Synthesis and photoluminescent properties of new aza-indenofluorene derivatives

Article abstract of DOI:10.1002/hc.21058

The carbazole derivatives 5a-h were synthesized by four steps involving Suzuki coupling of boronic acid 1 with 1-bromo-2-nitrobenzene, followed with the Cadogan ring closure reaction. Their UV and photoluminescence properties are also reported, and the co

Full text of DOI:10.1002/hc.21058

Heteroatom Chemistry
Volume 24, Number 1, 2013
Synthesis and Photoluminescent Properties
of New Aza-Indenofluorene Derivatives
Su Jin Jung,1 Won Sam Kim,2 Byung Sun Park,3 Jae Kyun Lee,4
Jung Hwan Park,2 Kihang Choi,1 and So Ha Lee3
1Department of Chemistry, Korea University, Seoul 136-701, Republic of Korea
2Duksan Hi-Metal Co., Ltd., Cheonan City, Chungcheongnam-do 331-821, Republic of Korea
3Chemical Kinomics Research Center, Korea Institute of Science and Technology, Seoul 130-650,
Republic of Korea
4Center for Neuro-medicine, Korea Institute of Science and Technology, Seoul 130-650, Republic of
Korea
Received 7 August 2012; revised 8 October 2012
of basic architecture for OLEDs was demonstrated
ABSTRACT: The carbazole derivatives 5a–h were
in 1987 by Tang and Van Slyke [2]. OLEDs con-
synthesized by four steps involving Suzuki coupling
sisted of a layer of organic or polymeric emit-
of boronic acid 1 with 1-bromo-2-nitrobenzene, fol-
ting materials situated between anode and cathode.
lowed with the Cadogan ring closure reaction. Their
The emitted color of OLEDs is controlled by the
UV and photoluminescence properties are also re-
combination of the dopant material and the host
ported, and the compounds showed medium-to-strong
material.
photoluminescence between 370 and 446 nm at the
Carbazole derivatives have many application
concentration of 1 × 10−5 M CH2Cl2. Also, the X-ray
fields such as Pigment Violet 23 for paints and inks
structure of the carbazole derivative 6 was elucidated
[3] and the blue host materials for OLEDs [4–6] (see
ꢀC
by an X-ray diffractometer.
2012 Wiley Periodi-
Fig. 1). Also the photophysical and photochemical
properties of the carbazole derivatives have been re-
searched for various hole and electron materials and
luminescence materials [7–12].
cals, Inc. Heteroatom Chem 24:18–24, 2013; View
this article online at wileyonlinelibrary.com. DOI
10.1002/hc.21058
In this paper, we studied the synthesis and pho-
toluminescent properties of new carbazole deriva-
tives by the Suzuki coupling and Cadogan ring clo-
sure reaction for application as luminescence mate-
rials.
INTRODUCTION
Organic light-emitting diodes (OLEDs) are consid-
ered as ideal components of light sources because of
their high efficiencies, lightweight, mechanical flex-
ibility, short response time, and the control of ra-
tionally tuned emission wavelength through molec-
ular structural modifications [1]. The first report
RESULTS AND DISCUSSION
The carbazole derivatives were synthesized as shown
in Scheme 1. Lithiation of 2-bromo-9,9-dimethyl-
9H-fluorene in THF with n-butyllithium at –78◦C
resulted in exchange of bromine for lithium, and
a reaction of the lithium-containing intermediate
with trimethyl borate afforded the boronic acid
Correspondence to: So Ha Lee; e-mail: LSH6211@kist.re.kr.
Contract grant sponsor: Korea Institute of Science and Technol-
ogy.
ꢀC
2012 Wiley Periodicals, Inc.
18

Synthesis and Photoluminescent Properties of New Aza-Indenofluorene Derivatives 19
2 on 87% yield as a yellow solid. The reductive Cado-
gan ring closure reaction in triphenylphosphine was
performed on molecule 2 to give a mixture of regioi-
somers 3a (33% yield) and 3b (55% yield) [14]. Two
regioisomers 3a and 3b were difficultly separated
by column chromatography in three times using the
mixed solvent of dichloromethane and n-hexane (sil-
ica gel) for analytical samples, respectively. Because
of the separation problem, a mixture of two regioi-
somers 3a and 3b was used to the next step for syn-
thesis of compounds 5a–5h without further purifi-
cation. Coupling of the crude mixture of 3a and 3b
with various aryl halides gave only compounds 5a–h
on modest yields in the presence of Pd(PPh3)4, 1,10-
phenanthroline, copper iodide, and potassium car-
bonate in DMF. Aryl halides did not react at all with
compound 3a, whereas it reacted very well with com-
pound 3b to give carbazole derivatives 5a–5h. In this
reaction condition, the reaction of aryl halides with
compound 3b showed excellent selectivity, whereas
that with compound 3a did not.
