Synthesis and characterization of benzo[c]thiophene analogs tethered with dibenzo-heterocycles as potential OLEDs

Article abstract of DOI:10.1016/j.tet.2008.11.044

Synthesis of mixed heterocyclic system containing benzo[c]thiophene, dibenzo-heterocycles, and thiophene unit is described.

Full text of DOI:10.1016/j.tet.2008.11.044

Tetrahedron 65 (2009) 822–830
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis and characterization of benzo[c]thiophene analogs tethered with
dibenzo-heterocycles as potential OLEDs
*
Natarajan Senthil Kumar, J. Arul Clement, Arasambattu K. Mohanakrishnan
Department of Organic Chemistry, University of Madras, Guindy Campus, Chennai 600 025, Tamil Nadu, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Synthesis of mixed heterocyclic system containing benzo[c]thiophene, dibenzo-heterocycles, and thio-
phene unit is described.
Received 25 September 2008
Received in revised form 6 November 2008
Accepted 14 November 2008
Available online 24 November 2008
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords:
Friedel–Crafts reaction
Carbazole
Triphenylamine
Thionation
Benzo[c]thiophene
1. Introduction
Electronic properties of the linear conjugated oligomers ac-
quired growing importance in many areas of modern chemistry. In
Ar
S
S
particular,
p-conjugated thiophene oligomers possess interesting
1 Ar = aryl/heteroaryl
electronic and optical properties and they have been investigated
as Organic Field Effect Transistors (OFETs)1 and Organic Light-
Emitting Diodes (OLEDs).2 Carbazole analogs due to their unique
optical and chemical properties are often used as functional
building blocks in the construction of organic materials for opto-
electronic devices.3 Triarylamine-substituted carbazole based
dendrimer containing oligothiophene core has been explored in
Organic Solar Cells (OSCs) as well as OLEDs.4 Promarak and co-
workers recently reported the synthesis of N-carbazole end-capped
oligothiophene-fluorenes as promising hole-transporting and
light-emitting layers in OLED devices. The incorporation of N-
carbazole units at the terminal ends improved its morphology and
electrochemical properties.5 Thus, the carbazole analogs due to
their intense luminescence6 have been widely used in OLEDs as
blue emitters,7 white emitters,8 green emitters,9 and red emitters.10
Over the years, benzo[c]thiophene analogs 1 (Fig. 1) are ex-
plored as components in OLEDs11 as well as photovoltaics.12 Very
recently, Swager and co-workers compared the effectiveness of
isobenzofuran over isothionaphthene as red-shifting component in
Figure 1.
donor–acceptor type dyes.13 In further continuation of our work on
benzo[c]thiophenes,14 we report here our results on the synthesis
of benzo[c]thiophene containing dibenzo-heterocycles.
2. Results and discussion
Friedel–Crafts phthaloylation of dibenzo-heterocycles 2a–f in
the presence of anhydrous AlCl3 in dry DCM at room temperature
for 4 h followed by workup afforded crude keto acids 4a–f. Selec-
tive reduction of the ketone carbonyl function of acids 4a–f using
NaBH4 in THF/EtOH (2:5) at reflux for 10 h followed by workup and
acid catalyzed cyclization furnished the required lactones 5a–f in
38–45% yields. Ring opening of the lactones 5a–f using freshly
prepared 2-thienyl/arylmagnesium bromides 6a–f followed by
quenching with aq NH4Cl led to the isolation of keto alcohols.
The DCM solution of keto alcohol on thionation using 0.5 equiv /
of Lawesson’s reagent followed by workup and column chromato-
graphic purification afforded the respective benzo[c]thiophene
* Corresponding author. Tel.: þ91 44 22202813; fax: þ91 44 22300488.
E-mail address: mohan_67@hotmail.com (A.K. Mohanakrishnan).
0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.11.044

N. Senthil Kumar et al. / Tetrahedron 65 (2009) 822–830
823
O
monomeric benzo[c]thiophene analogs showed Eg values in the
range of 2.7–2.8 eV. The dimerization of benzo[c]thiophenes re-
duced the Eg values around w0.3 eV. In general, dimerization only
slightly reduced and enhanced the HOMO energy levels (w5.2 eV
to w5.0 eV) and LUMO energy levels (w2.4 eV to w2.5 eV), re-
spectively (Table 2).
CO2H
i) NaBH4/EtOH-THF
reflux, 10 h
ii) H3O
38-45%(2 steps)
O
O
3
O
AlCl3/DCM
4 h, rt
X
2a-f
X
4a-f
4. Conclusions
i) ArMgBr
O
O
In summary, the synthesis of benzo[c]thiophene analogs in-
corporating dibenzo-heterocycle as well as triphenylamine units
was achieved in reasonable yields. The highly soluble nature of
these benz-annelated thiophenes may make them suitable for
transistor applications through spin-coating techniques. The
higher-lying HOMO energy levels of these dibenzo-heterocycles
incorporated benzo[c]thiophenes (w5.1 to 5.2 eV) may find them
as suitable candidates for application as hole-transporting mate-
rials in double-layer OLEDs.
6a-f
S
Ar
ii) NH4Cl
X
X
iii) Lawesson's reagent
(0.5 eq.)
7a-r
5a-f
48-61%
Compound
2a/4a/5a
X
N-n-C6H13
2b/4b/5b
2c/4c/5c
2d/4d/5d
N-(n-2-ethyllhexyl)
N-phenyl
N-p-anisyl
2e/4e/5e
2f/4f/5f
O
S
5. Experimental
5.1. General
Scheme 1.
All melting points are uncorrected. IR spectra were recorded on
a SHIMADZU FT-IR 8300 instrument. 1H and 13C NMR spectra were
recorded in CDCl3 using TMS as an internal standard on a Bruker-
300 spectrometer. Mass spectra were recorded on a JEOL DX 303 HF
spectrometer. Elemental analyses were carried out on a Perkin–
Elmer series II 2400 (IIT Madras) instrument. All UV–vis spectra
were recorded in CH2Cl2 solution. The emission spectra were
recorded on Perkin–Elmer LS-45 spectrophotometer. The cyclic
voltammogram of 10ꢀ3 M solution of benzo[c]thiophenes was
carried out on a CHI 600C electrochemical analyzer. All the mea-
surements were carried out under oxygen free condition using
three electrode cells in which glassy carbon electrode was working
electrode, saturated Ag/AgCl electrode was reference electrode, and
platinum wire was used as an auxiliary electrode. Tetrabutyl-
ammoniumhexafluoro phosphate (TBAPF6) was used as supporting
electrolyte and its concentration was 10ꢀ1 M.
analogs 7a–r in 48–61% yields (Scheme 1). Complete details such as
type of the lactones, Grignards employed, and the respective ben-
zo[c]thiophene analogs obtained along with their yields are pre-
sented in Table 1. Ring opening of the 9-alkyl and 9-arylcarbazolyl
lactones 5a/b, 5c, and 5d with 2-thienyl/aryl Grignards 6a–f fol-
lowed by subsequent thionation gave the respective 1-(carbazolyl)-
3-(thienyl/aryl)benzo[c]thiophenes 7a–n in 48–61% yields (Table 1,
entries 1–4). Similarly, the ring openingof dibenzofuranyl lactone 5e
using thienyl-2-magnesium bromides 6b/6c followed by thionation
furnished 1-(dibenzofuranyl)-3-(2/5-hexylthienyl)benzo[c]thioph-
enes 7o/7p in 51% and 55% yields (Table 1, entry 5).
Reaction of dibenzothiophenyl lactone 5f with 3-hexyl-2-thi-
enylmagnesium bromide/5-hexyl-2-thienylmagnesium bromide
gave 1-dibenzothiophenyl-3-thienylbenzo[c]thiophenes 7q/7r in
60% and 57% yields, respectively (Table 1, entry 6). All these ben-
zo[c]thiophenes 7a–r were found to be highly soluble in common
organic solvents.
Following the similar procedure as mentioned above, triphe-
nylamine incorporated benzo[c]thiophene analogs 11a–c are
smoothly prepared in 55–60% yields (Scheme 2).
Some selected dibenzo-heterocycles tethered benzo[c]thio-
phenes 7b, 7g, 7j, 7o, and 7q are converted into the corresponding
dimers 12a–e in moderate yields (47–61%) using anhydrous FeCl3 in
dry DCM (Scheme 3). However, all attempts to dimerize triphe-
nylamine based benzo[c]thiophene 11a or 11b were complicated
due to the poor solubility of the resulting dimerization products.
