Convenient synthesis of organic-electronics-oriented building blocks via on-water and under-air homocoupling of (hetero)aryl iodides

Article abstract of DOI:10.1039/c5ra13517f

We report herein an operationally simple homocoupling reaction that targets the convenient synthesis of organic-electronically important building blocks. A variety of synthetically useful bithiophene derivatives and functionalized biphenyls are efficiently prepared by an on-water and under-air protocol using Pd/C as catalyst. We find that Pd/C gives generally higher and cleaner homocoupling conversions than using Pd(OAc)₂ in the cases of (hetero)aryl iodides since Pd(OAc)₂ triggers more side reactions including dehalogenations and oligomerizations. Under the optimum conditions, a broad range of functional groups such as ester, ketone, aldehyde, nitrile, nitro, chloride, and bromide are well tolerated. We expect the present methodology would make a valuable synthetic contribution towards bridging green chemistry with thiophene-based organic materials.

Full text of DOI:10.1039/c5ra13517f

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PAPER
Convenient synthesis of organic-electronics-
oriented building blocks via on-water and under-air
homocoupling of (hetero)aryl iodides†
Cite this: RSC Adv., 2015, 5, 74180
Yi-An Chen and Ching-Yuan Liu*
We report herein an operationally simple homocoupling reaction that targets the convenient synthesis of
organic-electronically important building blocks. A variety of synthetically useful bithiophene derivatives
and functionalized biphenyls are efficiently prepared by an on-water and under-air protocol using Pd/C
as catalyst. We find that Pd/C gives generally higher and cleaner homocoupling conversions than using
2 2
Pd(OAc) in the cases of (hetero)aryl iodides since Pd(OAc) triggers more side reactions including
Received 10th July 2015
Accepted 25th August 2015
dehalogenations and oligomerizations. Under the optimum conditions, a broad range of functional
groups such as ester, ketone, aldehyde, nitrile, nitro, chloride, and bromide are well tolerated. We expect
the present methodology would make a valuable synthetic contribution towards bridging green
chemistry with thiophene-based organic materials.
DOI: 10.1039/c5ra13517f
www.rsc.org/advances
Introduction
The transition-metal-catalyzed homocoupling reaction is one of
the most convenient and reliable synthetic tools for the facile
2
2
1
construction of C(sp )–C(sp ) bonds. The resulting symmet-
rical bi(hetero)aryls are essential building blocks for numerous
2
3
bioactive compounds and organic optoelectronic materials.
Focusing on the eld of organic electronics, bithiophene-
containing molecules constitute an important class of p-func-
tional semiconducting materials, for instance, bithiophene and
its alkylated derivatives were oen incorporated into oligoaryls
Scheme 1 Synthetically versatile bithiophene derivatives prepared by
as p-spacers or utilized as electron-donating part for donor– homocoupling reactions conducted in organic phase or in aqueous
phase.
acceptor (D–A) type copolymers, both of which have been
4
5
6
extensively applied in OPVCs, DSSCs, and OFETs. Although
the bithiophene moiety is of substantial impact on modern
materials science, synthetic methods reported to date to access
it usually rely on the [Cu]- or [Pd]-catalyzed homocouplings of
extensively used as versatile building blocks for p-functional
materials (Scheme 1).
7,8
halogenated or metalated thiophenes in organic phases (eqn
1) and (2), Scheme 1). Despite some reports have disclosed the
(
Pd-catalyzed homocoupling of aryl halides using water as
reaction solvent, the synthetic focus has never placed on the
Results and discussion
9
preparation of organic-electronically versatile bithiophene To obtain the optimum reaction conditions, different palla-
derivatives. Therefore, we demonstrate herein a Pd-catalyzed dium sources, reducing agents, and solvents were screened, as
on-water and under-air homocoupling methodology that aims shown in Table 1, using the readily synthesized 3-hexyl-2-
to efficiently and environment-friendly synthesize bi(hetero) iodothiophene (1a), an important and representative mono-
aryls including various alkylated bithiophenes that are mer in polymer chemistry, as homocoupling substrate. In the
preliminary experiments (entries 1 and 2), it was found that the
addition of tetrabutylammonium bromide (TBAB) as surfactant
Department of Chemical and Materials Engineering, National Central University,
was essential to the success of the on-water type reactions. In
Jhongli District, Taoyuan, Taiwan 320, Republic of China. E-mail: cyliu0312@ncu.
the absence of TBAB, the homocoupling did not take place
edu.tw; Tel: +886-3-422-7151
1
13
(entry 1), whereas the desired product (2a) was isolated in 51%
†
Electronic supplementary information (ESI) available: NMR spectra ( H and C)
for compounds 1, 2, 4. See DOI: 10.1039/c5ra13517f
yield when 2 equiv. of TBAB was added (entry 2). More
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importantly, in addition to the homocoupled adduct, we have 1a was shown to exhibit poor reactivity and compound 2a was
observed, under the catalysis of Pd(OAc) , the formation of isolated in only 33% yield (entry 16).
2
undesired deiodinated byproducts and some oligomeric hexyl-
Encouraged by the optimal reaction conditions obtained in
thiophenes that were generated through direct C–H hetero- Table 1, we then tried to explore the substrate scope of present
10
arylation of 1a, both of which are competitive with the homocoupling reactions using inexpensive and nontoxic water
formation of 2a and led to the diminishment of reaction as sole solvent. As demonstrated in Table 2, we rstly focused
conversion. Therefore, we turned to examine the Pd(0)-based on the preparation of synthetically and organic-electronically
catalysts. In contrast to the results obtained by using useful biheteroaryls including various (alkyl)bithiophenes and
Pd(OAc)
deiodinated and oligomerized thiophenes) was effectively obtained in 70% yield (2b). Further, a serious of bithiophene
suppressed with the employment of all Pd(0)-catalysts (entries derivatives bearing different alkyl chains were efficiently
–5). We were pleased to nd that Pd/C gave a promising yield synthesized in moderate to good yields (48–83%, 2c–2h).