N
Cl
Cl
N
N
O
O
N
N
N
CBP
Pigment Violet 23
FIGURE 1 Structure of carbazole derivative Pigment Violet
23 and CBP.
derivative 1 at –78◦C [13]. The Suzuki coupling of
compound 1 with 1-bromo-2-nitrobenzene in the
presence of Pd(PPh3)4 in a mixed solvent of THF
and water (5/1, v/v) at 80◦C gave the nitro compound
NO2
O2N
Br
Trimethylborate,
B(OH)2
Br
n-BuLi, THF
Pd(PPh3)4, K2CO3, THF/H2O
2
1
PPh3, reflux,
-Dichlorobenzene
and
N
o
H
N
H
3a
3b
5a: R = phenyl
5b: R = 3-biphenyl
5c: R = 4-biphenyl
5d: R = 2-naphthyl
5e: R = 2-quinolinyl
5f: R = 6-quinolinyl
5g: R = 3-pyridyl
5h: R = 4-pyridyl
R-X, 1,10-phenanthroline,
CuI, K2CO3, DMF, reflux
N
R
5
I
N
N
H
Cu, K2CO3
nitrobenzene
3a
6
SCHEME 1 Synthesis of compounds 5a–5h and 6.
Heteroatom Chemistry DOI 10.1002/hc

20 Jung et al.
Because the structure determination of com-
pounds 3a and 3b was difficult, we tried to crystal-
lize the compound for X-ray crystallographic struc-
ture determination, but the crystal of compounds 3a
and 3b is not suitable for X-ray analysis. Also the
crystal of compound 5a was not suitable for X-ray
analysis.
Compound 3a was reacted with iodobenzene in
the presence of copper powder and potassium car-
bonate under nitrobenzene to give the excellent crys-
tal 6 (crystallized by methanol) suitable for X-ray
analysis.
Crystals of compound 6 for X-ray analysis were
obtained at a temperature of 19
1◦C to a maxi-
mum 2θ value of 54.8o. A colorless needle crystal 6
having approximate dimensions of 0.500 × 0.100 ×
0.100 mm was mounted on a glass fiber. All mea-
surements were made on a Rigaku R-AXIS Rapid
diffractometer using graphite monochromated Mo-
Ka radiation. All calculations were performed us-
ing the Crystal Structure Crystallographic Software
package [15] except for refinement, which was per-
formed using SHELXL-97 [16]. The ORTEP diagram
of compound 6 and data obtained by X-ray analysis
are presented in Fig. 2 and Table 1.
The absorption spectra and photoluminescence
(PL) spectra of the synthesized compounds 5a–h
were recorded using a UV–vis spectrometer and flu-
orescence spectrometer at the concentration of 1 ×
10−5 M CH2Cl2 solution. The UV and PL data are
presented in Table 2 and Fig. 3. The absorption
spectra of all compounds 5a–h showed maximum
absorption in the range between 240 and 326 nm.
Two UV–vis absorption λmax peaks were observed
for all compounds. The peaks correspond to the π–
π* transition of the conjugated aromatic rings. All
compounds showed a maximum PL of 370–446 nm
near the violet region. In PL emission spectra, 5e
and 5f have very weak emissions maximum at 438–
446 nm.
FIGURE 2 ORTEP diagram of compound 6.
The other six compounds have the main emis-
sion peaks at 370–392 nm. The PL spectra of 5a–d
and 5g–h are nearly identical. Quinoline moiety of
compounds 5e and 5f shifted the maximum emis-
sion to considerable low energies by comparison
with emission of the other six compounds. Also all
compounds 5a–d and 5g–h except molecules 5e and
5f comparatively showed narrow FWHM value (the
full widths at half maximum value) between 33 and
39 nm.
In summary, several new carbazole derivatives
were synthesized in four steps and UV/PL experi-
ments showed them to have potential as green light
emitting materials for OLED or fluorescence pig-
ment dye. Further studies on the electrolumines-
cence properties of the synthesized carbazole deriva-
tives 5a–h are currently under investigation and will
be presented later.
