Ethanol → 6-(4-Fluorophenyl)picolinic acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A solution of 2-bromo-picolinic acid (2.02 g, 10 mmol, Aldrich) in DME containing 4 mL of 10% aq. Na2CO3 was purged with Ar gas, treated with Pd(PPh3)4 followed by 2-(4-fluorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane (2.40 g, 11.5 mmol, Aldrich) and EtOH (20 mL). This mixture was then also 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. The filtrate was concentrated in vacuo, and the resulting residue was purified by flash column chromatography on silica gel eluting with EtOAc/MeOH (9:1) followed by EtOAc/MeOH/HOAc (14:30:1) to afford 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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