The Journal of Organic Chemistry
Note
5H), 6.54 (dd, J = 11.2, 7.7 Hz, 1H), 6.44 (dd, J = 12.3, 7.7 Hz, 1H),
4.23 (s, 2H), 3.36 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 144.7 (dd,
J = 236.7, 12.6 Hz), 143.0 (dd, J = 236.7, 12.6 Hz), 138.7, 134.11 (d, J
= 5.9 Hz), 130.08 (d, J = 5.1 Hz), 128.9, 127.9, 127.7, 105.54 (d, J =
20.6 Hz), 101.43 (d, J = 21.9 Hz), 49.0. HRMS (EI) calcd for
C13H12F2N2 [M]+, 234.0969; found, 234.0970.
(4-Amino-3-(benzylamino)phenyl)(phenyl)methanone (1t).
Eluent: petroleum ether/ethyl acetate = 3:1. Yield 77% (2328 mg).
Light yellow solid, mp 92−93 °C. 1H NMR (400 MHz, CDCl3) δ 7.68
(d, J = 7.1 Hz, 2H), 7.52 (t, J = 7.4 Hz, 1H), 7.45−7.27 (m, 8H), 7.24
(dd, J = 8.1, 1.6 Hz, 1H), 6.71 (d, J = 8.0 Hz, 1H), 4.31 (s, 2H), 3.80
(s, 3H). 13C NMR (126 MHz, CDCl3) δ 196.0, 140.6, 139.0, 138.9,
136.0, 131.4, 129.7, 129.1, 128.8, 128.1, 128.0, 127.5, 124.5, 114.4,
114.2, 48.8. HRMS (EI) calcd for C20H18N2O [M]+, 302.1419; found,
302.1415.
mp 303−304 °C. 1H NMR (300 MHz, CD3OD) δ 8.39 (d, J = 8.9 Hz,
2H), 8.29 (d, J = 8.9 Hz, 2H), 7.64 (s, 2H), 7.31 (dd, J = 6.1, 3.1 Hz,
2H). 13C NMR (151 MHz, DMSO) δ 149.0, 147.8, 136.0, 127.4,
124.3, 123.3, 122.5, 119.5, 111.9. HRMS (EI) calcd for C13H9N3O2
[M]+, 239.0695; found, 239.0687.
2-(3-Chlorophenyl)-1H-benzo[d]imidazole (2f). Eluent: petro-
leum ether/ethyl acetate = 3:1. Yield 94% (86 mg). White solid, mp
233−235 °C. 1H NMR (300 MHz, CD3OD) δ 8.13 (tt, J = 2.1, 0.9 Hz,
1H), 8.01 (dddd, J = 7.0, 2.7, 1.9, 0.9 Hz, 1H), 7.69−7.47 (m, 4H),
7.28 (dt, J = 5.5, 3.7 Hz, 2H). 13C NMR (101 MHz, CD3OD) δ 151.7,
136.2, 132.9, 131.8, 131.1, 127.7, 126.0, 124.3. HRMS (EI) calcd for
C13H9ClN2 [M]+, 228.0454; found, 228.0455.
2-(2,6-Dimethylphenyl)-1H-benzo[d]imidazole (2g). Eluent:
petroleum ether/ethyl acetate = 3:1. Yield 95% (84 mg). White solid,
mp 294−296 °C. 1H NMR (400 MHz, CDCl3) δ 7.51 (s, 2H), 7.32−
7.24 (m, 3H), 7.11 (d, J = 7.6 Hz, 2H), 2.10 (s, 6H). 13C NMR (151
MHz, CD3OD) δ 153.2, 139.1, 132.3, 130.7, 128.5, 123.6, 20.00.
HRMS (EI) calcd for C15H14N2 [M]+, 222.1157; found, 222.1154.
2-(1H-Benzo[d]imidazol-2-yl)benzonitrile (2h). Eluent: petro-
leum ether/ethyl acetate = 1:1. Yield 41% (36 mg). White solid, mp
N2-Benzylnaphthalene-2,3-diamine (1u). Eluent: petroleum
ether/ethyl acetate = 3:1. Yield 74% (1843 mg). Light gray solid,
mp 125−126 °C. 1H NMR (300 MHz, CDCl3) δ 7.62−7.51 (m, 2H),
7.47−7.28 (m, 5H), 7.25−7.16 (m, 2H), 7.06 (s, 1H), 6.93 (s, 1H),
4.42 (s, 2H), 4.00 (s, 1H), 3.57 (s, 2H). 13C NMR (126 MHz, CDCl3)
δ 139.0, 138.8, 135.6, 130.2, 128.7, 128.6, 128.0, 127.5, 125.9, 125.5,
123.4, 122.9, 111.4, 106.2, 48.7. HRMS (EI) calcd for C17H16N2 [M]+,
248.1313; found, 248.1319.
