Synthesis
Under nitrogen protection, 6-bromo-1H-indole (25 g, 0.128 mol), pinacol ester of bisboronic acid (48.58 g, 0.191 mol), Pd(dppf)Cl2 (5.2 g, 5 mol%) and KOAc (37.55 g, 0.383 mol) were dissolved in DMF (500 ml). The reaction mixture was stirred at 120°C for several hours. After completion of the reaction, extraction was carried out with ethyl acetate and the organic phase was dried with magnesium sulfate. Purification by column chromatography (eluent: hexane/ethyl acetate=10:1, v/v) afforded 6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-indole (20.15 g, 65% yield).
References
[1] Journal of the American Chemical Society, 2017, vol. 139, # 24, p. 8267 - 8276
[2] Synlett, 2003, # 8, p. 1204 - 1206
[3] Patent: JP2015/531758, 2015, A. Location in patent: Paragraph 0045-0046
[4] Patent: US2007/112005, 2007, A1. Location in patent: Page/Page column 82
[5] Patent: US2007/280928, 2007, A1. Location in patent: Page/Page column 80
