2-Methoxy-3-nitro-5-(4,4,5,5-tetramethyl-[1,3,2] dioxaborolan-2-yl)-pyridine

Synthesis

The reaction was carried out with 5-bromo-2-methoxy-3-nitropyridine (5 g, 21.5 mmol) and pinacol ester of bis(boronic acid) (6.6 g, 25.8 mmol) in the presence of PdCl2(dppf)-CH2Cl2 (500 mg) and potassium acetate (6.3 g, 64.5 mmol) in anhydrous 1,4-dioxane (200 mL) at reflux for 2 hour. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The crude product was purified by silica gel column chromatography with the eluent of petroleum ether:EtOAc = 10:1 to afford the target compound 2-methoxy-3-nitro-5-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-pyridine in 81% (5 g) yield. Mass spectral analysis showed m/z 281 (M + H)+.

References

[1] Patent: WO2012/34526, 2012, A1. Location in patent: Page/Page column 33
[2] Patent: US2013/190307, 2013, A1. Location in patent: Paragraph 0158; 0159
[3] Patent: WO2008/141119, 2008, A2. Location in patent: Page/Page column 105
[4] ACS Medicinal Chemistry Letters, 2018, vol. 9, # 3, p. 256 - 261