Synthesis of monofunctionalized p-quaterphenyls

Article abstract of DOI:10.1055/s-2008-1067163

p-Oligophenyls have proven to be versatile building blocks for the generation of self-assembled nanoaggregates via vapor deposition on solid supports whose optical properties and morphologies can be influenced by the introduction of functional groups. Non

Full text of DOI:10.1055/s-2008-1067163

2446
PAPER
Synthesis of Monofunctionalized p-Quaterphenyls
S
ynthesi
v
s
of Monofun
o
ctionalized
p
-Quaterphen
n
yls e Wallmann,a Manuela Schiek,b Rainer Koch,c Arne Lützen*a
a
Kekulé-Institute of Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
Fax +49(228)739608; E-mail: arne.luetzen@uni-bonn.de
b
c
Mads Clausen Institute, University of Southern Denmark, Alsion 2, 6400 Sønderborg, Denmark
Institute of Pure and Applied Chemistry, Centre of Interphase Science, University of Oldenburg, P.O. Box 2503,
26111 Oldenburg, Germany
Received 28 February 2008
trosymmetric properties of the molecules to the nanofiber,
which is a prerequisite for nonlinear optical activity.
Abstract: p-Oligophenyls have proven to be versatile building
blocks for the generation of self-assembled nanoaggregates via va-
por deposition on solid supports whose optical properties and mor-
phologies can be influenced by the introduction of functional
groups. Nonsymmetrically functionalized p,p¢-disubstituted deriva-
tives could even be demonstrated to form nanoaggregates that can
act as frequency doublers due to their nonlinear optical properties.
Monofunctionalized derivatives like 4-substituted species
also fulfill this requirement, of course, and quantum
chemical studies suggest that they should have very inter-
esting nonlinear optical properties on a molecular level.12
However, since there are hardly any known examples they
have not yet been tested with regard to their ability to form
nanofibers. Thus, we started an investigation to develop a
general approach for the synthesis of these compounds.
Similar properties can be expected from monofunctionalized deriv-
atives. Thus, we developed a general approach for the synthesis of
monofunctionalized 1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-quaterphenyls (p-quaterphe-
nylenes) through the application of a reliable Suzuki cross-coupling
strategy.
Although p-quaterphenyl has been known for almost 130
years,13 and it is even commercially available, a direct (re-
gio-)selective functionalization14 of this compound is very
difficult to achieve mainly because of the notoriously low
solubility of these compounds. In order to gain access to
these molecules it is, therefore, mandatory to introduce
the desired functional group(s) into smaller units and then
employ these to assemble the quaterphenyl scaffold. Al-
though some other approaches were also used in the
past,15 modern homo- and cross-coupling procedures, es-
pecially Karash- and Suzuki-type couplings, have been
shown to be very efficient in this content.16 However,
most of the compounds prepared in this way bear long
alkyl or alkoxy chains to improve the solubility in organic
solvents and there are only a few reports9,17,18 that also
give rise to the desired p-quaterphenyls that are only func-
tionalized in 4,4¢¢¢-positions.
Key words: cross-coupling reaction, p-oligophenyls, rodlike mole-
cules, Suzuki cross-coupling
p-Conjugated rodlike molecules1 such as oligothio-
phenes,2 perylenes,3 pentacenes,4 and p-oligophenyls (p-
oligophenylenes)5 have been used extensively over the
last years to build up organic materials, because of their
optical, electrical, and optoelectrical properties.6
Among these molecules, the p-oligophenyls, especially
the p-hexaphenyl and 4,4¢¢¢-disubstituted p-quaterphenyls
(1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-quaterphenyls), show a high tendency
to self assemble to mutually aligned fiberlike aggregates
on muscovite mica upon vapor deposition by a sophisti-
cated high-vacuum surface growth process.5c,d,6h,7 These
structures can reach lengths of up to one millimeter and
show high quantum yields of anisotropic blue lumines-
cence, which make them very interesting for optoelectron-
ic devices such as organic light emitting diodes (OLEDs).
