tert-butyl 4-(3-acrylamido-4-((tert-butoxycarbonyl)(6-(3-(2,6-dichloro-3,5-dimethoxyphenyl)-1-methyl-3-((2-(trimethylsilyl)ethoxy)methyl)ureido)pyrimidin-4-yl)amino)phenyl)piperazine-1-carboxylate (59 g, 0.06 mmol) was stirred in DCM (2.0 ml). TFA (97 μl, 1.3 mmol) was added and the mixture was stirred at room temperature for 6 hours. The reaction mixture was evaporated. The remaining residue was dissolved in DCM and washed with saturated NaHCO3, dried over MgSO4 and evaporated. The resulting material was dissolved in THF (2.0 ml) and NH4OH (74 μl, 1.9 mmol) was added. The reaction mixture was stirred at room temperature for 5 minutes. The reaction mixture was evaporated to obtain the title compound (34 mg, yield: 90%) which was taken to the next step without further purification. 1H-NMR (400 MHz, DMSO-d) δ 2.62 (br. s., 4H) 3.08-3.27 (m, 7H) 3.77-4.03 (m, 6H) 5.72 (d, 1H) 6.11-6.34 (m, 2H) 6.40-6.62 (m, 1H) 6.70-6.98 (m, 2H) 7.22-7.37 (m, 2H) 8.32 (s, 1H) 8.70 (s, 1H) 9.58 (br. s., 1H) 12.06 (s, 1H); ESI-MS: 601 [M+H]+.