General Procedure for the Synthesis of Benzimidazoles and
Benzoxazoles. Method A. To a solution of N-substituted 1,2-
phenylenediamines/2-(benzylamino)phenol (0.4 mmol, 1 equiv) in
DMF (4 mL) was added TEMPO (0.8 mmol, 2 equiv), and the
mixture was stirred at 110 °C for 5 h. The mixture was then diluted
with AcOEt, washed with water and a saturated NaCl(aq) solution,
and dried over anhydrous Na2SO4. After filtration, the filtrate was
concentrated in vacuo. The residue was purified by silica gel column
chromatography and subsequently washed with n-hexane.
1
252−254 °C. H NMR (300 MHz, CD3OD) δ 8.01−7.91 (m, 2H),
7.84 (td, J = 7.7, 1.4 Hz, 1H), 7.69 (td, J = 7.7, 1.3 Hz, 3H), 7.32 (dd, J
= 6.1, 3.2 Hz, 2H). 13C NMR (151 MHz, CD3OD) δ 150.2, 135.7,
134.5, 134.4, 131.5, 131.1, 124.5, 118.8, 112.5. HRMS (EI) calcd for
C14H9N3 [M]+, 219.0796; found, 219.0791.
2-(Pyridin-4-yl)-1H-benzo[d]imidazole (2i). Eluent: petroleum
ether/ethyl acetate = 1:1. Yield 92% (72 mg). White solid, mp 219−
1
221 °C. H NMR (300 MHz, CD3OD) δ 8.72 (d, J = 6.4 Hz, 2H),
8.08 (d, J = 6.4 Hz, 2H), 7.77−7.55 (m, 2H), 7.33 (dd, J = 6.3, 3.1 Hz,
2H). 13C NMR (151 MHz, CD3OD) δ 151.1, 150.0, 139.2, 125.0,
122.1. HRMS (EI) calcd for C12H9N3 [M]+, 195.0796; found,
195.0795.
Method B. To a solution of N-substituted 1,2-phenylenediamine/2-
(benzylamino)phenol (0.4 mmol, 1 equiv) in DMF (4 mL) was added
TEMPO (0.04 mmol, 0.1 equiv), and the reaction tube was sealed and
flushed with O2. Then, the mixture was stirred at 120 °C for 5 h. The
mixture was then diluted with AcOEt, washed with water and a
saturated NaCl( aq) solution, and dried over anhydrous Na2SO4. After
filtration, the filtrate was concentrated in vacuo. The residue was
purified by silica gel column chromatography and subsequently
washed with n-hexane.
(E)-2-Styryl-1H-benzo[d]imidazole (2j). Eluent: petroleum
ether/ethyl acetate = 1:1. Yield 72% (63 mg). Light yellow solid,
1
mp 201−203 °C. H NMR (300 MHz, CD3OD) δ 7.67−7.49 (m,
5H), 7.45−7.30 (m, 3H), 7.27−7.20 (m, 2H), 7.15 (d, J = 16.6 Hz,
1H). 13C NMR (101 MHz, CD3OD) δ 152.5, 137.1, 136.9, 130.2,
130.0, 128.2, 124.0, 117.3, 115.7. HRMS (EI) calcd for C15H12N2
[M]+, 220.1000; found, 220.0969.
2-Cyclohexyl-1H-benzo[d]imidazole (2k). Eluent: petroleum
ether/ethyl acetate = 1:1. Yield 79% (63 mg). White solid, mp 284−
1
286 °C. H NMR (300 MHz, CD3OD) δ 7.48 (d, J = 7.3 Hz, 2H),
2-Phenyl-1H-benzo[d]imidazole (2a). Eluent: petroleum ether/
ethyl acetate = 3:1. Yield 96% (75 mg). White solid, mp 296−298 °C.
1H NMR (400 MHz, CD3OD) δ 8.12−8.06 (m, 2H), 7.61 (dd, J = 6.0,
7.21−7.12 (m, 2H), 2.90 (tt, J = 11.9, 3.5 Hz, 1H), 2.08 (ddd, J = 13.3,
3.6, 1.6 Hz, 2H), 1.89 (dt, J = 12.6, 3.3 Hz, 2H), 1.83−1.59 (m, 3H),
1.41 (tddd, J = 24.7, 15.6, 12.3, 3.3 Hz, 3H). 13C NMR (101 MHz,
CD3OD) δ 160.8, 123.1, 115.2, 39.8, 32.8, 27.2, 27.0. HRMS (EI)
calcd for C13H16N2 [M]+, 200.1313; found, 200.1308.
3.2 Hz, 2H), 7.56−7.45 (m, 3H), 7.26 (dd, J = 6.1, 3.1 Hz, 2H). 13C
NMR (151 MHz, CD3OD) δ 153.3, 131.4, 131.0, 130.1, 127.8, 123.9.
HRMS (EI) calcd for C13H10N2 [M]+, 194.0844; found, 194.0840.
