To a solution of tert-butyl 4-(4-((4-(2-(2-amino-2-oxoethyl)phenethyl)-5-(trifluoromethyl)pyrimidin-2-yl)amino)benzoyl)piperazine-1-carboxylate (A26) (0.182 g, 0.297 mmol) in DCM (4 mL) was added TFA (1 mL) and the resulting mixture was stirred at room temperature for 16 hours. The volatiles were removed in vacuo and the residue partitioned between EtOAc (10 mL) and 2 M aqueous NaOH (10 mL). The aqueous layer was extracted with EtOAc (2×10 mL) then the combined organic fractions were washed with water (10 mL), brine (10 mL) and dried over MgSO4. The volatiles were removed in vacuo to give a yellow solid, which was suspended in cyclohexane and then filtered to give the title compound 6 as a white solid (0.132 g, 87%); 1H NMR (400 MHz, d4-MeOH) δ 8.62 (s, 1H), 7.83 (d, J=8.7 Hz, 2H), 7.42 (d, J=8.8 Hz, 2H), 7.27 (d, J=6.3 Hz, 1H), 7.23-7.15 (m, 3H), 3.68 (s, 2H), 3.82-3.46 (m, 4H), 3.23-3.15 (m, 2H), 3.12 (dd, J=9.8, 5.4 Hz, 2H), 3.02-2.71 (m, 4H). LCMS-A: rt 4.676 min; m/z 513.3 [M+H]+.