80%, entry 5) and there was no signicant yield variation when Interestingly, unprecedented examples such as bithiophenes
2
, it is worth noting that formation of both byproducts their related derivatives. A typical bithiophene molecule was
(
3
(
half amount of Pd/C was loaded (77%, entry 6). Next on, the possessing alkyl chains with a phenyl or an ester group were
solvent effect was investigated and the results revealed that successfully prepared for the rst time by this on-water meth-
using cosolvent systems did not lead to expected improvement odology and isolated in moderate yields (52–66%, 2i–2j). Next
of reaction conversion and 2a was isolated in poor to moderate on, since we had observed the poor reactivity of 2-bromo-3-
yields (10–63%, entries 7–10). Finally, we tested different hexylthiophene (entry 16, Table 1), we anticipated that a good
reducing agents including zinc, manganese, and copper, chemoselectivity would be obtained when using 3-bromo-2-
affording product 2a in 27–50% yields (entries 11–13). Without
the addition of either reducing agent or catalyst, the homo-
coupling reaction did not occur and starting material was
Table 2 Exploration of substrate scope using various thiophene-
recovered (entries 14–15). As expected, the bromo-congener of related heteroaryl iodidesa
Table 1 Optimization of the Pd-catalyzed on-water homocoupling
a
using 3-hexyl-2-iodothiophene as substrate
f
Entry
[Pd] (mol%)
Reducing agent
Solvent
Yield (%)
b
1
Pd(OAc)
Pd(OAc)
2
(10)
(10)
(10)
(10)
In
In
In
In
In
In
In
In
In
In
Zn
Mn
Cu
─
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
O
O
O
O
O
O
0
51
56
67
80
77
10
63
21
58
28
27
50
0
2
3
4
5
6
2
Pd
2
dba
3
Pd(dba)
2
Pd/C (10)
Pd/C (5)
Pd/C (5)
Pd/C (5)
Pd/C (5)
Pd/C (5)
Pd/C (5)
Pd/C (5)
Pd/C (5)
Pd/C (5)
─
c
7
O/t-BuOH
O/acetone
O/DMA
O/DMSO
O
O
O
O
O
O
c
8
c
9
c
1
1
1
1
1
1
1
0
1
2
3
4
5
6
d
e
In
In
0
33
Pd/C (5)
a
Unless otherwise noted, the homocoupling reaction was performed
with 3-hexyl-2-iodothiophene 1a (1.0 mmol) in the presence of [Pd]
(
(
5–10 mol%), reducing agents (0.5 mmol), lithium chloride
a
1.5 mmol), and tetrabutylammonium bromide (TBAB, 2.0 mmol)
Unless otherwise noted, the homocoupling reaction was conducted
ꢀ
b
using water as solvent (2.0 mL) at 90 C for 24 h under air. TBAB with heteroaryl iodides 1b–s (1.0 mmol) under the following optimum
c
d
was not added. A cosolvent system is used v/v ¼ 1 : 1. Indium conditions: Pd/C (5 mol%, 10% Pd basis), In (0.5 mmol), LiCl
e
ꢀ
powder and lithium chloride were not added. The bromo-congener (1.5 mmol), TBAB (2.0 mmol), H O as solvent (2.0 mL), 90 C, 24 h,
2
f
b
of compound 1a (2-bromo-3-hexylthiophene) was used. Isolated yields. under air. Isolated yields.
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iodothiophene as homocoupling substrate. However, desired
product 2k was isolated in only 32% yield and a signicant
amount of starting material (1k) was recovered, presumably
owing to the steric hindrance caused by the 3-positioned
bromine atom. In contrast, we acquired an improved yield when
an unhindered regioisomer of 1k was employed (1l: 2-bromo-5-
iodothiophene), giving the corresponding product 2l in 61%
yield. Additionally, a number of alkyl-terminated bithiophenes
were readily synthesized under identical reaction conditions,
affording compounds 2m–2q in moderate to good yields
(45–77%). Bis-ethylenedioxythiophene (bis-EDOT), an electron-
rich derivative of thiophenes, was prepared with a relatively
lower isolated yield (36%, 2r) because in this case the byproduct
resulted from deiodination was formed and it was difficult to be
separated from desired bis-EDOT. Finally, we were pleased to

nd that biselenophene could be also produced via present
Scheme 2 Proposed reaction mechanism.
synthetic approach (50%, 2s).
In order to further extend substrate scope and examine
functional groups (FGs) compatibility of this on-water homo-
coupling reaction, aryl iodides bearing a broad range of
synthetically useful FGs (3a–3m) were tested under optimal
conditions (Table 3). The results have shown that sensitive FGs
including ester, ketone, aldehyde, nitrile, nitro group, and
halides were well tolerated and the corresponding biaryls were
obtained in moderate to excellent isolated yields (45–92%,
3
e, and 3g) gave generally lower yields than their meta- or para-
isomers (3a–b, 3d, and 3f), which is attributed to the anticipated
steric hindrance caused by ortho substituents. More impor-
tantly, as discussed in Table 1, we also observed in each
example a large quantity of deiodinated byproducts when the
2
homocoupling reaction was catalyzed by Pd(OAc) , whereas
Pd/C was found to give more efficient and cleaner reactions with
the generation of only trace amount of deiodinated compounds.
Thus, it seems reasonable to conclude that, for current on-water
homocoupling reactions, Pd/C would be a better alternative
4a–4m). It was found that the ortho-substituted iodoarenes (3c,
2
catalyst than the commonly used Pd(OAc) . Moreover, Pd/C is
Table 3 Exploration of substrate scope using various aryl iodides
bearing sensitive functional groups
a
especially suitable for the thiophene-based substrates with
arylable C–H bonds because under Pd/C-catalysis the target
reaction (homocoupling) proceeds smoothly while the unde-
sired C–H oligomerization is inhibited.
As shown in Scheme 2, a plausible reaction mechanism for
the Pd-catalyzed homocoupling is proposed using iodothio-
phenes (A) as substrate. Pd(0) undergoes oxidative addition with
A to give a Pd(II) species (B). Reduction of B by indium/lithium
halide affords an anionic thienylpalladium intermediate (C).
Second oxidative addition of C with A proceeds to generate a
dithienylpalladium(II) intermediate (D). Reductive elimination
of D yields the desired bithiophene derivatives (E) and regen-
erates Pd(0).
Conclusions
In summary, we have developed an on-water and under air
homocoupling methodology targeting on the convenient
synthesis of various organic-electronically important bithio-
phene derivatives. In this report, we found that, compared with
2
Pd(OAc) , using Pd/C as catalyst enabled a higher conversion of
the homocoupled adduct because formation of the byproducts
such as deiodinated or oligomeric thiophenes was inhibited.
a
Unless otherwise noted, the homocoupling reaction was conducted
with aryl iodides 3a–m (1.0 mmol) under the following optimum Under optimum reaction conditions, a variety of functional
conditions: Pd/C (5 mol%, 10% Pd basis), In (0.5 mmol), LiCl
groups including ester, ketone, aldehyde, nitrile, nitro, and
halides were well tolerated in the homocouplings of aryl
iodides. We expect this convenient and viable on-water
ꢀ
(
1.5 mmol), TBAB (2.0 mmol), H
2
O as solvent (2.0 mL), 90 C, 24 h,
b
under air. Isolated yields.
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synthesis would become an user-friendly alternative route for ethyl acetate. The bi-phase ltrate was extracted with ethyl
polymer chemists to access various dialkyl-bithiophenes. acetate (2 ꢁ 20 mL). The combined organic layers were washed
Further synthetic investigation using water as solvent for with brine (60 mL), and dried over Na SO before concentrated
2
4
functional p-conjugated organic materials is currently in vacuo. Purication by ash chromatography yielded the
underway in our laboratory.
desired product 2a.
0
0
13
0
0
3
,3 -Dihexyl-2,2 -bithiophene (2a). 3,3 -Dihexyl-2,2 -bithio-
13
phene (2a) was prepared from 3-hexyl-2-iodothiophene (1a)
294 mg, 1.00 mmol), palladium on activated charcoal (Pd/C,
10% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg,
.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty-
Experimental section
General information
(
0
Unless otherwise specied, all reactions were carried out with
magnetic stirring and, if air or moisture sensitive, in ame-
dried glassware under nitrogen. Starting materials including
the alkylated thiophene derivatives were synthesized according
lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL)
according to the general procedure A and yielding aer column
chromatography (hexanes) the pure product 2a (134 mg, 80%).