Interestingly, not only the nanoaggregates’ optical proper-
ties like their luminescence properties (efficiency and
emission wavelength), but also their morphologies can be
tailored by the choice of suitable functional groups.8 Non-
symmetrically 4,4¢¢¢-functionalized p-quaterphenyls,9
however, were not only shown to have interesting linear
optical properties,8,10 but they could also be demonstrated
to exhibit exciting nonlinear optical activity such as fre-
quency doubling.8b,11 Obviously, (at least most of) the mo-
lecular building blocks arrange themselves in a head-to-
tail-orientation in the aggregates that transfers the noncen-
According to our previous protocol, we again used Suzuki
cross-coupling reactions as the key steps in the synthesis
of the monosubstituted target compounds.
Since the solubility of p-oligophenyls decreases already
drastically from biphenyls to p-terphenyls it seemed rea-
sonable to build up p-quaterphenyls from two biphenyl
building blocks. Thus, one either needs a biphenyl-4-yl
halide and a 4¢-functionalized biphenyl-4-ylboronic acid
derivative or the nonsubstituted boronic acid derivative
and the respective biphenyl-4-yl halide furnished with the
desired functional group.
The latter strategy requires the formation of 4¢-functional-
ized 4-iodobiphenyls 5–7, which were prepared starting
from 4-iodoaniline following a three-step protocol that we
reported earlier (Scheme 1).9 4¢-Functionalized 4-iodobi-
phenyls 5–7 were then coupled with commercially avail-
able biphenyl-4-ylboronic acid (8) to give the first set of
p-quaterphenyls 9–11 (Scheme 2). The use of 3 mol% of
SYNTHESIS 2008, No. 15, pp 2446–2450
x
x.
x
x
.
2
0
0
8
Advanced online publication: 08.07.2008
DOI: 10.1055/s-2008-1067163; Art ID: Z05508SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Synthesis of Monofunctionalized p-Quaterphenyls
2447
tetrakis(triphenylphosphine)palladium [Pd(PPh3)4] and ate and, thus, also the solvent to a mixture of toluene,
cesium fluoride proved to be efficient in the catalysis of methanol, and water in order to obtain satisfying results.
both the Suzuki cross-couplings to obtain the biphenyls However, this is actually an improvement because the
and the p-quaterphenyl in moderate to acceptable yields of base is inexpensive and the solvents no longer need to be
39% (9), 59% (10), and 57% (11).
anhydrous. Thus, this procedure is less time consuming
and much less expensive (despite the higher amount of
palladium catalyst) due to the fact that most starting mate-
rials are commercially available and several isolation and
purification steps can be saved. As can be seen by the
yield of 65% for 11, which was obtained when we fol-
lowed this approach, this procedure is equally well suited
for the synthesis of these compounds, although the purifi-
cation of the product proved to be more tedious than in the
other case. It should be noted, however, that this approach
also has its limitations, since we were able to obtain the
dimethylamino-substituted target compound 14 and also
benzylamine 18, but only in low yields of 5% and 27%
(after in situ deprotection of the Boc group), respectively,
but it allowed an elegant access to the desired bromo 15,
amino 16, and nitro 17 derivative in good to excellent
yield of 58–98%.
