Tetraalkynylated and tetraalkenylated benzenes and pyridines: Synthesis and photophysical properties

Article abstract of DOI:10.1002/adsc.201300201

Tetra(arylalkynyl)pyridines and tetra(arylalkenyl)pyridines and their benzene analogues were prepared by palladium-catalyzed cross-coupling reactions from the commercially available chlorinated substrates in good to excellent yields. The photophysical pro

Full text of DOI:10.1002/adsc.201300201

FULL PAPERS
DOI: 10.1002/adsc.201300201
Tetraalkynylated and Tetraalkenylated Benzenes and Pyridines:
Synthesis and Photophysical Properties
Peter Ehlers,a,b Ani Hakobyan,a,b,c,d Antje Neubauer,e Stefan Lochbrunner,e
and Peter Langera,b,*
a
Institut fꢀr Chemie, Universitꢁt Rostock, Albert Einstein Str. 3a, 18059 Rostock, Germany
E-mail: peter.langer@uni-rostock.de
Leibniz-Institut fꢀr Katalyse an der Universitꢁt Rostock e.V., Albert Einstein Str. 29a, 18059 Rostock, Germany
Faculty of Chemistry, Yerevan State University, Alex Manoogian 1, 0025 Yerevan, Armenia
Scientific and Production Center “Armbiotechnology” of NAS RA, Gyurjyan str. 14, 0056 Yerevan, Armenia
b
c
d
e
Institut fꢀr Physik, Universitꢁt Rostock, Universitꢁtsplatz 3, 18051 Rostock, Germany
Received: March 7, 2013; Published online: && &&, 0000
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201300201.
Abstract: Tetra(arylalkynyl)pyridines and tetra(aryl- vestigated and compared to each other. Very good
ACHTUNGTRENNUNGalkenyl)pyridines and their benzene analogues were fluorescence quantum yields were observed, especial-
prepared by palladium-catalyzed cross-coupling reac- ly for the pyridine derivatives.
tions from the commercially available chlorinated
substrates in good to excellent yields. The photo- Keywords: catalysis; cross-coupling; fluorescence;
physical properties of selected compounds were in- heterocycles; palladium
Introduction
tion and electron delocalization, these branched de-
rivatives exhibit excellent two-photon absorption
Highly conjugated organic molecules are of great in- properties.[11] Furthermore, they show good self-as-
terest owing to their wide applications in electronic sembling and thin film forming properties.[12]
devices.[1] In particular, scaffolds based on branched
In contrast to polyalkynylated and polyalkenylated
phenylacetylenes are the target of many studies.[2] benzene derivatives, their corresponding heterocyclic
Their large delocalized p-systems qualify these com- analogues (e.g., pyridines and pyrazines) have re-
pounds as ideal candidates for optical and non-linear ceived much less attention. Penta- and tetra-
optical (NLO) materials.[3] In particular, star-shaped
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
tical materials.[3d,e,f] Furthermore, they were described 2,3,5,6-tetrabromopyridine.[13] However, this proce-
as potential building blocks for new 2D-carbon allo- dure relies on the use of 2,3,5,6-tetrabromopyridine
tropes with a high degree of hardness and thermal which is rather difficult and tedious to synthesize. As
stability.[5] In this context, tetraalkynylbenzenes have a result of our ongoing interest in the development of
received considerable interest as carbon-rich, highly new palladium-catalyzed procedures for the construc-
conjugated molecules with impressive photophysical tion of highly conjugated heterocycles,[14] we recently
properties.[6] Their optical properties have been re- reported the synthesis and photophysical properties
ported to show high sensitivity to changes in the con- of the first pentaACHTNUGRTNEUNG
(alkynyl)pyridines.[15] Herein we
figuration of functional groups, which makes them report the first synthesis of tetraalkynyl- and tetrastyr-
ideal targets for the construction of more sophisticat- ylpyridines from polychlorinated precursors by multi-
ed optical devices.[7] Besides their interesting optical ple Sonogashira and Suzuki reactions, respectively.
properties, tetraalkynylbenzenes were used for the Furthermore, we applied our methodology to the syn-
construction of supramolecular self-assemblies[8] and thesis of the corresponding benzene derivatives. The
for nanoparticle stabilization.[9] Most studies related linear optical properties of a selection of the synthe-
to tetrastyrylbenzenes are focused on their optoelec- sized products were investigated and compared to
tronic applications.[2a,b,10] Due to the perfect conjuga- each other.
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Results and Discussion
The synthesis of 1,2,4,5-tetra
rivatives was next studied. The Sonogashira reaction
ACHTUNGTREN(NUNG alkynyl)benzene de-
Our first goal was to identify a catalytic system which of 1,2,4,5-tetrachlorobenzene 3 afforded the 1,2,4,5-
allows us to carry out Sonogashira cross-coupling re- tetra(alkynyl)benzene derivatives 4a–g (Scheme 2,
AHCTUNGTRENNUNG
actions of commercially available 2,3,5,6-tetrachloro- Table 2). During the optimization, the employment of
pyridine (1). At first, the reactions were carried out, a slightly increased amount of catalyst and of an
similar to the analogous reactions of pentachloropyri- excess (8.0 equiv.) of the acetylene proved to be im-
dine,[15] using PdCl
CHTUNTGREN(NNUG CH3CN)2 (4 mol%)/X-Phos portant. Higher yields were obtained for products de-
2A
(8 mol%) as the catalyst, CuI (3 mol%) as the co-cat- rived from arylalkynes containing electron-donating
alyst, 1,4-dioxane as the solvent, and HN(i-Pr)2 as the groups as compared to products derived from elec-
base. The Sonogashira reaction of 1 with various al- tron-poor arylalkynes.
kynes (5.0 equiv.) afforded the 2,3,5,6-tetra- Polyalkenylated benzenes are usually prepared by
(alkynyl)pyridines 2a–i in good to excellent yields Wittig reactions of the appropriate aldehydes.[11,12,16]
(Scheme 1, Table 1). Application of PPh3 or HP(t- In most cases, the application of the Heck reaction
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
Bu)BF4 as ligands led to lower yields of the desired fails, due to competing palladium-catalyzed cycliza-
products. However, only a moderate yield was ob- tions of two adjacent double bonds or other side reac-
tained for product 2f. This can be explained by the tions,[17] especially under Jeffrey conditions.[18] Some
electron-withdrawing effect of the keto group which years ago, de Meijere and co-workers reported the ap-
results in a reduced nucleophilicity of the correspond- plication of alkenylstannanes and alkenylboronic acid
ing cuprate. Triisopropylsilyl-protected acetylene pinacol esters for the synthesis of hexaalkenylbenze-
could be successfully employed in the reaction. How- nes.[17a,19] Styrylboronic acids were not employed in
ever, the silyl group was not cleaved, because of the this study.
potentially explosive character of unsubstituted poly-
alkynes.
