N-Di-, trialkoxybenzylisoquinuclidines and related compounds were synthesized and evaluated for expectorant activities. Structure-activity relationship investigations in this series showed that both the trialkoxyphenyl ring and the basic nitrogen atom at the benzylic position were necessary for activity. N-Trialkoxybenzylisoquinuclidines 7a, 7c, 7d, 7f and 7g significantly increased bronchial secretion, and ethoxy derivative 7c showed the highest ...