Step B. Synthesis of methyl 4-bromo-3-methoxybenzoate
Methyl 4-bromo-3-hydroxybenzoate (27 mmol), potassium carbonate (33 mmol) and dimethyl sulfate (32 mmol) obtained from Step A were dissolved in acetone (40 mL) under nitrogen protection. The reaction mixture was heated to reflux temperature and stirred for 3 hours. After completion of the reaction, the mixture was cooled and the reaction was quenched by slowly adding 5 mL of water. Subsequently, the acetone was removed by rotary evaporator and diluted by adding 30 mL of water. The product in the aqueous phase was extracted with dichloromethane (3 × 20 mL). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to afford the title compound methyl 4-bromo-3-methoxybenzoate (6.5 g, 99% yield) as a white crystalline solid.
[1] Patent: US2006/199806, 2006, A1. Location in patent: Page/Page column 23
[2] Patent: US2006/287522, 2006, A1. Location in patent: Page/Page column 24
[3] Beilstein Journal of Organic Chemistry, 2016, vol. 12, p. 2267 - 2273
[4] Yakugaku Zasshi, 1930, vol. 50, p. 224,227; dtsch. Ref. S. 26
[5] Chem.Abstr., 1930, p. 3513