Reaction Steps
A 50-mL three-neck round-bottomed flask equipped with a reflux condenser, magnetic stirrer and nitrogen inlet was charged with 115a (263 mg, 0.850 mmol), 103f (473 mg, 1.02 mmol), sodium carbonate (270 mg, 2.55 mmol), DMF (5 mL), water (2.5 mL) and 1,4-dioxane (8 mL). After bubbling nitrogen through the resulting suspension for 30 min, tetrakis(triphenylphosphine)palladium(0) (98 mg, 0.085 mmol) was added, and the reaction mixture was heated at reflux for 14 h. After this time, the mixture was cooled to room temperature and diluted with ethyl acetate (150 mL) and water (30 mL). The organic layer was separated, and the aqueous layer was extracted with ethyl acetate (3×150 mL). The combined organic layers were dried over sodium sulfate and concentrated under reduced pressure. The residue was dissolved in a mixture of THF (8 mL), methanol (4 mL) and water (4 mL). To the resulting solution was added lithium hydroxide monohydrate (420 mg, 10.0 mmol). The mixture was stirred for 4 h at room temperature and then concentrated in vacuo. The residue was partitioned between ethyl acetate (150 mL) and water (30 mL). The organic layer was separated, and the aqueous layer was extracted with a 20% (v/v) solution of methanol in methylene chloride (3×150 mL). The combined organic layers were dried over sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography (silica, 0% to 10% methanol/methylene chloride) to afford a 39% yield (175 mg) of 115 as an off-white solid: mp 173-175° C.; 1H NMR (500 MHz, DMSO-d6) δ 8.10 (s, 1H), 8.08 (d, 1H, J=2.5 Hz), 7.71 (m, 2H), 7.61 (dd, 1H, J=7.9, 1.5 Hz), 7.55 (d, 1H, J=2.5 Hz), 7.50 (m, 1H), 7.43 (dd, 1H, J=7.9, 1.5 Hz), 7.38 (dd, 1H, J=8.0, 1.5 Hz), 7.25 (d, 1H, J=2.1 Hz), 6.06 (d, 1H, J=2.4 Hz), 4.94 (s, 2H), 4.89 (t, 1H, J=4.5 Hz), 4.35 (d, 2H, J=4.5 Hz), 3.58 (s, 3H), 3.54 (m, 1H), 1.37 (s, 9H), 0.96 (m, 2H), 0.87 (m, 2H); MS (ESI+) m/z 524.2 (M+H).
