A mixture of 2-bromo-2-(4-chlorophenyl)1-[1-(3,4-dichlorophenyl)cyclobutyl]ethanone (3.68 g), imidazolidine-2-thione (0.87 g), ethanol (60 ml) and acetic acid (35 ml) was heated under reflux for 18 hours then allowed to cool to ambient temperature. The solvents were removed in vacuo and the residue was triturated with ethanol (30 ml). The resulting solid was collected by filtration and crystallised from acetic acid. The resulting product was collected by filtration, washed with acetic acid (10 ml) and dried in vacuo at 100° C. to give 2-(4-chlorophenyl)-3-[1-(3,4-dichlorophenyl)cyclobutyl]-5,6-dihydroimidazo[2,1-b]thiazole hydrobromide as a colourless solid (0.93 g), m.p. 302-304° C. (decomposes).
