To a solution of 4-[3-(6-Bromo-hexyl)-2-(2-ethoxycarbonyl-ethyl)-phenoxy]-butyric acid ethyl ester (5g, 10.60 mmol) in THF (100 mL), thiourea (0.889 g, 11.68 mmol) was added and heated to reflux overnight. According to HPLC analysis, the starting material was completely consumed. Tetraethylenepentamine (4.02 g, 2.7 mL, 21.23 mmol) was added and the reaction mixture was heated to reflux overnight. At this time, the reaction mixture was diluted with EtOAc (500 mL), washed with 3N HCl (100 mL), water brine and dried over Na2SO4. The solvent was removed in vacuo to afford an oil. FCC (2% EtOAc/Hex) provided an oil (3.65 g, yield 81%). 1H NMR (CDCl3): □ 7.09 (t, 1H), 6.75 (d, 1H), 6.69 (d, 1H), 4.18-4.08 (m, 4H), 3.99 (t, 2H), 2.95 (t, 2H), 2.64-2.46 (m, 8H), 2.13 (m, 2H), 1.67-1.39 (m, 8H), 1.27 (m, 6H).
