Synthesis
2-Bromo-3-methoxy-6-methylpyridine 760 mg (3.76 mmol) was dissolved in 15 ml of water, and to the resulting solution was added potassium permanganate (KMnO4) (1.49 g, 9.40mmol) and the mixture was heated at 80 °C for 3 hrs. After TLC was conducted, pH was adjusted to 4 with 10 percent hydrochloric acid (HCl) and filtration was conducted with celite. The filtrate was extracted with 50 ml of ethyl acetate (EA). The organic layer was treated with magnesium sulfate (MgSO4) and filtered, and the solution was concentrated to give 6-Bromo-5-methoxypicolinic acid as a white solid (665 mg, 2.87 mmol, 75 percent) without purification.
References
[1] Journal of Organic Chemistry, 1996, vol. 61, # 14, p. 4623 - 4633
[2] Patent: EP3255042, 2017, A2. Location in patent: Paragraph 0122; 0125
[3] Tetrahedron Letters, 1995, vol. 36, # 30, p. 5319 - 5322
[4] Patent: WO2014/78690, 2014, A1. Location in patent: Paragraph 00201
[5] Patent: WO2016/29214, 2016, A1. Location in patent: Page/Page column 148
