3-Phenyl-8-propylpyrimido[5,4-e][1,2,4]triazine-5,7(6H,8H)-dione (6a)

Yield: 71%; m.p. = 290–291 °C; IR (KBr) ν_max (cm⁻¹): 3173 (NH), 3024 (CH arom.), 2968, 2840 (CH aliph.), 1716, 1670 (C=O), 1565 (C=N), 1535 (C=C); ¹H-NMR (DMSO-d₆): 12.25 (s, 1H, NH), 8.42–8.40 (d, 2H, J = 5.2 Hz, H_arom), 7.62–7.61 (m, 3H, arom.), 3.24–3.21 (t, 2H, CH₂), 1.68–1.63 (m, 2H, CH₂), 0.98–0.94 (t, 3H, CH₃); ¹³C-NMR (DMSO-d₆): δ = 160.4, 154.7, 150.8, 149.4, 146.2, 134.2, 131.3, 129.3, 127.1, 42.4, 20.6, 11.0 ppm; MS: m/z (%) = M⁺, 283 (16), 255 (20), 254 (38), 213 (17), 171 (13), 105 (100), 104 (13), 103 (10), 77 (29); Anal. calcd. for C₁₄H₁₃N₅O₂ (283.28): C, 59.36; H, 4.63; N, 24.72. Found: C, 59.58; H, 4.71; N, 24.89.