Abstract: In order to investigate the relationships between the conformations of tricyclic hydroxycarboxylates and their anticholinergic activities, and to explore the effects of changing the linking groups between the two benzene rings in tricyclic compounds on anticholinergic activities and on the selectivity to the central nicotinic receptor, a series of new tricyclic anticholinergic compounds-dibenzo[b,e]oxepin (thiepin) hydroxycarboxylates (Fig. 1) were designed and synthesized.