53 mg (0.2 mol) of a mixture of 1-(4-chloro-benzoyl)-hexahydroazepine-4,5-dione and 1-(4-chloro-benzoyl)-hexhydroazepine-3,4-dione [prepared from 1-(4-chloro-benzoyl)-hexahydroazepine-4-one by selenium dioxide oxidation in dioxane/water] and 47 gm (0.2 mol) of 2-amino-acetamidine dihydrobromide were dissolved in 700 ml of methanol, and 200 ml of 2N sodium hydroxide were added dropwise to the solution at 5° C. The mixture was stirred at room temperature for one hour, then concentrated by evaporation and then, after addition of more sodium hydroxide, extracted with chloroform. The dried extract solution was concentrated by evaporation and chromatographed on silicagel with ethyl acetate/methanol (10:1) as the mobile phase. The crystals obtained thereby were digested with ethyl acetate and suction-filtered.