TABLE 1 Crystal Data and Structural Refinement of Compound 6
˚
Mo Kα (λ = 0.71075 A)
Diffractometer
Rigaku R-AXIS Rapid
Radiation
Graphite-Monochromated
Formula
Formula weight
Crystal color, habit
C27H21
359.47
Colorless, needle
N
Detector position
Pixel size
127.40 mm
0.100 mm
8.4993(6)
21.957(2)
21.989(2)
4103.7(5)
Pbca (#61)
8
˚
A (A)
˚
B (A)
˚
C (A)
3
˚
V (A )
Crystal dimensions
Crystal system
Goodness-of-fit indicator
M (Mo Kα)
0.50 × 0.10 × 0.10 mm
Orthorhombic
1.010
Space group
Z value
Dcalc
1.164 g/cm3
1520.00
0.668 cm−1
F(000)
Final R1, wR2 [I >2.00σ(I)]
0.0670, 0.1634
Reflection collected
33,834
Heteroatom Chemistry DOI 10.1002/hc

Synthesis and Photoluminescent Properties of New Aza-Indenofluorene Derivatives 21
TABLE 2 UV and PL Data of Compounds 5a–h.
λmax (nm)a
9,9-Dimethyl-2-(2-nitrophenyl)-9H-fluorene 2
9,9-Dimethyl-9H-fluoren-2-ylboronic acid 1 (55.50 g,
233.11 mmol), 1-bromo-2-nitrobenzene (47.09 g,
233.11 mmol), tetrakis(triphenylphosphine) palla-
Compound
UV
PLb
FWHM (nm)c
5a
5b
5c
5d
5e
5f
255, 319
240, 320
240, 316
247, 320
262, 320
252, 326
261, 320
262, 316
377, 391
377, 390
379, 392
379, 391
438
446
373, 384
370, 381
37
36
37
37
82
80
33
33
dium (13.47 g, 11.66 mmol), and potassium car-
bonate (96.65 g, 699.33 mmol) were mixed in THF
(500 mL) and H2O (100 mL) solution. The solu-
tion was refluxed for 24 h. After the reaction was
completed, the reaction mixture was left to cool
at room temperature and extracted with ethyl ac-
etate. The combined organic extracts were dried
over anhydrous MgSO4 and evaporated under vac-
uum. The residue was crystallized from ethanol to
give the product 2 as a yellow solid. Yield: 63.81 g
(87%). mp: 134–136◦C. IR (KBr): 3437, 2963, 1606,
1520, 1445, 1352, 859, 829, 790, 739 cm−1. Elemen-
tal analyses (C21H17NO2) calcd: C, 79.98; H, 5.43;
N, 4.44. Found: C, 80.00; H, 5.21; N, 4.41.1H NMR
(300 MHz, CDCl3): δ (ppm) 1.53 (s, 6H), 7.31–7.40
(m, 4H), 7.45–7.56 (m, 3H), 7.65 (d, J = 7.49 Hz,
1H), 7.75–7.80 (m, 2H), 7.88 (dd, J = 1.05, 8.02
Hz, 1H). 13C NMR (75 MHz, CDCl3): δ (ppm) 27.09,
47.02, 120.21, 120.26, 122.30, 122.63, 124.07, 126.92,
127.08, 127.63, 127.97, 132.04, 132.15, 136.12,
136.71, 138.53, 139.43, 149.53, 153.87, 154.09.
5g
5h
aMeasured at the concentration of 1 × 10−5 M CH2Cl2 solution.
bPL spectra recorded by single beam excitation using longer absorp-
tion of two UV λ
.
max
cThe full widths at half maximum value.
EXPERIMENTAL
General
The NMR spectra were recorded with a Bruker spec-
trometer (Germany), operating at 300 MHz for H
1
NMR and 75 MHz for 13C NMR. Melting points
were determined on a SRS Optimelt. FT-IR spec-
tra were obtained on a Perkin Elmer 16E PC FT-
IR spectrometer (USA). UV spectra and PL spectra
were recorded on a Perkin-Elmer Lambda25 UV–
vis spectrometer and Hitachi F-4500 fluorescence
spectrometer (Japan), respectively. Diffraction data
were collected on a Rigaku R-AXIS Rapid imaging
plate diffractometer (Japan) equipped with graphite-
monochromated Mo Kα radiation. Column chro-
matography was performed on Merck Silica Gel
(230–400 mesh). TLC was carried out using glass
sheets precoated with silica gel 60 F254 prepared by
Merck.
