2.50 g of trifluoromethanesulfonic anhydride in 330 ml of dichloromethane were treated at 0° C. under a nitrogen atmosphere with a suspension of 1.87 g of the pyrroledione product of Example 1 and 0.94 g of collidine in 280 ml of dichloromethane. After 2.5 hours, the mixture was allowed to warm to 10° C. Then, 37 ml of 33% aqueous ammonia were added and the mixture was allowed to warm to room temperature overnight. The mixture was washed with water, dried and evaporated. The residue was subjected to chromatography on silica gel with dichloromethane/methanol/acetic acid/water (90:18:3:2). The combined product-containing fractions were treated with 2M hydrochloric acid and evaporated to give 930 mg of 3-[8-(aminomethyl)-6,7,8,9-tetrahydropyrido[1,2-a]indol-10-yl]-4-(1-methyl-3-indolyl)-1H-pyrrole-2,5-dione hydrochloride of melting point 310°-313° C.
