1H NMR (400 MHz, CDCl3) δ6.94 (d, 2H), 6.61 (d, 2H), 5.35 (s, 1H), 3.57 (s, 2H), 3.43 (m, 2H), 2.66 (t, 3H), 2.07 (t, 2H), 1.55 (m, 3H), 1.24 (m, 5H), 0.84 (t, 3H). A mixture of heptanoic acid [2-(4-amino-phenyl)-ethyl]-amide (1.50 g, 6.04 mmol), cesium carbonate (7.87 g, 24.2 mmol), tert butyl-2-bromoisobutyrate (10.78 g, 48.3 mmol) and dimethylformamide (14.6 mL) was heated at 80° C. for 4 days. The reaction mixture was cooled to ambient temperature, diluted with water and extracted with ether (2×). The combined organics were washed with water and saturated aqueous sodium chloride, dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure and purified by flash column chromatography (2:3 ethyl acetate/hexanes) to provide 1.37 g (58%) of 2-[4-(2-heptanoylamino-ethyl)-phenylamino]-2-methyl-propionic acid tert-butyl ester as a colorless oil.
