Abstract: Compounds of formula I ##STR1## and pharmaceutically acceptable salts thereof in which A is methylene or --O--; B is methylene or --O--; and g is 0, 1, 2, 3 or 4;R.sub.1, R.sub.2, R.sub.3, R.sub.4, U, Q and T are defined in claim 1.The compounds have utility in the treatment of central nervous system disorders, for example depression, anxiety, psychoses (for example schizophrenia), tardive dyskinesia, Parkinson's disease, obesity, hypertension, Tourette's syndrome, sexual dysfunction, drug addiction, drug abuse, cognitive disorders, Alzheimer's disease, senile dementia, obsessive-compulsive behaviour, panic attacks, eating disorders and anorexia, cardiovascular and cerebrovascular disorders, non-insulin dependent diabetes mellitus, hyperglycaemia, constipation, arrhythmia, disorders of the neuroendocrine system, stress, prostatic hypertrophy, and spasticity.