[Synthesis]
General procedure for the synthesis of 4-bromo-6-methoxy-1H-indole from the compound (CAS: 1431711-54-4): (b) N-(3-bromo-5-methoxyphenyl)-N-hydroxyacetamide (360 mg, 1.384 mmol) was dissolved in vinyl acetate (1.92 mL) followed by addition of Li2PdCl4 (18.2 mg, 69 μmol). The reaction mixture was stirred at 60°C for 3 hours. After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtOAc) and brine, the organic layer was separated and concentrated under reduced pressure to give a solid. The solid was dissolved in methanol (20 mL), 1N NaOH aqueous solution (2.61 mL, 2.61 mmol) was added and stirred for 2 hours at room temperature. The reaction mixture was quenched with 2N HCl aqueous solution (1.3 mL, 2.6 mmol) followed by addition of sodium carbonate (500 mg). After addition of ethyl acetate (50 mL), the organic layer was separated, dried over anhydrous sodium sulfate (Na2SO4), filtered and concentrated. The residue was purified by column chromatography (20 g silica gel, ethyl acetate/heptane, gradient from 0/100 to 1/4) to afford the title compound as a liquid (145 mg, 46% yield, two steps).1H-NMR (600 MHz; DMSO-d6): δ 11.26 (brs, 1H), 7.31 (dd, 1H), 6.93 (d, 1H), and 6.90 (d, 1H), 6.29 (dd, 1H), 3.78 (s, 3H). |