5.2. A representative procedure for the preparation of lactone
5a from dibenzo-heterocycle 2a (procedure A)
5.2.1. 3-(9-Hexyl-9H-carbazol-3-yl)isobenzofuran-1(3H)-one (5a)
To
a stirred suspension of phthalic anhydride (7.07 g,
47.81 mmol) in dry DCM (150 mL), powdered anhydrous AlCl3
(7.96 g, 59.76 mmol) was added in two portions to get yellow
solution, which was cooled to 0 ꢁC. N-Hexyl carbazole 2a (10 g,
39.84 mmol) in DCM (20 mL) was added dropwise to the above
solution at 0 ꢁC and stirred for 4 h at room temperature. The re-
action mixture was quenched with ice water containing HCl and
extracted with DCM (2ꢂ30 mL). Evaporation of solvent gave crude
keto acid, which was dissolved in THF/EtOH (2:5). To this solution,
NaBH4 (7.57 g, 199.2 mmol) was added in portions and refluxed
for 10 h. The reaction mixture was poured into water and concd
HCl was added dropwise under stirring (pH¼1–2). It was then
extracted with EtOAc and dried (Na2SO4). Solvent was evaporated
in vacuo to give the crude product, which was purified by column
chromatography (10% EA/Hexane) to give the title compound 5a
[6.1 g, 40% (two steps)] as a thick yellow liquid. [Found: C, 81.6; H,
6.4; N, 3.5. C26H25NO2 requires: C, 81.43; H, 6.57; N, 3.65%.] Rf (10%
3. Photophysical and electrochemical studies
The UV–vis spectra of monomeric benzo[c]thiophenes exhibited
a strong absorption in the region of 445–465 nm due to the
p
–p
*
electronic transition of the conjugated backbone system. The di-
merization of monomeric benzo[c]thiophenes red shifted the lmax
values in the range of 35–60 nm. The exact absorption lmax values
of these compounds are given in Table 2. The qualitative emission
data of selected dibenzo-heterocycles incorporated benzo[c]thio-
phenes were recorded in DCM solution and the emission values are
also presented. The HOMO and LUMO energy levels of benzo[c]-
thiophenes were calculated from the absorption and the onset
oxidation potential. The Eg, HOMO, and LUMO values obtained for
the representative benzo[c]thiphenes are presented in Table 2. The
EA/Hexane) 0.62; nmax (KBr) 2851, 1759, 1595, 1500, 745 cmꢀ1
; dH
(300 MHz, CDCl3) 8.03–7.97 (3H, m, ArH), 7.64–7.48 (2H, m, ArH),
7.46–7.43 (1H, m, ArH), 7.40–7.31 (3H, m, ArH), 7.27–7.18 (2H, m,
ArH), 6.58 (1H, s, CH), 4.23 (2H, t, J 7.2 Hz, NCH2), 1.84–1.71 (2H,
m, CH2), 1.42–1.25 (6H, m, CH2), 0.90–0.82 (3H, m, CH3); dC

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N. Senthil Kumar et al. / Tetrahedron 65 (2009) 822–830
Table 1
Synthesis of benzo[c]thiophene analogs containing dibenzo-heterocycles
Entry
Lactones
ArMgBr
Products
Yield (%)a mp
52 (Orange liquid)
48 (Orange liquid)
53 (Orange liquid)
R1
S
R1
MgBr
R2
S
S
R2
1
5a
6a R1 = H, R2 = H
7a R1 = H, R2 = H
N
6b R1 = n-C6H13, R2 = H
6c R1 = H, R2 = n-C6H13
7b R1 = n-C6H13, R2 = H
7c R1 = H, R2 = n-C6H13
n-C6H13
55 (Orange liquid)
48 (Orange liquid)
57 (Orange liquid)
R1
R2
MgBr
R1
6d R1 = CH3, R2 = H
6e R1 = H, R2 = CH3
6f R1 = H, R2 = OCH3
R2
S
2
5a
7d R1 = CH3, R2 = H
7e R1 = H, R2 = CH3
7f R1 = H, R2 = OCH3
N
n-C6H13
57 (Orange liquid)
61 (Orange liquid)
50 (Orange liquid)
R1
R1
S
R2
S
R2
MgBr
S
3
5b
6a R1 = H, R2 = H
7g R1 = H, R2 = H
N
6b R1 = n-C6H13, R2 = H
2-ethylhexyl 7h R1 = n-C6H13, R2 = H
7i R1 = H, R2 = n-C6H13
6c R1 = H, R2 = n-C6H13
55 (114 ꢁC)
57 (62 ꢁC)
R1
51 (Orange liquid)
61 (Orange liquid)
49 (Orange liquid)
R1
S
R2
S
R2
7j R = H, R1 = H, R2 = H
MgBr
S
N
R
4
5c/5d
7k R = H, R1 = n-C6H13, R2 = H
6a R1 = H, R2 = H
7l R = H, R1 = H, R2 = n-C6H13
7m R = OMe, R1 = n-C6H13, R2 = H
7n R = OMe, R1 = H, R2 = n-C6H13
6b R1 = n-C6H13, R2 = H
6c R1 = H, R2 = n-C6H13
R1
R1
51 (115 ꢁC)
55 (Orange liquid)
R2
5
5e
MgBr
S
S
R2
S
6b R1 = n-C6H13, R2 = H
7o R1 = n-C6H13, R2 = H
6c R1 = H, R2 = n-C6H13
O
7p R1 = H, R2 = n-C6H13
60 (107 ꢁC)
57 (Orange liquid)
R1
R1
R2
6
5f
MgBr
S
S
R2
S
6b R1 = n-C6H13, R2 = H
6c R1 = H, R2 = n-C6H13
7q R1 = n-C6H13, R2 = H
S
7r R1 = H, R2 = n-C6H13
a
Isolated yield of products after column chromatography.
(75.6 MHz, CDCl3) 170.8, 150.3, 140.9, 134.2, 129.2, 126.4, 126.1,
126.0, 125.5, 124.9, 123.2, 123.0, 122.5, 120.5, 119.8, 119.2, 109.2,
109.0, 84.0, 43.2, 31.6, 28.9, 26.9, 22.5, 14.0; m/z (EI) 383 (100,
Mþ).
5.2.2. 3-(9-(2-Ethylhexyl)-9H-carbazol-3-yl)isobenzofuran-1(3H)-
one (5b)
Following the above-mentioned procedure (A), lactone 5b
(6.03 g, 41%) was obtained using N-(2-ethylhexyl carbazole) 2b

N. Senthil Kumar et al. / Tetrahedron 65 (2009) 822–830
825
(10 g, 35.84 mmol), phthalic anhydride (6.36 g, 43.00 mmol), AlCl3
(7.16 g, 53.75 mmol), and NaBH4 (6.81 g, 179.2 mmol) as a thick
yellow liquid. [Found: C, 82.0; H, 7.3; N, 3.2. C28H29NO2 requires: C,
81.72; H, 7.10; N, 3.40%.] Rf (10% EA/Hexane) 0.65; nmax (KBr) 2822,
O
CO2H
O
O
i) NaBH4/EtOH-THF
reflux, 10 h
1759, 1596, 1500, 762 cmꢀ1
; dH (300 MHz, CDCl3) 8.04–7.97 (3H, m,
3
O
N
AlCl3/DCM
4 h, rt
ArH), 7.66–7.60 (2H, m, ArH), 7.57–7.52 (1H, m, ArH), 7.48–7.43 (1H,
m, ArH), 7.39–7.35 (1H, m, ArH), 7.33 (1H, s, ArH), 7.27–7.18 (2H, m,
ArH), 6.59 (1H, s, CH), 4.13–4.10 (2H, m, NCH2), 2.03 (1H, m, CH),
1.42–1.21 (7H, m, CH2CH3), 0.91–0.82 (7H, m, CH2CH3); dC
(75.6 MHz, CDCl3) 170.8, 150.3, 140.4, 134.3, 129.2, 126.4, 126.1,
126.0, 125.5, 124.9, 123.2, 123.0, 122.4, 120.4, 119.8, 119.2, 109.5,
109.3, 84.0, 47.5, 39.4, 31.0, 28.8, 24.4, 23.0, 14.0, 10.9; m/z (EI) 411
(13, Mþ).
ii) H3O
N
8
9
R1
R1
O
O
S
S
2
i)
MgBr
R
S
6
N
N
R2
5.2.3. 3-(9-Phenyl-9H-carbazol-3-yl)isobenzofuran-1(3H)-one (5c)
Following the above-mentioned procedure (A), lactone 5c
(6.93 g, 45%) was obtained using N-phenyl carbazole 2c (10 g,
41.15 mmol), phthalic anhydride (7.30 g, 49.38 mmol), AlCl3 (8.22 g,
61.72 mmol), and NaBH4 (7.82 g, 205.76 mmol) as a colorless solid;
mp 87 ꢁC. [Found: C, 83.0; H, 4.8; N, 3.5. C26H17NO2 requires: C,
83.18; H, 4.56; N, 3.73%.] Rf (10% EA/Hexane) 0.55; nmax (KBr) 1761,
ii) NH4Cl
iii) Lawesson's reagent
(0.5 eq.)
55-60%
10
11a R1, R2 = H
11b R1 = n-C6H13, R2 = H
11c R1 = H, R2 = n-C6H13
1600, 1501, 753 cmꢀ1
; dH (300 MHz, CDCl3) 8.09–7.98 (3H, m, ArH),
Scheme 2.
7.64–7.41 (7H, m, ArH), 7.40–7.20 (6H, m, ArH), 6.60 (1H, s, CH); dC
(75.6 MHz, CDCl3) 170.8,150.3,141.5,141.4,137.3,134.3,130.0,129.3,
127.8, 127.7, 127.1, 126.5, 125.9, 125.6, 125.1, 123.6, 123.1, 122.9, 120.5,
120.3, 119.6, 110.3, 110.0, 83.8; m/z (EI) 375 (13, Mþ).