We examined the tetrafold Suzuki–Miyaura reac-
tion of styrylboronic acid with 2,3,5,6-tetrachloropyri-
dine 1. We chose pyridine derivative 1 for the initial
optimizations, as it is an electron-deficient molecule
which should undergo coupling reactions easier than
Scheme 1. Synthesis of 2a–i; i: PdCl2ACTHNUGTRNE(UNG CH3CN)2 (4 mol%),
X-Phos (8 mol%), CuI (3 mol), 1,4-dioxane, HN
alkyne (5 equiv.).
ACHTUNGTNER(NUNG i-Pr)2,
Scheme 2. Synthesis of 4a–g; i: PdCl2ACTHNUGTRNE(UNG CH3CN)2 (5 mol%),
X-Phos (10 mol%), CuI (5 mol%), 1,4-dioxane, HN
ACHTUNGTRENNUNG(i-Pr)2,
alkyne (8 equiv.).
Table 1. Synthesis of 2a–i.
Yield [%][a]
Table 2. Synthesis of 4a–g.
2
Alkyne
4
Alkyne
Yield [%][a]
a
b
c
96
93
77
65
69
a
b
c
82
99
70
53
d
e
d
e
f
85
f
52
g
85
74
99
h
i
85
62
g
[a]
[a]
Yields of isolated products.
Yields of isolated products.
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Tetraalkynylated and Tetraalkenylated Benzenes and Pyridines
Table 3. Optimization of the synthesis of 5a.
bility of the formed intermediates during the reaction.
Products 5f, 5h and 5j could not be obtained, due to
the precipitation of less alkenylated intermediates.
The moderate yield of 5j is also based on difficulties
during the purification caused by the low solubility of
this compound. The introduction of alkyl groups pre-
vents the precipitation of intermediates and the de-
sired products were obtained in excellent yields. The
trans-configuration of the alkenyl moieties was
proven by NMR spectroscopy. No cis-isomers were
observed.
In order to study the impact of electron-donor and
electron-acceptor functional groups on the photophys-
ical properties, steady-state UV/Vis absorption and
fluorescence measurements were performed. Absorp-
tion band maxima, molar absorption coefficients,
Stokes shifts, fluorescence maxima and quantum
yields of selected alkynylpyridines 2, alkynylbenzenes
4 and alkenyl derivatives 5 are summarized in
Table 5. Performing the optical measurements for the
Entry Ligand
Base
Solvent
Yield [%]
[a]
1
2
3
4
5
6
7
PPh3
K3PO4
toluene
toluene
1,4-dioxane 95
1,4-dioxane
1,4-dioxane traces
0
33
cataXCium A K3PO4
cataXCium A K3PO4
S-Phos
PCy3
cataXCium A Cs2CO3 1,4-dioxane 88
cataXCium A KF 1,4-dioxane traces
K3PO4
K3PO4
6
[a]
Used as Pd(PPh3)4.
ACHTUNGTRENNUNG
the corresponding benzene derivative 3. Results of alkenyl derivatives, precautions had to be taken in
the optimization are shown in Table 3. The reaction order to avoid photochemical reactions observed after
proved to be sensitive related to the employed ligand exposure to daylight for a certain period of time. Stil-
and solvent. Using PdACHTNUGRTNEUNG(PPh3)4 as the catalyst, no prod- benoid systems are known to undergo photochemical
uct was detected. Compound 5a was isolated in 33% reactions like E/Z-isomerizations, cyclizations,
yield by application of the electron-rich, sterically de- [2+2]dimerization by formation of cyclobutane rings
manding cataXCium A ligand[20] using toluene as the or polymerizations.[21] For the alkenyl derivatives,
solvent. The reaction with the more polar solvent 1,4- a bathochromic shift of absorption and emission
dioxane led to an impressive increase of the yield to bands compared to their alkynyl analogues is ob-
95%. Variation of the employed phosphine ligand or served. This well-known effect is caused by the small-
modification of the base gave no further improvement er p-orbital overlap for sp- and sp2-hybridized carbon
(Scheme 3).
atoms of the alkynyl moieties as compared to the all
With the optimized conditions in hand, we exam- sp2-hybridized carbon atoms in the alkenyl moieties.
ined the scope of the reaction. The Suzuki–Miyaura In addition, the absorption and fluorescence spectra
reaction of styrylboronic acids or their pinacol esters of pyridines 2a and 5a also show a bathochromic shift
with 1 or 3 afforded the tetra
ACHTUNGERTN(NUNG alkenyl)pyridines 5a– as compared to their corresponding benzene ana-
e and tetra(alkenyl)benzenes 5g, i, k, l in good to ex- logues 4a and 5g, respectively. In all cases, the donor
ACHTUNGTRENNUNG
cellent yields (Scheme 4, Table 4). The success of the substituents OCH3 or CH3 lead to a bathochromic
reaction proved to be highly dependent on the solu- shift of the absorption and emission spectra, while
Scheme 3. Optimization of the synthesis of 5a; i: PdACHTNUTRGNEUNG(dba)2, ligand, base, solvent, 1008C, 20 h.
