Synthesis of Carbazoles
130.00, 130.09, 131.75, 132.51, 137.82, 138.37, 146.52, 195.17.
GC-MS (m/z) 310 (5), 309 (M+ + 2, 23), 308 (17), 307 (M+, 47),
232 (34), 231 (16), 230 (100), 167 (43), 166 (14), 105 (15), 77
(24). Mp 123.3-124.3 °C (lit.35 mp 123-125 °C).
N4,N4′-Bis(2-bromophenyl)biphenyl-4,4′-diamine (18f). The
crude was extracted with ethyl acetate (3 × 50 mL). The organic
extract was dried with anhydrous MgSO4. The product was detected
by TLC and HPLC and purified by column chromatography on
silica gel eluting with petroleum ether/diethyl ether (75:25). Yellow
crystals were isolated in 45% yield (210.8 mg, 0.427 to 0.95 mmol).
1H NMR (CCl3D) δ 6.15 (2H, s), 6.77 (2H, m), 7.21 (6H, m), 7.32
(2H, dd, 1J ) 8.3 Hz, 2J ) 1.5 Hz), 7.56 (6H, m). 13C NMR (CCl3D)
δ 112.34, 116.05, 120.39, 121.06, 127.61, 128.17, 133.05, 135.02,
140.63, 141.29. MS direct injection (m/z) 497 (20), 496 (70), 495
(78), 494 (M+, 100), 493 (99), 492 (84), 491 (82), 490 (28), 414
(18), 413 (18), 412 (15), 411 (13), 333 (11), 332 (15), 331 (12),
330 (9), 329 (6), 247 (14), 246 (11), 245 (6), 244 (7), 243 (24),
242 (20), 241 (17), 240 (13), 168 (10), 167 (37), 166 (38), 165
(35), 164 (15), 76 (9), 75 (9), 63 (10). Mp 173.0-175.0 °C. HR
MS (EI) calcd for C24H18Br2N2 491.9837, found 491.9830.
Representative Procedure for Photostimulated Reactions:
Preparation of 9H-Carbazole (4) in Liquid Ammonia. The
following procedure is representative of all these reactions. Liquid
ammonia (150 mL), previously dried over Na metal, was distilled
into a 250 mL three-necked, round-bottomed flask equipped with
a coldfinger condenser and a magnetic stirrer under a nitrogen
atmosphere. The base t-BuOK (2.0 equiv, 49.4 mg) and then the
substrate 2-bromo-N-phenylbenzenamine (18a) (1 equiv, 40.7 mg)
were added to the liquid ammonia and the solution was irradiated
for 30 min. The reaction was quenched with an excess of
ammonium nitrate and the liquid ammonia was allowed to
evaporate. Water was added to the residue and the mixture was
extracted with CH2Cl2 (3 × 50 mL). The organic extract was dried
over anhydrous MgSO4 then filtered, and the solvent was removed
to leave the crude products. The products were separated and
isolated by radial thin-layer chromatography on silica gel. In other
similar experiments the products were quantified by GC by using
the internal standard method. The yield of halide ions in the aqueous
solution was determined potentiometrically.
2-Bromo-N-phenylbenzenamine (18a). 36 The product was
purified by column chromatography on silica gel eluting with
petroleum ether/CH2Cl2 (90:10). Colorless oil was isolated in 80%
1
yield (395.2 mg, 1.60 mmol). H NMR (CCl3D) δ 6.12 (1H, s),
6.78 (1H, t, J ) 7.6 Hz), 7.08 (1H, t, J ) 7.4 Hz), 7.20 (3H, m),
7.29 (1H, d, J ) 7.7 Hz), 7.36 (2H, t, J ) 7.7 Hz), 7.56 (1H, d, J
) 8.0 Hz). 13C NMR (CCl3D) δ 112.22, 115.83, 120.31, 120.93,
122.74, 128.13, 129.49, 133.01, 141.47, 141.63. GC-MS (m/z) 250
(6), 249 (M+ + 2, 47), 247 (M+, 49), 169 (14), 168 (100), 167
(97), 166 (18), 139 (12), 84 (57), 77 (11), 71 (11), 51 (16).
