5-Ethylidene-10,11-dihydro-5H-dibenzo[a,d]cycloheptene is an intermediate in the synthesis of Amitriptyline N-Oxide-d6 (A633357), which is an isotope analog of Amitriptyline N-Oxide (A633355). Amitriptyline N-oxide is used in biological studies to metabolize drugs by fungi colonizing cadavers using LC-ESI-MS/MS and GC-MS. This compound is also used in the development of antidepressant drugs.