Gacyclidine (GK-11) is a psychoactive drug which acts as a dissociative via functioning as a non-competitive NMDA receptor antagonist. It is closely related to phencyclidine (PCP), and specifically, is a derivative of tenocyclidine (TCP).

The condensation of 2-methylcyclohexanone (I) with 2-thienyl lithium (II) or 2-thienylmagnesium bromide (III) gives cyclohexanol (IV) as a diastereomeric mixture, which was treated with Na-N3 in trichloroacetic acid to yield the azide (V). The reduction of (V) with LiAlH4 or RaNi/iPr-OH affords the corresponding amine (VI), preferentially with the cis-configuration. Finally, this compound is condensed with 1,5-dibromopentane (VII) by means of K2CO3 in acetonitrile to provide the target compound as a diastereomeric mixture.