Abstract: There are disclosed various compounds of the formula below, ##STR1## where n, X and R.sub.1 through R.sub.4 are as defined in the specification, which are useful for alleviating various memory dysfunctions characterized by a cholinergic deficit such as Alzheimer's disease.Compounds of this invention also inhibit monoamine oxidase and/or act at central .alpha..sub.2 -adrenergic receptors, and hence are useful as antidepressants.