by 1, 2, 3 or 4 substituents selected from the group consisting of: halogen, cyano, C1-4alkyl, haloC1-4alkyl, C1-4alkoxy, C1-4alkanoyl and SF5; R5 is selected from a group consisting of: isoxazolyl, —CH2—N-pyrrolyl, 1,1-dioxido-2-isothiazolidinyl, thienyl, thiazolyl, pyridyl and 2-pyrrolidinonyl, and such a group is optionally substituted by one or two substituents selected from a group consisting of: halogen, cyano, C1-4alkyl, haloC1-4alkyl, C1-4alkoxy and C1-4alkanoyl; and when R1 corresponds to R5, p is 1; processes for their preparation, intermediates used in these processes, pharmaceutical compositions containing them and their use in therapy, as modulators of dopamine D3 receptors, e.g. to treat drug dependency, as antipsychotic agents, to treat obsessive compulsive spectrum disorders, premature ejaculation or cognition impairment.