A pale yellow liquid. H NMR (CDCl
2
1
1
1
3
, 300 MHz, ppm): d 7.29
to the reported procedures. Reagents including a part of the
hetero)aryl iodides (1b, 3a–3m), palladium catalysts, ligands,
(
d, J ¼ 5.2 Hz, 2H), 6.97 (d, J ¼ 5.2 Hz, 2H), 2.50 (t, J ¼ 7.7 Hz,
(
4
6
1
H), 1.44–1.62 (comp, 4H), 1.14–1.41 (comp, 12H), 0.86 (t, J ¼
and other additives are commercially available. In addition to
the deionized water from Elix Millipore, organic solvents used
in Table 1 such as acetone, tbutyl alcohol, tetrahydrofuran
13
.5 Hz, 6H); C NMR (CDCl
3
, 75 MHz, ppm): d 142.3, 128.7,
28.5, 125.2, 31.6, 30.7, 29.1, 28.8, 22.6, 14.0.
(THF), chloroform, and toluene were purchased from Sigma-
Aldrich or Acros and used directly without further purica-
tions. Syringes used to transfer reagents and solvents were
purged with nitrogen prior to use. Reactions were monitored by
thin layer chromatography (TLC, aluminum plates coated with
silica gel, Merck 60, F-254). The spots were visualized by UV
light. Flash column chromatography was performed using silica
gel 60 (spherical, 63–210 mm) from Merck. The diameters of the
columns and the amount of silica gel loaded were calculated
General procedure B for Table 2: on-water homocoupling
reactions of various heteroaryl iodides
To a heterogeneous solution of palladium on activated charcoal
(Pd/C, 10% Pd basis, 0.05 mmol), indium powder (0.50 mmol),
lithium chloride (1.50 mmol), and tetrabutylammonium
bromide (TBAB) (2.00 mmol) in water (2 mL) was added the
corresponding heteroaryl iodides (1b–1s) (1.00 mmol) under air.
12
according to the recommendation of W. C. Still. Melting
points were measured on a Fargo MP-2D apparatus. NMR
spectra were recorded on a Bruker Magnet System 300 or
ꢀ
The reaction mixture was then heated at 90 C for 24 h. Aer
cooled to room temperature, the precipitate/solid was ltered
off under vacuum and washed with ethyl acetate. The bi-phase
ltrate was extracted with ethyl acetate (2 ꢁ 20 mL). The
combined organic layers were washed with brine (60 mL), and
dried over Na SO before concentrated in vacuo. Purication by
5
00 MHz instrument. Chemical shis were given relative to
1
13
CDCl (7.26 ppm for H NMR, 77.0 ppm for C NMR), CD Cl
2
3
2
1
13
(
(
(
5.32 ppm for H NMR, 54.0 ppm for C NMR), DMSO-d6
2.50 ppm for H NMR, 39.4 ppm for C NMR), acetone-d6
2.04 ppm for H NMR, 29.3 ppm for C NMR). For the char-
1
13
2
4
1
13
ash chromatography yielded the desired products 2b–2s.
0
14
0
14
2
,2 -Bithiophene (2b). 2,2 -Bithiophene (2b) was prepared
acterization of the observed signal multiplicities, the following
abbreviations were applied: s (singlet), d (doublet), dd (doublet
of doublets), dt (doublet of triplets), dm (doublet of multiplets),
t (triplet), td (triplet of doublets), q (quartet), quint (quintet), m
from 2-iodothiophene (210 mg, 1.00 mmol), palladium on
activated charcoal (Pd/C, 10% Pd basis, 53 mg, 0.05 mmol),
indium powder (58 mg, 0.50 mmol), lithium chloride (65 mg,
1
2
.50 mmol), tetrabutylammonium bromide (644 mg,
.00 mmol), and H O (2 mL) according to the general procedure
(multiplet), comp (complex), app (apparent), and br (broad).
2
Mass spectra were recorded on a JEOL JMS-700 for electron
impact ionization (EI) and high resolution mass spectra (HRMS)
on a JEOL JMS-700 spectrometers. Fast atom bombardment
B and yielding aer column chromatography (hexanes) the pure
ꢀ
1
product 2b (58 mg, 70%). A green solid; m.p.: 32.0–33.2 C. H
NMR (CDCl , 300 MHz, ppm): d 7.19–7.25 (comp, 4H), 7.04 (dd, J
5.1, 3.7 Hz, 2H); C NMR (CDCl
3
(FAB) samples were recorded in a 3-nitrobenzyl alcohol- or
1
3
¼
3
, 75 MHz, ppm): d 137.4,
glycerine-matrix.
1
27.7, 124.3, 123.7.
0
0
15
0 0
(2c). 3,3 -Dimethyl-2,2 -
3
,3 -Dimethyl-2,2 -bithiophene
General procedure A for Table 1: reaction conditions
optimization of the on-water homocoupling reactions
15
bithiophene (2c) was prepared from 2-iodo-3-methylthiophene
224 mg, 1.00 mmol), palladium on activated charcoal (Pd/C,
(
To a heterogeneous solution of palladium catalysts (0.05– 10% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg,
.10 mmol), reducing agents (0.50 mmol), lithium chloride 0.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty-
1.50 mmol), and tetrabutylammonium bromide (TBAB) lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL)
2.00 mmol) in water (2 mL) or cosolvents (2 mL, v/v ¼ 1 : 1) was according to the general procedure B and yielding aer column
0
(
(
2
added 3-hexyl-2-iodothiophene (1a) (1.00 mmol) under air. The chromatography (hexanes) the pure product 2c (81 mg, 83%). A
ꢀ
1
reaction mixture was then heated at 90 C for 24 h. Aer the colorless liquid. H NMR (CDCl , 300 MHz, ppm): d 7.26 (d, J ¼
3
1
3
reaction mixture had cooled to room temperature, the 5.1 Hz, 2H), 6.92 (d, J ¼ 5.1 Hz, 2H), 2.81 (s, 6H); C NMR
precipitate/solid was ltered off under vacuum and washed with (CDCl
3
, 75 MHz, ppm): d 136.5, 130.0, 129.4, 125.0, 14.7.
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0
0
16
0 0
3,3 -Diheptyl-2,2 - charcoal (Pd/C, 10% Pd basis, 53 mg, 0.05 mmol), indium powder
3
,3 -Diheptyl-2,2 -bithiophene
(2d).
16
bithiophene (2d) was prepared from 3-heptyl-2-iodothiophene (58 mg, 0.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetra-
308 mg, 1.00 mmol), palladium on activated charcoal (Pd/C, butylammonium bromide (644 mg, 2.00 mmol), and H O (2 mL)
0% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg, according to the general procedure B and yielding aer column
.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty- chromatography (hexanes) the pure product 2h (106 mg, 54%). A
(
1
0
2
1
lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL) yellow liquid. H NMR (CDCl
3
, 300 MHz, ppm): d 7.27 (d, J ¼ 5.2
2
according to the general procedure B and yielding aer column Hz, 2H), 6.92 (d, J ¼ 5.2 Hz, 2H), 2.42 (d, J ¼ 7.2 Hz, 4H), 1.50–1.57
chromatography (hexanes) the pure product 2d (100 mg, 55%). (comp, 2H), 1.10–1.27 (comp, 16H), 0.84 (t, J ¼ 6.8 Hz, 6H), 0.75 (t,
1
13
A pale yellow liquid. H NMR (CDCl
3
, 300 MHz, ppm): d 7.29 (d, J J ¼ 7.4 Hz, 6H); C NMR (CDCl
3
, 75 MHz, ppm): d 141.4, 129.4,
¼
5.3 Hz, 2H), 6.97 (d, J ¼ 5.3 Hz, 2H), 2.51 (t, J ¼ 7.8 Hz, 4H), 128.9, 125.0, 40.3, 33.0, 32.7, 28.8, 25.8, 23.0, 14.1, 10.8.
