Ethanol → 6-(4-Fluorophenyl)picolinic acid

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A solution of 2-bromo-picolinic acid (Aldrich, 2.02 g, 10 mmol) in DME containing 4 mL of 10% aq Na2CO3 was purged with Ar gas. To this mixture was added Pd(PPh3)4 followed by 2-(4-fluorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane (Aldrich, 2.40 g, 11.5 mmol) and EtOH (20 mL), and the mixture was purged with Ar gas. The reaction mixture was heated at 100° C. for 2.5 h in a sealed tube. Additional 2-bromo-picolinic acid (900 mg) and Pd(PPh3)4 was added, and after purging with Ar gas it was heated at 100° C. for 4.5 h. Trifluoroacetic acid (20 mL) was added to the reaction and the mixture was concentrated in vacuo. MeOH (150 mL) was added to the residue and the insoluble material was filtered, and the filtrate solution was concentrated in vacuo. Purification of the resulting residue by flash column chromatography on silica gel eluting with EtOAc/MeOH/900:100 followed by EtOAc/MeOH/HOAc/700:1500:50 provided the desired product (1.0 g, 40% based on borinane starting material) as a white solid. 1H NMR (CD3OD) δ 8.01 (d, 1H, J=7.7 Hz), 7.94-7.87 (m, 3H), 7.73 (d, 1H, J=7.7 Hz), 7.13 (t, 2H, J=8.8 Hz); MS (ESI+) m/z 234 (M+H)+.

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