To a mixture of 1-(4,6-dichloro-[1,3,5]-triazin-2-yl-amino)-imidazolidine-2,4-dione (Example 1.1, Part A) (3.84 g, 14.6 mmol) and K2CO3 (4.4 g, 31.8 mmol) in CH3CN (50 mL) was added (4-methoxyphenyl)-methanamine (2.0 g, 14.6 mmol) drop-wise at 0° C. The mixture was stirred at r.t. overnight. TLC showed the reaction was complete. The mixture was filtered and the cake was portioned between water and EtOAc. The organic layer was separated, and the aqueous layer was extracted with EtOAc. The combined organic layers were washed with brine, dried over Na2SO4 and concentrated in vacuo to give the expected compound (3.50 g, yield: 66%) as a white solid. It was used for the next step without further purification. δH (400 MHz, DMSO-d6): 11.30-11.23 (m, 1H), 10.06-9.83 (m, 1H), 8.67-8.60 (m, 1H), 7.24-7.13 (m, 2H), 6.90-6.83 (m, 2H), 4.40-4.35 (m, 2H), 4.26-4.05 (m, 214), 3.73 (s, 3H). Mass spectrum (ESI) m/z 364 (100%, MH+).