0
0
0
1
6
1
.48–1.68 (comp, 4H), 1.16–1.42 (comp, 16H), 0.88 (t, J ¼ 6.6 Hz,
3,3 -Bis(3-phenylpropyl)-2,2 -bithiophene (2i). 3,3 -Bis(3-phe-
1
3
0
H); C NMR (CDCl
3
, 75 MHz, ppm): d 142.3, 128.7, 128.5, nylpropyl)-2,2 -bithiophene (2i) was prepared from 2-iodo-3-(3-
25.2, 31.8, 30.7, 29.4, 29.1, 28.8, 22.6, 14.1.
phenylpropyl)thiophene (328 mg, 1.00 mmol), palladium on
,3 -Dioctyl-2,2 -bithiophene (2e). 3,3 -Dioctyl-2,2 -bithio- activated charcoal (Pd/C, 10% Pd basis, 53 mg, 0.05 mmol),
0
1
0
17
0
0
3
7
phene
(2e) was prepared from 2-iodo-3-octylthiophene indium powder (58 mg, 0.50 mmol), lithium chloride (65 mg,
322 mg, 1.00 mmol), palladium on activated charcoal (Pd/C, 1.50 mmol), tetrabutylammonium bromide (644 mg, 2.00
(
1
0
0% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg, mmol), and H
.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty- and yielding aer column chromatography (ethyl acetate–
O (2 mL) hexanes ¼ 2 : 98) the pure product 2i (105 mg, 52%). A yellow
2
O (2 mL) according to the general procedure B
lammonium bromide (644 mg, 2.00 mmol), and H
according to the general procedure B and yielding aer column liquid. H NMR (CDCl
chromatography (hexanes) the pure product 2e (125 mg, 64%). A 12H), 6.97 (d, J ¼ 5.2 Hz, 2H), 2.56 (t, J ¼ 7.5 Hz, 8H), 1.76–1.97
2
1
, 300 MHz, ppm): d 7.05–7.42 (comp,
3
1
13
pale yellow liquid. H NMR (CDCl , 300 MHz, ppm): d 7.29 (d, J (comp, 4H); C NMR (CDCl
3
, 75 MHz, ppm): d 142.2, 141.7,
5.2 Hz, 2H), 6.97 (d, J ¼ 5.2 Hz, 2H), 2.51 (t, J ¼ 7.8 Hz, 4H), 128.9, 128.5, 128.3, 128.2, 125.7, 125.5, 35.6, 32.3, 28.5; MS (EI,
.48–1.69 (comp, 4H), 1.14–1.44 (comp, 20H), 0.88 (t, J ¼ 6.5 Hz, 70 eV): 402 (M , 100%), 298 (9%), 207 (16%), 193 (59%), 173
3
¼
+
1
6
1
1
3
H); C NMR (CDCl
3
26 2
, 75 MHz, ppm): d 142.3, 128.7, 128.5, (28%), 91 (94%); HRMS (EI): calcd for C26H S : 402.1476,
25.2, 31.9, 30.7, 29.42, 29.39, 29.2, 28.8, 22.7, 14.1.
found: 402.1483.
0
0
18
0
0
0
0
0
3
,3 -Didecyl-2,2 -bithiophene (2f). 3,3 -Didecyl-2,2 -bithio-
Diethyl 6,6 -([2,2 -bithiophene]-3,3 -diyl)dihexanoate (2j).
18
0
0
0
phene
350 mg, 1.00 mmol), palladium on activated charcoal (Pd/C, prepared from ethyl 6-(2-iodothiophen-3-yl)hexanoate (352 mg,
(2f) was prepared from 3-decyl-2-iodothiophene Diethyl 6,6 -([2,2 -bithiophene]-3,3 -diyl)dihexanoate (2j) was
(
1
0
0% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg, 1.00 mmol), palladium on activated charcoal (Pd/C, 10% Pd
.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty- basis, 53 mg, 0.05 mmol), indium powder (58 mg, 0.50 mmol),
lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL) lithium chloride (65 mg, 1.50 mmol), tetrabutylammonium
2
according to the general procedure B and yielding aer column bromide (644 mg, 2.00 mmol), and H
2
O (2 mL) according to the
chromatography (hexanes) the pure product 2f (108 mg, 48%). A general procedure B and yielding aer column chromatography
1
pale yellow liquid. H NMR (CDCl
3
, 300 MHz, ppm): d 7.38 (d, J (ethyl acetate–hexanes ¼ 20 : 80) the pure product 2j (148 mg,
1
¼
5.4 Hz, 2H), 6.76 (d, J ¼ 5.4 Hz, 2H), 2.56 (t, J ¼ 7.7 Hz, 4H), 66%). A yellow liquid. H NMR (CD
Cl , 300 MHz, ppm): d 7.29
2 2
1
6
1
.49–1.68 (comp, 4H), 1.15–1.45 (comp, 28H), 0.89 (t, J ¼ 6.7 Hz, (d, J ¼ 5.3 Hz, 2H), 6.96 (d, J ¼ 5.3 Hz, 2H), 4.05 (q, J ¼ 7.1 Hz,
1
3
H); C NMR (CDCl , 75 MHz, ppm): d 142.3, 128.7, 128.5, 4H), 2.50 (t, J ¼ 7.8 Hz, 4H), 2.23 (t, J ¼ 7.5 Hz, 4H), 1.46–1.64
3
1
3
25.2, 31.9, 30.7, 29.60, 29.55, 29.4, 29.3, 28.8, 22.7, 14.1.
(comp, 8H), 1.10–1.32 (comp, 10H); C NMR (CDCl
3
, 75 MHz,
0
0
19
0
0
3
,3 -Didodecyl-2,2 -bithiophene
(2g). 3,3 -Didodecyl-2,2 - ppm): d 173.6, 141.9, 128.7, 128.4, 125.3, 60.1, 34.2, 30.3, 28.8,
19
+
bithiophene
(2g) was prepared from 3-dodecyl-2- 28.5, 24.7, 14.2; MS (EI, 70 eV): 450 (M , 96%), 193 (100%), 179
iodothiophene (378 mg, 1.00 mmol), palladium on activated (46%), 147 (50%), 55 (52%); HRMS (EI): calcd for C24
charcoal (Pd/C, 10% Pd basis, 53 mg, 0.05 mmol), indium 450.1899, found: 450.1893.
