General procedure for the synthesis of 4-amino-3-fluorophenylboronic acid pinacol ester from 2-fluoro-4-iodoaniline and bis(pinacolato) borate:
1. 2-Fluoro-4-iodoaniline (5.0 g, 21.1 mmol) and bis(pinacolato)ethylborane (5.89 g, 23.2 mmol) were dissolved in 130 mL of DMSO under argon protection.
2. Potassium acetate (6.21 g, 63.3 mmol) was added and argon was continuously passed for 10 minutes to exclude oxygen.
3. a 1:1 complex of [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride (1.21 g, 1.50 mmol) with dichloromethane was added, and the reaction mixture was heated at 85 °C for 4.5 hours.
4. After the reaction was complete, it was cooled to room temperature and diluted with 500 mL of water.
5. The mixture was extracted with ethyl acetate (3 x 200 mL), the organic phases were combined, washed with water, dried over anhydrous sodium sulfate, and then concentrated to dryness under reduced pressure.
6. The crude product was purified by silica gel column chromatography with cyclohexane/ethyl acetate (90/10, v/v) as eluent.
7. 3.73 g of white powder was obtained in 75% yield. 8. The product had a melting point of 11.0%.
8. The melting point of the product was 112 °C. 9.
9. 1H NMR (400 MHz, CDCl3) data: δ (ppm): 1.2 (s, 12H); 3.8 (br s, 2H); 6.55 (t, 1H, J=7Hz); 7.25-7.35 (m, 2H).