I
NH2
p-TsOH,
toluene
+
I
N
O
95%
1
O
[Pd(PPh3)4],
CsF, THF,
∆, 18 h
R
B(OH)2
1. H2SO4,
NaNO2
R
I
R
N
2. KI
R = OMe (5, 91%)
Cl (6, 61%)
R = OMe (2, 85%)
Cl (3, 83%)
CN (7, 54%)
CN (4, 94%)
Scheme 1 Synthesis of 4¢-functionalized 4-iodobiphenyls 5–7 from
4-iodoaniline
R
I
+
(HO)2B
B(OH)2
13
[Pd(PPh3)4],
K2CO3,
+
R
I
(HO)2B
toluene–MeOH–H2O
∆, 3 h
5–7
8
[Pd(PPh3)4],
CsF, THF,
∆, 50 h
R
B(OH)2
R
R = OMe (9, 36%), Cl (10, 59%), CN (11, 57%)
additional
portion of
[Pd(PPh3)4]
X
12a (X = I), 12b (X = Br)
Scheme 2 Synthesis of monofunctionalized p-quaterphenyls 9–11
The other strategy involves 4¢-functionalized biphenyl-4-
ylboronic acid derivatives, which are then reacted with
commercially available 4-iodo- (12a) or 4-bromobiphenyl
(12b). Of course, one can prepare, isolate, and purify the
functionalized boronic acids in a stepwise manner like the
iodides 5–7 shown previously, however, during the course
of our study we found that there is a much more elegant
way to gain access to our target compounds: In fact, we
were able to show that one can perform two Suzuki cross-
coupling reactions with commercially available benzene-
1,4-yldiboronic acid (13) in a stepwise manner in a one-
pot reaction. Therefore, 13 was first reacted with the
readily available 4-functionalized iodobenzene to give the
functionalized biphenylylboronic acid, which was then
transformed without further purification into the desired
p-quaterphenyl in a second Suzuki reaction upon addition
of commercially available 4-iodobiphenyl (12a) and some
further palladium catalyst directly to the reaction mixture
of the first coupling (Scheme 3). It should be noted at this
point, that we had to change the base to potassium carbon-
R
R = CN (11, 65%), NMe2 (14, 5%), Br (15, 58%),
NH2 (16, 94%), NO2 (17, 98%), CH2NHBoc
in situ deprotection
CH2NH2 (18, 27%)
Scheme 3 Synthesis of monofunctionalized p-quaterphenyls 11,
14–18
All products 9–11, and 14–18 are even less soluble than
their 4,4¢¢¢-difunctionalized analogues. Thus, they precip-
itated from the reaction mixture and were purified by re-
peated washing with water and organic solvents in some
cases also with diluted trifluoroacetic acid. Unfortunately,
this purification method usually leads to retention of re-
sidual solvents in the products, which cannot always be
Synthesis 2008, No. 15, 2446–2450 © Thieme Stuttgart · New York

2448
I. Wallmann et al.
PAPER
itate was collected and washed with THF, CH2Cl2, and H2O to ob-
tain the desired quaterphenyl.
removed upon drying under normal laboratory high vacu-
um but only by out-gassing under ultrahigh vacuum.
Actually, the solubility proved to be so low, that we were
not even able to record H NMR spectra of these com-
1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-Quaterphenyls; General Procedure 2
1
A 2-necked flask equipped with a condenser was charged with ben-
zene-1,4-diyldiboronic acid (13, 1 equiv). A 4-substituted iodoben-
zene, K2CO3 (3 equiv), and Pd(PPh3)4 (5 mol%) were added and
dissolved in a mixture of toluene, MeOH, and H2O. The mixture
was refluxed until TLC monitoring indicated the complete con-
sumption of the starting material (~3 h). The mixture was allowed
to cool to r.t. and 4-iodobiphenyl (12a, 1.2 equiv) and an additional
portion of Pd(PPh3)4 (5 mol%) were added. The soln was refluxed
for a further 36 h. The mixture was cooled to r.t. and the precipitate
collected and washed with different organic solvents and H2O to
give the desired quaterphenyl.
pounds that show all the expected resonances. Neverthe-
less, we were able to characterize these compounds by
(high resolution) mass spectrometry, UV/Vis, and fluo-
rescence spectroscopy, and elemental analysis (in some
cases).
In conclusion we have developed two reliable protocols
for the synthesis of monofunctionalized p-quaterphenyls
by using Suzuki cross-coupling reactions, which allow the
isolation of the target compounds in sufficient purity to
perform vapor deposition studies. These compounds are
promising candidates for the formation of well-defined
nanoaggregates with interesting linear and nonlinear opti-
cal properties.
1-Methoxy-1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-quaterphenyl (9)22
Following general procedure 1 using 4-iodo-4¢-methoxybiphenyl
(5, 2.0 g, 6.44 mol) with 8 (1.33 g, 6.77 mmol), CsF (2.93 g, 19.3
mmol), and Pd(PPh3)4 (223 mg, 0.19 mmol) in THF (120 mL) gave
9 as a slightly yellow amorphous solid; yield: 780 mg (36%).
