Used as a key intermediate in the synthesis of antidepressant pharmaceuticals, particularly tricyclic antidepressants like imipramine and related analogs. Its aldehyde functional group allows for condensation reactions to form imines or undergo reduction to produce amine derivatives essential for biological activity. Commonly employed in medicinal chemistry for constructing the tricyclic core structure with a seven-membered ring bearing a nitrogen atom. Also utilized in research settings to develop novel psychoactive agents and study structure-activity relationships in central nervous system drugs.