A mixture of -[(E)-3-(4-Chloro-phenyl)-allyl]-4-[1-methoxy-meth-(Z)-ylidene]-perhydro-azepine (0.6 g) and 4-chlorophenylhydrazine hydrochloride (0.41 g) in chloroform (20 ml) was treated with trifluoroacetic acid (2.1 ml) and heated at reflux under argon for 18 hours. The reaction mixture was cooled to room temperature, triethylsilane (3.1 ml) was added and the solution refluxed for 2 hours. The reaction mixture was cooled to room temperature, diluted with dichloromethane, neutralised with 30% aqueous ammonium hydroxide, washed with brine, dried (sodium sulphate) and concentrated. The dark residue was purified by silica gel chromatography (cyclohexane:ethyl acetate 1:9) to afford 5-chloro-1′-[trans-3-(4-chlorophenyl)allyl]spiro[perhydro-azepine-3,3′-piperidine] (529 mg). MS (ES+) 387/389 (M+H′).
