5-(2-chloroethylidene)-10,11-dihydro-5H-dibenzo[a,d][7]annulene

5-(2-Chloroethylidene)-10,11-dihydro-5H-Dibenzo[a,d]cycloheptene is used as a regeant in the synthesis of [(dihydrodibenzocyclohepthylidene)ethyl]piperazine derivatives which exhibit vasodilatory activity similar to common drugs such as cinnarizine and flunarizine. It may also be used in the preparation of N-(dihydrodibenzocycloheptenylideneethyl)ephedrines which are anti-ulcer agents.