Jamalian et al.
imidazole C4-H), 6.98 (s, 1H, imidazole C2-H). 7.31-7.43 (m,
dimedone following the above general procedure by refluxing
for 4 h. (81% yield), m.p.: 278-280 ºC, IR (potassium
bromide): 3433 (NH), 1677 (C=O) cm-1, 1H NMR (DMSO-d6)
δ: 0.99 and 1.07 (2s, 12H, gem-dimethyl), 2.02-2.20 (2d, 4H,
C4 and C5-CH2, J = 16.1 Hz), 2.30-2.44 (2d, 4H, C2 and C7-
CH2, J = 17.1 Hz), 4.77 (s, 1H, C9-H), 9.36 (s, 1H, NH), EI-
MS m/z (%) 409 (M++2, 60) 407 (M+, 100), 342 (73), 307
(49), 305 (18), 272 (15), 835 (15).
9-(1-Methyl-1H-imidazol-5-yl)-3,3,6,6-tetramethyl-3,4,
6,7,9,10-hexahydro-2H,5H-acridine-1,8-dione (12d). This
compound was obtained from 1-methyl-1H-imidazole-4-
carbaldehyde (10d) (110.11 mg, 1 mmol) and dimedone
following the above general procedure by refluxing for 6.5 h
(79% yield), m.p.: 279-281 ºC, IR (potassium bromide): 3421
(NH), 1657 (C=O), 1530 (C=C) cm-1, 1H NMR (DMSO-d6) δ:
0.88 and 1.00 (2s, 12H, gem-dimethyl), 2.02-2.10 (2d, 4H, C4
and C5-CH2, J = 16.0 Hz), 2.33-2.48 (2d, 4H, C2 and C7-CH2,
J = 16.9 Hz), 3.04 (s, 3H, N-CH3), 4.58 (s, 1H, C9-H), 6.33 (s,
1H, imidazole C3-H), 7.21 (s, 1H, imidazole C5-H), 9.34 (s,
1H, NH), EI-MS m/z (%) 353 (M+, 100), 268 (49), 226 (14),
143 (14), 98 (14), 82 (79).
9-(1-Methyl-2-methylthio-1H-imidazol-5-yl)-3,3,6,6-
tetramethyl-3,4,6,7,9,10-hexahydro-2H,5H-acridine-1,8-
dione (12e). This compound was obtained from 1-methyl-2-
methylthio-1H-imidazole-4-carbaldehyde (10e) (156 mg, 1
mmol) and dimedone following the above general procedure
by refluxing for 8 h (50% yield), m.p. > 300 ºC, IR (potassium
bromide): 3445 (NH), 1645 (C=O) cm-1, 1H NMR (DMSO-d6)
δ: 0.93 and 1.05 (2s, 12H, gem-dimethyl), 2.15-2.24 (2d, 4H,
C4 and C5-CH2, J = 15.8 Hz), 2.39-2.1 (2d, 4H, C2 and C7-
CH2, J = 16.5 Hz), 3.8 (s, 3H, S-CH3), 4.64 (s, 1H, C9-H), 6.49
(s, 1H, C3-H imidazole), 9.5 (s, 1H, NH), EI-MS m/z (%) 399
( M+, 100), 385 (35), 314 (8), 294 (13), 271 (27), 182 (13), 82
(13).
5H, Ar-H), 8.28 (s, 1H, NH), EI-MS m/z (%) 429 (M+, 9), 272
(100), 188 (11), 83 (5).
General procedure for synthesis of 9-substituted-3,3,6,
6-tetramethyl-3,4,6,7-tetrahydro-2H,5H-acridine-1,8-dione
(13a-f). To a solution of 9-substituted-3,3,6,6-tetramethyl-
3,4,6,7,9,10-hexahydro-2H,5H-acridine-1,8-dione (1 mmol) in
dichloromethane (5 ml) was added silica coated sulfuric acid
(1.52 g, 4 mmoles), wet SiO2 (50% w/w) (0.4 g) and NaNO2
(0.257 g, 4 mmol) were added [16]. The resulting mixture was
gradually heated and refluxed for variable time (3-7 h)
monitored by TLC. The reaction mixture was filtered and the
residue was washed with CH2Cl2. Anhydrous Na2SO4 (1 g)
was added to the filtrate. The resulting mixture was filtered
again. Dichloromethane was evaporated and the brownish to
red solids were crystallized from methanol to afford the
compound.
9-(1H-Imidazol-2-yl)-3,3,6,6-tetramethyl-3,4,6,7-tetra-
hydro-2H,5H-acridine-1,8-dione (13a). Compound 12a
(339.43 mg) was dissolved in dichloromethane. Following the
above general procedure and refluxing for 7 h the desired
compound was obtained in 53% yield, m.p. > 300 ºC, IR
1
(potassium bromide): 1698 (C=O) cm-1, H NMR (DMSO-d6)
δ: 1.16 (s, 12H, gem-dimethyl), 2.08 and 2.49 (2s, 8H, C2, C4,
C5 and C7-CH2), 7.99-8.88 (2d, 2H, imidazole-H), EI-MS m/z
(%) 337 (M+, 8), 322 (3), 269 (53), 176 (66), 98 (36), 55
(100).
9-(1-Methyl-5-nitro-1H-imidazol-2-yl)-3,3,6,6-tetra-
methyl-3,4,6,7-tetrahydro-2H,5H-acridine-1,8-dione (13b).
The acridinedione 12b (397.53 mg, 1 mmol) was dissolved in
dichloromethane. Following the above general procedure by
refluxing for 11 h, the desired compound was obtained in 66%
yield, m.p. > 300 ºC, IR (potassium bromide): 1677 (C=O),
1
1509 and 1378 (NO2) cm-1, H NMR (DMSO-d6) δ: 0.93 &
1.05 (2s, 12H, gem-dimethyl), 2.15 and 2.24 (2s, 8H, C2, C4,
C5 and C7-CH2), 4.19 (s, 3H, N-CH3), 7.90 (s, 1H, imidazole-
H), EI-MS m/z (%) 396 (M+, 100), 381 (25), 312 (47), 271
(32), 215 (18), 161 (18), 81 (18), 53 (32).
9-(1-Benzyl-1H-imidazol-5-yl)-3,3,6,6-tetramethyl-3,4,6,
7,9,10-hexahydro-2H,5H-acridine-1,8-dione (12f). This
compound was obtained from 1-benzyl-1H-imidazole-5-
carbaldehyde (10f) (186.21 mg, 1 mmol) and dimedone
following the above general procedure by refluxing for 3.5 h.
(82% yield), m.p. > 300 ºC, IR (potassium bromide): 3440
9-(4,5-Dichloro-1H-imidazol-2-yl)-3,3,6,6-tetramethyl-
3,4,6,7-tetrahydro-2H,5H-acridine-1,8-dione
(13c).
1
(NH), 1648 (C=O) cm-1, H NMR (DMSO-d6) δ: 0.92 and
Compound 12c (406.31 mg, 1 mmol) was dissolved in
dichloromethane. Following the above general procedure by
refluxing for 5 h, the desired compound was obtained in 50%
yield, m.p.: 278-280 ºC, IR (potassium bromide): 3421 (NH),
1.03 (2s, 12H, gem-dimethyl), 2.00-2.20 (2d, 4H, C4 and C5-
CH2, J = 16.0), 2.27-2.44 (2d, 4H, C2 and C7-CH2, J = 16.7
Hz), 4.83 (s, 1H, C9-H), 5.42 (s, 2H, benzyl CH2), 6.45 (s, 1H,
986