[C:1]([C:5]1[CH:6]=[CH:7][C:8]([C:17](=[O:23])[N:18]([CH2:21]C)CC)=[C:9]([CH:16]=1)CNC(=O)OC)([CH3:4])([CH3:3])[CH3:2].O1CCCC1.[OH-].[Li+].Cl>CO>[C:1]([C:5]1[CH:16]=[C:9]2[C:8](=[CH:7][CH:6]=1)[C:17](=[O:23])[NH:18][CH2:21]2)([CH3:2])([CH3:3])[CH3:4]A 25-mL microwave vial equipped with a magnetic stirrer was charged with 103b (858 mg, 2.68 mmol), tetrahydrofuran (5 mL), methanol (5 mL) and 2 M aqueous lithium hydroxide (5 mL). The vial was loaded in a Biotage microwave and heated at 110° C. for 2.5 h. After this time, the solution was neutralized with 2 M hydrochloric acid to pH 7 and concentrated in vacuo. The resulting residue was partitioned between ethyl acetate (150 mL) and water (30 mL). The aqueous layer was extracted with ethyl acetate (3×20 mL). The combined organic layers were washed with brine (30 mL), dried over sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography (silica, 50% ethyl acetate to 100% ethyl acetate/hexanes) to afford a 56% yield (285 mg) of 103c as an off-white solid: mp=132-134° C.; 1H NMR (300 MHz, CDCl3) δ 7.80 (d, 1H, J=7.8 Hz), 7.52 (m, 2H), 6.71 (br s, 1H), 4.44 (s, 2H), 1.37 (s, 9H), MS (ESI+) m/z 190.1 (M+H).
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