366
Helvetica Chimica Acta – Vol. 91 (2008)
(pos.): 418 (100, [M þ H]þ), 401 (3, [M þ HꢀNH3]þ), 311 (11, [M þ HꢀNH3ꢀMeC6H3]þ), 283 (51,
[M þ HꢀNH3ꢀMeC6H3ꢀCO]þ). APCI-MS/MS (pos.) of m/z 418: 401 (52, [M þ HꢀNH3]þ), 375 (8,
[M þ HꢀNHCO]þ), 311 (100, [M þ HꢀNH3ꢀMeC6H3]þ), 285 (54, [M þ HꢀC6H5CH2NCO]þ).
APCI-MS (neg.): 416 (100, [M ꢀ H]ꢀ), 282 (41, [M ꢀ HꢀPhꢀBu]ꢀ), 255 (3, [M ꢀ HꢀPhꢀBu ꢀ
HCN]ꢀ). APCI-MS/MS (neg.) of m/z 416: 283 (100, [M ꢀ HꢀPhꢀbutene]ꢀ). Anal. calc. for
C28H23N3O (417.50): C 80.55, H 5.55, N 10.06; found: C 80.42, H 5.67, N 10.11.
2.17. 4-(2-Acetamidophenyl)-1-benzyl-3,5-diphenyl-1,3-dihydro-2H-imidazol-2-one (¼ N-[2-(1-Ben-
zyl-2-oxo-3,5-diphenyl-2,3-dihydro-1H-imidazol-4-yl)phenyl]acetamide; 8n). Prepared from 6n (Method
D, besides 4n and 6n). Colorless crystals. M.p. 237– 241 8 (benzene/hexane). IR: 3341, 3335, 3061, 2953,
1677, 1595, 1579, 1520, 1493, 1453, 1383, 1296, 1253, 1231, 1158, 1125, 1042, 1015, 957, 887, 820, 781, 763,
1
747, 736, 710, 700, 651, 592, 519, 502. H- and 13C-NMR: see Table 4. APCI-MS (pos.): 460 (100, [M þ
H]þ), 416 (15, [M þ HꢀNCO]þ). APCI-MS/MS (pos.) of m/z 460: 442 (50, [M þ H ꢀ H2O]þ), 418
(32, [M þ HꢀNCO]þ), 401 (9, [M þ HꢀNCOꢀNH3]þ), 369 (100, [M þ HꢀMeC6H4]þ), 352 (12,
[M þ HꢀMeC6H4ꢀNH3]þ), 327(48, [ M þ HꢀMeC6H4ꢀNCO]þ), 309 (11, [M þ HꢀMeC6H4ꢀ
NCO ꢀ H2O]þ). APCI-MS (neg.): 458 (100, [M ꢀ H]ꢀ), 416 (5, [M ꢀ HꢀNCO]ꢀ). APCI-MS/MS
(neg.) of m/z 458: 416 (12, [M ꢀ HꢀNCO]ꢀ), 325 (55, [M ꢀ HꢀC6H5CH2NCO]ꢀ), 282 (100, [M ꢀ
HꢀC6H5CH2NCOꢀNCO]ꢀ). Anal. calc. for C30H25N3O2 (459.54): C 78.41, H 5.48, N 9.14; found: C
78.29, H 5.62, N 9.09.
3. General Procedure for the Preparation of 4-(2-Aminophenyl)-1,3-dihydro-2H-imidazol-2-ones (6)
from Compounds 2, 3, 4, and 8 (Method C). A soln. of respective starting compound 2, 3, 4, and 8
(2.5 mmol) in conc. HCl (25 ml) was heated to reflux for the time given in Table 2. If necessary, AcOH
was added to dissolve poorly soluble starting compound. After cooling, the soln. was evaporated in vacuo
to dryness. The residue was dissolved in pyridine (5 ml), anh. K2CO3 (350 mg) was added and the mixture
was stirred for 1 h. The insoluble material was filtered off, the filtrate was evaporated to dryness, and the
residue was crystallized from an appropriate solvent or separated by CC on silica gel.
3.1. 5-(2-Aminophenyl)-1,4-dibutyl-1,3-dihydro-2H-imidazol-2-one (6a). Prepared from 2a and 3a.