R1
R1
S
S
i) FeCl3/DCM
S
5.2.4. 3-(9-(4-Methoxyphenyl)-9H-carbazol-3-yl)isobenzofuran-
1(3H)-one (5d)
S
rt, 12 h
7b, 7g
7j, 7o, 7q
ii) NH2.NH2.H2O
47-61%
Following the above-mentioned procedure (A), lactone 5d
(6.22 g, 42%) was obtained using N-(p-anisyl)carbazole 2d (10 g,
36.49 mmol), phthalic anhydride (6.48 g, 43.79 mmol), AlCl3 (7.29 g,
54.74 mmol), and NaBH4 (6.93 g, 182.48 mmol) as a colorless solid;
mp 95 ꢁC. [Found: C, 80.2; H, 4.5; N, 3.3. C27H19NO3 requires: C,
79.98; H, 4.72; N, 3.45%.] Rf (10% EA/Hexane) 0.51; nmax (KBr) 2811,
X
X
12a-e
R1
Yield
Compound
X
1759, 1605, 1500, 755, 685 cmꢀ1
; dH (300 MHz, CDCl3) 8.04–8.01
(3H, m, ArH), 7.61–7.54 (2H, m, ArH), 7.36–7.25 (8H, m, ArH), 7.08
(2H, s, ArH), 6.59 (1H, s, CH), 3.87 (3H, s, OCH3); dc (75.6 MHz, CDCl3)
170.8, 159.1, 150.3, 141.9, 141.8, 134.3, 129.83, 129.3, 128.5, 127.5,
126.4, 126.0, 125.6, 125.1,123.4, 123.1,122.7,120.4,120.1,119.6,115.2,
110.3, 110.0, 83.9, 55.6; m/z (EI) 405 (13, Mþ).
N-n-C6H13
12a
12b
12c
12d
12e
n-C6H13 61%
N-n-2-Ethylhexyl
50%
47%
H
H
N-Ph
O
S
n-C6H13 52%
n-C6H13 55%
Scheme 3.
5.2.5. 3-(Dibenzofuran-3-yl)isobenzofuran-1(3H)-one (5e)
Following the above-mentioned procedure (A), lactone 5e
(7.14 g, 40%) was obtained using dibenzofuran 2e (10 g,
59.52 mmol), phthalic anhydride (10.57 g, 71.43 mmol), AlCl3
(11.89 g, 89.28 mmol), and NaBH4 (11.3 g, 297.61 mmol) as a color-
less solid; mp 171 ꢁC. [Found: C, 80.2; H, 3.8; C20H12O3 requires: C,
79.99; H, 4.03%.] Rf (10% EA/Hexane) 0.60; nmax (KBr) 1755, 1585,
Table 2
Summary of the physical properties of selected benzo[c]thiophenes
Compound lmax (nm) lemissb (nm) Egc (eV) E
(eV) HOMOd (eV) LUMOe (eV)
a
onset
ox
7a
7b
7g
7h
7j
7l
7o
7q
11a
11b
11c
12a
12b
12c
12d
12e
455
450
465
458
445
458
445
458
457
445
440
497
492
498
505
510
550
540
544
550
530
545
530
545
545
535
540
615
597
605
650
645
2.72
2.75
2.67
2.71
2.78
2.71
2.78
2.71
2.71
2.78
2.82
2.49
2.52
2.49
2.45
2.43
0.70
0.69
0.71
0.68
0.70
0.73
0.70
0.73
0.65
0.72
0.71
0.57
0.55
0.58
0.55
0.57
5.14
5.13
5.15
5.12
5.14
5.17
5.14
5.17
5.09
5.16
5.15
5.01
4.99
5.02
4.99
5.01
2.42
2.38
2.48
2.41
2.36
2.46
2.36
2.46
2.38
2.38
2.33
2.52
2.47
2.53
2.54
2.58
1500, 741 cmꢀ1
; dH (300 MHz, CDCl3) 7.99 (1H, t, J 7.5 Hz, ArH),
7.92–7.83 (2H, m, ArH), 7.66–7.61 (1H, m, ArH), 7.58–7.52 (3H, m,
ArH), 7.44 (1H, t, J 7.5 Hz, ArH), 7.34–7.25 (3H, m, ArH), 6.55 (1H, s,
CH); dC (75.6 MHz, CDCl3) 170.6, 156.7, 156.5, 149.9, 134.5, 131.0,
129.5, 127.7, 126.2, 125.7, 124.9, 123.6, 123.0, 123.0, 120.9, 119.7,
112.2, 111.8, 83.0; m/z (EI) 300 (100, Mþ).
5.2.6. 3-(Dibenzothiophen-3-yl)isobenzofuran-1(3H)-one (5f)
Followingtheabove-mentionedprocedure(A), lactone5f(6.52 g,
38%) was obtained using dibenzothiophene 2f (10 g, 54.34 mmol),
phthalic anhydride (9.65 g, 65.22 mmol), AlCl3 (10.86 g,
81.52 mmol), and NaBH4 (10.3 g, 271.74 mmol) as a colorless solid;
mp 90 ꢁC. [Found: C, 75.7; H, 3.7; S, 10.4. C20H12O2S requires: C,
75.93; H, 3.82; S, 10.14%.] Rf (10% EA/Hexane) 0.65; nmax (KBr) 1759,
a
b
c
Measured in dilute dichloromethane solution.
Excited at absorption maxima.
1595, 1500, 741 cmꢀ1
; dH (300 MHz, CDCl3) 8.09–8.04 (2H, m, ArH),
7.99 (1H, t, J 7.5 Hz, ArH), 7.82–7.80 (2H, m, ArH), 7.65–7.52 (2H, m,
ArH), 7.45–7.42 (2H, m, ArH), 7.34–7.26 (2H, m, ArH), 6.55 (1H, s, CH);
Estimated from the absorption (Eg¼1240/lmax).
d
e
Calculated using the empirical equation: HOMO¼(4.44þEooxnset).
Calculated from LUMO¼HOMOꢀEg.

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N. Senthil Kumar et al. / Tetrahedron 65 (2009) 822–830
dC (75.6 MHz, CDCl3) 170.6, 149.8, 140.5, 139.9, 136.0, 134.9, 134.5,
132.8,129.5,127.2,125.7,125.6,125.3,124.6,123.4,123.0,122.9,121.8,
120.3, 82.9; m/z (EI) 316 (45, Mþ).
CDCl3) 146.0, 141.0, 140.0, 135.0, 134.9, 133.8, 127.3, 126.5, 126.1,
124.8, 124.7, 124.6, 124.3, 123.9, 123.5, 122.8, 121.6, 121.5, 121.2,
120.6, 119.2, 109.2, 109.0, 43.3, 31.6, 30.3, 29.0, 28.9, 27.0, 22.6, 22.6,
14.1, 14.0; m/z (EI) 549 (27, Mþ).
5.3. A representative procedure for the preparation of
benzo[c]thiophene (7a) from lactone (5a) (procedure B)
5.3.4. 9-Hexyl-3-(1-o-tolylbenzo[c]thiophen-3-yl)-9H-
carbazole (7d)
5.3.1. 9-Hexyl-3-(1-(thiophen-2-yl)benzo[c]thiophen-3-yl)-9H-
carbazole (7a)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7d (1.36 g, 55%) was obtained using lactone 5a (2 g,
5.22 mmol), o-tolylmagnesium bromide [prepared from 2-bromo-
toluene (1.07 g, 6.26 mmol) and Mg (0.16 g, 6.88 mmol)], and
Lawesson’s reagent (1.06 g, 2.61 mmol) as a thick orange liquid.
[Found: C, 83.5; H, 6.8; N, 2.8; S, 6.5. C33H31NS requires: C, 83.68; H,
6.60; N, 2.96; S, 6.77%.] Rf (100% Hexane) 0.72; dH (300 MHz, CDCl3)
8.39 (1H, s, ArH), 8.12 (1H, d, J 7.5 Hz, ArH), 7.90 (1H, d, J 8.4 Hz,
ArH), 7.76 (1H, d, J 8.4 Hz, ArH), 7.46–7.44 (3H, m, ArH), 7.39–7.27
(6H, m, ArH), 7.02 (2H, t, J 8.4 Hz, ArH), 4.26 (2H, t, J 6.9 Hz, NCH2),
2.33 (3H, s, CH3), 1.85 (2H, q, J 6.4 Hz, CH2), 1.40–1.29 (6H, m, CH2),
0.85 (3H, t, J 5.8 Hz, CH3); dC (75.6 MHz, CDCl3) 141.0, 140.0, 139.0,
138.1,136.7,135.8,134.0,133.2,132.3,131.7,130.9,130.6,128.3,127.4,
126.1, 125.8, 125.1, 123.7, 122.9, 121.6, 121.4, 121.2, 120.7, 119.2, 109.2,
109.0, 43.3, 31.7, 29.1, 27.1, 22.7, 20.8, 14.0; m/z (EI) 473 (23, Mþ).
To a solution of lactone 5a (2 g, 5.22 mmol) in anhydrous THF
(25 mL) was added 2-thienylmagnesium bromide [prepared from
2-bromothiophene (1.02 g, 6.26 mmol) and magnesium turnings
(0.16 g, 6.88 mmol)] at 0 ꢁC under N2. The reaction mixture was
slowly raised to room temperature and stirred for 4 h. It was then
quenched with aq NH4Cl solution, extracted with DCM (2ꢂ20 mL),
and dried (Na2SO4). The DCM solution was then stirred with Law-
esson’s reagent (1.06 g, 2.61 mmol) at room temperature for 4 h.
