Br[C:2]1[C:10]2[O:9][CH:8]=[CH:7][C:6]=2[CH:5]=[C:4]([O:11][CH3:12])[CH:3]=1.[CH3:13]B(O)O.C([O-])([O-])=O.[Cs+].[Cs+]>O1CCOCC1.O.C1C=CC(P(C2C=CC=CC=2)[C-]2C=CC=C2)=CC=1.C1C=CC(P(C2C=CC=CC=2)[C-]2C=CC=C2)=CC=1.Cl[Pd]Cl.[Fe+2]>[CH3:12][O:11][C:4]1[CH:3]=[C:2]([CH3:13])[C:10]2[O:9][CH:8]=[CH:7][C:6]=2[CH:5]=1
A mixture of the product from Step C (3.6 g, 16 mmol), methylboronic acid (1.4 g, 24 mmol), Pd(dppf)2Cl2 (0.65 g, 0.8 mmol) and Cs2CO3 (13.0 g, 40 mmol) in 1,4-dioxane (50 mL) and H2O (10 mL) was refluxed for 3 hrs under N2 atmosphere. The reaction was cooled to room temperature and filtered through a celite pad. The filtrate was diluted with EtOAc (200 mL) and washed with brine (50 mL), dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica column chromatography (eluted with PE) to afford the title compound (1.0 g, 38%) as an oil. 1H-NMR (600 MHz, CDCl3) δ 7.63 (d, J=1.6 Hz, 1H), 6.92 (d, J=2.1 Hz, 1H), 6.76 (s, 1H), 6.73 (d, J=1.8 Hz, 1H), 3.86 (s, 3H), 2.53 (s, 3H) ppm.
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