A mixture of 2-((2-bromo-4-(1-tert-butoxy-1-oxopropan-2-yl)phenylamino)methyl)benzoic acid (4.40 g, 10.1 mmol), 1-(3-(dimethylamino)propyl)-3-ethylcarbodiimide hydrochloride (2.13 g, 11.1 mmol) and 4-dimethylaminopyridine (0.617 g, 5.05 mmol) in methylene chloride (80 mL) was stirred at 0° C. and was allowed to warm to room temperature overnight. The mixture was then concentrated and the residue was purified by flash chromatography (silica, 4:1 hexanes/ethyl acetate) to afford tert-butyl 2-(3-bromo-4-(1-oxoisoindolin-2-yl)phenyl)propanoate (3.55 g, 85%) as white foam: 1H NMR (500 MHz, CDCl3) δ 7.96 (d, J=7.6 Hz, 1H), 7.64-7.50 (m, 4H), 7.35 (d, J=1.0 Hz, 2H), 4.79 (s, 2H), 3.63 (q, J=7.2 Hz, 1H), 1.47 (d, J=7.2 Hz, 3H), 1.44 (s, 9H); ESI MS m/z 418 [(M+2)+H]+.
