The preparation of a series of novel tricyclic ketones-heterocyclic analogs of dibenzosuberone-is described. These compounds served as intermediates toward analogs of the amitriptyline type in which an oxazole, thiazole, or imidazole ring was substituted for one of the benzene moieties. The oxazole and thiazole analogs of amitriptyline were highly potent CNS depressant drugs. This CNS depressant spectrum could be shifted toward an ...