Synthesis
Example 1: Synthesis of 3-(3-methylaminosulfonyl-phenylethynyl)-2-pyrrol-1-yl-benzoic acid 2-amino-3-bromo-benzoic acid methyl ester: 2-amino-3-bromo-benzoic acid (5 g, 23 mmol) was dissolved in methanol (30 mL) and concentrated sulfuric acid (1 mL) was added slowly and dropwise. The reaction mixture was refluxed at 80 °C for 24 h and subsequently cooled to room temperature. Upon completion of the reaction, the solvent was removed by concentration under reduced pressure. The residue was diluted with distilled water (10 mL) and the pH was adjusted to alkaline with saturated sodium bicarbonate solution. Extraction was performed using ethyl acetate (20 mL x 3) and the organic layers were combined. The organic phase was dried with anhydrous magnesium sulfate, filtered and concentrated. Purification was carried out by silica gel column chromatography (80 g) with ethyl acetate/hexane (10%) as eluent to give the colorless oily product methyl 2-amino-3-bromo-benzoate (5 g, 95% yield).
References
[1] Patent: WO2015/73864, 2015, A1. Location in patent: Paragraph 0253-0254; 0413
[2] Patent: WO2011/25859, 2011, A1. Location in patent: Page/Page column 59
[3] Patent: US2011/71136, 2011, A1. Location in patent: Page/Page column 31
[4] Bioorganic and Medicinal Chemistry Letters, 2017, vol. 27, # 12, p. 2781 - 2787
[5] Patent: US2009/239859, 2009, A1. Location in patent: Page/Page column 298