Solvent was evaporated in vacuo to give the crude product, which
was purified by column chromatography (100% Hexane) to give the
title compound 7a (1.26 g, 52%) as an orange liquid. [Found: C, 77.1;
H, 5.7; N, 3.2; S, 14.0. C30H27NS2 requires: C, 77.38; H, 5.84; N, 3.01;
S, 13.77%.] Rf (100% Hexane) 0.70; nmax (KBr) 2822, 1596, 1500,
762 cmꢀ1
; dH (300 MHz, CDCl3) 8.34 (1H, s, ArH), 8.12 (1H, d, J
7.5 Hz, ArH), 7.97 (1H, d, J 8.7 Hz, ArH), 7.87 (1H, d, J 8.7 Hz, ArH),
7.72 (1H, d, J 8.4 Hz, ArH), 7.70–7.37 (3H, m, ArH), 7.34–7.30 (2H, m,
ArH), 7.23 (1H, t, J 6.9 Hz, ArH), 7.14–7.06 (3H, m, ArH), 4.26 (2H, t, J
7.05 Hz, NCH2), 1.90–1.81 (2H, m, CH2), 1.38–1.25 (6H, m, CH2),
0.88–0.84 (3H, m, CH3); dC (75.6 MHz, CDCl3) 141.0, 140.1, 136.5,
135.8, 135.4, 135.0, 127.9, 127.3, 126.1, 125.7, 125.1, 124.9, 124.6,
124.6, 124.0, 123.6, 122.8, 121.7, 121.4, 121.2, 120.6, 119.2, 109.3,
109.0, 43.3, 31.7, 29.1, 27.1, 22.6, 14.1; m/z (EI) 465 (13, Mþ).
5.3.5. 9-Hexyl-3-(1-p-tolylbenzo[c]thiophen-3-yl)-9H-
carbazole (7e)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7e (1.18 g, 48%) was obtained using lactone 5a (2 g,
5.22 mmol), p-tolylmagnesium bromide [prepared from 4-bromo-
toluene (1.07 g, 6.26 mmol) and Mg (0.16 g, 6.88 mmol)], and Law-
esson’s reagent (1.06 g, 2.61 mmol) as a thick orange liquid. [Found:
C, 83.4; H, 6.7; N, 2.8; S, 6.6. C33H31NS requires: C, 83.68; H, 6.60; N,
2.96; S, 6.77%.] Rf (100% Hexane) 0.72; dH (300 MHz, CDCl3) 8.37 (1H,
s, ArH), 8.14 (1H, d, J 7.8 Hz, ArH), 7.91–7.84 (2H, m, ArH), 7.78–7.75
(1H, m, ArH), 7.61 (1H, d, J 7.8 Hz, ArH), 7.49–7.43 (3H, m, ArH), 7.40–
7.20 (5H, m, ArH), 7.09–7.05 (1H, m, ArH), 4.31 (2H, t, J 7.2 Hz, NCH2),
2.42 (3H, s, CH3),1.91–1.87 (2H, m, CH2),1.41–1.25 (6H, m, CH2), 0.87
(3H, t, J 6.9 Hz, CH3); dC (75.6 MHz, CDCl3) 141.0, 140.0, 137.1, 135.4,
135.0,134.9,133.2,131.8,129.8,129.1,127.4,126.8,126.1,125.0,124.0,
123.8, 123.5, 122.8, 121.6, 121.2, 120.6, 119.1, 109.2, 109.0, 43.3, 37.6,
29.1, 27.0, 22.6, 21.3, 14.1; m/z (EI) 473 (35, Mþ).
5.3.2. 9-Hexyl-3-(1-(3-hexylthiophen-2-yl)benzo[c]thiophen-3-yl)-
9H-carbazole (7b)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7b (1.38 g, 48%) was obtained using lactone 5a (2 g,
5.22 mmol), 3-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-3-hexylthiophene (1.55 g, 6.27 mmol) and Mg (0.16 g,
6.90 mmol)], and Lawesson’s reagent (1.06 g, 2.61 mmol) as a thick
orange liquid. [Found: C, 78.4; H, 7.3; N, 2.8; S, 11.4. C36H39NS2 re-
quires: C, 78.64; H, 7.15; N, 2.55; S,11.66%.] Rf (100% Hexane) 0.72; dH
(300 MHz, CDCl3) 8.37 (1H, s, ArH), 8.13 (1H, d, J 7.8 Hz, ArH), 7.91–
7.87 (1H, m, ArH), 7.76 (1H, d, J 10.2 Hz, ArH), 7.61–7.60 (1H, m, ArH),
7.48–7.34 (4H, m, ArH), 7.24 (1H, d, J 7.35 Hz, ArH), 7.08–7.05 (3H, m,
ArH), 4.29 (2H, t, J 7.2 Hz, NCH2), 2.68 (2H, d, J 7.8 Hz, CH2),1.94–1.85
(2H, m, CH2), 1.63–1.58 (2H, m, CH2), 1.41–1.21 (12H, m, CH2), 0.88–
0.79 (6H, m, CH3); dC (75.6 MHz, CDCl3) 142.2, 141.0, 140.1, 137.9,
137.1,134.2,129.3,128.6,127.4,126.1,125.7,124.8,124.0,123.8,123.7,
123.6, 122.8, 121.7, 121.3, 121.2, 120.6, 119.2, 109.2, 109.0, 43.3, 31.7,
30.9, 29.2, 29.1, 29.0, 27.0, 22.6, 14.1, 14.0; m/z (EI) 549 (45, Mþ).
5.3.6. 9-Hexyl-3-(1-(4-methoxyphenyl)benzo[c]thiophen-3-yl)-9H-
carbazole (7f)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7f (1.45 g, 57%) was obtained using lactone 5a (2 g,
4.86 mmol), p-anisylmagnesium bromide [prepared from 4-bro-
moanisole (1.17 g, 6.26 mmol) and Mg (0.16 g, 6.88 mmol)], and
Lawesson’s reagent (1.06 g, 2.61 mmol) as a thick orange liquid.
[Found: C, 80.7; H, 6.6; N, 2.7; S, 6.8. C33H31NOS requires: C, 80.94;
H, 6.38; N, 2.86; S, 6.55%.] Rf (100% Hexane) 0.69; dH (300 MHz,
CDCl3) 8.37 (1H, s, ArH), 8.14 (1H, d, J 7.5 Hz, ArH), 7.81–7.75 (2H, m,
ArH), 7.91–7.88 (1H, m, ArH), 7.50–7.43 (3H, m, ArH), 7.25 (1H, t, J
6.9 Hz, ArH), 7.08–7.02 (3H, m, ArH), 6.94 (1H, d, J 8.7 Hz, ArH), 4.31
(2H, t, J 7.05 Hz, NCH2), 3.87 (3H, s, OCH3), 1.92–1.89 (2H, m, CH2),
1.42–1.25 (6H, m, CH2), 0.88 (3H, t, J 6.9 Hz, CH3); dC (75.6 MHz,
CDCl3) 159.1, 158.7, 141.0, 139.9, 134.9, 133.5, 133.0, 130.4, 127.7,
127.4, 126.0, 125.0, 123.9, 123.7, 123.5, 122.8, 121.5, 121.1, 120.6, 119.1,
114.5, 114.2, 109.2, 108.9, 55.4, 43.3, 31.6, 29.0, 27.0, 22.6, 14.0; m/z
(EI) 489 (13, Mþ).
5.3.3. 9-Hexyl-3-(1-(5-hexylthiophen-2-yl)benzo[c]thiophen-3-yl)-
9H-carbazole (7c)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7c (1.52 g, 53%) was obtained using lactone 5a (2 g,
5.22 mmol), 5-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-5-hexylthiophene (1.55 g, 6.27 mmol) and Mg (0.16 g,
6.90 mmol)], and Lawesson’s reagent (1.06 g, 2.61 mmol) as a thick
orange liquid. [Found: C, 78.4; H, 7.3; N, 2.8; S, 11.4. C36H39NS2 re-
quires: C, 78.64; H, 7.15; N, 2.55; S, 11.66%.] Rf (100% Hexane) 0.72;
dH (300 MHz, CDCl3) 8.34 (1H, s, ArH), 8.13 (1H, d, J 7.5 Hz, ArH), 7.97
(1H, d, J 8.4 Hz, ArH), 7.86 (1H, d, J 8.7 Hz, ArH), 7.74 (1H, d, J 8.4 Hz,
ArH), 7.51–7.40 (3H, m, ArH), 7.23–7.22 (1H, m, ArH), 7.17–7.04 (3H,
m, ArH), 6.80 (1H, t, J 3.3 Hz, ArH), 4.30 (2H, t, J 6.9 Hz, NCH2), 2.85
(2H, t, J 7.5 Hz, CH2), 1.91–1.83 (2H, m, CH2), 1.76–1.69 (2H, m, CH2),
1.39–1.25 (12H, m, CH2), 0.93–0.85 (6H, m, CH3); dC (75.6 MHz,
5.3.7. 9-(2-Ethylhexyl)-3-(1-(thiophen-2-yl)benzo[c]thiophen-3-
yl)-9H-carbazole (7g)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7g (1.37 g, 57%) was obtained using lactone 5b (2 g,
4.86 mmol), 2-thienylmagnesium bromide [prepared from 2-bro-
mothiophene (0.95 g, 5.84 mmol) and Mg (0.15 g, 6.41 mmol)], and

N. Senthil Kumar et al. / Tetrahedron 65 (2009) 822–830
827
Lawesson’s reagent (0.98 g, 2.43 mmol) as a thick orange liquid.
