To a solution of 1-[5-(1-piperazinylcarbonylamino)-indole-2-carbonyl]-4-[3-(1-methylethylamino)-2-pyridinyl]piperazine (EXAMPLE 46, 0.41 g) in methanol (50 ml) is added sodium cyanoborohydride (53 mg) and acetone (1 ml). Additional sodium cyanoborohydride (44.3 mg total) and excess acetone are added in portions until the reaction is complete as judged by TLC on silica gel. The mixture is acidified with acetic acid, neutralized with 50% aqueous sodium hydroxide and concentrated. The residue is dissolved in methylene chloride, washed with water, saturated potassium carbonate solution, and saline and dried over sodium sulfate followed by concentration. The resulting material is purified by chromatography on silica gel (100 ml) packed in methanol/chloroform (1/99) and eluted with a methanol/chloroform gradient (1→5%) to give the title compound, NMR (chloroform-d) 9.14, 7.71, 7.33, 7.17, 6.95, 6.86, 6.74, 4.06, 3.58, 3.20, 2.78, 2.60, 1.27, 1.08 δ.
