The present invention relates to novel compounds of formula (I) or a pharmaceutically acceptable salt thereof: wherein G is selected from a group consisting of: phenyl, pyridyl, benzothiazolyl, 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; R2 is hydrogen or C1-4alkyl; R3 is C1-4alkyl; R4 is C1-4 alkyl or C1-6 cycloalkyl optionally substituted by 1 or 2 substituents selected from the group consisting of: halogen, cyano, C1-4alkyl, haloC1-4alkyl, C1-4alkoxy, C1-4alkanoyl; R5 is a moiety selected from the group consisting of: isoxazolyl, —CH2—N-pyrrolyl, 1,1-dioxido-2-isothiazolidinyl, thienyl, thiazolyl, pyridyl, 2-pyrrolidinonyl, and such a group is optionally substituted by one or two substituents selected from: halogen, cyano, C1-4alkyl, haloC1-4alkyl, C1-4alkoxy, C1-4alkanoyl; processes for their preparation, intermediates used in these processes, pharmaceutical compositions containing them and their use in therapy, as modulators of dopamine D3 receptors, as antipsychotic agents, or to treat obsessive compulsive spectrum disorders or premature ejaculation.