Scheme 4. Synthesis of 5a–l; i: Pd
col ester, 1008C, 20 h.
ACHTUGNTREN(NUNG dba)2 (5 mol%), cataXCium A (10 mol%), K3PO4, 1,4-dioxane, styrylboronic acid or -pina-
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Table 4. Synthesis of 5a–l.
5
Nucleophile
Product
Yield [%][a]
a
95
b
c
99
99
87
99
d
e
f
0
g
91
h
i
0
99
0
j
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Tetraalkynylated and Tetraalkenylated Benzenes and Pyridines
Table 4. (Continued)
5
Nucleophile
Product
Yield [%][a]
k
89
l
63
[a]
Isolated yields.
Table 5. UV/Vis absorption and fluorescence data of com- lar as chromophores for the blue and near UV region.
pounds 2, 4 and 5 in dichloromethane. For the measure-
ments of the fluorescence quantum yields a solution of qui-
nine bisulfate in 0.05M H2SO4 (ff =0.52)[23] or anthracene in
ethanol (ff =0.27)[24] was applied as standard.
All alkenyl compounds reveal a larger Stokes shift ac-
companied by a slight decrease of the fluorescence
quantum yields than the alkynyl compounds. None-
theless, considering the magnitude of the Stokes shift
and quantum yields as well as the shape of the fluo-
rescence bands, the intramolecular charge transfer
(ICT) is for all investigated compounds rather small.
It decreases for the alkynyl compared to the alkenyl
derivatives. Even though a bathochromic shift is ob-
served for donor substituents, the Stokes shift is
rather unaffected indicating that the impact on ICT in
ground and excited state is similar. Very good fluores-
cence quantum yields were observed, especially for
the pyridine derivatives.
fluo
max
[nm]
˜
nStokes
Compd labs [nm]
([104 MÀ1 cmÀ1)
l
ffluo quantum
yield
[cmÀ1]
317 (10.0)
353 (5.7)
370 (5.8)
340 (10.9)
387 (6.8)
317 (11.4)
354 (6.6)
373 (6.6)
317 (12.6)
347 (4.5)
331 (13.3)
367 (5.5)
315 (4.9)
345 (2.1)
330
368
351
382
327
369
337
375
335
1520
392
0.42 (Æ0.06)
2a
2b
1570
1300
412
392
0.45 (Æ0.07)
0.43 (Æ0.06)
2d
4a
4b
4d
5a
5b
5c
5e
5g
5i
3050
2620
3150
5440
5350
5220
5300
4980
4750
5200
388
406
387
460
480
457
468
446
446
452
0.45 (Æ0.07)
0.50 (Æ0.07)
0.39 (Æ0.06)
0.33 (Æ0.05)
0.33 (Æ0.05)
0.28 (Æ0.04)
0.35 (Æ0.05)
0.26 (Æ0.04)
0.24 (Æ0.04)
0.31 (Æ0.05)
Conclusions
We have developed an efficient, convenient and high
yielding procedure for the synthesis of tetra-
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
sponding benzene analogues were prepared by palla-
dium-catalyzed cross-coupling reactions in one-pot
procedures from chlorinated substrates in good to ex-
cellent yields. The success of the alkenylation reaction
depends highly on the solubility of the formed inter-
mediates during the reaction. In addition, photophysi-
cal properties of selected compounds were investigat-
ed and compared to each other. For all studied com-
pounds, the ICT has to be considered to be rather
small, but increases for the alkenyl derivatives com-
pared to the alkynyl derivatives. The impact of the
donor and acceptor functional groups was rather
sh 365
335
sh 368
339
5k
sh 366
substitution with the acceptor groups F and CF3 re- small with exception of the OCH3 donor group result-
sults in an only marginal hypsochromic shift com- ing in a bathochromic shift for absorption and fluores-
pared to the unsubstituted phenyl derivatives. The cence spectra. The alkynyl derivatives show higher
fluorescence quantum yields are quite high indicating daylight stability than the alkenyl derivatives. The
that the synthesized compounds are promising build- fluorescence quantum yields are quite high indicating
ing blocks for optoelectronic applications, in particu-
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that the synthesized compounds are promising build- Synthesis of 1,2,4,5-Tetra
ACHTUNGRETN(NUNG alkynyl)benzenes 4a–g
ing blocks for optoelectronic applications.
0.02 mmol (5 mol%) of PdCl2ACHTNUTRGNE(UNG CH3CN)2, 0.04 mmol
(10 mol%) of X-Phos, 0.02 mmol (5 mol%) of CuI and
0.4 mmol of 1,2,4,5-tetrachlorobenzene 3 were added to an
argon-flushed glass pressure tube. The solids were dissolved
with 4.0 mL of dry 1,4-dioxane and 2 mL of diisopropyla-
mine. The solution was stirred at ambient temperature for
ten minutes and afterwards the appropriate acetylene
(3.2 mmol; 8 equiv) was added. The pressure tube was
closed with a teflon cap and the reaction mixture was stirred
at 1008C. After 20 h, the reaction mixture was cooled to
room temperature and diluted with distilled water and di-
chloromethane. The aqueous layer was extracted with di-
chloromethane (three times). The combined organic layers
were dried with sodium sulphate, filtered and the solvent
was evaporated under reduced pressure. Column chroma-
tography (eluents: hexane/dichloromethane) was used to
purify compounds 4a–g.
Experimental Section
General
All reactions were carried out under an argon atmosphere.
Unless otherwise cited, all chemicals are commercially avail-
able and were used without further purification. Column
chromatography was performed using Merck silica gel 60
(0.043–0.06 mm). NMR data were recorded on Bruker ARX
300 and Bruker ARX 400 spectrometers. 13C and H NMR
1
spectra were referenced to signals of deutero solvents and
residual protonated solvents, respectively. Peak characteriza-
tion: s=singlet, d=doublet, t=triplet, m=multiplet, dd=
doublet of doublet, q=quartet. Infrared spectra were re-
corded on a Nicolet 550 FT-IR spectrometer with ATR sam-
pling technique for solids as well as liquids. Signal character-
ization: w=weak, m=medium, s=strong. Gas chromatog-
raphy-mass analysis was carried out on an Agilent HP-5890
instrument with an Agilent HP-5973 Mass Selective Detec-
tor (EI) and HP-5 capillary column using helium carrier gas.