2-(4-Chlorophenyl)-1H-benzo[d]imidazole (2b). Eluent: petro-
leum ether/ethyl acetate = 3:1. Yield 96% (88 mg). White solid, mp
2-Propyl-1H-benzo[d]imidazole (2l). Eluent: dichlormethane/
methanol = 20:1. Yield 47% (30 mg). White solid, mp 153−155 °C.
1H NMR (300 MHz, CDCl3) δ 7.54 (ddd, J = 6.0, 3.0, 1.3 Hz, 2H),
7.20 (ddd, J = 6.0, 3.0, 1.4 Hz, 2H), 2.92 (t, J = 7.6 Hz, 2H), 1.98−1.79
(m, 2H), 0.98 (t, J = 7.4 Hz, 3H). 13C NMR (151 MHz, CD3OD) δ
156.7, 139.5, 123.1, 115.3, 31.7, 22.7, 14.0. HRMS (EI) calcd for
C17H12N2 [M]+, 160.1000; found, 160.0993.
1
288−290 °C. H NMR (300 MHz, CD3OD) δ 8.07 (d, J = 8.8 Hz,
2H), 7.57 (t, J = 9.6 Hz, 4H), 7.27 (dd, J = 6.1, 3.2 Hz, 2H). 13C NMR
(151 MHz, DMSO) δ 150.2, 143.7, 135.0, 134.5, 129.1, 128.2, 122.8,
121.9, 119.0, 111.5. HRMS (EI) calcd for C13H9ClN2 [M]+, 228.0454;
found, 228.0461.
5,6-Dimethyl-2-phenyl-1H-benzo[d]imidazole (2m). Eluent:
2-(4-Bromophenyl)-1H-benzo[d]imidazole (2c). Eluent: petro-
petroleum ether/ethyl acetate = 2:1. Yield 88% (78 mg). White solid,
leum ether/ethyl acetate = 2:1. Yield 98% (107 mg). White solid, mp
1
1
mp 249−251 °C. H NMR (300 MHz, CD3OD) δ 8.04 (dq, J = 7.0,
293−294 °C. H NMR (300 MHz, CD3OD) δ 8.00 (d, J = 8.5 Hz,
1.4 Hz, 2H), 7.55−7.45 (m, 3H), 7.36 (s, 2H), 2.37 (s, 6H). 13C NMR
(101 MHz, DMSO) δ 150.3, 130.5, 129.5, 128.9, 126.2, 20.1. HRMS
(EI) calcd for C15H14N2 [M]+, 222.1157; found, 222.1152.
2H), 7.71 (d, J = 8.5 Hz, 2H), 7.61 (s, 2H), 7.31−7.23 (m, 2H). 13C
NMR (101 MHz, DMSO) δ 150.2, 143.7, 135.0, 132.0, 129.4, 128.4,
123.3, 122.8, 122.0, 119.0, 111.5. HRMS (EI) calcd for C13H9BrN2
[M]+, 271.9949; found, 271.9950.
6-Methyl-2-phenyl-1H-benzo[d]imidazole (2n). Eluent: petro-
leum ether/ethyl acetate = 2:1. Yield 92% (77 mg). White solid, mp
2-(4-Methoxyphenyl)-1H-benzo[d]imidazole (2d). Eluent: pe-
1
240−242 °C. H NMR (400 MHz, CD3OD) δ 8.09−8.03 (m, 2H),
troleum ether/ethyl acetate = 2:1. Yield 92% (83 mg). White solid, mp
1
7.56−7.44 (m, 4H), 7.39 (s, 1H), 7.12−7.06 (m, 1H), 2.47 (s, 3H).
13C NMR (101 MHz, CD3OD) δ 153.0, 133.9, 131.2, 131.1, 130.1,
127.7, 125.4, 115.8, 21.7. HRMS (EI) calcd for C14H12N2 [M]+,
208.1000; found, 208.0996.
231−233 °C. H NMR (400 MHz, CD3OD) δ 8.05 (d, J = 8.9 Hz,
2H), 7.59 (dd, J = 6.0, 3.2 Hz, 2H), 7.25 (dd, J = 6.0, 3.1 Hz, 2H), 7.11
(d, J = 8.9 Hz, 2H), 3.90 (s, 3H). 13C NMR (101 MHz, CD3OD) δ
162.9, 153.5, 129.4, 123.6, 123.4, 115.5, 55.9. HRMS (EI) calcd for
C14H12N2O [M]+, 224.0950; found, 224.0951.
7-Methyl-2-phenyl-1H-benzo[d]imidazole (2o). Eluent: petro-
2-(4-Nitrophenyl)-1H-benzo[d]imidazole (2e). Eluent: petro-
leum ether/ethyl acetate = 6:1. Yield 89% (85 mg). Light yellow solid,
leum ether/ethyl acetate = 3:1. Yield 86% (72 mg). White solid, mp
248−250 °C. H NMR (300 MHz, CD3OD) δ 8.13 (d, J = 7.9 Hz,
1
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dx.doi.org/10.1021/jo5005179 | J. Org. Chem. 2014, 79, 4727−4734