MS (EI): m/z = 336.2 ([M+], 100).
Solvents were dried, distilled, and stored under argon according to
standard procedures. Reactions with air- and moisture-sensitive
transition metal compounds were performed under an argon atmo-
sphere in oven-dried glassware using standard Schlenk techniques.
HRMS (EI): m/z calcd for C25H20O: 336.1514; found: 336.1516.
UV/Vis (CH2Cl2): lmax = 265 nm.
Fluorescence (CH2Cl2): lmax = 384 nm.
TLC was performed on aluminum TLC plates (silica gel 60 F254)
from Merck and the products were visualized under UV light (254
or 366 nm). Products were purified either by column chromatogra-
phy on silica gel 60 (70–230 mesh or 230–400 mesh) from Merck
or by extraction and washing procedures. Because of the low solu-
4-Chloro-1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-quaterphenyl (10)
Following general procedure 1 using 4-chloro-4¢-iodobiphenyl (6,
1.16 g, 3.69 mmol) with 8 (0.76 g, 3.87 mmol), CsF (1.68 g, 11.07
mmol), and Pd(PPh3)4 (127 mg, 0.11 mmol) in THF (70 mL) gave
10 as an off-white amorphous solid; yield: 740 mg (59%).
bility of the quaterphenyls it was not possible to record 1H and 13
C
NMR spectra that show all the expected resonances, thus, they are
not listed here. Mass spectra were recorded on a Finnigan MAT-
95XL. UV/Vis spectra were measured on a Jena Analytic Specord
200 spectrometer in a 1-cm quartz cuvette. Fluorescence spectra
were taken on a Aminco Bowman AB2 spectrometer in a 1-cm
quartz cuvette. Since the p-quaterphenyls were obtained as amor-
phous solids they usually contain residual amounts of solvents from
the extraction and washing procedure that could not be removed
completely in all cases even after heating for longer periods of time
under standard laboratory high vacuum (10–3 mbar). Thus, not all of
the quaterphenyls gave satisfactory elemental analysis. Thus, we
also give HRMS data in all cases.
MS (EI): m/z = 340.2 ([M+], 100).
HRMS (EI): m/z calcd for C24H17Cl: 340.1019; found: 340.1022.
Anal. Calcd for C24H17Cl·0.5 H2O: C, 82.39; H, 5.29. Found: C,
82.68; H, 5.20.
UV/Vis (CH2Cl2): lmax = 301.5 nm.
Fluorescence (CH2Cl2): lmax = 356 nm.
4-Cyano-1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-quaterphenyl (11)
Following general procedure 1 using 4-cyano-4¢-iodobiphenyl (7,
1.68 g, 5.51 mmol) with 8 (1.14 g, 5.78 mmol), CsF (2.51 g, 16.53
mmol), and Pd(PPh3)4 (191 mg, 0.17 mmol) in THF (70 mL) gave
11 as a slightly brownish amorphous solid; yield: 1.04 g (57%);.
4-Bromophenylboronic acid, 4-chlorophenylboronic acid, 4-meth-
oxyphenylboronic acid, 4-nitrophenylboronic acid, 4-cyanophenyl-
boronic acid, biphenyl-4-ylboronic acid (8), 4-iodobiphenyl (12a),
4-bromobiphenyl (12b), benzene-1,4-diyldiboronic acid (13), 1-
iodo-4-nitrobenzene, 4-iodobenzonitrile, CsF, and Pd(PPh3)4 were
purchased from Sigma-Aldrich, Alfa Aesar, Merck, Lancaster, or
Strem and used as received.
1-(2,5-Dimethyl-1H-pyrrol-1-yl)-4-iodobenzene (1),19 4-iodo-N,N-
dimethylaniline,20 4-(2,5-dimethyl-1H-pyrrol-1-yl)-4¢-methoxybi-
phenyl (2),9 4-chloro-4¢-(2,5-dimethyl-1H-pyrrol-1-yl)biphenyl
(3),9 4-cyano-4¢-(2,5-dimethyl-1H-pyrrol-1-yl)biphenyl (4),9 4-
iodo-4¢-methoxybiphenyl (5),9 4-chloro-4¢-iodobiphenyl (6),9 4-cy-
ano-4¢-iodobiphenyl (7),9 and N-Boc-protected 4-bromobenzyl-
amine21 were prepared according to published procedures.