ESI HR-MS measurements were performed on an Agilent
1969A TOF mass-spectrometer. For high resolution MS
(HR-MS) was a Finnigan MAT 95 XP used. Only the meas-
urements with an average deviation from the theoretical
mass of Æ2 mDa were accounted as correct. The absorption
spectra were measured on an Analytik Jena Specord 50 with
a concentration 5ꢃ10À6 M in dichloromethane. Quantitative
absorption spectra were recorded on a Perkin–Elmer UV/
VIS spectrometer Lambda2 with a 5ꢃ10À6 M solution in di-
chloromethane. The fluorescence spectra were recorded
with a Fluoromax-4 Spectrofluorometer (Horiba Scientific).
A solution of quinine sulphate in 0.05M sulphuric acid was
applied as standard for the measurement of the fluorescence
quantum yields (ff =0.52).[22] Sample and standard were ex-
cited with an absorbance of ~0.1. Elemental analysis (EA)
was performed with a Leco Mikroanalysator – TrueSpec
CHNS Micro. Melting points were determined on a Micro-
Hot-Stage GalenTM III Cambridge Instruments. The melt-
ing points are not corrected.
Synthesis of 2,3,5,6-TetraACTHNUGRTNEUNG(styryl)pyridines 5a–e
0.015 mmol (5 mol%) of PdACTHNUTRGNE(UNG dba)2, 0.03 mmol (10 mol%) of
cataXCium A, 0.3 mmol of 2,3,5,6-tetrachloropyridine 1,
2.25 mmol (7.5 equiv.) of alkenylboronic acid or pinacol
ester, and 2.1 mmol (7 equiv.) of potassium phosphate were
added to an argon-flushed glass pressure tube. The solids
were dissolved with 4.0 mL of dry 1,4-dioxane. The pressure
tube was closed with a teflon cap and the reaction mixture
was stirred at 1008C. After 20 h, the reaction mixture was
cooled to room temperature and diluted with distilled water
and dichloromethane. The aqueous layer was extracted with
dichloromethane (three times). The combined organic layers
were dried with sodium sulphate, filtered and the solvent
was evaporated under reduced pressure. Column chroma-
tography (eluents: hexane/dichloromethane) was used to
purify compounds 5a–e.
Synthesis of 1,2,3,4-TetraACTHNUGTRNEUNG(styryl)benzenes 5g–l
0.015 mmol (5 mol%) of PdACTHNUTRGNE(UNG dba)2, 0.03 mmol (10 mol%) of
cataXCium A, 0.3 mmol of 1,2,4,5-tetrachlorobenzene 3,
2.55 mmol (8.5 equiv.) of alkenylboronic acid or pinacol
ester, and 2.4 mmol (8 equiv.) of potassium phosphate were
added to an argon-flushed glass pressure tube. The solids
were dissolved with 5.0 mL of dry 1,4-dioxane. The pressure
tube was closed with a teflon cap and the reaction mixture
was stirred at 1008C. After 20 h, the reaction mixture was
cooled to room temperature and diluted with distilled water
and dichloromethane. The aqueous layer was extracted with
dichloromethane (three times). The combined organic layers
were dried with sodium sulphate, filtered and the solvent
was evaporated under reduced pressure. Column chroma-
tography (eluents: hexane/dichloromethane) was used to
purify compounds 5g–l.
Synthesis of 2,3,5,6-TetraACTHNUGRTNEUNG(alkynyl)pyridines 2a–i
0.01 mmol (4 mol%) of PdCl2ACHTNUTRGNE(UNG CH3CN)2, 0.02 mmol
(8 mol%) of X-Phos, 0.0075 mmol (3 mol%) of CuI and
0.25 mmol of 2,3,5,6-tetrachloropyridine 1 were added to an
argon-flushed glass pressure tube. The solids were dissolved
with 3.5 mL of dry 1,4-dioxane and 1 mL of diisopropyl-
ACHTUNGTRENNUNGamine. The solution was stirred at ambient temperature for
ten minutes and afterwards the appropriate acetylene was
added. The pressure tube was closed with a teflon cap and
the reaction mixture was stirred at 908C. After 20 h, the re-
action mixture was cooled to room temperature and diluted
with distilled water and dichloromethane. The aqueous layer
was extracted with dichloromethane (three times). The com-
bined organic layers were dried with sodium sulphate, fil-
tered and the solvent was evaporated under reduced pres-
sure. Column chromatography (eluents: hexane/dichlorome-
thane) was used to purify compounds 2a–i.
2,3,5,6-Tetrakis(phenylethynyl)pyridine (2a): According to
the general procedure compound 2a was isolated as a yellow
solid; yield: 115 mg (96%); mp 167–1708C. 1H NMR
(300 MHz, CDCl3): d=7.24–7.34 (m, 12H, CH), 7.47–7.59
(m, 8H, CH), 7.91 (s, 1H, CH); 13C NMR (75 MHz, CDCl3):
ꢀ
d=85.4, 87.6, 95.2, 97.7 (C C), 121.5, 122.1, 122.4 (CAr/Hetar),
128.4, 128.5, 129.2, 129.4, 131.7, 132.2 (CH), 141.1 (CHPyr
)
143.5 (CHetar); IR (ATR): n=3053 (w), 2925 (w), 2204 (w),
6
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Tetraalkynylated and Tetraalkenylated Benzenes and Pyridines
1744 (w), 1490 (m), 1413 (m), 1260 (w), 1066 (w), 908 (m),
745 (s), 680 (s), 528 cmÀ1 (s); MS (EI, 70 eV): m/z (%)=479
(M+, 100), 450 (4), 401 (7), 350 (3), 238 (18), 226 (20); HR-
MS (ESI): m/z=480.17455, calcd. for [M+H]+ C37H22N:
480.17468.
