1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (0.41 g, 2.14 mmol) was added to a solution of trans-cinnamic acid (0.317 g, 2.14 mmol), 2-(4-aminobutyl)-7-methoxy-1,2,3,4-tetrahydroisoquinoline (0.5 g, 2.14 mmol) and 1-hydroxybenzotriazole (0.1 g, 0.7 mmol) in dichloromethane (8 ml). The mixture was shaken for 18 h, saturated aqueous potassium carbonate (5 ml) added and shaking continued for a further 1 h. The organic layer was chromatographed on silica gel using 10-100% ethyl acetate-hexane gradient elution to afford the title compound as a yellow gum (0.53 g, 68%).
