N2, N4-Bis(4-bromophenyl)quinazoline-2,4-diamine (10)

4-Bromoaniline (0.17 g, 1.0 mmol, 1.3 eq) was reacted with compound 21 (0.25 g, 0.75 mmol) to produce 10, which was purified by recrystallization from boiling MeOH and obtained as a light-brown solid (0.29 g, 82%), m.p. 183–184 °C, Rf = 0.6 (EtOAc/hexane, 50:50). ¹H NMR (400 MHz, DMSO-d₆) δ_H 9.69 (1H, s), 9.31 (1H, s), 8.38 (1H, dd, J 7.5, 1.2 Hz), 7.92 – 7.88 (4H, m), 7.69 (1H, td, J 7.5, 1.2 Hz), 7.57 (2H, d, J 8.9 Hz), 7.52 (1H, dd, J 7.5, 1.2 Hz), 7.41 (2H, d, J 8.9 Hz), 7.31 (1H, td, J 7.5, 1.2 Hz); ¹³C NMR (101 MHz, DMSO-d₆) δ_C 158.2 (C-q), 155.9 (C-q), 151.4 (C-q), 140.5 (C-q), 138.8 (C-q), 133.1, 131.2, 130.9, 125.7, 124.4, 123.1, 122.2, 120.7, 115.2 (C-q), 112.1 (C-q), 111.8 (C-q); HRMS (ESI) m/z: Found 468.9663. Calculated 468.9663, C₂₀H₁₅Br₂N₄ [M+H]⁺; HPLC purity: 98%.