Dimethyldihydroindenocarbazole 3a and 3b
A solution of 9,9-dimethyl-2-(2-nitrophenyl)-9H-
fluorene 2 (3.3 g, 10.3 mmol) and triphenylphos-
phine (7.0 g, 26.8 mmol) in o-dichlorobenzene
(21 mL) was heated to reflux with vigorous stir-
ring for 24 h, during which time the color changed
from yellow to brown. The reaction mixture was
cooled to room temperature and concentrated un-
der high vacuum. The reaction mixture was ex-
tracted with dichloromethane, and the organic layer
was dried over anhydrous MgSO4 and evacuated
9,9-Dimethyl-9H-fluoren-2-ylboronic Acid 1
The compound was synthesized as reported in the
literature [13].
FIGURE 3 UV–vis. absorption (left) and PL emission spectra (right) of compounds 5a–h in concentration of 1 × 10−5
M
CH2Cl2 solution.
Heteroatom Chemistry DOI 10.1002/hc

22 Jung et al.
under vacuum. The crude mixture 3a and 3b
was purified by flash chromatography on silica gel
(dichloromethane/hexane) to afford the product 3a
(1.5 g, 33%) and 3b (2.5 g, 55%).
7.43 (m, 2H), 7.49–7.57 (m, 2H), 7.67–7.73(m, 6H),
8.20 (d, J = 7.10 Hz, 2H). 13C NMR (75 MHz, CDCl3):
δ (ppm) 28.08, 46.31, 100.96, 109.71, 114.00, 119.88,
119.94, 120.00, 122.71, 123.24, 123.49, 125.64,
126.93, 127.20, 127.36, 127.53, 129.99, 137.94,
138.15, 139.52, 140.99, 141.59, 146.38, 154.43.
12,12-Dimethyl-11,12-dihydroindeno[2,1-
a]carbazole 3a. Yield: 1.5 g (33%). mp: 221–223◦C.
IR (KBr): 3441, 2957, 1608, 1456, 1442, 1420, 1324,
820, 747 cm−1. Elemental analyses (C21H17N) calcd:
C, 89.01; H, 6.05; N, 4.94. Found: C, 89.21; H, 6.11;
11,11-Dimethyl-5-(biphenyl-3-yl)-5,11-
dihydroindeno[1,2-b]carbazole 5b
1
N, 5.00. H NMR (300 MHz, CDCl3): δ (ppm) 1.75
A mixture of the crude 3a and 3b (7.43 g,
26.22 mmol, the mixture of 3a of 38% and 3b of
62%), 3-bromobiphenyl (3.1 mL, 18.35 mmol), 1,10-
phenanthroline (2.13 g, 11.80 mmol), copper io-
dide (4.99 g, 26.22 mmol), and potassium carbon-
ate (10.87 g, 78.66 mmol) was refluxed in DMF
(53 mL) under N2 for 24 h. After the reaction was
completed, the mixture was filtered and evaporated.
The filtrate was extracted with dichloromethane,
and the organic layer was dried over anhydrous
MgSO4. The solvent was removed in vacuo, and the
residue was purified by flash chromatography on sil-
ica gel (ethyl acetate/hexane) to afford the product
5b. Yield: 2.29 g (32%). mp: 209–211◦C. IR (KBr) :
3443, 2954, 1598, 1483, 1448, 1331, 1238, 762, 750,
700, 691 cm−1. Elemental analyses (C33H25N) calcd:
C, 91.00; H, 5.79; N, 3.22. Found: C, 91.30; H, 5.77;
N, 3.10. 1H NMR (300 MHz, CDCl3): δ (ppm) 1.66 (s,
6H), 7.31–7.35 (m, 3H), 7.40–7.53 (m, 6H), 7.62–7.65
(m, 1H), 7.70–7.78 (m, 6H), 7.89 (s, 1H), 8.21 (d, J
= 7.43 Hz, 2H). 13C NMR (75 MHz, CDCl3): δ (ppm)
28.08, 46.32, 101.00, 109.76, 114.04, 119.95, 119.99,
120.04, 122.70, 123.29, 123.54, 125.70, 125.92,
126.06, 126.23, 126.93, 127.21, 127.89, 129.01,
130.39, 138.20, 138.43, 139.48, 140.13, 140.99,
141.59, 143.22, 146.45, 154.42.