Following general procedure 2 using 4-iodobenzonitrile (1.5 g, 6.6
mmol) with 13 (1.09 g, 6.6 mmol), K2CO3 (2.73 g, 19.7 mmol), and
Pd(PPh3)4 (380 mg, 0.33 mmol) in toluene–MeOH–H2O (70 mL:50
mL:0.5 mL) gave the respective biphenylboronic acid, which was
reacted in situ with 12a (2.21 g, 7.9 mmol) and an additional portion
of Pd(PPh3)4 (380 mg, 0.33 mmol) to give 11; yield: 1.42 g (65%).
MS (EI): m/z = 331.1 ([M+], 100)
HRMS (EI): m/z = calcd for C25H17N: 331.1361; found: 331.1361.
Anal. Calcd for C25H17N·0.5 CH2Cl2: C, 81.92; H, 4.85; N, 3.75.
Found: C, 82.13; H, 5.02; N, 3.55.
UV/Vis (CH2Cl2): lmax = 312 nm.
Fluorescence (CH2Cl2): lmax = 390 nm.
1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-Quaterphenyls; General Procedure 1
A 2-necked flask equipped with a condenser was charged with bi-
phenyl-4-boronic acid (8, 1.05 equiv). A 4¢-substituted 4-iodobi-
phenyl, CsF (3 equiv), and Pd(PPh3)4 (3 mol%) were added and
dissolved in anhyd THF under an argon atmosphere. The mixture
was refluxed for 15 h. The mixture was cooled to r.t. and the precip-
4-(Dimethylamino)-1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-quaterphenyl (14)
Following general procedure 2 using 4-iodo-N,N¢-dimethylaniline
(0.75 g, 3.04 mmol) with 13 (0.5 g, 3.04 mmol), K2CO3 (1.26 g,
9.12 mmol), and Pd(PPh3)4 (176 mg, 0.15 mmol) in toluene–
MeOH–H2O (45 mL:30 mL:0.5 mL) gave the respective biphenyl-
boronic acid, which was reacted in situ with 12a (1.02 g, 3.65
Synthesis 2008, No. 15, 2446–2450 © Thieme Stuttgart · New York

PAPER
Synthesis of Monofunctionalized p-Quaterphenyls
2449
mmol) and an additional portion of Pd(PPh3)4 (176 mg, 0.15 mmol)
to give 14 as an off-white amorphous solid; yield: 53 mg (5%). (A
further increase in the amount of the palladium catalyst unfortunate-
ly did not increase the yield.)
soln was made alkaline by dropwise addition of concd aq NaOH re-
sulting in a bulky light yellow precipitate. The crude product was
collected by filtration and washed repeatedly with H2O and CH2Cl2.
Following recrystallization (hot DMSO) gave 18 as a yellow-green
amorphous solid; yield: 319 mg (27%).
MS (EI): m/z = 349.2 ([M+], 100)
MS (EI): m/z = 335.2 (M+, 100)
HRMS (EI): m/z calcd for C26H23N: 349.1830; found: 349.1833.
UV/Vis (CH2Cl2): lmax = 331.5 nm.
HRMS (EI): m/z calcd for C25H21N: 335.1674; found: 335.1670
UV/Vis (CH2Cl2): lmax = 319 nm.
Fluorescence (CH2Cl2): lmax = 448 nm.
4-Bromo-1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-quaterphenyl (15)23
Acknowledgment
Following general procedure 2 using 1-bromo-4-iodobenzene (0.75
g, 2.66 mmol) with 13 (0.45 g, 2.66 mmol), K2CO3 (1.10 g, 7.98
mmol), and Pd(PPh3)4 (153 mg, 0.13 mmol) in toluene–MeOH–
H2O (45 mL:30 mL:0.5 mL) gave the respective biphenylboronic
acid, which was reacted in situ with 12a (0.89 g, 3.19 mmol) and an
additional portion of Pd(PPh3)4 (153 mg, 0.13 mmol) to give 15 as
a brownish amorphous solid; yield: 585 mg (58%).
