Synthesis
Example 7:1-7:2 (Method F)
Step 1: 2-Amino-5-hydroxybenzoic acid (100 g, 0.653 mol) was dissolved in methanol (2 L) and concentrated sulfuric acid (100 mL, 100%) was added slowly. The reaction mixture was heated to reflux for 48 hours. After the reaction was completed, it was cooled to room temperature and neutralized with solid sodium bicarbonate to neutral. The reaction mixture was concentrated under reduced pressure, water (1.5 L) was added and the pH was adjusted with solid sodium bicarbonate to about 8. The precipitated solid was collected by filtration, washed with cold water and dried to give methyl 2-amino-5-hydroxybenzoate. Yield: 94 g (86% yield).
References
[1] Angewandte Chemie - International Edition, 2016, vol. 55, # 41, p. 12643 - 12649
[2] Angew. Chem., 2016, vol. 128, p. 12833 - 12839,7
[3] Journal of Organic Chemistry, 2001, vol. 66, # 8, p. 2784 - 2788
[4] Synlett, 2004, # 9, p. 1625 - 1627
[5] Patent: WO2009/127822, 2009, A2. Location in patent: Page/Page column 87
