A 100-mL three-neck round-bottomed flask equipped with a reflux condenser, magnetic stirrer was purged with nitrogen and charged with 102c (570 mg, 3.02 mmol), 102d (1.85 g, 6.04 mmol), cesium carbonate (1.96 g, 6.04 mmol), N,N′-dimethyl-ethylenediamine (266 mg, 3.02 mmol), and 1,4-dioxane (27 mL). After bubbling nitrogen through the resulting suspension for 30 min, copper iodide (287 mg, 1.51 mmol) was added, and the reaction mixture was heated at 105° C. (oil bath temperature) for 14 h. After this time, the mixture was cooled to room temperature and filtered. The filtrate was diluted with ethyl acetate (150 mL) and water (30 mL). The organic layer was separated, and the aqueous layer was extracted with ethyl acetate (3×50 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 50% ethyl acetate/hexanes) to afford a 41% yield (555 mg) of 102e as an off-white solid: mp 176-178° C.; 1H NMR (300 MHz, CDCl3) δ 7.86 (d, 1H, J=8.1 Hz), 7.66 (dd, 1H, J=7.9, 1.5 Hz), 7.59 (dd, 1H, J=8.1, 1.5 Hz), 7.52 (s, 1H), 7.29 (m, 2H), 5.20 (s, 2H), 4.77 (s, 2H), 1.99 (s, 3H), 1.40 (s, 9H); MS (ESI+) m/z 416.1 (M+H).