(s, 6H), 7.28–7.56 (m, 6H), 7.72 (d, J = 7.99 Hz, 1H),
7.84–7.87 (m, 1H), 8.12–8.16 (m, 3H). 13C NMR (75
MHz, CDCl3): δ (ppm) 25.72, 46.71, 110.74, 112.31,
119.38, 119.84, 120.00, 120.26, 122.21, 123.56,
123.88, 125.73, 126.77, 127.22, 134.25, 135.35,
137.45, 140.09, 140.31, 153.36.
11,11-Dimethyl-5,11-dihydroindeno[1,2-
b]carbazole 3b. Yield: 2.5 g (55%). mp: 230◦C.
IR (KBr): 3382, 2958, 1608, 1503, 1452, 1442, 1316,
1249, 745, 692 cm−1. Elemental analyses (C21H17N)
calcd: C, 89.01; H, 6.05; N, 4.94. Found: C, 89.70;
H, 6.18; N, 5.10. 1H NMR (300 MHz, DMSO-d6):
δ (ppm) 1.52 (s, 6H), 7.15 (t, J = 7.50 Hz, 1H),
7.27–7.39 (m, 3H), 7.47–7.54 (m, 2H), 7.89 (t, J =
7.50 Hz, 2H), 8.13 (d, J = 7.80 Hz, 1H), 8.24 (s,
1H), 11.29 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ
(ppm) 28.38, 46.17, 102.50, 111.32, 114.55, 118.91,
120.43, 122.92, 123.04, 123.22, 125.69, 127.44,
127.53, 137.49, 139.66, 140.07, 140.88, 145.09,
154.44, 162.34.
11,11-Dimethyl-5-phenyl-5,11-dihydroindeno
[1,2-b]carbazole 5a
A mixture of the crude 3a and 3b (15.64 g,
55.19 mmol, the mixture of 3a of 38% and 3b of
62%), bromobenzene (4.06 mL, 38.63 mmol), 1,10-
phenanthroline (4.48 g, 24.84 mmol), copper io-
dide (10.51 g, 55.19 mmol), and potassium car-
bonate (22.88 g, 165.57 mmol) was refluxed in
DMF (110 mL) under N2 for 24 h. After the reac-
tion was completed, the reaction mixture was fil-
tered and evaporated. The filtrate was extracted with
dichloromethane, and the organic layer was dried
over anhydrous MgSO4. The solvent was removed in
vacuo, and the residue was purified by flash chro-
matography on silica gel (ethyl acetate/hexane) to
afford the product 5a. Yield: 4.57 g (37%). mp: 184–
186◦C. IR (KBr): 3436, 2954, 1596, 1503, 1479, 1447,
1330, 1238, 760, 749, 699, 690 cm−1. Elemental anal-
yses (C27H21N) calcd: C, 90.21; H, 5.89; N, 3.90.
Found: C, 90.87; H, 5.99; N, 4.10. 1H NMR (300 MHz,
CDCl3): δ (ppm) 1.65 (s, 6H), 7.35–7.36 (m, 3H), 7.42–
11,11-Dimethyl-5-(biphenyl-4-yl)-5,11-
dihydroindeno[1,2-b]carbazole 5c
A mixture of the crude 3a and 3b (13.16 g,
46.44 mmol, the mixture of 3a of 38% and 3b of
62%), 4-bromobiphenyl (5.41 g, 23.22 mmol), 1,10-
phenanthroline (3.77 g, 20.90 mmol), copper io-
dide (8.84 g, 46.44 mmol), and potassium carbon-
ate (19.26 g, 139.32 mmol) was refluxed in DMF
(100 mL) under N2 for 24 h. After the reaction was
completed, the reaction mixture was filtered and
evaporated. The filtrate was extracted with ethyl ac-
etate, and the organic layer was dried over anhy-
drous MgSO4. The solvent was removed in vacuo,
and the residue was purified by flash chromatog-
raphy on silica gel (ethyl acetate/hexane) to af-
ford product 5c. Yield: 3.41 g (48%), mp: 222–
224◦C. IR (KBr): 3448, 2959, 1605, 1519, 1487,
Heteroatom Chemistry DOI 10.1002/hc

Synthesis and Photoluminescent Properties of New Aza-Indenofluorene Derivatives 23
1446, 1328, 1237, 763, 740, 731, 690 cm−1. Elemen-
tal analyses (C33H25N) calcd: C, 91.00; H, 5.79; N,
3.22. Found: C, 91.06; H, 5.70; N, 3.20. 1H NMR
(300 MHz, CDCl3): δ (ppm) 1.68 (s, 6H), 7.32–7.38
(m, 3H), 7.42–7.59 (m, 6H), 7.71–7.81 (m, 6H),
7.9 (d, J = 8.40 Hz, 2H), 8.23 (d, J = 6.79 Hz,
2H); 13C NMR (75 MHz, CDCl3): δ (ppm) 28.10,
46.35, 101.07, 109.81, 114.05, 119.99, 120.05, 122.73,
123.35, 123.61, 125.71, 126.97, 127.21, 127.55,
127.70, 128.64, 129.02, 137.10, 138.23, 139.54,
140.33, 140.38, 140.98, 141.57, 146.49, 154.46.
