One aspect of the present invention relates to heterocyclic compounds formula A; whereof the substituents are defined in the description. A second aspect of the present invention relates to the use of the heterocyclic compounds as ligands for various mammalian cellular receptors, including dopamine, serotonin, or norepinephrine transporters. The compounds of the present invention will find use in the treatment of numerous aliments, conditions and diseases which afflict mammals, including but not limited to addiction, anxiety, depression, sexual dysfunction, hypertension, migraine, Alzheimer's disease, obesity, emesis, psychosis, schizophrenia, Parkinson's disease, inflammatory pain, neuropathic pain, Lesche-Nyhane disease, Wilson's disease, and Tourette's syndrome. An additional aspect of the present invention relates to the synthesis of combinatorial libraries of the heterocyclic compounds, and the screening of those libraries for biological activity, e.g., in assays based on dopamine transporters.