Synthesis of methyl 6-methoxy-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine-2-carboxylate (C31). [1,1′-Bis(diphenylphosphino)ferrocene]dichloropalladium(II), complex with dichloromethane (740 mg, 0.91 mmol) was added in one portion to a degassed mixture of methyl 5-bromo-6-methoxypyridine-2-carboxylate (C30) (7.42 g, 30.2 mmol), 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi-1,3,2-dioxaborolane (9.19 g, 36.2 mmol) and potassium acetate (8.88 g, 90.5 mmol) in dioxane (150 mL) at room temperature under argon and the reaction was heated at 100° C. for 18 hours. The mixture was cooled to room temperature, filtered through Celite, washed with ethyl acetate (400 mL) and concentrated in vacuo. Silica gel chromatography (Gradient: 15% to 35% ethyl acetate in heptane) afforded the title compound as a colorless oil, which solidified on standing to form a white crystalline solid. Yield: 7.14 g, 24.4 mmol, 81%. LCMS m/z 212.1 (M for boronic acid+1). 1H NMR (400 MHz, CDCl3) δ 1.37 (s, 12H), 3.97 (s, 3H), 4.06 (s, 3H), 7.67 (d, J=7.3 Hz, 1H), 8.09 (d, J=7.3 Hz, 1H). A second crop of material (1.13 g, 13%) was also obtained from the purification; this contained minor impurities by NMR analysis.
