[C:1]1(B(O)O)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.Br[C:11]1[CH:12]=[CH:13][C:14]([OH:21])=[C:15]([CH:20]=1)[C:16]([O:18][CH3:19])=[O:17].O.C(=O)([O-])[O-].[K+].[K+]>CC(C)=O.C([O-])(=O)C.[Pd+2].C([O-])(=O)C.[Pd].CCOCC>[OH:21][C:14]1[CH:13]=[CH:12][C:11]([C:1]2[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=2)=[CH:20][C:15]=1[C:16]([O:18][CH3:19])=[O:17]
A solution of phenylboronic acid (1.34 g, 11.0 mmol) and methyl 5-bromo-2-hydroxybenzoate (2.42 g, 10.5 mmol) in acetone (25 ml) was treated with water (30 ml), followed by potassium carbonate (3.77 g, 27.3 mmol) and finally, palladium (II) acetate (0.16 g, 0.7 mmol). Upon addition of the palladium, the reaction mixture rapidly darkened. The reaction mixture was heated to reflux and stirred for 6 h. After cooling the dark mixture, ether (40 ml) was added, stirred vigorously and decanted. This extraction process was repeated an additional four times. The ethereal extracts were dried over sodium sulphate and evaporated in vacuo to give a yellow liquid. The crude product was dissolved in petrol and loaded onto a silica flash column. The column was eluted with petrol, followed by 5-10% ethyl acetate in petrol. The second product collected was evaporated in vacuo and then recrystallised from petrol to provide a white crystalline solid (1.35 g, 5.90 mmol, 56% yield). 1H NMR (200 MHz., d6-DMSO) δ 4.05 (3H, s); 7.20 (1H, m); 7.50-7.58 (3H, m); 7.74 (2H, m); 7.97 (1H, m); 8.13 (1H, m); 10.67 (1H, s, OH).
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