560 R. Mohebat et al.
3.1.2. 1,3-Dimethyl 7-thioxo-5-o-tolyl 7,8-dihydro1H-pyrimido[4,5,d]pyrimidine-2,4-dione
(4b)
Yellow powder; m.p. 195–197◦C, IR (KBr) (νmax cm−1): 3455, 1701, 1621, 1524, 1439.Analyses:
Calcd. for C15H14N4O2S: C, 57.31; H, 4.49; N, 17.82%. Found: C, 57.48; H, 4.34; N, 17.90. MS
(m/z, %): 314 (M+, 8); 91 (100). 1H NMR (500 MHz, DMSO-d6): δ 2.40, 3.21, and 3.36 (9 H,
3s, 3CH3), 7.31–7.52 (4 H, m, 4CH aromatic), 14.96 (1 H, s, NH) ppm.13C NMR (125.8 MHz,
DMSO-d6): δ 20.56, 29.24, and 31.48 (3CH3), 93.67, 126.95, 127.91, 131.60, 132.14, 136.76,
=
137.48, 148.79, 159.53, 164.12, and 168.19 (11C), 191.24 (C S) ppm.
3.1.3. 1,3-Dimethyl 7-thioxo-5-m-tolyl 7,8-dihydro1H-pyrimido[4,5,d]pyrimidine-2,4-dione
(4c)
Yellow powder; m.p. 196–198◦C, IR (KBr) (νmax cm−1): 3460, 1700, 1621, 1529, 1430.Analyses:
Calcd. for C15H14N4O2S: C, 57.31; H, 4.49; N, 17.82%. Found: C, 57.48; H, 4.34; N, 17.90. MS
(m/z, %): 314 (M+, 11); 91 (100). 1H NMR (500 MHz, DMSO-d6): δ 2.39, 3.22, and 3.38 (9 H,
3s, 3CH3), 7.46–7.75 (4 H, m, 4CH aromatic), 15.43 (1 H, s, NH) ppm.13C NMR (125.8 MHz,
DMSO-d6): δ 20.51, 29.35, and 31.43 (3CH3), 93.61, 126.97, 127.85, 131.43, 132.25, 136.80,
=
137.67, 148.56, 159.42, 164.23, and 168.35 (11C), 191.28 (C S) ppm.
3.1.4. 5-(4-Bromophenyl) 1,3-dimethyl 7-thioxo-7,8-dihydro1H-pyrimido[4,5,d]pyrimidine-
2,4-dione (4d)
Yellow powder; m.p. 202–204◦C, IR (KBr) (νmax cm−1): 3350, 1707, 1623, 1530, 1441.Analyses:
Calcd. for C14H11BrN4O2S: C, 44.34; H, 2.92; N, 14.77%. Found: C, 44.50; H, 3.05; N, 14.90.
MS (m/z, %): 379 (M+, 5); 381 (M+2, 4.97); 155 (100). 1H NMR (500 MHz, DMSO-d6): δ 3.19
and 3.34 (6 H, 2s, 2CH3), 7.64 (2 H, d, 3JHH = 8 Hz, 2 CH of C6H4Br), 7.91 (2 H, d, 3JHH = 8 Hz,
2 CH of C6H4Br), 15.51 (1 H, s, NH) ppm. 13C NMR (125.8 MHz, DMSO-d6): δ 29.38 and 31.53
(2CH3), 93.85, 123.48, 127.69, 133.14, 138.46, 149.46, 159.58, 164.26, and 164.49 (9C), 191.46
=
(C S) ppm.
3.1.5. 5-(4-Chlorophenyl) 1,3-dimethyl 7-thioxo-7,8-dihydro1H-pyrimido[4,5,d]pyrimidine-
2,4-dione (4e)
Yellow powder; m.p. 207–209◦C, IR (KBr) (νmax cm−1): 3352, 1705, 1627, 1536, 1440.Analyses:
Calcd. for C14H11ClN4O2S: C, 50.23; H, 3.31; N, 16.74%. Found: C, 50.10; H, 3.44; N, 16.85.
MS (m/z, %): 334 (M+, 7); 336 (M+2, 2.2); 112 (100). 1H NMR (500 MHz, DMSO-d6): δ 3.21
and 3.35 (6 H, 2s, 2CH3), 7.57 (2 H, d, 3JHH = 8 Hz, 2 CH of C6H4Cl), 8.11 (2 H, d, 3JHH = 8 Hz,
2 CH of C6H4Cl), 15.51 (1 H, s, NH) ppm.13C NMR (125.8 MHz, DMSO-d6): δ 29.27 and 31.45
(2CH3), 93.62, 126.72, 129.95, 132.27, 135.22, 148.53, 159.17, 164.26, and 165.53 (9C), 194.28
=
(C S) ppm.
3.1.6. 5-(3-Nitrophenyl) 1,3-dimethyl 7-thioxo-7,8-dihydro1H-pyrimido[4,5,d]pyrimidine-
2,4-dione (4f)
Yellow powder; m.p. 200–202◦C, IR (KBr) (νmax cm−1): 3450, 1709, 1631, 1533, 1436, 1373.
Analyses: Calcd. for C14H11N5O4S: C, 48.69; H, 3.21; N, 20.28%. Found: C, 48.55; H, 3.30; N,
20.41. MS(m/z, %):345(M+, 5);122(100). 1HNMR(500 MHz, DMSO-d6):δ 3.23and3.34(6 H,
2s, 2CH3), 7.89–8.68 (4 H, m, 4CH aromatic), 15.59 (1 H, s, NH) ppm. 13C NMR (125.8 MHz,