The present invention relates a method for treating depression, anxiety disorders, bipolar disorder, attention deficit hyperactivity disorder, stress-related disorders, psychotic disorders such as schizophrenia, neurological diseases such as Parkinson's disease, neurodegenerative disorders such as Alzheimer's disease, epilepsy, migraine, hypertension, substance abuse and metabolic disorders such as eating disorders, diabetes, diabetic complications, obesity, dyslipidemia, disorders of energy consumption and assimilation, disorders and malfunction of body temperature homeostasis, disorders of sleep and circadian rhythm, and cardiovascular disorders which comprises administering to an individual a therapeutically effective amount of a compound of formula I wherein R, R1, R2, A and n are as defined in the specification and to their pharmaceutically active salts. The invention also relates to novel compounds of formula I, pharmaceutical compositions containing them, and methods for their preparation.