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To a solution of methyl 5-bromo-1H-pyrazolo[3,4-b]pyridine-3-carboxylate (XVII) (2.92 Kg, 11.4 mol) in anhydrous DCM (88 L) was added TEA (2.38 L, 17.1 mol). The solution was cooled to 0° C. before adding dropwise a solution of TrCl (4.0 Kg, 14.3 mol) in anhydrous DCM (51 L). The solution was warmed to room temperature and stirred for 20 hours. The reaction was then washed once with water (29 L), once with aqueous 25% NaCl (29 L), dried over Na2SO4 and concentrated to a volume of 3.0 L to give methyl 5-bromo-1-trityl-1H-pyrazolo[3,4-b]pyridine-3-carboxylate (XXII) (5.69 Kg, 11.4 mol, 77.3% purity, 99.5% assay yield). 1H NMR (DMSO-d6, 400 MHz) δ ppm 3.91 (s, 3H), 7.19 (d, J=8.4 Hz, 5H), 7.21-7.32 (m, 10H), 8.45 (d, J=2.4 Hz, 1H), 8.61 (d, J=2 Hz, 1H); ESIMS found C27H20BrN3O2 m/z 520.0 (M+Na).

1. temperatureThe solution was warmed to room temperature
2. washThe reaction was then washed once with water (29 L), once with aqueous 25% NaCl (29 L)
3. dry with materialdried over Na2SO4
4. concentrationconcentrated to a volume of 3.0 L