Financial support from the DFG is gratefully acknowledged.
References
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MS (EI): m/z = 384.1 ([M+], 100)
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HRMS (EI): m/z calcd for C24H17Br: 384.0514; found: 384.0515
Anal. Calcd for C24H17Br·H2O: C, 71.47; H, 4.75. Found: C, 71.84;
H, 4.59.
UV/Vis (CH2Cl2): lmax = 303.5 nm.
Fluorescence (CH2Cl2): lmax = 378 nm.
(4) Bendikov, M.; Wudl, F.; Perepichka, D. F. Chem. Rev. 2004,
104, 4891.
4-Amino-1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-quaterphenyl (16)24
Following general procedure 2 using 4-iodoaniline (1.5 g, 6.88
mmol) with 13 (1.14 g, 6.88 mmol), K2CO3 (2.85 g, 20.64 mmol),
and Pd(PPh3)4 (398 mg, 0.34 mmol) in toluene–MeOH–H2O (90
mL:60 mL:0.5 mL) gave the respective biphenylboronic acid,
which was reacted in situ with 12a (2.31 g, 8.26 mmol) and an ad-
ditional portion of Pd(PPh3)4 (398 mg, 0.34 mmol) to give 16 as a
slightly yellow-green solid; yield: 2.08 mg (94%).
(5) (a) James, D. K.; Tour, J. M. Top. Curr. Chem. 2005, 257,
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Oligomer Approach; Wiley-VCH: Weinheim, 1998.
(b) Fichou, D. Handbook of Oligo- and Polythiophenes;
Wiley-VCH: Weinheim, 1999. (c) Nalva, H. S. Handbook
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Devices; Academic Press: San Diego, 2000. (d) Witte, G.;
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MS (EI): m/z = 349.2 (M+, 100)
HRMS (EI): m/z calcd for C26H23N: 349.1830; found: 349.1833.
UV/Vis (CH2Cl2): lmax = 311 nm.
Fluorescence (CH2Cl2): lmax = 386 nm.
4-Nitro-1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-quaterphenyl (17)24
Following general procedure 2 using 1-iodo-4-nitrobenzene (2 g,
8.06 mmol) with 13 (1.34 g, 8.06 mmol), K2CO3 (3.34 g, 24.18
mmol), and Pd(PPh3)4 (466 mg, 0.40 mmol) in toluene–MeOH–
H2O (90 mL:60 mL:0.5 mL) gave the respective biphenylboronic
acid which was reacted in situ with 12a (2.8 g, 9.67 mmol) and an
additional portion of Pd(PPh3)4 (466 mg, 0.40 mmol) to give 17 as
an off-white amorphous solid; yield: 2.78 g (98%).
MS (EI): m/z = 351.2 (M+, 100)
HRMS (EI): m/z calcd for C24H17NO2: 351.1259; found: 351.1258.
UV/Vis (CH2Cl2): lmax = 323.5 nm.
Fluorescence (CH2Cl2): lmax = 390 nm.
(9) Schiek, M.; Al-Shamery, K.; Lützen, A. Synthesis 2007,
613.
4-(Aminomethyl)-1,1¢:4¢,1¢¢:4¢¢,1¢¢¢-quaterphenyl (18)
Following general procedure 2 using N-Boc-protected 4-iodoben-
zylamine (952 mg, 3.5 mmol) with 13 (580 mg, 3.5 mmol), K2CO3
(1.45 g, 10.5 mmol), and Pd(PPh3)4 (202 mg, 0.175 mmol) in tolu-
ene–MeOH–H2O (45 mL:30 mL:0.5 mL) gave the respective biphe-
nylboronic acid, which was reacted in situ with 12b (979 mg, 4.2
mmol) and an additional portion of Pd(PPh3)4 (202 mg, 0.175
mmol) to give N-Boc-protected quaterphenyl, which was suspended
in CH2Cl2 (100 mL). The mixture was cooled to 0 °C and TFA (10
mL) was added dropwise to give an intense yellow soln. The mix-
ture was allowed to warm up to r.t. and stirred for a further 1 h. The
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(11) Brewer, J.; Schiek, M.; Lützen, A.; Al-Shamery, K.;
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PAPER
(12) Koch, R.; Finnerty, J. J.; Bruhn, T. J. Phys. Org. Chem.
submitted for publication.
