[Cl:1][C:2]1[CH:7]=[C:6](I)[C:5]([O:9][CH3:10])=[CH:4][C:3]=1[C:11]1[CH:16]=[CH:15][CH:14]=[C:13]([F:17])[CH:12]=1.[B:18](OC(C)C)([O:23]C(C)C)[O:19]C(C)C.C([Li])CCC.[OH-].[Na+]>C1COCC1>[Cl:1][C:2]1[CH:7]=[C:6]([B:18]([OH:23])[OH:19])[C:5]([O:9][CH3:10])=[CH:4][C:3]=1[C:11]1[CH:16]=[CH:15][CH:14]=[C:13]([F:17])[CH:12]=1
A round-bottom flask was charged with 2-chloro-3′-fluoro-4-iodo-5-methoxy-1,1′-biphenyl (1.68 g, 4.63 mmol), triisopropyl borate (1.399 ml, 6.02 mmol), and THF (23.17 ml). The flask was cooled in a dry ice-acetone bath for 10 min, then n-butyllithium (2.5 M in hexane) (2.409 ml, 6.02 mmol) was added drop wise over 1 min. After 40 min, a solution of 2 N aq. NaOH (25 mL) was added. The resulting biphasic mixture was stirred for 10 min, and then partitioned between water and ether. The layers were separated, and the ethereal layer was extracted with water (2×). The combined aq. extracts were washed with ether, and the ethereal layer was back-extracted with water. The combined aq. layers were acidified with 3N aq. HCl (50 mL), and the aq. mixture was extracted with DCM (3×). The combined DCM-layers were dried over sodium sulfate, filtered, and concentrated to give (2-chloro-3′-fluoro-5-methoxy-[1,1′-biphenyl]-4-yl)boronic acid (0.859 g, 3.06 mmol, 66.1% yield) as an oily solid. m/z (ESI) 281.1 (M+H)+.
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