Br[C:2]1[CH:3]=[C:4]([CH:9]=[C:10]([CH2:12][OH:13])[CH:11]=1)[C:5]([O:7][CH3:8])=[O:6].[C:14](=O)([O-])[O-].[Cs+].[Cs+].C(=O)([O-])[O-].[K+].[K+].CB1OB(C)OB(C)O1>O1CCOCC1>[OH:13][CH2:12][C:10]1[CH:9]=[C:4]([CH:3]=[C:2]([CH3:14])[CH:11]=1)[C:5]([O:7][CH3:8])=[O:6]
To a stirred solution of methyl 3-bromo-5-(hydroxymethyl)benzoate (4.53 g, 18.5 mmol) in dioxane (74 mL) is added cesium carbonate (6.0 g, 18.5 mmol), potassium carbonate (5.1 g, 37 mmol), and palladium(0)tetrakis(triphenylphosphine) (2.1 g, 1.85 mmol), followed by trimethyl boroxine (5.1 mL, 37 mmol). The reaction mixture is refluxed for 12 h, cooled to room temperature, and then partitioned between water and ethyl acetate. The organic layer is washed with water and brine, dried (magnesium sulfate), filtered, and concentrated under reduced pressure. The black oil is adsorbed onto silica gel followed by purification by flash column chromatography (silica, 25% ethyl acetate/hexanes) to provide the title compound. 1H NMR (300 MHz, CDCl3) δ 7.75 (s, 1H), 7.65 (s, 1H), 7.39 (s, 1H), 5.31 (br s, 1H), 4.53 (s, 1H), 3.84 (s, 3H), 2.36 (s, 3H).
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