4-(2-Aminoethyl)benzenesulfonamide → 3'-[{2-[4-(aminosulfonyl)phenyl]ethyl}aminomethyl]-N-[2-(1-pyrrolidinyl)ethyl][1,1'-biphenyl]-3-carboxamide

4-(2-Aminoethyl)benzene sulfonamide (2.37 g) and molecular sieves 3A (4.0 g) were added to a solution of 3′-formyl-N-[2-(1-pyrrolidinyl)ethyl][1,1′-biphenyl]-3-carboxamide (3.81 g) in methanol (50 ml), and the mixture was stirred at room temperature for 1.5 hours. After the reaction mixture was diluted with tetrahydrofuran (THF), the molecular sieves were filtered off, and the filtrate was concentrated under reduced pressure. The residues were dissolved in a mixed solvent (100 ml) of methanol-THF (1:1), and sodium borohydride (0.89 g) was added thereto. The reaction mixture was stirred at room temperature for 5 hours, and then the solvent was evaporated under reduced pressure. The residues were diluted with water and extracted with ethyl acetate. The extract was washed with brine and then dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The residues were crystallized from hexane, whereby the title compound (3.71 g) was obtained.