H
O
S
:
34
4
2
0
0
21
0
0
powder (58 mg, 0.50 mmol), lithium chloride (65 mg, 1.50 mmol),
tetrabutylammonium bromide (644 mg, 2.00 mmol), and H
2 mL) according to the general procedure B and yielding aer (289 mg, 1.00 mmol), palladium on activated charcoal (Pd/C,
column chromatography (hexanes) the pure product 2g 10% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg,
3,3 -Dibromo-2,2 -bithiophene
bithiophene (2k) was prepared from 3-bromo-2-iodothiophene
(2k). 3,3 -Dibromo-2,2 -
21
2
O
(
ꢀ
1
(
138 mg, 55%). A transparent solid; m.p.: 52.1–53.2 C. H NMR 0.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty-
CDCl
, 300 MHz, ppm): d 7.28 (d, J ¼ 5.3 Hz, 2H), 6.96 (d, J ¼ 5.3 lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL)
(
3
2
Hz, 2H), 2.50 (t, J ¼ 7.7 Hz, 4H), 1.50–1.67 (comp, 4H), 1.18–1.39 according to the general procedure B and yielding aer column
1
3
(
comp, 36H), 0.89 (t, J ¼ 6.6 Hz, 6H); C NMR (CDCl
ppm): d 142.3, 128.7, 128.5, 125.2, 31.9, 30.7, 29.68, 29.65, 29.6, white solid; m.p.: 96.3–97.8 C. H NMR (CDCl
9.43, 29.42, 29.4, 28.8, 22.7, 14.0.
3
, 75 MHz, chromatography (hexanes) the pure product 2k (52 mg, 32%). A
ꢀ
1
, 300 MHz,
3
1
3
2
ppm): d 7.41 (d, J ¼ 5.4 Hz, 2H), 7.08 (d, J ¼ 5.4 Hz, 2H); C NMR
0
0
20
0
3
,3 -Bis(2-ethylhexyl)-2,2 -bithiophene (2h). 3,3 -Bis(2-ethyl- (CDCl
3
0
, 75 MHz, ppm): d 130.8, 128.9, 127.5, 112.6.
0
20
0
22
0
0
hexyl)-2,2 -bithiophene (2h) was prepared from 3-(2-ethylhexyl)-
5,5 -Dibromo-2,2 -bithiophene
(2l). 5,5 -Dibromo-2,2 -
22
2
-iodothiophene (322 mg, 1.00 mmol), palladium on activated bithiophene (2l) was prepared from 2-bromo-5-iodothiophene
(289 mg, 1.00 mmol), palladium on activated charcoal (Pd/C,
74184 | RSC Adv., 2015, 5, 74180–74188
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Paper
0% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg, 0.50 m.p.: 49.2–50.4 C. H NMR (CDCl
RSC Advances
ꢀ
1
1
3
, 300 MHz, ppm): d 6.89 (d, J ¼
mmol), lithium chloride (65 mg, 1.50 mmol), tetrabutylammo- 3.8 Hz, 2H), 6.64 (d, J ¼ 3.8 Hz, 2H), 2.77 (t, J ¼ 7.5 Hz, 4H), 1.60–
nium bromide (644 mg, 2.00 mmol), and H O (2 mL) according 1.75 (comp, 4H), 1.21–1.44 (comp, 28H), 0.88 (t, J ¼ 6.5 Hz, 6H);
2
1
3
to the general procedure B and yielding aer column chroma-
C NMR (CDCl , 75 MHz, ppm): d 144.7, 135.5, 124.5, 122.5, 31.9,
3
tography (hexanes) the pure product 2l (99 mg, 61%). A white 31.6, 30.1, 29.60, 29.55, 29.4, 29.3, 29.1, 22.7, 14.1; MS (EI, 70 eV):
ꢀ
1
+
3
solid; m.p.: 143.0–144.2 C. H NMR (CDCl , 300 MHz, ppm): d 446 (M , 92%), 319 (100%), 205 (29%), 192 (50%), 57 (38%);
1
3
6
7
.96 (d, J ¼ 3.8 Hz, 2H), 6.84 (d, J ¼ 3.8 Hz, 2H); C NMR (CDCl
5 MHz, ppm): d 137.8, 130.6, 124.1, 111.5.
3
,
HRMS (EI): calcd for C28
H
46
S
2
: 446.3041, found: 446.3041.
0
0
0
0
5,5 -Didodecyl-2,2 -bithiophene (2q). 5,5 -Didodecyl-2,2 -
0
0
23
0
0
5
,5 -Dihexyl-2,2 -bithiophene (2m). 5,5 -Dihexyl-2,2 -bithio- bithiophene (2q) was prepared from 2-dodecyl-5-iodothiophene
23
phene (2m) was prepared from 2-hexyl-5-iodothiophene (378 mg, 1.00 mmol), palladium on activated charcoal (Pd/C,
294 mg, 1.00 mmol), palladium on activated charcoal (Pd/C, 10% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg,
(
1
0
0% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg, 0.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty-
.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty- lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL)
O (2 mL) according to the general procedure B and yielding aer column
according to the general procedure B and yielding aer column chromatography (hexanes) the pure product 2q (113 mg, 45%).
2
lammonium bromide (644 mg, 2.00 mmol), and H
2
ꢀ
1
chromatography (hexanes) the pure product 2m (129 mg, 77%). A yellow solid; m.p.: 55.0–56.2 C. H NMR (CDCl
3
, 300 MHz,
, 300 MHz, ppm): d 6.89 (d, J ¼ ppm): d 6.89 (d, J ¼ 3.5 Hz, 2H), 6.64 (d, J ¼ 3.5 Hz, 2H), 2.77 (t, J
.5 Hz, 2H), 6.64 (dt, J ¼ 3.5, 0.9 Hz, 2H), 2.77 (t, J ¼ 7.6 Hz, 4H), ¼ 7.5 Hz, 4H), 1.57–1.75 (comp, 4H), 1.14–1.49 (comp, 36H),
1
A yellow liquid. H NMR (CDCl
3
3
1
6
1
1
3
.60–1.73 (comp, 4H), 1.22–1.50 (comp, 12H), 0.89 (t, J ¼ 6.6 Hz, 0.88 (t, J ¼ 6.6 Hz, 6H); C NMR (CDCl , 125 MHz, ppm): d
3
1
3
H); C NMR (CDCl , 75 MHz, ppm): d 144.7, 135.3, 124.5, 144.7, 135.3, 124.5, 122.6, 31.9, 31.6, 30.1, 29.7, 29.6, 29.5, 29.4,
22.6, 31.6, 30.1, 28.8, 22.6, 14.1.
3
+
29.1, 22.7, 14.1; MS (EI, 70 eV): 502 (M , 70%), 347 (10%), 193
0
0
0
0
5
,5 -Diheptyl-2,2 -bithiophene (2n). 5,5 -Diheptyl-2,2 -bithio- (100%), 179 (24%), 57 (44%); HRMS (EI): calcd for C32
54 2
H S :
phene (2n) was prepared from 2-heptyl-5-iodothiophene 502.3667, found: 502.3668.
0
0
0
25
(
308 mg, 1.00 mmol), palladium on activated charcoal (Pd/C,
2,2 ,3,3 -Tetrahydro-5,5 -bithieno[3,4-b][1,4]dioxine
(2r).