solvent was removed in vacuo, and the residue was
purified by flash chromatography on silica gel (ethyl
acetate/hexane) to afford the product 5e. Yield: 7 mg
(5%). mp: 170–172◦C. IR (KBr): 3436, 2956, 1595,
1503, 1445, 1427, 1375, 1325, 829, 749 cm−1. Ele-
mental analyses (C30H22N2) calcd: C, 87.77; H, 5.40;
1
N, 6.82. Found: C, 87.71; H, 5.41; N, 6.55. H NMR
(300 MHz, CDCl3): δ (ppm) 1.70 (s, 6H), 7.40–7.44
(m, 3H), 7.49–7.56 (m, 2H), 7.67 (t, J = 7.39 Hz,
1H), 7.82–8.07 (m, 5H), 8.22–8.31 (m, 3H), 8.40–8.45
(m, 2H). 13C NMR (75 MHz, CDCl3): δ (ppm) 28.03,
46.43, 102.98, 111.49, 114.00, 117.96, 120.02, 121.26,
122.76, 124.53, 124.83, 126.08, 126.43, 126.60,
127.00, 127.30, 127.74, 128.89, 130.43, 138.50,
138.85, 139.61, 140.23, 147.68, 147.89, 151.13,
154.45, 162.33.
11,11-Dimethyl-5-(naphthalen-2-yl)-5,11-
dihydroindeno[1,2-b]carbazole 5d
A mixture of the crude 3a and 3b (13 g, 45.88 mmol,
the mixture of 3a of 38% and 3b of 62%), 2-
bromonaphthalene (6.65 g, 32.12 mmol), 1,10-
phenanthroline (3.72 g, 20.65 mmol), copper io-
dide (8.74 g, 45.88 mmol), and potassium car-
bonate (19.02 g, 137.64 mmol) was refluxed in
DMF (110 mL) under N2 for 24 h. After the re-
action was completed, the reaction mixture was
filtered and evaporated. The filtrate was extracted
with dichloromethane, and the organic layer was
dried over anhydrous MgSO4. The solvent was re-
moved in vacuo, and the residue was crystallized by
dichloromethane to give the product 5d. Yield: 7.35 g
(63%). mp: 230◦C. IR (KBr): 3440, 2953, 1625, 1598,
11,11-Dimethyl-5-(quinolin-6-yl)-5,11-
dihydroindeno[1,2-b]carbazole 5f
A mixture of the crude 3a and 3b (100 mg,
0.35 mmol, the mixture of 3a of 38% and 3b of
62%), 6-bromoquinoline (33 μL, 0.25 mmol), 1,10-
phenanthroline (29 mg, 0.16 mmol), copper io-
dide (67 mg, 0.35 mmol), and potassium carbonate
(145 mg, 1.05 mmol) was refluxed in DMF (3 mL) un-
der N2 for 24 h. After the reaction was completed, the
reaction mixture was filtered and evaporated. The
filtrate was extracted with dichloromethane, and the
organic layer was dried over anhydrous MgSO4. The
solvent was removed in vacuo, and the residue was
purified by flash chromatography on silica gel (ethyl
acetate/hexane) to afford the product 5f. Yield: 17
mg (19%). mp: 230◦C. IR (KBr): 3441, 2957, 1620,
1508, 1481, 1449, 1326, 1313, 1240, 755, 745 cm−1
.
