The general procedure for the synthesis of 2-(dimethoxymethyl)pyridine-5-boronic acid pinacol ester from 5-bromo-2-(dimethoxymethyl)pyridine and pinacol ester of bisboronic acid was as follows: Pd(dppf)Cl2 (630.73 mg, 862.00 μmol) was added to a solution containing 5-bromo-2-(dimethoxymethyl)pyridine (2 g, 8.62 mmol), pinacol ester of bisboronic acid (2.85 g, 11.21 mmol) and potassium acetate (2.54 g, 25.86 mmol) in a solution of dioxane (10 mL). The reaction mixture was stirred at 110 °C for 2 hours. The progress of the reaction was monitored by LC-MS, and after confirming the completion of the reaction, the reaction solution was cooled to room temperature, filtered to remove insoluble matter, and the filtrate was concentrated in vacuum to remove the solvent. The residue was purified by fast silica gel column chromatography to afford the target product 2-(dimethoxymethyl)pyridine-5-boronic acid pinacol ester as a black oil (2 g, 83.12% yield). The structure of the product was confirmed by 1H NMR (400 MHz, chloroform-d): δ 8.94 (s, 1H), 8.11 (dd, J = 1.4, 7.7 Hz, 1H), 7.54 (d, J = 7.8 Hz, 1H), 5.40 (s, 1H), 3.39 (s, 6H), 1.35 (s, 12H).
