To a solution of 2,4-dihydroxy-benzoic acid methyl ester (1.42 g, 8.45 mmol) and 2-(3-bromo-propoxy)-isoindole-1,3-dione (2.00 g, 7.04 mmol) ) in acetone (50 mL) was added cesium carbonate (6.88 g, 21.1 mmol). The mixture was heated to reflux for 3 hours and allowed to cool back to room temperature. The mixture was partitioned between ethyl acetate and brine and the layers were then separated. The aqueous layer was extracted with two additional portions of ethyl acetate. The organics were combined, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The crude material was purified by flash chromatography through silica gel using chloroform to give 4-[3-(1,3-dioxo-1,3-dihydro-isoindol-2-yloxy)-propoxy]-2-hydroxy-benzoic acid methyl ester (0.76 g, 30%) as a white solid. 1H NMR (400 MHz, CDCl3); δ 10.86 (s, 1H), 7.76 (m, 2H), 7.68 (m, 3H), 6.40 (m, 2H), 4.35 (t, 2H), 4.21 (t, 2H), 3.85 (s, 3H), 2.20 (m, 2H).