(2r) was
.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty- prepared from 5-iodo-2,3-dihydrothieno[3,4-b][1,4]dioxine
0
0
0
25
1
0
0% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg, 2,2 ,3,3 -Tetrahydro-5,5 -bithieno[3,4-b][1,4]dioxine
lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL) (268 mg, 1.00 mmol), palladium on activated charcoal (Pd/C,
2
according to the general procedure B and yielding aer column 10% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg,
chromatography (hexanes) the pure product 2n (109 mg, 60%). 0.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty-
ꢀ
1
3 2
A transparent solid; m.p.: 58.2–60.0 C. H NMR (CDCl , 300 lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL)
MHz, ppm): d 6.90 (d, J ¼ 3.5 Hz, 2H), 6.65 (d, J ¼ 3.5 Hz, 2H), according to the general procedure B and yielding aer column
2
1
1
.78 (t, J ¼ 7.6 Hz, 4H), 1.60–1.76 (comp, 4H), 1.18–1.46 (comp, chromatography (ethyl acetate–hexanes ¼ 20 : 80) the pure
13
6H), 0.90 (t, J ¼ 6.8 Hz, 6H); C NMR (CDCl
3
, 75 MHz, ppm): d product 2r (51 mg, 36%). A greenish yellow solid; m.p.:
ꢀ
1
44.7, 135.3, 124.5, 122.6, 31.8, 31.6, 30.1, 29.0, 22.7, 14.1; MS 204.1–205.9 C. H NMR (CD Cl , 300 MHz, ppm): d 6.26 (s, 2H),
2
2
+
13
(EI, 70 eV): 362 (M , 66%), 277 (100%), 205 (18%), 192 (48%); 4.18–4.36 (comp, 8H); C NMR (CD Cl , 75 MHz, ppm): d 141.9,
2 2
HRMS (EI): calcd for C H S : 362.2102, found: 362.2105.
137.7, 110.3, 97.9, 65.7, 65.3.
2
2
34 2
0
0
24
0
0
0
26
0
26
5
,5 -Dioctyl-2,2 -bithiophene (2o). 5,5 -Dioctyl-2,2 -bithio-
2,2 -Biselenophene
(2s). 2,2 -Biselenophene
(2s) was
24
phene
(2o) was prepared from 2-iodo-5-octylthiophene prepared from 2-iodoselenophene (257 mg, 1.00 mmol), palla-
(322 mg, 1.00 mmol), palladium on activated charcoal (Pd/C, dium on activated charcoal (Pd/C, 10% Pd basis, 53 mg,
1
0
0% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg, 0.05 mmol), indium powder (58 mg, 0.50 mmol), lithium
.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty- chloride (65 mg, 1.50 mmol), tetrabutylammonium bromide
lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL) (644 mg, 2.00 mmol), and H O (2 mL) according to the general
2
2
according to the general procedure B and yielding aer column procedure B and yielding aer column chromatography
chromatography (hexanes) the pure product 2o (107 mg, 55%). (hexanes) the pure product 2s (65 mg, 50%). A pale yellow solid;
ꢀ
1
1
A yellow solid; m.p.: 47.2–49.0 C. H NMR (CDCl
ppm): d 6.90 (d, J ¼ 3.5 Hz, 2H), 6.65 (d, J ¼ 3.5 Hz, 2H), 2.77 (t, J 5.7 Hz, 2H), 7.23–7.29 (comp, 2H), 7.17–7.23 (comp, 2H);
7.6 Hz, 4H), 1.58–1.77 (comp, 4H), 1.10–1.46 (comp, 20H), NMR (CHCl , 75 MHz, ppm): d 144.8, 130.2, 129.7, 126.7.
3
, 300 MHz, m.p.: 40.2–42.0. H NMR (CHCl
3
, 300 MHz, ppm): d 7.87 (d, J ¼
13
C
¼
3
1
3
0
.89 (t, J ¼ 6.8 Hz, 6H); C NMR (CDCl
3
, 75 MHz, ppm): d 144.7,
1
35.3, 124.5, 122.6, 31.9, 31.6, 30.1, 29.3, 29.2, 29.1, 22.7, 14.1.
0
0
0
0
General procedure C for Table 3: on-water homocoupling
reactions of various functionalized aryl iodides
5
,5 -Didecyl-2,2 -bithiophene (2p). 5,5 -Didecyl-2,2 -bithio-
phene (2p) was prepared from 2-decyl-5-iodothiophene (350 mg,
1.00 mmol), palladium on activated charcoal (Pd/C, 10% Pd To a heterogeneous solution of palladium on activated charcoal
basis, 53 mg, 0.05 mmol), indium powder (58 mg, 0.50 mmol), (Pd/C, 10% Pd basis, 0.05 mmol), indium powder (0.50 mmol),
lithium chloride (65 mg, 1.50 mmol), tetrabutylammonium lithium chloride (1.50 mmol), and tetrabutylammonium
bromide (644 mg, 2.00 mmol), and H O (2 mL) according to the bromide (TBAB) (2.00 mmol) in water (2 mL) was added the
2
general procedure B and yielding aer column chromatography corresponding aryl iodides (3a–3m) (1.00 mmol) under air. The
ꢀ
(
hexanes) the pure product 2p (105 mg, 47%). A yellow solid; reaction mixture was then heated at 90 C for 24 h. Aer cooled
This journal is © The Royal Society of Chemistry 2015
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Paper
0
0
0
31
0 0
(4e). 1,1 -([1,1 -
to room temperature, the precipitate/solid was ltered off under
1,1 -([1,1 -Biphenyl]-2,2 -diyl)diethanone
0
31
vacuum and washed with ethyl acetate. The bi-phase ltrate was Biphenyl]-2,2 -diyl)diethanone (4e) was prepared from 1-(2-
extracted with ethyl acetate (2 ꢁ 20 mL). The combined organic iodophenyl)ethanone (246 mg, 1.00 mmol), palladium on acti-
layers were washed with brine (60 mL), and dried over Na SO
vated charcoal (Pd/C, 10% Pd basis, 53 mg, 0.05 mmol), indium
2
4
before concentrated in vacuo. Purication by ash chromatog- powder (58 mg, 0.50 mmol), lithium chloride (65 mg, 1.50 mmol),
raphy yielded the desired product 4a–4m.
tetrabutylammonium bromide (644 mg, 2.00 mmol), and H O
2
0
0
0
27
27
Dimethyl [1,1 -biphenyl]-4,4 -dicarboxylate (4a). Dimethyl (2 mL) according to the general procedure C and yielding aer
0
[
4
1,1 -biphenyl]-4,4 -dicarboxylate (4a) was prepared from methyl column chromatography (ethyl acetate–hexanes ¼ 30 : 70) the
ꢀ
-iodobenzoate (262 mg, 1.00 mmol), palladium on activated pure product 4e (54 mg, 45%). A white solid; m.p.: 91.2–93.0 C.
