0.28 g of 5,6,7,8-tetrahydro-2-phenyl-3-formylimidazo[2,1-b]benzothiazole and 0.15 g of benzohydrazide were stirred over night in 20 ml of a 0.1N hydrochloric acid-ethanol solution at room temperature and the precipitated crystal obtained by filtration. The crystals were dissolved in water and the solution was made alkaline by ammonia solution, then extracted by chloroform. The extract was washed with water and dried, then the solvent was distilled off and the residue was crystallized from ethyl acetate to obtain the desired substance in an amount of 0.35 g (yield of 84.0%).