2,3,5,6-Tetrakis-[(4-methoxyphenyl)ethynyl]pyridine (2b):
According to the general procedure compound 2b was iso-
lated as a yellow solid; yield: 277 mg (93%); mp 202–2048C.
1H NMR (300 MHz, CDCl3): d=3.73, 3.75 (s, 12H, OMe),
6.76–6.83 (m, 8H, CH), 7.39–7.51 (m, 8H, CH), 7.82 (s, 1H,
CHPyr); 13C NMR (75 MHz, CDCl3): d=55.3 (OMe), 77.2,
171–1738C. 1H NMR (300 MHz, CDCl3): d=0.86 (t, 12H,
3
3J=7.3 Hz, CH3), 1.30 (sext, 8H, J=7.3 Hz, CH2), 1.54–1.65
3
(m, 8H, CH2), 2.81 (t, 4H, J=7.4 Hz, CH2), 2.82 (t, 4H,
3
3J=7.3 Hz. CH2), 7.44 (d, 4H, J=8.7 Hz, CH), 7.50 (d, 4H,
3J=8.6 Hz, CH), 7.7–7.80 (m, 8H, CH); 13C NMR (75 MHz,
CDCl3): d=13.8 (CH3), 22.3 (CH2), 26.1 (CH2), 38.3 (CH2),
ꢀ
87.7, 89.8, 94.2, 97.2 (C C), 121.4 (CPyr), 126.0, 126.3 (CAr),
127.9, 128.0, 131.7, 132.1 (CH), 136.8, 137.0 (CAr), 141.2
(CHPyr), 143.3 (CPyr), 199.1, 199.1 (C=O); IR (ATR): n=
2953 (m), 2930 (m), 2867 (m), 2204 (w), 1682 (s), 1598 (s),
1554 (w), 1413 (s), 1343 (m), 1251 (m), 1202 (s), 1109 (m),
969 (m), 853 cmÀ1 (m); MS (EI, 70 eV): m/z (%)=815 (M+,
3), 457 (33), 289 (5), 207 (12), 169 (22), 154 (31); HR-MS
(ESI): m/z=816.40363, calcd. for [M+H]+ C57H54N1O4:
816.40474; anal. calcd. for C57H53NO4 (816.04): C 83.89, H
6.55, N 1.72; found: C 83.79, H 6.428, N 1.827.
ꢀ
84.5, 86.7, 97.7 (C C), 114.1, 114.2 (CH), 114.6, 121.2,
(CAr/Hetar), 133.3, 133.9 (CH), 140.8 (CHPyr), 142.9 (CHetar),
160.3, 160.5 (CAr); IR (ATR): n=2932 (w), 2835 (w), 2200
(m), 1602 (m), 1508 (s), 1292 (m), 1245 (s), 1024 (m), 923
(w), 826 (s), 532 (s). MS (EI, 70 eV): m/z (%)=599 (M+,
100), 584 (4), 426 (1), 329 (4), 300 (4), 213 cmÀ1 (2); HR-MS
(EI, 70 eV): m/z=599.20907, calcd. for C41H29NO4:
599.20911.
2,3,5,6-Tetrakis[(4-pentylphenyl)ethynyl]pyridine
(2g):
According to the general procedure compound 2g was iso-
lated as a brown solid; yield: 323 mg (85%); mp 99–1008C.
1H NMR (300 MHz, CDCl3): d=0.82 (t, 12H, 3J=6.3 Hz,
CH3), 1.16–1.30 (m, 16H, CH2), 1.49–1.60 (m, 8H, CH2),
2,3,5,6-Tetrakis((4-tert-butylphenyl)ethynyl)pyridine (2c):
According to the general procedure compound 2c was iso-
lated as an orange solid; yield: 271 mg (77%); mp 276–
3
2.51–2.57 (m, 8H, CH2), 7.08 (d, 4H, J=8.1 Hz, CH), 7.10
1
3
3
2788C. H NMR (300 MHz, CDCl3): d=1.25, 1.26 (s, 36H,
(d, 4H, J=8.1 Hz, CH), 7.41 (d, 4H, J=8.1 Hz, CH), 7.47
(d, 4H, 3J=8.1 Hz, CH); 13C NMR (75 MHz, CDCl3): d=
14.0 (CH3), 22.5, 30.8, 30.8, 31.4, 35.9, 36.0 (CH2), 85.1, 87.4,
CH3), 7.28–7.33 (m, 8H, CH), 7.43–7.51 (m, 8H, CH), 7.88
(s, 1H, CH); 13C NMR (75 MHz, CDCl3): d=31.1 (CH3),
ꢀ
ꢀ
34.9 (Ct-Bu), 85.1, 87.3, 95.3, 97.7 (C C), 119.2, 119.5, 121.4
95.3, 97.8 (C C), 119.4, 119.7, 121.4 (CAr/HetAr), 128.5, 128.6,
(CAr/Hetar), 125.4, 125.5, 131.5, 132.0 (CH), 141.1 (CHPyr),
143.4, 152.5, 152.7 (CAr/Hetar); IR (ATR): n=2957 (m), 2903
(w), 2865 (w), 2204 (m), 1604 (w), 1504 (m), 1416 (m), 1362
(m), 1266 (m), 1104 (m), 1016 (w), 829 cmÀ1 (s); MS (EI,
70 eV): m/z (%)=703 (M+, 100), 688 (13), 632 (5), 616 (4),
560 (3), 337 (7), 119 (2); HR-MS (ESI): m/z=704.42574,
calcd. for [M+H]+ C53H54N: 704.42508.
