This invention concerns compounds of the general formula (1): ##STR00001## and derivatives thereof, which are antagonists of 5-HT.sub.6 receptors, wherein the symbols have the meanings given in the description. The invention also concerns methods for the preparation of these compounds, to novel intermediates useful for their synthesis, and to uses of such compounds and compositions, particularly their use in administering them to patients to achieve a therapeutic effect in treating at least on disease or condition chosen from Parkinson's disease, Huntington's chorea, schizophrenia, anxiety, depression, manic depression, psychoses, epilepsy, obsessive compulsive disorders, mood disorders, migraine, Alzheimer's disease, age related cognitive decline, mild cognitive impairment, sleep disorders, eating disorders, anorexia, bulimia, binge eating disorders, panic attacks, akathisia, attention deficit hyperactivity disorder, attention deficit disorder, withdrawal from abuse of cocaine, ethanol, nicotine or benzodiazepines, pain, disorders associated with spinal trauma or head injury, hydrocephalus, functional bowel disorder, Irritable Bowel Syndrome, obesity and type-2 diabetes.