To a solution of 3-aminobenzonitrile (0.5 g, 4.23 mmol) in acetonitrile (30 mL) was added tert-butyl nitrite (0.7 mL, 6.34 mmol) and pinacol ester of bis(boronic acid) (1.29 g, 5.076 mmol) sequentially at 0 °C. The reaction mixture was warmed to 80 °C and stirred continuously for 2 hours. After completion of the reaction, the mixture was cooled to room temperature and subsequently concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (combiflash system) with the eluent being a 4% ethyl acetate/hexane solvent mixture, resulting in pinacol ester of 3-cyanobenzeneboronic acid (0.35 g, 99.8% yield). The molecular weight of the product was confirmed by LCMS analysis: m/z 294 ([M+H]+).
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