131.7, 132.2 (CH), 140.8 (CHPyr), 143.5, 144.4, 144.6
(CAr/Hetar). IR (ATR): n=2955 (m), 2926 (s), 2854 (s), 2207
(m), 1908 (w), 1605 (w), 1510 (s), 1465 (m), 1414 (s), 1263
(w), 1223 (w), 1158 (m), 1115 (m), 1018 (m), 911 (s), 827 (s),
729 cmÀ1 (s); MS (EI, 70 eV): m/z (%)=759 (M+, 100), 702
(3), 646 (12), 546 (3), 380 (4), 267 (6); HR-MS (ESI): m/z=
760.48643, calcd. for [M+H]+ C57H62N: 760.48768.
2,3,5,6-Tetrakis-[(4-fluorophenyl)ethynyl]pyridine
(2d):
2,3,5,6-Tetrakis[(triisopropylsilyl)ethynyl]pyridine
(2h):
According to the general procedure compound 2d was iso-
lated as a yellow solid; yield: 178 mg (65%); mp 2708C.
1H NMR (300 MHz, CDCl3): d=7.04–7.12 (m, 8H, CH),
7.53–7.62 (m, 8H, CH); 13C NMR (75 MHz, CDCl3): due to
the low solubility measurement of a 13C NMR-experiment
was impossible; IR (ATR): n=3060 (w), 2225 (w), 2209 (m),
1600 (m), 1505 (s), 11416 (m), 1219 (s), 1152 (s), 1016 (w),
909 (w), 828 (s), 767 (m), 526 cmÀ1 (s); MS (EI, 70 eV): m/z
(%)=551 (M+, 100), 530 (3), 455 (3), 404 (2), 276 (5), 262
(13); HR-MS (ESI): m/z=552.13752, calcd. for [M+H]+
C37H18F4N: 552.13699; anal. calcd. for C37H17F4N (551.53): C
80.57, H 3.11, N 2.54; found: C 79.92, H 2.982, N 2.753.
2,3,5,6-Tetrakis-(p-tolylethynyl)pyridine (2e): According
to the general procedure compound 2e was isolated as an
orange solid; yield: 183 mg (69%); mp 2798C. 1H NMR
(300 MHz, CDCl3): d=2.28, 2.29 (s, 12H, CH3), 7.06–7.10
(m, 8H, CH), 7.36–7.46 (m, 8H, CH), 7.85 (s, 1H, CHPyr);
13C NMR (75 MHz, CDCl3): d=21.6, 21.6 (CH3), 85.0, 87.3,
According to the general procedure compound 2h was iso-
lated as a yellowish solid; yield: 337 mg (85%); mp 2378C.
1H NMR (300 MHz, CDCl3): d=1.00–1.07 (m, 84H, CH,
CH3), 7.63 (s, 1H, CH); 13C NMR (75 MHz, CDCl3): d=
11.3, 11.4 (CH), 18.7, 18.7 (CH3), 97.6, 100.5, 102.3, 104.2
(C< =3>C), 121.0 (CPyr), 142.7 (CH), 144.8 (CPyr); IR
(ATR): n=2942 (s), 2890 (m), 2864 (s), 2148 (w), 1461 (m),
1404 (s), 1226 (w), 1175 (w), 11072 (w), 996 (m), 919 (m),
880 (s), 773 (m), 676 (s), 659 cmÀ1 (s); MS (EI, 70 eV): m/z
(%)=800 (M+, 11), 756 (79), 714 (100), 686 (4), 672 (3), 630
(2); HR-MS (ESI): m/z=800.58267, calcd. for [M+H]+
C49H86NSi4: 800.58318.
2,3,5,6-Tetrakis(hex-1-ynyl)pyridine (2i): According to the
general procedure compound 2i was isolated as a brown oil;
1
yield: 122 mg (62%). H NMR (300 MHz, CDCl3): d=0.82
(t, 6H, 3J=7.0 Hz, CH3), 0.84 (t, 6H, 3J=7.2 Hz, CH3),
3
1.33–1.55 (m, 16H, CH2), 3.35 (t, 4H, J=6.8 Hz, CH2), 2.36
(t, 4H, 3J=6.9 Hz, CH2), 7.51 (s, 1H, CH); 13C NMR
(75 MHz, CDCl3): d=13.6 (CH3), 19.3, 19.4, 21.9, 22.0, 30.3,
ꢀ
95.4, 97.8 (C C), 119.1, 119.4, 121.4 (CAr/HetAr), 129.2, 129.3,
ꢀ
131.6, 132.1 (CH), 139.4, 139.7 (CAr/HetAr), 140.9 (CHPyr); IR
(ATR): n=2199 (w), 1508 (w), 1409 (w), 1040 (s), 969 (w),
806 (m), 527 (m), 441 (s). MS (EI, 70 eV): m/z (%)=535
(M+, 100), 520 (4), 504 (8), 489 (1), 268 (2), 252 cmÀ1 (4);
HR-MS (ESI): m/z=536.23679, calcd. for [M+H]+
C41H30N: 536.23728.
30.5 (CH2), 76.9, 79.2, 96.0, 98.1 (C C), 121.2 (CPyr), 141.6
(CH), 143.2 (CPyr); IR (ATR): n=2956 (m), 2930 (m), 2870
(m), 2229 (m), 1498 (w), 1416 (s), 1322 (w), 1200 (w), 1105
(s), 915 (m), 774 cmÀ1 (m); MS (EI, 70 eV): m/z (%)=399
(M+, 100), 370 (24), 356 (48), 342 (23), 328 (18), 315 (11),
284 (9); HR-MS (EI, 70 eV): m/z=399.29209, calcd. for
C29H37N: 399.29205.
2,3,5,6-Tetrakis(4-(pentan-1-one)phenylethynyl)pyridine
(2f): According to the general procedure compound 2f was
isolated as a yellow-brown solid; yield: 209 mg (52%); mp
1,2,4,5-Tetrakis(phenylethynyl)benzene (4a): According to
the general procedure compound 4a was isolated as an
Adv. Synth. Catal. 0000, 000, 0 – 0
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
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Peter Ehlers et al.
FULL PAPERS
orange solid; yield: 196 mg (82%); mp 194–1968C (report-
ed: 193–194). The synthesis of 4a has been previously re-
ported.[24] 1H NMR (300 MHz, CDCl3): d=7.35–7.40 (m,
as a yellow solid; yield: 186 mg (74%); mp 156–1578C.