[Found: C, 77.6; H, 6.1; N, 2.6; S, 13.2. C32H31NS2 requires: C, 77.85;
H, 6.33; N, 2.84; S, 12.99%.] Rf (100% Hexane) 0.75; dH (300 MHz,
CDCl3) 8.24 (1H, s, ArH), 8.02 (1H, d, J 7.8 Hz, ArH), 7.87 (1H, d, J
8.7 Hz, ArH), 7.77 (1H, d, J 8.4 Hz, ArH), 7.63–7.60 (1H, m, ArH),
7.39–7.21 (5H, m, ArH), 7.16–7.08 (1H, m, ArH), 7.04–6.94 (3H, m,
ArH), 4.05–4.02 (2H, m, NCH2), 1.99–1.96 (1H, m, CH), 1.32–1.15 (7H,
m, CH2CH3), 0.84–0.75 (7H, m, CH2CH3); dC (75.6 MHz, CDCl3) 141.5,
140.6,136.5,135.8,135.4,135.0,127.9,127.3,126.1,125.7,125.1,125.0,
124.6,124.5,124.0,123.5,122.8, 121.7,121.4,121.1,120.6,119.2,109.5,
109.3, 47.6, 39.5, 31.1, 28.9, 24.5, 23.2, 14.1, 11.0; m/z (EI) 493 (100,
Mþ).
CDCl3) 141.5,140.5,137.5,136.3,135.4,135.3,135.1,130.1,130.0,127.8,
127.7, 127.6, 127.1, 126.5, 125.8, 125.2, 125.1, 124.6, 124.1, 124.0, 123.2,
121.5, 121.4, 121.1, 120.6, 120.3, 110.4, 110.1; m/z (EI) 457 (41, Mþ).
5.3.11. 3-(1-(3-Hexylthiophen-2-yl)benzo[c]thiophen-3-yl)-9-
phenyl-9H-carbazole (7k)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7k (1.47 g, 52%) was obtained using lactone 5c (2 g,
5.33 mmol), 3-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-3-hexylthiophene (1.58 g, 6.4 mmol) and Mg (0.17 g,
7.02 mmol)], and Lawesson’s reagent (1.08 g, 2.66 mmol) as an or-
ange solid; mp 62 ꢁC. [Found: C, 79.5; H, 6.0; N, 2.8; S, 11.6.
C36H31NS2 requires: C, 79.81; H, 5.77; N, 2.59; S, 11.84%.] Rf (100%
Hexane) 0.70; dH (300 MHz, CDCl3) 8.41 (1H, d, J 6.3 Hz, ArH), 8.16
(1H, t, J 8.1 Hz, ArH), 7.90–7.85 (1H, m, ArH), 7.72–7.69 (1H, m, ArH),
7.60–7.55 (5H, m, ArH), 7.51–7.36 (4H, m, ArH), 7.34–7.27 (2H, m,
ArH), 7.09–7.02 (3H, m, ArH), 2.71–2.63 (2H, m, CH2), 1.63–1.56 (2H,
m, CH2), 1.21–1.19 (6H, m, CH2), 0.81–0.77 (3H, m, CH3); dC
(75.6 MHz, CDCl3) 142.2, 141.4,140.5,137.9,137.5,136.7,134.3, 130.0,
129.3, 128.5, 127.7,127.1,127.0,126.5, 126.0,125.7,124.1,124.0, 123.9,
123.3, 121.7, 121.2, 121.1, 120.6, 120.3, 110.4, 110.1, 31.7, 30.9, 29.2,
29.1, 22.6, 14.1; m/z (EI) 541 (100, Mþ).
5.3.8. 9-(2-Ethylhexyl)-3-(1-(3-hexylthiophen-2-yl)benzo[c]-
thiophen-3-yl)-9H-carbazole (7h)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7h (1.71 g, 61%) was obtained using lactone 5b (2 g,
4.86 mmol), 3-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-3-hexylthiophene (1.44 g, 5.84 mmol) and Mg (0.5 g,
6.41 mmol)], and Lawesson’s reagent (0.98 g, 2.43 mmol) as a thick
orange liquid. [Found: C, 77.8; H, 7.3; N, 2.2; S, 11.3. C38H43NS2 re-
quires: C, 78.98; H, 7.50; N, 2.42; S, 11.10%.] Rf (100% Hexane) 0.70;
dH (300 MHz, CDCl3) 8.49–8.48 (1H, m, ArH), 8.24 (1H, d, J 7.8 Hz,
ArH), 8.02–7.99 (1H, m, ArH), 7.88–7.85 (1H, m, ArH), 7.73–7.70 (1H,
m, ArH), 7.60–7.44 (4H, m, ArH), 7.37–7.31 (1H, m, ArH), 7.20–7.15
(3H, m, ArH), 4.30–4.24 (2H, m, NCH2), 2.78 (2H, d, J 7.5 Hz, CH2),
2.23–2.18 (1H, m, CH), 1.74–1.67 (2H, m, CH2), 1.52–1.33 (13H, m,
CH2CH3), 1.05–0.98 (10H, m, CH2CH3); dC (75.6 MHz, CDCl3) 142.2,
141.5, 140.6, 137.9, 137.1, 134.2, 129.3, 128.6, 127.4, 126.1, 125.7, 124.8,
124.1,123.8, 123.7, 123.5, 122.8, 121.7, 121.4, 121.2, 120.6, 119.2, 109.5,
109.3, 47.6, 39.6, 31.7, 31.1, 31.0, 29.8, 29.2, 29.2, 28.9, 24.5, 23.2,
22.7, 14.2, 11.0; m/z (EI) 577 (25, Mþ).
5.3.12. 3-(1-(5-Hexylthiophen-2-yl)benzo[c]thiophen-3-yl)-9-
phenyl-9H-carbazole (7l)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7l (1.47 g, 51%)was obtained using lactone 5c (2 g,
5.33 mmol), 5-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-5-hexylthiophene (1.58 g, 6.4 mmol) and Mg (0.17 g,
7.02 mmol)], and Lawesson’s reagent (1.08 g, 2.66 mmol) as a thick
orange liquid. [Found: C, 79.6; H, 6.1; N, 2.8; S, 11.6. C36H31NS2 re-
quires: C, 79.81; H, 5.77; N, 2.59; S, 11.84%.] Rf (100% Hexane) 0.72;
nmax (KBr) 2851, 1597, 1500, 765 cmꢀ1
; dH (300 MHz, CDCl3) 8.43–
5.3.9. 9-(2-Ethylhexyl)-3-(1-(5-hexylthiophen-2-yl)benzo[c]-
thiophen-3-yl)-9H-carbazole (7i)
8.42 (1H, m, ArH), 8.19 (1H, d, J 7.5 Hz, ArH), 7.91–7.88 (1H, m, ArH),
7.74–7.65 (1H, m, ArH), 7.64–7.59 (5H, m, ArH), 7.52–7.46 (4H, m,
ArH), 7.43 (1H, d, J 3.9 Hz, ArH), 7.36–7.30 (2H, m, ArH), 7.10–7.06
(2H, m, ArH), 2.69 (2H, t, J 7.65 Hz, CH2), 1.64–1.59 (2H, m, CH2),
1.29–1.22 (6H, m, CH2), 0.84–0.80 (3H, m, CH3); dC (75.6 MHz,
CDCl3) 142.2, 141.4, 140.5, 137.9, 137.5, 136.7, 134.3, 130.0, 129.3,
128.5, 127.7, 127.1,127.0, 126.5, 126.0, 125.7,124.1,124.0,123.9, 123.3,
121.7, 121.2, 121.1,120.6, 120.3, 110.4,110.1, 31.7, 30.9, 29.2, 29.1, 22.6,
14.1; m/z (EI) 541 (51, Mþ).
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7i (1.40 g, 50%) was obtained using lactone 5b (2 g,
4.86 mmol), 5-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-5-hexylthiophene (1.44 g, 5.84 mmol) and Mg (0.5 g,
6.41 mmol)], and Lawesson’s reagent (0.98 g, 2.43 mmol) as a thick
orange liquid. [Found: C, 78.8; H, 7.3; N, 2.6; S, 11.3. C38H43NS2 re-
quires: C, 78.98; H, 7.50; N, 2.42; S, 11.10%.] Rf (100% Hexane) 0.75;
dH (300 MHz, CDCl3) 8.41–8.40 (1H, m, ArH), 8.07 (1H, d, J 8.1 Hz,
ArH), 8.03–8.01 (1H, m, ArH), 7.95–7.92 (1H, m, ArH), 7.81–7.78 (1H,
m, ArH), 7.57–7.45 (3H, m, ArH), 7.33–7.28 (1H, m, ArH), 7.18–7.10
(3H, m, ArH), 6.86 (1H, d, J 3.6 Hz, ArH), 4.24–4.21 (2H, m, NCH2),
2.92 (2H, d, J 7.5 Hz, CH2), 2.22–2.14 (2H, m, CH2), 1.80 (2H, q, J
7.5 Hz, CH2), 1.47–1.40 (12H, m, CH2), 1.04–0.92 (10H, m, CH2CH3);
dC (75.6 MHz, CDCl3) 146.0, 141.5, 140.5, 135.0, 134.9, 133.8, 127.3,
126.5, 126.1, 124.8, 124.8, 124.7, 124.3, 123.9, 123.5, 122.8, 121.6,
121.1, 120.5, 119.1, 109.5, 109.3, 47.6, 39.5, 31.7, 31.1, 30.9, 30.3, 29.8,
28.9, 24.5, 23.1, 22.6, 14.1, 14.0, 11.1; m/z (EI) 577 (13, Mþ).
