Abstract New spiro[3 H ‐2‐benzazepine‐3,4′‐piperidines] and their precursors, N ‐substituted 4‐allyl‐4‐ N ‐benzyl‐aminopiperidines, have been prepared as potential psychotic agents from readily available 4‐iminopiperidines, by a sequence of reactions that included nucleophilic addition of Grignard reagents and Bronsted acid‐mediated intramolecular cyclisation. Some of the compounds prepared have been tested in albine mice for spontaneous motor activity. All compounds prepared were characterized by ir and 1 H nmr spectroscopies and cg‐ms spectrometry.