1
charcoal (Pd/C, 10% Pd basis, 53 mg, 0.05 mmol), indium powder
H NMR (CDCl , 300 MHz, ppm): d 7.73 (dd, J ¼ 7.3, 1.5 Hz, 2H),
3
(
58 mg, 0.50 mmol), lithium chloride (65 mg, 1.50 mmol), tet- 7.36–7.61 (comp, 4H), 7.17 (dd, J ¼ 6.3, 1.3 Hz, 2H), 2.26 (s, 6H);
1
3
rabutylammonium bromide (644 mg, 2.00 mmol), and H O
3
C NMR (CDCl , 75 MHz, ppm): d 201.5, 140.6, 138.7, 131.0,
2
(
2 mL) according to the general procedure C and yielding aer 130.7, 128.5, 127.6, 29.2.
0
0
32
0
(4f). [1,1 -Biphenyl]-
column chromatography (ethyl acetate–hexanes ¼ 30 : 70) the
[1,1 -Biphenyl]-4,4 -dicarbaldehyde
0
32
pure product 4a (95 mg, 70%). A white solid; m.p.: 210.0– 4,4 -dicarbaldehyde (4f) was prepared from 4-iodobenzalde-
ꢀ
1
2
4
7
11.9 C. H NMR (CDCl
3
, 300 MHz, ppm): d 8.13 (d, J ¼ 8.2 Hz, hyde (232 mg, 1.00 mmol), palladium on activated charcoal
13
H), 7.69 (d, J ¼ 8.2 Hz, 4H), 3.95 (s, 6H); C NMR (CDCl
3
,
(Pd/C, 10% Pd basis, 53 mg, 0.05 mmol), indium powder
(58 mg, 0.50 mmol), lithium chloride (65 mg, 1.50 mmol), tet-
5 MHz, ppm): d 166.8, 144.3, 130.2, 129.7, 127.2, 52.2.
0
0
28
Dimethyl [1,1 -biphenyl]-3,3 -dicarboxylate (4b). Dimethyl rabutylammonium bromide (644 mg, 2.00 mmol), and H O
2
0
0
28
[1,1 -biphenyl]-3,3 -dicarboxylate
(4b) was prepared from (2 mL) according to the general procedure C and yielding aer
methyl 3-iodobenzoate (262 mg, 1.00 mmol), palladium on column chromatography (ethyl acetate–hexanes ¼ 20 : 80) the
activated charcoal (Pd/C, 10% Pd basis, 53 mg, 0.05 mmol), pure product 4f (97 mg, 92%). A white solid; m.p.: 146.0–
ꢀ
1
indium powder (58 mg, 0.50 mmol), lithium chloride (65 mg, 147.8 C. H NMR (CDCl , 300 MHz, ppm): d 10.06 (s, 2H), 7.98
3
1
3
1
2
.50 mmol), tetrabutylammonium bromide (644 mg, (d, J ¼ 8.2 Hz, 4H), 7.78 (d, J ¼ 8.2 Hz, 4H); C NMR (CDCl3,
.00 mmol), and H O (2 mL) according to the general procedure 75 MHz, ppm): d 191.6, 145.4, 135.9, 130.3, 127.9.
2
0
0
33
0
0
C and yielding aer column chromatography (ethyl acetate–
hexanes ¼ 30 : 70) the pure product 4b (99 mg, 73%). A white dicarbaldehyde (4g) was prepared from 2-iodobenzaldehyde
[1,1 -Biphenyl]-2,2 -dicarbaldehyde (4g). [1,1 -Biphenyl]-2,2 -
33
ꢀ
1
solid; m.p.: 104.2–105.0 C. H NMR (CDCl , 300 MHz, ppm): d (232 mg, 1.00 mmol), palladium on activated charcoal (Pd/C, 10%
3
8
.31 (s, 2H), 8.05 (d, J ¼ 7.8 Hz, 2H), 7.82 (d, J ¼ 7.8 Hz, 2H), 7.54 Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg, 0.50 mmol),
13
(
t, J ¼ 7.8 Hz, 2H), 3.96 (s, 6H); C NMR (CDCl
3
, 75 MHz, ppm): lithium chloride (65 mg, 1.50 mmol), tetrabutylammonium
bromide (644 mg, 2.00 mmol), and H O (2 mL) according to the
d 166.8, 140.3, 131.4, 130.8, 128.9, 128.7, 128.2, 52.1.
2
0
0
0
29
29
Dimethyl [1,1 -biphenyl]-2,2 -dicarboxylate (4c). Dimethyl general procedure C and yielding aer column chromatography
0
[
2
1,1 -biphenyl]-2,2 -dicarboxylate (4c) was prepared from methyl (ethyl acetate–hexanes ¼ 20 : 80) the pure product 4g (79 mg,
ꢀ
-iodobenzoate (262 mg, 1.00 mmol), palladium on activated 75%). A yellow solid; m.p.: 58.5–60.0 C. H NMR (CDCl , 300
3
1
charcoal (Pd/C, 10% Pd basis, 53 mg, 0.05 mmol), indium powder MHz, ppm): d 9.84 (s, 2H), 8.06 (d, J ¼ 7.3 Hz, 2H), 7.73–7.54
1
3
(
58 mg, 0.50 mmol), lithium chloride (65 mg, 1.50 mmol), tet- (comp, 4H), 7.35 (d, J ¼ 7.1 Hz, 2H); C NMR (CDCl , 75 MHz,
3
rabutylammonium bromide (644 mg, 2.00 mmol), and H
2
O
ppm): d 191.0, 141.2, 134.6, 133.4, 131.7, 128.8, 128.5.
0
0
34
0
0
(2 mL) according to the general procedure C and yielding aer
[1,1 -Biphenyl]-2,2 -dicarbonitrile (4h). [1,1 -Biphenyl]-2,2 -
34
column chromatography (ethyl acetate–hexanes ¼ 30 : 70) the dicarbonitrile (4h) was prepared from 2-iodobenzonitrile
ꢀ
pure product 4c (70 mg, 52%). A white solid; m.p.: 71.9–72.4 C. (229 mg, 1.00 mmol), palladium on activated charcoal (Pd/C,
1
H NMR (CDCl
3
, 300 MHz, ppm): d 8.01 (dd, J ¼ 7.7, 1.4 Hz, 2H), 10% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg,
7
.49–7.58 (comp, 2H), 7.37–7.47 (comp, 2H), 7.21 (dd, J ¼ 7.7, 1.1 0.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty-
1
3
Hz, 2H), 3.62 (s, 6H); C NMR (CDCl , 75 MHz, ppm): d 167.4, lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL)
3
2
1
43.2, 131.4, 130.2, 129.8, 129.3, 127.1, 51.7.
according to the general procedure C and yielding aer column
0
0
0
30
0
0
1
,1 -([1,1 -Biphenyl]-4,4 -diyl)diethanone
(4d). 1,1 -([1,1 - chromatography (ethyl acetate–hexanes ¼ 30 : 70) the pure
0
30
ꢀ
1
Biphenyl]-4,4 -diyl)diethanone (4d) was prepared from 1-(4- product 4h (55 mg, 54%). A white solid; m.p.: 175.2–177.0 C. H
iodophenyl)ethanone (246 mg, 1.00 mmol), palladium on acti- NMR (CDCl , 300 MHz, ppm): d 7.80–7.88 (comp, 2H), 7.68–7.76
3
1
3
vated charcoal (Pd/C, 10% Pd basis, 53 mg, 0.05 mmol), indium (comp, 2H), 7.52–7.64 (comp, 4H); C NMR (CDCl , 75 MHz,
3
powder (58 mg, 0.50 mmol), lithium chloride (65 mg, 1.50 mmol), ppm): d 141.5, 133.5, 132.8, 130.5, 129.2, 117.5, 112.3.
