C[C:2]1(C)[O:7][C:6]2[CH:8]=[CH:9][CH:10]=[C:11]([C:12]3[CH:13]=[C:14]([CH:20]=[CH:21][CH:22]=3)[C:15]([O:17][CH2:18]C)=[O:16])[C:5]=2[C:4](=[O:23])[O:3]1.C[O-].[Na+]>CO>[OH:7][C:6]1[CH:8]=[CH:9][CH:10]=[C:11]([C:12]2[CH:22]=[CH:21][CH:20]=[C:14]([C:15]([O:17][CH3:18])=[O:16])[CH:13]=2)[C:5]=1[C:4]([O:3][CH3:2])=[O:23]To a solution of 3-(2,2-dimethyl-4-oxo-4H-1,3-benzodioxin-5-yl)benzoic acid, ethyl ester (1.4 g, 4.3 mmol) in methanol (10 mL) was added sodium methoxide (0.5 M in methanol, 25 mL) at 0° C. The solution was stirred at room temperature for 15 minutes. The reaction was quenched by addition of 1 N HCl (30 mL) and extracted with EtOAc (3×30 mL). The combined organic extracts were dried over MgSO4 and concentrated to afford 3-hydroxy-[1,1′-biphenyl]-2,3′-dicarboxylic acid, dimethyl ester (1.2 g, 95%) as a yellow solid: 1H NMR (CDCl3) δ 3.43 (s, 3H), 3.93 (s, 3H), 6.79 (dd, J=7.5, 0.9 Hz, 1H), 7.04 (dd, J=7.5, 0.9 Hz, 1H), 7.43 (m, 3H), 7.93 (m, 1H) 8.02 (dm, J=7.0 Hz, 1H), 10.8 (s, 1H).
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