Elemental analyses (C31H23N) calcd: C, 90.92; H,
1
5.66; N, 3.42. Found: C, 90.91; H, 5.55; N, 3.40. H
NMR (300 MHz, CDCl3): δ (ppm) 1.69 (s, 6H), 7.34–
7.43 (m, 3H), 7.45–7.55 (m, 3H), 7.64–7.79 (m, 5H),
7.98–8.08 (m, 2H), 8.17 (d, J = 8.70 Hz, 2H), 8.25
(d, J = 6.90 Hz, 2H). 13C NMR (75 MHz, CDCl3): δ
(ppm) 28.15, 46.38, 101.08, 109.80, 114.12, 120.00,
120.05, 120.13, 122.75, 123.40, 123.67, 125.60,
125.72, 125.77, 126.61, 126.94, 126.99, 127.27,
128.03, 130.04, 132.57, 134.17, 135.45, 138.28,
139.54, 141.28, 141.84, 146.56, 154.49, 162.34.
1595, 1502, 1447, 1332, 1313, 1241, 763, 749 cm−1
.
Elemental analyses (C30H22N2) calcd: C, 87.77; H,
1
5.40; N, 6.82. Found: C, 87.41; H, 5.48; N, 6.58. H
NMR (300 MHz, CDCl3): δ (ppm) 1.66 (s, 6H), 7.28–
7.37 (m, 2H), 7.41–7.51 (m, 3H), 7.56 (q, J = 3.09
Hz, 2H), 7.70–7.76 (m, 2H), 8.00–8.03 (m, 1H), 8.11–
8.12 (m, 1H), 8.26 (d, J = 9.86 Hz, 3H), 8.42 (d, J =
6.64 Hz, 1H), 9.07–9.08 (m, 1H). 13C NMR (75 MHz,
CDCl3): δ (ppm) 28.07, 46.38, 100.83, 109.60, 114.19,
119.96, 120.18, 120.34, 121.95, 122.75, 123.49,
125.21, 125.87, 126.99, 127.35, 129.10, 131.61,
136.10, 138.39, 139.36, 141.00, 141.56, 146.84,
147.20, 150.91, 154.44, 162.40.
11,11-Dimethyl-5-(quinolin-2-yl)-5,11-
dihydroindeno[1,2-b]carbazole 5e
A mixture of the crude 3a and 3b (100 mg,
0.35 mmol, the mixture of 3a of 38% and 3b of
62%), 2-chloroquinoline (40 mg, 0.25 mmol), 1,10-
phenanthroline (29 mg, 0.16 mmol), copper io-
dide (67 mg, 0.35 mmol), and potassium carbon-
ate (145 mg, 1.05 mmol) was refluxed in DMF (3
mL) under N2 for 24 h. After the reaction was com-
pleted, the mixture was filtered and evaporated. The
filtrate was extracted with dichloromethane, and the
organic layer was dried over anhydrous MgSO4. The
11,11-Dimethyl-5-(pyridin-3-yl)-5,11-
dihydroindeno[1,2-b]carbazole 5g
A mixture of the crude 3a and 3b (100 mg,
0.35 mmol, the mixture of 3a of 38% and 3b of
62%), 3-bromopyridine (24 μL, 0.25 mmol), 1,10-
phenanthroline (29 mg, 0.16 mmol), copper io-
dide (67 mg, 0.35 mmol), and potassium carbonate
Heteroatom Chemistry DOI 10.1002/hc

24 Jung et al.
(145 mg, 1.05 mmol) was refluxed in DMF (3 mL) un-
der N2 for 24 h. After the reaction was completed, the
reaction mixture was filtered and evaporated. The
filtrate was extracted with dichloromethane, and
the organic layer was dried over anhydrous MgSO4.
The solvent was removed in vacuo, and the residue
was purified by flash chromatography on silica gel
(ethyl acetate/hexane) to afford the product 5g.