0
0
35
0
0
35
tetrabutylammonium bromide (644 mg, 2.00 mmol), and H O
4,4 -Dinitro-1,1 -biphenyl (4i). 4,4 -Dinitro-1,1 -biphenyl
2 mL) according to the general procedure C and yielding aer (4i) was prepared from 1-iodo-4-nitrobenzene (249 mg,
2
(
column chromatography (ethyl acetate–hexanes ¼ 30 : 70) the 1.00 mmol), palladium on activated charcoal (Pd/C, 10% Pd
pure product 4d (82 mg, 69%). A white solid; m.p.: 192.4–193.2 basis, 53 mg, 0.05 mmol), indium powder (58 mg, 0.50 mmol),
ꢀ
1
C. H NMR (CDCl
.71 (d, J ¼ 8.2 Hz, 4H), 2.64 (s, 6H); C NMR (CDCl
ppm): d 197.5, 144.2, 136.5, 128.9, 127.4, 26.6.
3
, 300 MHz, ppm): d 8.05 (d, J ¼ 8.2 Hz, 4H), lithium chloride (65 mg, 1.50 mmol), tetrabutylammonium
1
3
7
3
, 75 MHz, bromide (644 mg, 2.00 mmol), and H O (2 mL) according to the
2
general procedure C and yielding aer column chromatography
74186 | RSC Adv., 2015, 5, 74180–74188
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(
7
ethyl acetate–hexanes ¼ 20 : 80) the pure product 4i (87 mg,
References
ꢀ
1%). A yellow solid; m.p.: 235.7–237.0 C. H NMR (CDCl , 300
3
1
MHz, ppm): d 8.35 (d, J ¼ 8.4 Hz, 4H), 7.79 (d, J ¼ 8.4 Hz, 4H);
1 (a) C.-L. Sun and Z.-J. Shi, Chem. Rev., 2014, 114, 9219–9280;
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1
3
C NMR (CDCl , 75 MHz, ppm): d 148.1, 145.0, 128.3, 124.4.
3
0
0
36
0
0
36
4
,4 -Diuoro-1,1 -biphenyl (4j). 4,4 -Diuoro-1,1 -biphenyl
4j) was prepared from 1-uoro-4-iodobenzene (222 mg,
.00 mmol), palladium on activated charcoal (Pd/C, 10% Pd
(
1
basis, 53 mg, 0.05 mmol), indium powder (58 mg, 0.50 mmol),
lithium chloride (65 mg, 1.50 mmol), tetrabutylammonium
bromide (644 mg, 2.00 mmol), and H O (2 mL) according to the
2
general procedure C and yielding aer column chromatography
(
8
hexanes) the pure product 4j (66 mg, 70%). A white solid; m.p.:
ꢀ
1
7.1–88.0 C. H NMR (CDCl , 300 MHz, ppm): d 7.42–7.56
3
1
3
3
(comp, 4H), 7.02–7.20 (comp, 4H); C NMR (CDCl , 75 MHz,
1
4
ppm): d 162.4 (d, JC,F ¼ 245 Hz), 136.3 (d, JC,F ¼ 4 Hz), 128.5 (d,
3
2
J
C,F ¼ 8 Hz), 115.6 (d, JC,F ¼ 22 Hz).
0
0
37
0
(4k). 4,4 -Bis(tri-
4
,4 -Bis(triuoromethyl)-1,1 -biphenyl
uoromethyl)-1,1 -biphenyl (4k) was prepared from 4-iodo-
0
37

benzotriuoride (272 mg, 1.00 mmol), palladium on activated
charcoal (Pd/C, 10% Pd basis, 53 mg, 0.05 mmol), indium
powder (58 mg, 0.50 mmol), lithium chloride (65 mg, 1.50 mmol),
tetrabutylammonium bromide (644 mg, 2.00 mmol), and
H
2
O (2 mL) according to the general procedure C and yielding
aer column chromatography (hexanes) the pure product 4k
ꢀ
1
(
(
(
1
107 mg, 74%). A white solid; m.p.: 82.0–83.9 C. H NMR
1
3
CDCl , 300 MHz, ppm): d 7.65–7.82 (comp, 8H); C NMR
3
2
CDCl , 75 MHz, ppm): d 143.3, 130.3 (q, J ¼ 32 Hz), 127.6,
3
C,F
3
1
26.0 (q, J ¼ 4 Hz), 124.1 (q, J ¼ 270 Hz).
C,F
C,F
0
0
38
0 0
4,4 -Dichloro-1,1 -
4
,4 -Dichloro-1,1 -biphenyl
(4l).
biphenyl (4l) was prepared from 1-chloro-4-iodobenzene
238 mg, 1.00 mmol), palladium on activated charcoal (Pd/C,
38
(
1
0
0% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg,
.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty-
2013, 135, 11724–11727; (f) K. W. R. de França, M. Navarro,
E´ . L ´e onel, M. Durandetti and J.-Y. N ´e d ´e lec, J. Org. Chem.,
lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL)
2002, 67, 1838–1842.
2
according to the general procedure C and yielding aer column
chromatography (hexanes) the pure product 4l (84 mg, 75%). A
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Met., 2014, 187, 24–29.
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W.-F. Su, S.-P. Rwei, K.-C. Ho and L. Wang, Adv. Energy
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ꢀ
1
white solid; m.p.: 148.9–150.0 C. H NMR (CDCl
ppm): d 7.45–7.50 (comp, 4H), 7.38–7.43 (comp, 4H); C NMR
3
, 300 MHz,
1
3
(
CDCl
3
0
, 75 MHz, ppm): d 138.4, 133.7, 129.0, 128.2.
0
39
0
0
4,4 -Dibromo-1,1 -biphenyl
(4m).
4,4 -Dibromo-1,1 -
39
biphenyl (4m) was prepared from 1-bromo-4-iodobenzene
283 mg, 1.00 mmol), palladium on activated charcoal (Pd/C,
(
1
0
0% Pd basis, 53 mg, 0.05 mmol), indium powder (58 mg,
.50 mmol), lithium chloride (65 mg, 1.50 mmol), tetrabuty-
2
lammonium bromide (644 mg, 2.00 mmol), and H O (2 mL)
according to the general procedure C and yielding aer column
chromatography (hexanes) the pure product 4m (105 mg, 67%).
ꢀ
1
A white solid; m.p.: 168.2–170.4 C. H NMR (CDCl
ppm): d 7.56 (d, J ¼ 8.4 Hz, 4H), 7.41 (d, J ¼ 8.4 Hz, 4H); C NMR
CDCl , 75 MHz, ppm): d 138.9, 132.0, 128.5, 121.9.
3
, 300 MHz,
1
3
(
3
Acknowledgements
Financial support provided by the Ministry of Science and
Technology (MOST), Taiwan (MOST 103-2113-M-008-009-MY2)
and the National Central University (NCU) are gratefully
acknowledged.
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74188 | RSC Adv., 2015, 5, 74180–74188
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