2-Bromo-N-(4-methoxyphenyl)benzenamine (18b). The prod-
uct was purified by column chromatography on silica gel eluting
with petroleum ether/CH2Cl2 (60:40). Colorless oil was isolated in
1
85% yield (436.6 mg, 1.58 mmol). H NMR (CCl3D) δ 3.84 (3H,
s), 5.97 (1H, s), 6.67 (1H, td, 1J ) 7.8 Hz, 2J ) 1.5 Hz), 6.94 (3H,
1
2
m), 7.13 (3H, m), 7.50 (1H, dd, J ) 7.9 Hz, J ) 1.5 Hz). 13C
NMR (CCl3D) δ 55.50, 110.51, 113.96, 114.71, 119.53, 124.65,
128.10, 132.72, 134.08, 143.22, 156.37. GC-MS (m/z) 280 (11),
279 (M+ + 2, 78), 277 (M+, 77), 265 (12), 264 (97), 263 (12), 262
(100), 183 (10), 182 (22), 155 (48), 154 (49), 128 (15), 127 (13),
99 (15), 77 (15), 64 (10), 63 (13). HR MS (EI) calcd for
C13H12BrNO 277.0102, found 277.0096.
N-(2-Bromophenyl)naphthalen-1-amine (18c). The product
was purified by column chromatography on silica gel eluting with
petroleum ether/CH2Cl2 (100:0 f 60:40). White crystals were
isolated in 84% yield (471.9 mg, 1.59 mmol). 1H NMR (CCl3D) δ
1
2
6.41 (1H, s), 6.73 (1H, m), 6.87 (1H, dd, J ) 8.2 Hz, J ) 1.5
1
2
Hz), 7.10 (1H, m), 7.52 (5H, m), 7.72 (1H, dd, J ) 7.4 Hz, J )
1.5 Hz), 7.92 (1H, m), 8.05 (1H, m). 13C NMR (CCl3D) δ 111.21,
115.46, 119.77, 120.19, 122.32, 124.94, 125.93, 126.20, 126.34,
128.20, 128.53, 129.14, 132.77, 134.78, 137.25, 143.13. GC-MS
(m/z) 299 (M+ + 2, 34), 298 (6), 297 (M+, 35), 219 (11), 218
(79), 217 (100), 216 (26), 109 (67), 94 (13). Mp 74.0-75.0 °C.
HR MS (EI) calcd for C16H12BrN 297.0153, found 297.0147.
N-(2-(1H-Pyrrol-1-yl)phenyl)-2-bromobenzenamine (18d).
The product was purified by column chromatography on silica gel
eluting with petroleum ether/CH2Cl2 (60:40). Colorless oil was
isolated in 88% yield (551.9 mg, 1.77 mmol). 1H NMR (CCl3D) δ
Photostimulated Reaction of N-(2-Bromophenyl)naphthalen-
1-amine (18c) in DMSO. The reaction was carried out in a Schlenk
tube equipped with a nitrogen inlet and magnetic stirrer at room
temperature. DMSO (10 mL) was dried and deoxygenated, then
t-BuOK (2.0 equiv, 44.8 mg) was added and after 5 min 18c (1
equiv, 59.4 mg) was added and the reaction mixture was irradiated
for 60 min. The reaction was quenched with water and ammonium
nitrate in excess. The residue was extracted with CH2Cl2 (3 × 50
mL) and the organic extract was washed with water and dried with
anhydrous MgSO4.
1
5.97 (1H, s), 6.37 (2H, t, J ) 2.2 Hz), 6.81 (1H, td, J ) 7.9 Hz,
2J ) 1.6 Hz), 6.88 (2H, t, J ) 2.2 Hz), 7.04 (1H, td, 1J ) 7.5 Hz,
1
2J ) 1.4 Hz), 7.21 (1H, m), 7.33 (4H, m), 7.52 (1H, dd, J ) 7.9
2
Hz, J ) 1.4 Hz). 13C NMR (CCl3D) δ 109.95, 114.22, 117.68,
The same procedure was carried out when THF was used as a
solvent. THF was dried over Na metal and benzophenone.