Yield: 15 mg (19%). mp: 174–176◦C. IR (KBr): 3445,
2954, 1579, 1477, 1446, 1424, 1330, 1238, 1025, 765,
713, 690 cm−1. Elemental analyses (C26H20N2) calcd:
C, 86.64; H, 5.59; N, 7.77. Found: C, 86.99; H, 5.70;
N, 7.51. 1H NMR (300 MHz, CDCl3): δ (ppm)1.69
(s, 6H), 7.36–7.55 (m, 6H), 7.64–7.68 (m, 1H), 7.73
(s, 1H), 7.76–7.80 (m, 1H), 8.02 (d, J = 8.10 Hz,
1H), 8.24 (d, J = 6.00 Hz, 2H), 8.84 (s, 1H), 9.04
(s, 1H). 13C NMR (75 MHz, CDCl3): δ (ppm) 28.05,
46.40, 100.58, 109.32, 114.28, 120.01, 120.26, 120.59,
122.79, 123.58, 123.92, 124.63, 126.01, 127.08,
127.47, 134.70, 138.55, 139.26, 140.80, 141.35,
147.08, 148.61, 148.89, 154.45, 162.34.
mmol), and potassium carbonate (0.7 g, 5.3 mmol)
were stirred at 180◦C in nitrobenzene (100 mL)
under N2 for 12 h. After the reaction was completed,
the solvent was removed by vacuum distillation.
The residue was extracted with dichloromethane,
and the organic layer was dried over anhydrous
MgSO4. The solvent was removed in vacuo, and the
residue was purified by flash chromatography on
silica gel (dichloromethane/hexane) to afford the
product 6 (1.3 g, 70%). mp: 186–188◦C (methanol).
IR (KBr): 3425, 2961, 1594, 1499, 1463, 1431, 1409,
1215, 749, 702 cm−1. Elemental analyses (C27H21N)
calcd: C, 90.21; H, 5.89; N, 3.90. Found: C, 90.50; H,
1
5.90; N, 4.00. H NMR (300 MHz, CDCl3): δ (ppm)
1.22 (s, 6H), 6.84–6.87 (m, 1H), 7.33–7.42 (m, 5H),
7.58–7.67 (m, 5H), 7.81–7.86 (m, 2H), 8.19 (d, J =
7.50 Hz, 1H), 8.26 (d, J = 8.10 Hz, 1H). 13C NMR (75
MHz, CDCl3): δ (ppm) 26.27, 48.08, 110.85, 112.95,
119.36, 119.44, 119.63, 120.12, 122.00, 123.71,
125.11, 125.77, 126.84, 126.90, 129.37, 129.55,
131.39, 135.92, 139.41, 139.45, 139.76, 141.34,
144.70, 154.62, 162.33.
11,11-Dimethyl-5-(pyridin-4-yl)-5,11-
dihydroindeno[1,2-b]carbazole 5h
REFERENCES
A mixture of the crude 3a and 3b (100 mg, 0.35
mmol, the mixture of 3a of 38% and 3b of 62%), 4-
bromopyridine hydrochloride (48 mg, 0.25 mmol),
1,10-phenanthroline (29 mg, 0.16 mmol), copper io-
dide (67 mg, 0.35 mmol), and potassium carbonate
(145 mg, 1.05 mmol) was refluxed in DMF (3 mL)
under N2 for 24 h. After the reaction was completed,
the reaction mixture was filtered and evaporated.
The filtrate was extracted with dichloromethane,
and the organic layer was dried over anhydrous
MgSO4. The solvent was removed in vacuo, and the
residue was purified by flash chromatography on
silica gel (ethyl acetate/hexane) to afford the prod-
uct 5h. Yield: 31 mg (29%). mp: 230◦C. IR (KBr):
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3435, 2958, 1586, 1503, 1446, 1330, 1239, 763 cm−1
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Elemental analyses (C26H20N2) calcd: C, 86.64; H,
5.59; N, 7.77. Found: C, 86.41; H, 5.77; N, 7.75.
1H NMR (300 MHz, CDCl3): δ (ppm) 1.66 (s, 6H),
7.39–7.89 (m, 10H), 8.20 (d, J = 8.1 Hz, 2H), 8.96
(s, 2H). 13C NMR (75 MHz, CDCl3): δ (ppm) 27.96,
46.41, 100.99, 109.73, 114.32, 119.99, 120.29, 121.10,
122.80, 124.02, 124.38, 126.09, 127.08, 127.54,
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12,12-Dimethyl-11-phenyl-11,12-dihydroindeno
[2,1-a]carbazole 6
12,12-Dimethyl-11,12-dihydroindeno[2,1-
a]carbazole 3a (1.5 g, 5.3 mmol), iodobenzene
(2.2 g, 10.6 mmol), copper powder (0.03 g, 0.53
Heteroatom Chemistry DOI 10.1002/hc