A chemical compound of formula (I), wherein n is 1, 2 or 3; R1 and R2 are independently selected from hydrogen and alkyl; R3 is alkyl; R4 to R7 are independently selected from hydrogen, halogen, hydroxy, alkyl, aryl, alkoxy, aryloxy, alkylthio, arylthio, alkylsulfoxyl, alkylsulfonyl, arylsulfoxyl, arylsulfonyl, amino, monoalkylamino, dialkylamino, nitro, cyano, carboxaldehyde, alkylcarbonyl, arylcarbonyl, aminocarbonyl, monoalkylaminocarbonyl, dialkylaminocarbonyl, alkoxycarbonylamino, aminocarbonyloxy, monoalkylaminocarbonyloxy, dialkylaminocarbonyloxy, monoalkylaminocarbonylamino and dialkylaminocarbonylamino, or R5 and R6 together form a carbocyclic or heterocyclic ring, and pharmaceutically acceptable salts and prodrugs thereof, and the use thereof in therapy, particularly for the treatment of disorders of the central nervous system; damage to the central nervous system; cardiovascular disorders; gastrointestinal disorders, diabetes insipidus, and sleep apnea, and particularly for the treatment of obesity.