Synthesis
General steps:
1. Stirring reaction: potassium acetate (KOAc, 0.073 g, 0.09 mmol) and 1,1'-bis(diphenylphosphino)ferrocene-palladium(II) dichloride-dichloromethane complex (PdCl2(dppf)-CH2Cl2, 0.613 g, 3.5 mmol) were added under argon protection to a mixture of potassium acetate (1b, R = F 0.613 g, 3.5 mmol) and bis(pinacolato)diboron (2, 1.161 g, 4.5 mmol) in a solution of dimethyl sulfoxide (DMSO, 1.601 g). The reaction mixture was stirred at 80°C for 1.5 hours.
2. Extraction: Upon completion of the reaction, the reaction solution was cooled to room temperature, the reaction was quenched by the addition of ice water, followed by extraction of the organic layer with ethyl acetate (EtOAc, 80 mL × 2).
3. Drying and concentration: The organic layers were combined, dried with anhydrous magnesium sulfate (MgSO4), filtered and concentrated under reduced pressure to obtain the crude product.
4. Purification: The crude product was purified by column chromatography (silica gel, eluent: hexane/EtOAc = 9:1) to afford 4-fluorophenylboronic acid pinacol ester (3b, R = F) in 93% yield.
References
[1] Patent: JP5966165, 2016, B2. Location in patent: Paragraph 0056-0062
[2] Journal of the American Chemical Society, 2016, vol. 138, # 9, p. 2985 - 2988
[3] Advanced Synthesis and Catalysis, 2016, vol. 358, # 6, p. 977 - 983
[4] Journal of Fluorine Chemistry, 2015, vol. 178, p. 195 - 201
[5] ACS Catalysis, 2018, vol. 8, # 5, p. 4049 - 4054
