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Organic & Biomolecular Chemistry
134.2, 133.4, 132.3, 131.3, 130.0, 128.6, 128.3, 128.0, 126.1, 1H), 7.86 (s, 1H), 7.52 (d, J = 8.1 Hz, 1H), 7.45 (dd, J = 8.1,
125.5, 121.9, 115.1, 112.2; IR (ν, cm−1) 3296, 3075, 1653, 1618, 6.8 Hz, 1H), 7.38 (dd, J = 8.3, 6.8 Hz, 1H), 6.98 (d, J = 8.6 Hz,
1597, 1576, 1506, 1478, 1450, 1398, 1321, 1266, 1245, 1227, 1H), 4.60 (q, J = 7.1 Hz, 2H), 3.98 (s, 6H), 1.56 (t, J = 7.1 Hz,
1185, 1116, 1014; HRMS calcd for C21H14N2O2 326.1055, found 3H); 13C NMR (CDCl3, 100.6 MHz) δ 184.7, 153.9, 148.8, 146.6,
326.1045.
141.9, 135.4, 129.7, 127.3, 125.3, 123.4, 121.9, 112.3, 110.4,
(5-Nitro-1H-benzo[d]imidazol-2-yl)(phenyl)methanone
4e. 110.1, 56.2, 56.0, 40.5, 15.6; IR (ν, cm−1) 2974, 2936, 2842,
The general procedure was followed using the benzimidazole 1642, 1593, 1579, 1517, 1482, 1468, 1419, 1335, 1297, 1262,
3e (100 mg, 0.39 mmol). The crude product was purified using 1238, 1210, 1178, 1133, 1025, 1004; HRMS calcd for
silica gel column chromatography (CH2Cl2). 31 mg (29%) of C18H18N2O3 310.1317, found 310.1316.
the desired adduct (yellow solid, M.p.: 256–257 °C) were iso-
(1-(4-(tert-Butyl)benzyl)-1H-benzo[d]imidazol-2-yl)(p-tolyl)-
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lated. Rf 0.9 (8 : 2 CH2Cl2–AcOEt); H NMR (DMSO, 400 MHz) methanone 4j. The general procedure was followed using the
δ 14.17 (s, 1H), 8.70 (br s, 1H), 8.56 (d, J = 7.1 Hz, 2H), 8.26 (d, benzimidazole 3j (100 mg, 0.27 mmol). The crude product was
J = 8.3 Hz, 1H), 7.90 (br s, 1H), 7.78 (dd, J = 7.6, 7.3 Hz, 1H), purified using silica gel column chromatography (CH2Cl2).
7.65 (dd, J = 7.3, 7.1 Hz, 2H); 13C NMR (DMSO, 100.6 MHz) 87 mg (84%) of the desired adduct (white solid, M.p.:
δ 138.3, 151.5, 144.0, 135.0, 134.2, 131.0, 128.6, 119.8, 116.5, 146–147 °C) were isolated. Rf 0.6 (100% CH2Cl2); 1H NMR
116.0; IR (ν, cm−1) 3267, 2151, 2022, 1963, 1635, 1590, 1572, (CDCl3, 400 MHz) δ 8.23 (d, J = 8.1 Hz, 2H), 7.96 (d, J = 7.6 Hz,
1534, 1346, 1332, 1265, 1018; HRMS calcd for C14H9N3O3 1H), 7.47 (d, J = 7.6 Hz, 1H), 7.42–7.27 (m, 6H), 7.15 (d, J =
267.0644, found 267.0653.
7.8 Hz, 2H), 5.82 (s, 2H), 2.45 (s, 3H), 1.26 (s, 9H); 13C NMR
(5-Methyl-1H-benzo[d]imidazol-2-yl)(thiophen-2-yl)metha- (CDCl3, 100.6 MHz) δ 186.1, 150.5, 146.6, 144.5, 141.9, 136.0,
none and (6-methyl-1H-benzo[d]imidazol-2-yl)(thiophen-2- 134.3, 133.6, 131.3, 129.0, 126.5, 125.6, 123.6, 122.0, 111.1,
yl)methanone 4g. The general procedure was followed using 48.2, 34.4, 31.2, 21.8; IR (ν, cm−1) 2964, 2866, 1642, 1607,
the benzimidazole 3g (100 mg, 0.44 mmol). The crude product 1520, 1478, 1450, 1398, 1335, 1269, 1175, 1011; HRMS calcd
was purified using silica gel column chromatography (CH2Cl2). for C26H26N2O 382.2045, found 382.2047.