5.3.13. 3-(1-(3-Hexylthiophen-2-yl)benzo[c]thiophen-3-yl)-9-(4-
methoxyphenyl)-9H-carbazole (7m)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7m (1.20 g, 61%) was obtained using lactone 5d (2 g,
4.94 mmol), 3-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-3-hexylthiophene (1.46 g, 5.92 mmol) and Mg (0.16 g,
6.48 mmol)], and Lawesson’s reagent (1.00 g, 2.47 mmol) as a thick
orange liquid. [Found: C, 77.5; H, 6.0; N, 2.7; S, 11.4. C37H33NOS2
requires: C, 77.72; H, 5.82; N, 2.45; S,11.22%.] Rf (100% Hexane) 0.65;
dH (300 MHz, CDCl3) 8.23–8.22 (1H, m, ArH), 8.00 (1H, d, J 7.5 Hz,
ArH), 7.87–7.84 (1H, m, ArH), 7.87–7.59 (4H, m, ArH), 7.52–7.49 (1H,
m, ArH), 7.37–7.34 (4H, m, ArH), 7.15–7.12 (2H, m, ArH), 6.77–6.74
(3H, m, ArH), 3.76 (3H, s, OCH3), 2.70 (2H, t, J 7.8 Hz, CH2), 1.28–1.23
(8H, m, CH2), 0.85–0.81 (3H, m, CH3); dC (75.6 MHz, CDCl3) 142.4,
140.0, 138.8, 137.9, 136.4, 135.3, 134.6, 130.6, 130.3, 129.3, 128.1,
127.1, 125.9, 125.2, 124.8, 124.5, 124.2, 123.3, 123.2, 123.0, 122.1,
121.8,121.7,120.8, 120.6, 119.7,117.1,116.4, 55.5, 31.6, 30.9, 29.1, 29.0,
22.6, 14.1; m/z (EI) 571 (53, Mþ).
5.3.10. 3-(1-(Thiophen-2-yl)benzo[c]thiophen-3-yl)-9-phenyl-9H-
carbazole (7j)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7j (1.33 g, 55%) was obtained using lactone 5c (2 g,
5.33 mmol), 2-thienylmagnesium bromide [prepared from 2-bro-
mothiophene (1.04 g, 6.4 mmol) and Mg (0.17 g, 7.02 mmol)], and
Lawesson’s reagent (1.08 g, 2.66 mmol) as an orange solid; mp 80 ꢁC.
[Found: C, 79.0; H, 4.3; N, 2.8; S,13.8. C30H19NS2 requires: C, 78.74; H,
4.18; N, 3.06; S,14.01%.] Rf (100% Hexane) 0.70; nmax (KBr) 1600,1505,
761 cmꢀ1
;
dH (300 MHz, CDCl3) 8.40–8.39 (1H, m, ArH), 8.18 (1H, d, J
5.3.14. 3-(1-(5-Hexylthiophen-2-yl)benzo[c]thiophen-3-yl)-9-(4-
methoxyphenyl)-9H-carbazole (7n)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7n (1.38 g, 49%) was obtained using lactone 5d (2 g,
7.8 Hz, ArH), 8.00 (1H, d, J 8.4 Hz, ArH), 7.88 (1H, d, J 8.4 Hz, ArH),
7.71–7.58 (6H, m, ArH), 7.53–7.48 (2H, m, ArH), 7.46–7.42 (2H, m,
ArH), 7.37–7.30 (2H, m, ArH), 7.16–7.09 (3H, m, ArH); dC (75.6 MHz,

828
N. Senthil Kumar et al. / Tetrahedron 65 (2009) 822–830
4.94 mmol), 5-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-5-hexylthiophene (1.46 g, 5.92 mmol) and Mg (0.16 g,
6.48 mmol)], and Lawesson’s reagent (1.00 g, 2.47 mmol) as a thick
orange liquid. [Found: C, 77.5; H, 6.0; N, 2.7; S, 11.5. C37H33NOS2
requires: C, 77.72; H, 5.82; N, 2.45; S,11.22%.] Rf (100% Hexane) 0.65;
dH (300 MHz, CDCl3) 8.22–8.20 (1H, m, ArH), 8.01 (1H, d, J 7.8 Hz,
ArH), 7.85–7.79 (1H, m, ArH), 7.87–7.57 (4H, m, ArH), 7.52–7.49 (1H,
m, ArH), 7.37–7.34 (4H, m, ArH), 7.15–7.12 (2H, m, ArH), 6.77–6.74
(3H, m, ArH), 3.77 (3H, s, OCH3), 2.75 (2H, t, J 7.65 Hz, CH2), 1.28–
1.23 (8H, m, CH2), 0.85–0.79 (3H, m, CH3); dC (75.6 MHz, CDCl3)
142.4, 141.9, 141.7, 139.8, 138.9, 138.1, 137.9, 136.7, 135.7, 135.0, 134.6,
133.8, 132.9, 132.1, 131.1, 129.8, 128.1, 127.9, 125.5, 125.1, 124.7, 123.7,
123.1, 120.6, 120.4, 120.3, 120.2, 55.4, 31.4, 30.6, 29.6, 23.8, 22.5,
14.0; m/z (EI) 571 (15, Mþ).
129.3, 128.1, 128.0, 127.1, 125.9, 125.2, 124.6, 124.4, 124.1, 123.3,
123.0, 122.1, 121.8, 120.8, 31.6, 30.9, 29.1, 29.0, 22.6, 14.1; m/z (EI)
482 (15, Mþ).
5.3.18. 3-(1-(5-Hexylthiophen-2-yl)benzo[c]thiophen-3-
yl)dibenzothiophene (7r)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7r (1.74 g, 57%) was obtained using lactone 5f (2 g,
6.33 mmol), 5-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-5-hexylthiophene (1.87 g, 7.59 mmol) and Mg (0.20 g,
8.33 mmol)], and Lawesson’s reagent (1.28 g, 3.16 mmol) as a thick
orange liquid. [Found: C, 74.8; H, 5.2; S, 19.7. C30H26S3 requires: C,
74.64; H, 5.43; S, 19.93%.] Rf (100% Hexane) 0.70; nmax (KBr) 2871,
1610, 1500, 775 cmꢀ1
; dH (300 MHz, CDCl3) 8.46 (1H, s, ArH), 8.29–
8.25 (1H, m, ArH), 8.00–7.90 (3H, m, ArH), 7.78 (1H, d, J 8.2 Hz, ArH),
7.68–7.65 (1H, m, ArH), 7.53–7.51 (2H, m, ArH), 7.44 (1H, d, J 5.4 Hz,
ArH), 7.17–7.12 (3H, m, ArH), 2.76 (2H, t, J 7.65 Hz, CH2), 1.71–1.65
(2H, m, CH2), 1.34–1.27 (6H, m, CH2), 0.87–0.81 (3H, m, CH3); dC
(75.6 MHz, CDCl3) 142.5, 140.0, 138.8, 138.0, 136.4, 135.3, 135.2,
134.6, 130.6, 129.3, 128.2, 128.1, 127.1, 126.0, 125.2, 124.6, 124.5,
124.2, 123.4, 123.0, 122.1, 121.8, 120.8, 31.7, 30.9, 29.2, 29.1, 22.6,
14.1; m/z (EI) 482 (22, Mþ).
5.3.15. 3-(1-(3-Hexylthiophen-2-yl)benzo[c]thiophen-3-
yl)dibenzofuran (7o)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7o (1.58 g, 51%) was obtained using lactone 5e (2 g,
6.66 mmol), 3-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-3-hexylthiophene (1.98 g, 8.00 mmol) and Mg (0.21 g,
8.82 mmol)], and Lawesson’s reagent (1.35 g, 3.33 mmol) as an or-
ange solid; mp 115 ꢁC. [Found C, 77.0; H, 5.5; S, 13.5. C30H26OS2
requires: C, 77.21; H, 5.62; S, 13.74%.] Rf (100% Hexane) 0.70; dH
(300 MHz, CDCl3) 8.30 (1H, s, ArH), 7.93–7.88 (2H, m, ArH), 7.78
(1H, d, J 8.1 Hz, ArH), 7.67 (1H, d, J 8.1 Hz, ArH), 7.56–7.48 (2H, m,
ArH), 7.42–7.37 (1H, m, ArH), 7.28 (1H, t, J 7.35 Hz, ArH), 7.20 (1H, d,
J 5.1 Hz, ArH), 6.98–6.89 (3H, m, ArH), 2.95 (t, J 7.8 Hz, 2H, CH2), 1.71
(q, J 7.65 Hz, 2H, CH2), 1.39 (2H, q, J 6.9 Hz, CH2), 1.27–1.18 (4H, m,
CH2), 0.78–0.73 (3H, m, CH3); dC (75.6 MHz, CDCl3) 156.7, 155.2,
143.7, 140.5, 139.3, 130.3, 127.5, 127.0, 126.7, 125.4, 125.0, 124.7,
124.2,124.1, 123.9, 122.9, 120.9, 120.8, 120.5, 119.7, 116.5, 112.2,111.8,
31.9, 31.0, 30.1, 29.6, 22.7, 14.1; m/z (EI) 466 (25, Mþ).