(13) Schmidt, H.; Schultz, G. Justus Liebigs Ann. Chem. 1880,
203, 129.
(14) (a) Scheinbaum, M. L. J. Chem. Soc., Chem. Commun. 1969,
1235. (b) Pavlopoulos, T. G.; Hammond, P. R. J. Am. Chem.
Soc. 1974, 96, 6568. (c) Péres, L. O.; Guileet, F.; Froyer, G.
Org. Biomol. Chem. 2004, 2, 452.
(15) In the past p-quaterphenyl syntheses were achieved by
cyclotrimerizations of acetylenes, Diels–Alder reactions of
cyclopentadienones and subsequent aromatization, Wittig
reactions of cinnamaldehydes followed by Diels–Alder
reactions with acetylenedicarboxylates and subsequent
aromatization, addition of Grignard reagents to arenes,
Grignard reactions with p-quinones and subsequent
dehydration, or Ullmann-type coupling reactions. For a
detailed list of references see citations 20–25 listed in ref 9.
(16) For a detailed list of references see citations 26–30 listed in
ref 9.
(17) (a) Fran, J.; Karakaya, B.; Schäfer, A.; Schlüter, A. D.
Tetrahedron 1997, 53, 15459. (b) Hensel, V.; Schlüter,
A.-D. Chem. Eur. J. 1999, 5, 421.
(18) (a) Percec, V.; Okita, S. J. Polym. Sci., Part A: Polym. Chem.
1993, 31, 877. (b) Morikawa, A. Macromolecules 1998, 31,
5999. (c) Li, Z. H.; Wong, M. S.; Tao, Y.; D’Iorio, M.
J. Org. Chem. 2004, 69, 921. (d) Lee, M.; Jang, C.-J.; Ryu,
J.-H. J. Am. Chem. Soc. 2004, 126, 8082. (e) Ryu, J.-H.;
Jang, C.-J.; Yoo, Y.-S.; Lim, S.-G.; Lee, M. J. Org. Chem.
2005, 70, 8956. (f) Welter, S.; Salluce, N.; Benetti, A.; Rot,
N.; Belser, P.; Sonar, P.; Grimsdale, A. C.; Müllen, K.; Lutz,
M.; Spek, A. L.; de Cola, L. Inorg. Chem. 2005, 44, 4706.
(19) Thiemann, F.; Piehler, T.; Haase, D.; Saak, W.; Lützen, A.
Eur. J. Org. Chem. 2005, 1991.
(20) Umzawa, H.; Okada, S.; Oikawa, H.; Matsuda, H.;
Nakanishi, H. J. Phys. Org. Chem. 2005, 18, 468.
(21) Howell, S. J.; Spencer, N.; Philp, D. Tetrahedron 2001, 57,
4945.
(22) This compound has been described in some Japanese
patents, however, without any data concerning its synthesis
no characterization.
(23) This compound has been described before, however, using a
different synthetic approach giving 15 in considerably lower
yield, see ref 14c. It has also been described in a recent
Japanese patent (written in Japanese): Yabunouchi, N.;
Moriwaki, F. WO 2007,080,704, 2007; Chem. Abstr. 2007,
147, 166040.
(24) The nitro compound 17 and the amino compound 16 have
been described before, however, they were obtained in very
low yields by nitration of p-quaterphenyl to give 17 and
subsequent reduction to give 16, see ref 14a. Furthermore,
these compounds are also listed in some Japanese patents,
however, without any data concerning their synthesis or
characterization. Finally, 17 has also been described in a
theoretical study concerning organic electrodes: Solak, A.
O.; Eichhorst, L. R.; Clark, W. J.; McCreery, R. L. Anal.
Chem. 2003, 75, 296.
Synthesis 2008, No. 15, 2446–2450 © Thieme Stuttgart · New York