Colorless crystals. M.p. 134 – 1398 (benzene/cyclohexane), identical in all respects to authentic 6a of
m.p. 135 – 1408, prepared from 4a [9].
3.2. 5-(2-Aminophenyl)-4-butyl-1-phenyl-1,3-dihydro-2H-imidazol-2-one (6b). Prepared from 2b.
Colorless crystals. M.p. 134 – 1408 (without recrystallization), identical in all respects to authentic 6b of
m.p. 138 – 1418, prepared from 4b [9].
3.3. 5-(2-Aminophenyl)-1-butyl-4-phenyl-1,3-dihydro-2H-imidazol-2-one (6c). Prepared from 2c, 3c,
and 4c. Colorless crystals. M.p. 167– 169 8 (benzene/hexane). IR: 3457, 3345, 3142, 3057, 2959, 2933, 2871,
1675, 1615, 1604, 1574, 1506, 1490, 1453, 1403, 1376, 1361, 1310, 1264, 1158, 1115, 1077, 1031, 969, 935, 908,
751, 693, 665, 520, 498. 1H- and 13C-NMR: see Table 5. APCI-MS (pos.): 308 (100, [M þ H]þ), 291 (59,
[M þ HꢀNH3]þ), 263 (28, [M þ HꢀCOOH]þ). APCI-MS/MS (pos.) of m/z 308: 291 (100, [M þ
HꢀNH3]þ), 265 (15, [M þ HꢀNHCO]þ), 252 (21, [M þ Hꢀbutene]þ), 235 (22, [M þ HꢀNH3ꢀ
butene]þ), 209 (29, [M þ HꢀBuNCO]þ). APCI-MS (neg.): 306 (100, [M ꢀ H]ꢀ), 261 (11, [M ꢀ
HꢀCOOH]ꢀ), 233 (4, [M ꢀ HꢀBuNH2]ꢀ). APCI-MS/MS (neg.) of m/z 306: 263 (82, [M ꢀ
HꢀNHCO]ꢀ), 249 (92, [M ꢀ HꢀBu]ꢀ), 206 (100, [M ꢀ HꢀBuꢀNHCO]ꢀ). Anal. calc. for C19H21N3O
(307.39): C 74.24, H 6.89, N 13.67; found: C 74.29, H 6.98, N 13.53.
3.4. 5-(2-Aminophenyl)-1,4-diphenyl-1,3-dihydro-2H-imidazol-2-one (6d). Prepared from 2d and 4d.
Colorless crystals. M.p. 297– 309 8 (benzene/dioxane). IR: 3432, 3333, 3134, 3061, 3030, 2978, 2878, 2762,
1674, 1622, 1596, 1492, 1454, 1392, 1309, 1256, 1151, 1072, 1030, 915, 853, 776, 764, 747, 709, 693, 664, 649,
549, 504. 1H- and 13C-NMR: see Table 5. APCI-MS (pos.): 328 (100, [M þ H]þ), 311 (4, [M þ
HꢀNH3]þ), 283 (99, [M þ HꢀCOOH]þ), 208 (3, [M þ HꢀCOOHꢀC6H3]þ). APCI-MS/MS (pos.)
of m/z 328: 311 (82, [M þ HꢀNH3]þ), 285 (78, [M þ HꢀNHCO]þ), 235 (48, [M þ HꢀNH3ꢀC6H4]þ),
209 (100, [M þ HꢀNHCOꢀC6H4]þ), 182 (51, [M þ HꢀNHCOꢀC6H4-HCN]þ). APCI-MS (neg.): 326
(66, [M ꢀ H]ꢀ), 282 (100, [M ꢀ HꢀNH2CO]ꢀ), 255 (31, [M ꢀ HꢀNH2CO ꢀ HCN]ꢀ). APCI-MS/MS
(neg.) of m/z 326: 283 (100, [M ꢀ HꢀNHCO]ꢀ). Anal. calc. for C21H17N3O (327.38): C 77.04, H 5.23, N
12.84; found: C 76.85, H 5.35, N 12.71.
3.5. 4-(2-Aminophenyl)-3,5-dibutyl-1-methyl-1,3-dihydro-2H-imidazol-2-one (6e). Prepared from 3e
and 4e. Colorless crystals. M.p. 74 – 788 (hexane). IR: 3401, 3337, 3226, 3028, 2957, 2931, 2866, 1668, 1632,