A solution of 2.08 g (9.06 mmol) of 3-(benzylmethylamino)propionic acid, 2.72 g (8.96 mmol) of tert.-butyl 2-[4-(2-methylaminoethyl)phenyl]-4,5-dihydroimidazole-1-carboxylate (see procedure 1 g), 5.05 ml (36.24 mmol) of triethylamine and 2.91 g (9.06 mmol) of TBTU in 350 ml of tetrahydrofuran was stirred at room temperature overnight. The mixture was then evaporated to dryness, and the residue was purified by column chromatography (mobile phase: dichloromethane/methanol/aqueous ammonia solution 9:1:0.1).