5.3.19. 3-(4-(Diphenylamino)phenyl)isobenzofuran-1(3H)-one (10)
Following the above-mentioned procedure (A), lactone 10
(6.46 g, 42%) was obtained using triphenylamine
8 (10 g,
40.81 mmol), phthalic anhydride (7.25 g, 48.97 mmol), AlCl3
(8.15 g, 61.22 mmol), and NaBH4 (7.74 g, 204.00 mmol) as colorless
solid; mp 96 ꢁC. [Found: C, 82.5; H, 5.3; N, 3.5. C26H19NO2 requires:
C, 82.74; H, 5.07; N, 3.71%.] Rf (10% EA/Hexane) 0.61; nmax (KBr)
1759, 1600, 1505, 755 cmꢀ1
; dH (300 MHz, CDCl3) 7.95 (1H, t, J
7.5 Hz, ArH), 7.68 (1H, t, J 7.2 Hz, ArH), 7.56 (1H, t, J 7.5 Hz, ArH), 7.38
(1H, t, J 7.5 Hz, ArH), 7.27–7.20 (4H, m, ArH), 7.09–7.00 (10H, m,
ArH), 6.36 (1H, s, CH); dC (75.6 MHz, CDCl3) 170.5, 149.6, 149.0,
147.9, 147.3, 134.3, 129.4, 129.3, 129.2, 128.4, 125.6, 124.9, 124.2,
123.5, 123.1, 122.9, 122.7, 82.8; m/z (EI) 377 (11, Mþ).
5.3.16. 3-(1-(5-Hexylthiophen-2-yl)benzo[c]thiophen-3-
yl)dibenzofuran (7p)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7p (1.71 g, 55%) was obtained using lactone 5e (2 g,
6.66 mmol), 3-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-3-hexylthiophene (1.98 g, 8.00 mmol) and Mg (0.21 g,
8.82 mmol)], and Lawesson’s reagent (1.35 g, 3.33 mmol) as a thick
orange liquid. [Found: C, 77.1; H, 5.4; S, 13.5. C30H26OS2 requires: C,
77.21; H, 5.62; S, 13.74%.] Rf (100% Hexane) 0.70; nmax (KBr) 2835,
5.3.20. N-Phenyl-N-(4-(1-(thiophen-2-yl)benzo[c]thiophen-3-
yl)phenyl)benzenamine (11a)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 11a (1.33 g, 55%) was obtained using lactone 10 (2 g,
5.30 mmol), 2-thienylmagnesium bromide [prepared from 2-bro-
mothiophene (1.04 g, 6.36 mmol) and Mg (0.17 g, 7.02 mmol)], and
Lawesson’s reagent (1.07 g, 2.65 mmol) as orange solid; mp 140 ꢁC.
[Found: C, 78.6; H, 4.8; N, 2.9; S, 14.2. C30H21NS2 requires: C, 78.39;
H, 4.61; N, 3.05; S, 13.95%.] Rf (100% Hexane) 0.70; nmax (KBr) 1601,
1605, 1510, 771 cmꢀ1
; dH (300 MHz, CDCl3) 8.40 (1H, s, ArH), 7.93–
7.28 (9H, m, ArH), 7.05–6.85 (3H, m, ArH), 2.92–2.90 (2H, m, CH2),
1.78–1.28 (8H, m, CH2), 0.93–0.91 (3H, m, CH3); dC (75.6 MHz,
CDCl3) 156.7, 155.2, 145.2, 143.0, 140.4, 131.2, 129.6, 127.5, 125.4,
125.0, 124.9, 124.7, 124.3, 124.1, 122.9, 122.0, 121.3, 121.1, 120.9,
120.2, 119.9, 116.6, 112.2, 111.8, 31.6, 31.6, 30.2, 28.8, 22.6, 14.1; m/z
(EI) 466 (45, Mþ).
1500, 765 cmꢀ1
; dH (300 MHz, CDCl3) 8.01 (1H, d, J 8.1 Hz, ArH), 7.87
(1H, d, J 8.1 Hz, ArH), 7.57 (2H, d, J 7.8 Hz, ArH), 7.38–7.32 (6H, m,
ArH), 7.24–7.12 (11H, m, ArH); dC (75.6 MHz, CDCl3) 147.5, 136.2,
135.4, 134.9, 134.1, 129.9, 129.4, 127.9, 127.7, 125.9, 125.2, 124.8,
124.6, 124.1, 123.5, 123.4, 121.5; m/z (EI) 459 (13, Mþ).
5.3.17. 3-(1-(3-Hexylthiophen-2-yl)benzo[c]thiophen-3-
yl)dibenzothiophene (7q)
5.3.21. 4-(1-(3-Hexylthiophen-2-yl)benzo[c]thiophen-3-
Following the above-mentioned procedure (B), benzo[c]thio-
phene 7q (1.83 g, 60%) was obtained using lactone 5f (2 g,
6.33 mmol), 3-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-3-hexylthiophene (1.87 g, 7.59 mmol) and Mg (0.20 g,
8.33 mmol)], and Lawesson’s reagent (1.28 g, 3.16 mmol) as an
orange solid; mp 117 ꢁC. [Found: C, 74.4; H, 5.7; S, 19.7. C30H26S3
requires: C, 74.64; H, 5.43; S, 19.93%.] Rf (100% Hexane) 0.70; dH
(300 MHz, CDCl3) 8.47 (1H, s, ArH), 8.26–8.23 (1H, m, ArH), 8.00–
7.90 (3H, m, ArH), 7.81 (1H, d, J 8.4 Hz, ArH), 7.68–7.65 (1H, m,
ArH), 7.53–7.51 (2H, m, ArH), 7.44 (1H, d, J 5.4 Hz, ArH), 7.17–7.12
(3H, m, ArH), 2.73 (2H, t, J 7.8 Hz, CH2), 1.69–1.64 (2H, m, CH2),
1.34–1.27 (6H, m, CH2), 0.89–0.84 (3H, m, CH3); dC (75.6 MHz,
CDCl3) 142.4, 140.0, 138.8, 138.0, 136.4, 135.3, 135.1, 134.6, 130.6,
yl)benzenamine (11b)
Following the above-mentioned procedure (B), benzo[c]thio-
phene 11b (1.73 g, 60%) was obtained using lactone 10 (2 g,
5.30 mmol), 3-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-3-hexylthiophene (1.57 g, 6.36 mmol) and Mg (0.17 g,
7.00 mmol)], and Lawesson’s reagent (1.08 g, 2.66 mmol) as a thick
orange liquid. [Found: C, 79.7; H, 6.3; N, 2.3; S, 11.6. C36H33NS2 re-
quires: C, 79.51; H, 6.12; N, 2.58; S, 11.79%.] Rf (100% Hexane) 0.70;
dH (300 MHz, CDCl3) 7.88–7.85 (1H, m, ArH), 7.63–7.56 (3H, m, ArH),
7.40 (1H, d, J 5.1 Hz, ArH), 7.36–7.28 (4H, m, ArH), 7.23–7.19 (6H, m,
ArH), 7.12–7.07 (5H, m, ArH), 2.69 (2H, t, J 7.8 Hz, CH2), 1.65–1.60
(2H, m, CH2), 1.33–1.24 (6H, m, CH2), 0.89–0.82 (3H, m, CH3); dC
(75.6 MHz, CDCl3) 147.5,147.4, 142.3, 137.9, 135.4, 134.1, 129.9, 129.4,

N. Senthil Kumar et al. / Tetrahedron 65 (2009) 822–830
829
129.3, 128.3, 127.9, 125.7, 124.8, 124.0, 123.9, 123.5, 123.3, 121.7,
5.4.3. 9-Phenyl-3-(1-(5-(5-(1-(9-phenyl-9H-carbazol-3-yl)benzo-
[c]thiophen-3-yl)thiophen-2-yl)thiophen-2-yl)benzo[c]-
thiophen-3-yl)-9H-carbazole (12c)
121.1, 31.6, 30.9, 29.1, 29.0, 22.6, 14.0; m/z (EI) 543 (33, Mþ).
5.3.22. 4-(1-(5-Hexylthiophen-2-yl)benzo[c]thiophen-3-
yl)benzenamine (11c)
Following the above-mentioned procedure (C), compound 12c
(0.23 g, 47%) was obtained using compound 7j (0.5 g, 1.09 mmol)
and FeCl3 (0.35 g, 2.19 mmol) as a red solid; mp 220 ꢁC. [Found: C,
78.7; H, 4.2; N, 2.9; S, 14.3. C60H36N2S4 requires: C, 78.91; H, 3.97; N,
3.07; S, 14.05%.] Rf (100% Hexane) 0.70; nmax (KBr) 1595, 1500,
Following the above-mentioned procedure (B), benzo[c]thio-
phene 11c (1.64 g, 57%) was obtained using lactone 10 (2 g,
5.30 mmol), 5-hexyl-2-thienylmagnesium bromide [prepared from
2-bromo-5-hexylthiophene (1.57 g, 6.36 mmol) and Mg (0.17 g,
7.00 mmol)], and Lawesson’s reagent (1.08 g, 2.66 mmol) as a thick
orange liquid. [Found: C, 79.7; H, 6.4; N, 2.3; S, 11.5. C36H33NS2 re-
quires: C, 79.51; H, 6.12; N, 2.58; S, 11.79%.] Rf (100% Hexane) 0.70;
dH (300 MHz, CDCl3) 8.03–8.00 (1H, m, ArH), 7.87–7.84 (1H, m,
ArH), 7.57 (2H, d, J 8.4 Hz, ArH), 7.38–7.32 (4H, m, ArH), 7.25–7.20
(7H, m, ArH), 7.16–7.09 (4H, m, ArH), 6.86 (1H, d, J 3.6 Hz, ArH), 2.91
(2H, t, J 7.65 Hz, CH2),1.83–1.78 (2H, m, CH2),1.51–1.31 (6H, m, CH2),
1.00–0.90 (3H, m, CH3); dC (75.6 MHz, CDCl3) 147.5, 147.3, 146.2,
135.1, 134.9, 133.6, 133.3, 129.9, 129.4, 127.9, 126.8, 125.0, 124.8,
124.8, 124.3, 124.1, 123.6, 123.3, 121.7, 121.4, 31.7, 30.3, 28.9, 22.7,
14.2; m/z (EI) 543 (55, Mþ).