1H NMR (300 MHz, CDCl3): d=0.69 (q, 24H, 3J=7.9 Hz,
CH2), 1.06 (t, 36H, 3J=7.9 Hz, CH3), 7.55 (s, 2H, CH);
13C NMR (75 MHz, CDCl3): d=4.3 (CH2), 7.6 (CH3), 98.2,
12H, CH), 7.56–7.61 (m, 8H, CH), 7.78 (s, 2H, CH);
13
ꢀ
ꢀ
C NMR (75 MHz, CDCl3): d=87.5, 95.5 (C C), 123.0,
103.3 (C C), 125.2 (CH), 137.0 (C); IR (ATR): n=2954
125.3 (CAr), 128.4, 128.7, 131.7, 134.9 (CH); IR (ATR): n=
3047 (w), 2201 (w), 1594 (w), 1492 (m), 1440 (m), 1257 (w),
1068 (w), 889 (m), 752 (s), 686 (s), 526 cmÀ1 (m); MS (EI,
70 eV): m/z (%)=478 (M+, 100), 474 (14), 448 (2), 400 (8),
299 (7), 237 (22), 225 (4); HR-MS (EI, 70 eV): m/z=
478.17259, calcd. for C38H22: 478.17160.
(m), 2910 (m), 2874 (m), 2160 (w), 1477 (m), 1375 (w), 1234
(w), 1183 (m), 1005 (m), 865 (s), 777 (s), 713 cmÀ1 (s); MS
(EI, 70 eV): m/z (%)=630 (M+, 100), 573 (28), 517 (5), 489
(6), 461 (4), 373 (4), 345 (5); HR-MS (EI, 70 eV): m/z=
630.39227, calcd. for C38H62Si4: 630.39231.
1,2,4,5-Tetrakis[(4-pentylphenyl)ethynyl]benzene
(4g):
1,2,4,5-Tetrakis(4-methoxyphenylethynyl)benzene
(4b):
According to the general procedure compound 4g was iso-
lated as a red-brown, viscous oil; yield: 333 mg (99%).
1H NMR (300 MHz, CDCl3): d=0.94 (t, 12H, 3J=6.8 Hz,
CH3), 1.30–1.44 (m, 16H, CH2), 1.61–1.71 (m, 8H, CH2),
According to the general procedure compound 4b was iso-
lated as a yellow solid; yield: 298 mg (99%); mp 242–2438C.
1H NMR (300 MHz, CDCl3): d=3.84 (s, 12H, OCH3), 6.89
3
3
3
3
(d, 8H, J=9.0 Hz. CH), 7.51 (d, 8H, J=9.0 Hz, CH), 7.70
2.66 (t, 8H, J=6.8 Hz, CH2), 7.20 (d, 8H, J=8.0 Hz. CH),
(s, 2H, CH); 13C NMR (75 MHz, CDCl3): d=55.3 (OCH3),
7.53 (d, 8H, J=8.1 Hz, CH), 7.76 (s, 2H, CH); 13C NMR
3
ꢀ
86.6, 95.2 (C C), 114.1 (CH), 115.2, 125.1 (C), 133.2, 134.4
(75 MHz, CDCl3): d=14.0 (CH3), 22.4 (CH2), 30.9 (CH2),
ꢀ
(CH), 159.9 (CAr); IR (ATR): n=2961 (w), 2203 (w), 1601
(m), 1567 (w), 1509 (s), 1439 (m), 1289 (m), 1244 (s), 1172
(s), 1024 (s), 898 (m), 828 (s), 532 cmÀ1 (s); MS (EI, 70 eV):
m/z (%)=598 (M+, 100), 583 (10), 568 (2), 437 (2), 424 (4),
299 (33); HR-MS (EI, 70 eV): m/z=598.21565, calcd. for
C42H30O4: 598.21386.
31.5 (CH2), 35.9 (CH2), 87.2, 95.6 (C C), 120.2, 125.2 (C),
128.5, 131.7, 134.7 (CH), 143.9 (CAr); IR (ATR): n=3024
(w), 2955 (m), 2925 (s), 2854 (s), 2201 (w), 1689 (w), 1606
(w), 1510 (s), 1464 (m), 1264 (w), 1114 (w), 1019 (w), 895
(m), 825 cmÀ1 (s); MS (EI, 70 eV): m/z (%)=758 (M+, 100),
701 (5), 645 (14), 516 (7), 266 (11), 129 (13); HR-MS (EI,
70 eV): m/z=758.48409, calcd. for C58H62: 758.48460.
1,2,4,5-Tetrakis(4-tert-phenylethynyl)benzene (4c): Ac-
cording to the general procedure compound 4c was isolated
as a yellow solid; yield: 244 mg (70%); mp 2868C. H NMR
2,3,5,6-Tetrastyrylpyridine (5a): According to the general
procedure compound 5a was isolated as a yellow solid; yild:
1
3
1
(300 MHz, CDCl3): d=1.36 (s, 36H, CH3), 7.40 (d, 8H, J=
139 mg (95%); mp 250–2518C. H NMR (300 MHz, CDCl3):
8.7 Hz. CH), 7.53 (d, 8H, 3J=8.7 Hz, CH), 7.76 (s, 2H,
d=7.12 (d, 2H, J=16.2 Hz, CH), 7.31–7.44 (m, 13H, CH),
3
CH); 13C NMR (75 MHz, CDCl3): d=31.2 (CH3), 34.9 (C)
7.51 (d, 3H, J=16.2 Hz, CH), 7.60 (d, 4H, J=7.4 Hz, CH),
3
3
3
3
ꢀ
87.1, 95.5 (C C), 120.1, 125.2 (C), 125.4, 131.5, 134.9 (CH),
7.67 (d, 4H, J=7.4 Hz, CH), 7.97 (d, 2H, J=15.4 Hz, CH),
8.03 (s, 1H, CH); 13C NMR (75 MHz, CDCl3): due to the
low solibility of this compound we were unable to obtain
a suitable 13C NMR spectrum; IR (ATR): n=3023 (w), 1626
(w), 1594 (w), 11573 (w), 1491 (m), 1447 (m), 1411 (m),
1329 (w), 1193 (w), 1072 (w), 953 (s), 864 (w), 747 (s),
689 cmÀ1 (s); MS (EI, 70 eV): m/z (%)=487 (M+, 100), 410
(91), 396 (21), 384 (20), 319 (15), 306 (6); HR-MS (ESI):
m/z=488.23692, calcd. for [M+H]+ C37H30N: 488.23728.