9H-Carbazole (4). The product was purified by radial thin-layer
chromatography on silica gel eluting with petroleum ether/CH2Cl2
(50:50) and then it was sublimated. White crystals were isolated
118.23, 121.73, 121.77, 122.32, 127.51, 128.05, 128.21, 131.38,
133.17, 137.63, 140.23. GC-MS (m/z) 314 (M+ + 2, 8), 313 (9),
312 (M+, 8), 234 (17), 233 (100), 232 (20), 231 (10), 204 (11),
116 (31). HR MS (EI) calcd for C16H13BrN2 312.0262, found
312.0256.
1
in 93% yield (46.7 mg, 0.28 to 0.3 mmol). H NMR (CCl3D) δ
N-(2-Bromophenyl)biphenyl-2-amine (18e). The product was
purified by column chromatography on silica gel eluting with
petroleum ether/CH2Cl2 (75:25). Yellow pale oil was isolated in
7.25 (2H, m), 7.43 (4H, m), 8.05 (1H, s), 8.10 (2H, d, J ) 7.8 Hz).
13C NMR (CCl3D) δ 110.53, 119.41, 120.30, 123.33, 125.80,
139.44. GC-MS (m/z) 168 (M+ + 1, 13), 167 (M+, 100), 166 (22),
140 (9), 139 (12), 84 (15), 69 (8). Mp 245.3-247.0 °C (lit.37 mp
246 °C).
1
78% yield (502.4 mg, 1.55 mmol). H NMR (CCl3D) δ 6.07 (1H,
s br), 6.72 (1H, t, J ) 7.5 Hz), 7.09 (1H, t, J ) 7.5 Hz), 7.16 (1H,
t, J ) 7.6 Hz), 7.38 (10H, m). 13C NMR (CCl3D) δ 112.90, 116.12,
119.57, 121.05, 122.54, 127.58, 128.05, 128.21, 128.82, 129.14,
131.02, 132.98, 133.45, 138.72, 138.78, 141.40. GC-MS (m/z) 326
(13), 325 (M+ + 2, 70), 324 (18), 323 (M+, 70), 245 (18), 244
(100), 243 (43), 242 (26), 241 (24), 167 (21), 166 (16), 122 (38),
121 (24). HR MS (EI) calcd for C18H14BrN 323.0310, found
323.0292.
3-Phenyl-9H-carbazole (8).38 The product was purified by radial
thin-layer chromatography on silica gel eluting with petroleum ether/
CH2Cl2 (70:30 f 50:50). White crystals were isolated in 86% yield
(55.8 mg, 0.23 to 0.268 mmol). 1H NMR (CCl3D) δ 7.28 (1H, m),
1
2
7.37 (1H, m), 7.49 (5H, m), 7.70 (1H, dd, J ) 8.4 Hz, J ) 1.9
1
2
Hz), 7.74 (2H, m), 8.10 (1H, s), 8.15 (1H, dd, J ) 7.8 Hz, J )
0.4 Hz), 8.32 (1H, m). 13C NMR (CCl3D) δ 142.09, 139.93, 138.92,
133.03, 128.74, 127.31, 126.48, 126.03, 125.44, 123.88, 123.46,
(35) Jensen, T. A.; Liang, X.; Tanner, D.; Skjaerbaek, N. J. Org. Chem. 2004,
69, 4936–4947.
(36) Lakshmi Kantam, M.; Venkanna, G. T.; Sridhar, C.; Sreedhar, B.;
Choudary, B. M. J. Org. Chem. 2006, 71, 9522–9524. This compound is
commercial. CAS registry no.: 61613-22-7. Exhibited spectral data identical to
report.
(37) Dictionary of Organic Compounds, 4th, ed.; Eyre & Spottiswoode
Publishers Ltd.: New York, 1969; p 552.
(38) Watanabe, T.; Ueda, S.; Inuki, S.; Oishi, S.; Fujii, N.; Ohno, H. Chem.
Commun. 2007, 43, 4516–4518. Exhibited spectral data identical to report.
J. Org. Chem. Vol. 74, No. 12, 2009 4497