A stirred solution of 1-(5-(3-(4-(bis(4-methoxybenzyl)amino)-6-methyl-1,3,5-triazin-2-yl)pyridin-2-ylamino)pyridin-2-yl)-3-isopropylurea (0.104 g, 0.168 mmol) in TFA (2 mL) was treated with trifluoromethanesulfonic acid (TCI) (0.02 mL, 0.2 mmol) and the reaction mixture was stirred at 70° C. for 2 h, then 80° C. for 2 h. TFA (2 mL) and trifluoromethanesulfonic acid (0.05 mL) were added. The heating was resumed at 75° C. for another 2 h. The mixture was cooled to rt, and some of the TFA was removed in vacuo. Sat'd NaHCO3 was added slowly until effervescence was no longer observed. The aqueous phase was extracted with 25% iPrOH in CHCl3+1% NH4OH (3×10 mL). The combined organic phases were dried over sodium sulfate, filtered and concentrated in vacuo. The crude product was purified by silica gel chromatography (25 g, eluent: iPrOH (w/10% NH4OH) in CHCl3 0%-10%) to give 1-(5-(3-(4-amino-6-methyl-1,3,5-triazin-2-yl)pyridin-2-ylamino)pyridin-2-yl)-3-isopropylurea (0.0312 g, 49% yield) as a yellow powder. 1H NMR (300 MHz, d6-DMSO) δ 11.77 (s, 1H); 8.92 (s, 1H); 8.77 (d, J=7.75 Hz, 1H); 8.65 (br. s., 1H); 8.31 (br. s., 1H); 8.10 (br. s., 1H); 7.85 (br. s., 2H); 7.71 (br. s., 1H); 7.38 (d, J=8.92 Hz, 1H); 6.80-6.99 (m, 1H); 3.77-3.91 (m, 1H); 2.43 (s, 3H); 1.15 (d, J=6.28 Hz, 6H). m/z (ESI, +ve ion) 380.1 (M+H)+.
