Trifluoroacetic acid → N-tert-butyl-2-(5-methoxy-1-methyl-1H-indazol-3-yl)-5H-pyrrolo[2,3-b]pyrazine-7-carboxamide

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To a pale yellow solution of N-tert-butyl-2-(5-methoxy-1-methyl-1H-indazol-3-yl)-5-((2-(trimethylsilyl)ethoxy)methyl)-5H-pyrrolo[2,3-b]pyrazine-7-carboxamide (40 mg, 78.6 μmol) in dichloromethane (2 mL) was added TFA (2.96 g, 2000 μL, 26.0 mmol, Eq: 330), the reaction mixture turned bright orange and was stirred at 25° C. for 3 h, then concentrated. The residue was re-dissolved in 5 mL of a solution of (dichloromethane/MeOH/ammonium hydroxide; 60:10:1) and stirred at 25° C. overnight then evaporated to a light yellow solid, dissolved in dichloromethane (containing a few drops of MeOH) and purified by chromatography (spherical silica 20-45 μm, 23 g, Versaflash Supelco) eluting with 0 to 5% over 15 min (MeOH containing 10% ammonium hydroxide)/dichloromethane. The pure product dissolved in a small amount of dichloromethane/MeOH, added cyclohexane and some solvents evaporated to allow solid formation, which was separated by filtration and dried to give N-tert-butyl-2-(5-methoxy-1-methyl-1H-indazol-3-yl)-5H-pyrrolo[2,3-b]pyrazine-7-carboxamide (25 mg, 66.1 μmol, 84.0%) as an off-white solid. MS (M+H)+=379 (>90% purity); 1H NMR (CDCl3) δ: 9.11 (s, 1H), 8.31 (d, J=3.0 Hz, 1H), 8.22 (s, 1H), 7.86 (d, J=2.3 Hz, 1H), 7.41 (d, J=9.1 Hz, 1H), 7.26 (br. s., 2H), 7.17-7.23 (m, 1H), 4.18 (s, 3H), 3.92 (s, 3H), 1.59 (s, 9H).

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