2,6-Difluoro-4-(4,4,5,5-tetraMethyl-1,3,2-dioxaborolan-2-yl)benzoic acid

183065-68-1

73183-34-3

1008119-07-0

Under argon protection, 2,6-difluoro-4-bromobenzoic acid (0.4 g, 1.6 mmol), pinacol ester of bisboronic acid (0.5 g, 2.0 mmol), PdCl2(dppf) (0.12 g, 0.17 mmol), and potassium acetate (0.49 g, 4.9 mmol) were dissolved in dioxane (16.5 mL). The reaction mixture was transferred to a sealed vial and degassed twice by vacuum-N2 displacement cycle. Subsequently, the reaction system was heated to 80 °C and the reaction was stirred at this temperature for 21 hours. Upon completion of the reaction, the mixture was cooled to room temperature and filtered through a short column of silica gel to remove solid impurities. The filtrate was concentrated under reduced pressure and purified by fast column chromatography (ISCO 12 g silica gel column with an elution gradient of 20-100% ethyl acetate/hexane) to afford the target product, 2,6-difluoro-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoic acid, as a brown oil (0.11 g, 19% yield). Mass Spectrometry (ES-) m/z: 283 ([M-H]-); Liquid Chromatography Retention Time: 1.48 min (Analytical HPLC Method D).