61 mg (57%) of the desired adduct (yellow solid, M.p.:
(1-(But-3-en-1-yl)-1H-benzo[d]imidazol-2-yl)(3,4-dimethoxy-
174–175 °C) were isolated as an inseparable 4 : 6 mixture of 2 phenyl)methanone 4k. The general procedure was followed
isomers. Rf 0.7 (100% CH2Cl2); 1H NMR (CDCl3, 400 MHz) δ using the benzimidazole 3k (96 mg, 0.30 mmol). The crude
10.74 (br s, 0.4H), 10.67 (br s, 0.6H), 8.93–8.91 (m, 1H), product was purified using silica gel column chromatography
7.84–7.82 (m, 1.6H), 7.74 (s, 0.4H), 7.49 (d, J = 8.3 Hz, 0.4H), (CH2Cl2–AcOEt). 76 mg (76%) of the desired adduct (yellow
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7.38 (s, 0.6H), 7.28–7.26 (m, 1.4H), 7.20 (d, J = 8.3 Hz, 0.6H), oil) were isolated. Rf 0.8 (8 : 2 CH2Cl2–AcOEt); H NMR (CDCl3,
2.52 (s, 1.8H), 2.51 (s, 1.2H); 13C NMR (CDCl3, 100.6 MHz) 400 MHz) δ 8.11 (d, J = 8.3 Hz, 1H), 7.91 (d, J = 8.1 Hz, 1H),
δ 175.9, 175.8, 147.3, 146.9, 144.2, 142.1, 140.5, 140.4, 137.8, 7.82 (s, 1H), 7.49 (d, J = 8.1 Hz, 1H), 7.44 (dd, J = 8.1, 7.1 Hz,
137.7, 136.9, 136.8, 136.5, 136.4, 133.7, 133.6, 128.6, 128.3, 1H), 7.36 (dd, J = 8.1, 7.1 Hz, 1H), 6.96 (d, J = 8.3 Hz, 1H), 5.80
125.8, 121.5, 121.4, 111.6, 111.5, 22.1, 21.7; IR (ν, cm−1) 3281, (ddt, J = 16.9, 10.1, 7.1 Hz, 1H), 5.02 (d, J = 16.9 Hz, 1H), 4.99
1611, 1527, 1412, 1356, 1325, 1269, 1053, 1001; HRMS calcd (d, J = 10.1 Hz, 1H), 4.62 (t, J = 7.1 Hz, 2H), 3.97 (s, 6H),
for C13H10N2OS 242.0514, found 242.0507.
2.68–2.63 (m, 2H); 13C NMR (CDCl3, 100.6 MHz) δ 184.9, 153.9,
(1H-Benzo[d]imidazol-2-yl)(phenyl)methanone
4h. The 148.8, 146.8, 141.8, 135.6, 134.0, 129.7, 127.4, 125.3, 123.4,
general procedure was followed using the benzimidazole 3h 121.9, 117.9, 112.3, 110.6, 110.0, 56.1, 56.0, 44.6, 34.6; IR
(100 mg, 0.48 mmol). The crude product was purified using (ν, cm−1) 3058, 3009, 2939, 2915, 2838, 1642, 1593, 1583, 1513,
silica gel column chromatography (CH2Cl2). 22 mg (21%) of 1478, 1461, 1419, 1336, 1266, 1234, 1175, 1133, 1021; HRMS
the desired adduct (white solid, M.p.: 218–219 °C) were iso- calcd for C20H20N2O3 336.1474, found 336.1483.
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lated. Rf 0.8 (9 : 1 CH2Cl2–AcOEt); H NMR (CDCl3, 400 MHz)
N-Cyclohexyl-2-(2-(3,4-dimethoxybenzoyl)-1H-benzo[d]imida-
δ 10.76 (br s, 1H), 8.71 (d, J = 7.1 Hz, 2H), 7.98 (d, J = 8.1 Hz, zol-1-yl)butanamide 4n. The general procedure was followed
1H), 7.66 (d, J = 7.3 Hz, 1H), 7.62–7.55 (m, 3H), 7.45 (dd, J = using the Ugi adduct 3n (100 mg, 0.23 mmol). The crude
8.1, 7.1 Hz, 1H), 7.38 (dd, J = 7.3, 7.1 Hz, 1H); 13C NMR product was purified by flash chromatography on silica gel
(CDCl3, 100.6 MHz) δ 184.0, 147.7, 143.9, 135.3, 133.9, 133.1, (CH2Cl2–AcOEt). 83 mg (80%) of the desired adduct (colorless
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131.3, 128.5, 126.5, 123.8, 122.3, 112.0; IR (ν, cm−1) 3302, oil) were isolated. Rf 0.8 (8 : 2 CH2Cl2–AcOEt); H NMR (CDCl3,
3065, 1646, 1600, 1579, 1510, 1489, 1422, 1321, 1262, 1182, 400 MHz) δ 8.06 (d, J = 8.6 Hz, 1H), 7.89 (d, J = 7.1 Hz, 1H),
1147, 1039, 1021; HRMS calcd for C14H10N2O 222.0793, found 7.79–7.77 (m, 2H), 7.40–7.34 (m, 2H), 6.99 (d, J = 8.6 Hz, 1H),
222.0796.
6.88 (s, 1H), 5.30–5.26 (m, 1H), 3.99 (s, 3H), 3.98 (s, 3H),
(3,4-Dimethoxyphenyl)(1-ethyl-1H-benzo[d]imidazol-2-yl)- 3.80–3.75 (m, 1H), 2.34–2.20 (m, 2H), 1.97–1.94 (m, 1H),
methanone 4i. The general procedure was followed using the 1.70–1.62 (m, 2H), 1.52–1.51 (m, 2H), 1.39–1.20 (m, 4H),
benzimidazole 3i (50 mg, 0.17 mmol). The crude product was 0.98–0.90 (m, 1H), 0.62 (t, J = 7.3 Hz, 3H); 13C NMR (CDCl3,
purified using silica gel column chromatography (CH2Cl2– 100.6 MHz) δ 185.8, 167.1, 154.8, 149.1, 148.3, 142.1, 134.1,
AcOEt). 47 mg (90%) of the desired adduct (yellow solid, M.p.: 128.9, 128.2, 125.6, 123.8, 121.7, 113.6, 111.9, 110.2, 61.1, 56.2,
82–83 °C) were isolated. Rf 0.9 (100% CH2Cl2); 1H NMR 56.0, 48.4, 32.7, 32.5, 25.4, 24.6, 24.4, 21.8, 10.3; IR (ν, cm−1
(CDCl3, 400 MHz) δ 8.16 (d, J = 8.6 Hz, 1H), 7.93 (d, J = 8.3 Hz, 2932, 2859, 1649, 1607, 1520, 1485, 1447, 1395, 1332, 1272,
)
3286 | Org. Biomol. Chem., 2013, 11, 3282–3287
This journal is © The Royal Society of Chemistry 2013