762 cmꢀ1
; dH (300 MHz, CDCl3) 8.37 (2H, s, ArH), 8.15 (2H, d, J
7.5 Hz, ArH), 7.96 (2H, d, J 8.4 Hz, ArH), 7.85 (2H, d, J 8.4 Hz, ArH),
7.63–7.52 (8H, m, ArH), 7.46–7.39 (8H, m, ArH), 7.32–7.26 (6H, m,
ArH), 7.13–7.05 (6H, m, ArH); dC (75.6 MHz, CDCl3) 141.5, 140.5,
137.5, 136.4, 135.5, 135.4, 135.1, 130.0, 127.9, 127.7, 127.6, 127.1, 126.5,
126.0, 125.8, 125.2, 125.1,124.7,124.2,124.1,123.3,121.6,121.5,121.2,
120.6, 120.4, 110.4, 110.1; m/z (EI) 912 (33, Mþ).
5.4.4. 3-(1-(3-Hexyl-5-(4-hexyl-5-(1-(dibenzofuran-3-yl)benzo-
[c]thiophen-3-yl)thiophen-2-yl)thiophen-2-yl)benzo[c]-
thiophen-3-yl)dibenzofuran (12d)
Following the above-mentioned procedure (C), compound 12d
(0.26 g, 52%) was obtained using compound 7o (0.5 g, 1.07 mmol)
and FeCl3 (0.35 g, 2.14 mmol) as a red solid; mp 112 ꢁC. [Found: C,
77.6; H, 5.2; S,14.0. C60H50O2S4 requires: C, 77.38; H, 5.41; S,13.77%.]
5.4. A representative procedure for the preparation of
compound 12a (procedure C)
Rf (100% Hexane) 0.70; nmax (KBr) 2825, 1595, 1495, 762 cmꢀ1
; dH
(300 MHz, CDCl3) 8.27 (2H, s, ArH), 8.04 (2H, d, J 6.9 Hz, ArH), 7.89–
7.64 (10H, m, ArH), 7.56–7.52 (m, 2H, ArH), 7.44–7.42 (2H, m, ArH),
7.19–7.17 (6H, m, ArH), 2.75–2.71 (4H, m, CH2), 1.70–1.60 (4H, m,
CH2),1.37–1.27 (12H, m, CH2), 0.89–0.85 (6H, m, CH3); dC (75.6 MHz,
CDCl3) 156.8,155.9,143.1,137.8,137.2,135.5,134.7,128.8,128.7,127.6,
127.4,125.9,125.2,124.4,124.3,124.0,123.0,121.8,121.4,120.9,112.2,
111.9, 31.6, 30.8, 29.4, 29.1, 22.6, 14.1; m/z (EI) 930 (55, Mþ).
5.4.1. 9-Hexyl-3-(1-(3-hexyl-5-(4-hexyl-5-(1-(9-hexyl-9H-
carbazol-3-yl)benzo[c]thiophen-3-yl)thiophen-2-yl)thiophen-2-
yl)benzo[c]thiophen-3-yl)-9H-carbazole (12a)
To a stirred solution of 7b (0.5 g, 0.91 mmol) in dry DCM
(20 mL) was added FeCl3 (0.29 g, 1.82 mmol) under N2 atmo-
sphere. The reaction mixture was stirred for 12 h at room tem-
perature and quenched with dilute solution of N2H4$H2O. Then, it
was filtered through Celite, extracted with DCM, and dried
(Na2SO4). Solvent was evaporated in vacuo to give the crude
product, which was purified by column chromatography (100%
Hexane) to give the title compound 12a (0.30 g, 61%) as a red
solid; mp 80 ꢁC. [Found C, 78.6; H, 7.3; N, 2.7; S, 11.5. C72H76N2S4
requires: C, 78.78; H, 6.98; N, 2.55; S, 11.68%.] Rf (100% Hexane)
5.4.5. 3-(1-(3-Hexyl-5-(4-hexyl-5-(1-(dibenzothiophen-3-yl)benzo-
[c]thiophen-3-yl)thiophen-2-yl)thiophen-2-yl)benzo[c]-
thiophen-3-yl)dibenzothiophene (12e)
Following the above-mentioned procedure (C), compound 12e
(0.27 g, 55%) was obtained using compound 7q (0.5 g, 1.04 mmol)
and FeCl3 (0.33 g, 2.07 mmol) as a red solid; mp 105 ꢁC. [Found: C,
74.6; H, 5.1; S, 20.2. C60H50S6 requires: C, 74.80; H, 5.23; S, 19.97%.]
0.70; nmax (KBr) 2911, 1600, 1510, 771 cmꢀ1
; dH (300 MHz, CDCl3)
8.30 (2H, s, ArH), 8.05 (2H, d, J 7.8 Hz, ArH), 7.83–7.80 (2H, m, ArH),
7.67 (4H, t, J 8.4 Hz, ArH), 7.40–7.31 (6H, m, ArH), 7.18–7.00 (8H, m,
ArH), 4.21 (4H, t, J 6.6 Hz, NCH2), 2.62 (4H, t, J 7.5 Hz, CH2), 1.82–
1.78 (4H, m, CH2), 1.62–1.53 (4H, m, CH2), 1.35–1.15 (24H, m, CH2),
0.80–0.74 (12H, m, CH3); dC (75.6 MHz, CDCl3) 142.9, 141.0, 140.1,
137.8, 137.4, 137.0, 134.3, 127.8, 127.4, 126.1, 125.9, 124.7, 124.2,
123.9, 123.6, 123.4, 122.8, 121.8, 121.34, 121.2, 120.6, 119.2, 109.3,
109.0, 43.3, 31.7, 31.6, 30.9, 29.4, 29.2, 29.1, 27.1, 22.6, 22.5, 14.1,
14.0; m/z (EI) 1096 (13, Mþ).
Rf (100% Hexane) 0.70; nmax (KBr) 2911, 1596, 1505, 765 cmꢀ1
; dH
(300 MHz, CDCl3) 8.34–8.33 (2H, m, ArH), 8.13–8.10 (2H, m, ArH),
7.87–7.77 (4H, m, ArH), 7.69–7.65 (4H, m, ArH), 7.40–7.37 (6H, m,
ArH), 7.13–7.12 (2H, m, ArH), 7.07–7.04 (4H, m, ArH), 2.62 (4H, d, J
7.5 Hz, CH2), 1.58–1.55 (4H, m, CH2), 1.25–1.16 (12H, m, CH2), 0.79–
0.72 (6H, m, CH3); dC (75.6 MHz, CDCl3) 143.1, 140.0, 138.9, 137.9,
137.2, 136.4, 135.4, 135.3, 134.7, 130.5, 128.0, 127.4, 127.2, 126.0,
124.8, 124.6, 124.6, 124.4, 123.4, 123.0, 122.1, 121.8, 120.9, 31.6, 30.8,
29.4, 29.1, 22.6, 14.1; m/z (EI) 962 (22, Mþ).
5.4.2. 9-(2-Ethylhexyl)-3-(1-(5-(5-(1-(9-(2-ethylhexyl)-9H-
carbazol-3-yl)benzo[c]thiophen-3-yl)thiophen-2-yl)thiophen-2-
yl)benzo[c]thiophen-3-yl)-9H-carbazole (12b)
Acknowledgements
The authors thank DST, New Delhi (SR/S1/OC-37/2005) and UGC
potential for excellence for a financial support. N.S.K. thanks DST for
a fellowship. Authors thank DST-FIST for 300 MHz NMR facility.
Following the above-mentioned procedure (C), compound 12b
(0.25 g, 50%) was obtained using compound 7g (0.5 g, 1.01 mmol)
and FeCl3 (0.33 g, 2.02 mmol) as a black solid; mp 112 ꢁC. [Found: C,
77.8; H, 6.5; N, 3.0; S, 12.9. C64H60N2S4 requires: C, 78.00; H, 6.14; N,
2.84; S, 13.02%.] Rf (100% Hexane) 0.70; nmax (KBr) 2875, 1596, 1505,
References and notes
775 cmꢀ1
; dH (300 MHz, CDCl3) 8.35 (2H, s, ArH), 8.14 (2H, d, J
7.8 Hz, ArH), 8.04 (2H, d, J 8.7 Hz, ArH), 7.89 (2H, d, J 8.7 Hz, ArH),
7.73 (2H, d, J 9.3 Hz, ArH), 7.53–7.36 (6H, m, ArH), 7.28–7.07 (10H,
m, ArH), 4.21–4.16 (4H, m, NCH2), 2.16–2.09 (2H, m, CH), 1.42–1.30
(14H, m, CH2), 0.96–0.86 (14H, m, CH2CH3); dC (75.6 MHz, CDCl3)
141.5, 140.6, 136.3, 136.0, 135.4, 135.3, 135.1, 127.2, 126.1, 125.6,
125.4,124.8, 124.5,124.1,124.0,123.5, 122.7,121.8,121.5,121.1,120.5,
119.2, 109.5, 109.3, 47.6, 39.5, 31.1, 28.9, 24.5, 23.1, 14.1, 10.9; m/z (EI)
984 (35, Mþ).
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