2,3,5,6-Tetrakis(4-methoxystyryl)pyridine (5b): According
to the general procedure compound 5b was isolated as
151.1 (CAr); IR (ATR): n=2948 (m), 2902 (w), 2865 (w),
2203 (w), 1518 (m), 1364 (w), 1264 (m), 1103 (m), 895 (m),
827 (s), 736 (w), 557 cmÀ1 (s); MS (EI, 70 eV): m/z (%)=
702 (M+, 100), 687 (8), 615 (2), 351 (2), 336 (10), 221 (3);
HR-MS (EI, 70 eV): m/z=702.42088, calcd. for C54H54
702.42200.
1,2,4,5-Tetrakis[(4-fluorophenyl)ethynyl]benzene
(4d):
According to the general procedure compound 2h was iso-
lated as a brown solid; yield: 118 mg (72%); mp 1968C.
Due to the low solubility of this compound we were unable
to obtain NMR spectra; IR (ATR): n=2921 (m), 2851 (m),
2209 (w), 1891 (w), 1599 (m), 1505 (s), 1217 (s), 1153 (s),
1092 (m), 1012 (w), 892 (w), 811 cmÀ1 (s); MS (EI, 70 eV):
m/z (%)=550 (M+, 100), 528 (3), 454 (4), 409 (4), 275 (8),
264 (5); HR-MS (EI, 70 eV): m/z=550.13390, calcd. for
C38H18F4: 550.13391.
a
yellow solid; yield: 188 mg (99%); mp 196–1988C.
1H NMR (300 MHz, CDCl3): d=3.86 (s, 6H, OCH3), 3.86 (s,
3
3
6H, OCH3), 6.93 (d, 8H, J=8.9 Hz, CH), 6.98 (d, 2H, J=
3
15.5 Hz, CH), 7.29 (d, 2H, J=15.4 Hz, CH), 7.35 (d, 2H,
3J=15.5 Hz, CH), 7.49 (d, 4H, J=8.9 Hz, CH), 7.57 (d, 4H,
3
3J=8.9 Hz, CH), 7.86 (s, 1H, CH), 7.87 (d, 2H, J=15.4 Hz,
3
1,2,4,5-Tetrakis(m-tolylethynyl)benzene (4e): According
to the general procedure compound 4e was isolated as an
orange solid; yield: 180 mg (85%); mp 157–1598C. H NMR
(300 MHz, CDCl3): d=2.34 (s, 12H, CH3), 7.17–7.19 (m,
4H, CH), 7.26 (m, 4H, CH), 7.39–7.43 (m, 8H, CH), 7.74 (s,
2H, CH); 13C NMR (75 MHz, CDCl3): d=21.2 (CH3), 87.4,
CH); 13C NMR (75 MHz, CDCl3): d=55.3, 55.3 (OCH3),
114.0, 114.1, 122.1, 122.2, 127.9, 128.6 (CH), 129.6, 130.1,
130.1 (C), 131.0 (CHPyr), 131.0, 133.5 (CH), 150.5, 159.5,
159.7 (C); IR (ATR): n=2996 (w), 2930 (w), 2833 (w), 1602
(m), 1509 (s), 1421 (m), 1285 (m), 1247 (s), 1171 (s), 1024
(m), 949 (m), 801 cmÀ1 (m); MS (EI, 70 eV): m/z (%)=607
(M+, 100), 500 (67), 486 (13), 475 (40), 368 (30), 354 (9);
HR-MS (EI, 70 eV): m/z=607.271109, calcd. for
C41H37N1O4: 607.27171.
2,3,5,6-Tetrakis(4-trifluoromethylstyryl)pyridine (5c): Ac-
cording to the general procedure compound 5c was isolated
as a yellow solid; yield: 225 mg (99%); mp 291–2928C.
1H NMR (300 MHz, CDCl3): d=7.16 (d, 2H, 3J=16.1 Hz,
CH), 7.58 (d, 2H, 3J=15.5 Hz, CH), 7.59 (d, 2H, 3J=
15.5 Hz, CH), 7.66 (d, 4H, 3J=8.5 Hz, CH), 7.69 (s, 8H,
1
ꢀ
95.7 (C C), 122.8, 125.4 (CAr), 128.3, 128.8, 129.6, 132.2,
134.6 (CH), 138.1 (CAr); IR (ATR): n=3030 (w), 2918 m
(w), 2850 (w), 1599 (w), 1495 (m), 1451 (w), 1261 (w), 1036
(w), 896 (m), 782 (s), 684 cmÀ1 (s); MS (EI, 70 eV): m/z
(%)=534 (M+, 100), 517 (2), 503 (2), 454 (3), 427 (2), 329
(2), 267 (4); HR-MS (EI, 70 eV): m/z=534.23430, calcd. for
C42H30: 534.23420.
1,2,4,5-Tetrakis[(triethylsilyl)ethynyl]benzene (4f): Ac-
cording to the general procedure compound 4f was isolated
8
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Adv. Synth. Catal. 0000, 000, 0 – 0
ÝÝ
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Tetraalkynylated and Tetraalkenylated Benzenes and Pyridines
3
3
3
3
CH), 7.76 (d, 4H, J=8.5 Hz, CH), 8.00 (d, 2H, J=15.8 Hz,
CH), 8.06 (s, 1H, CHPyr); due to the low solubility, no
13C NMR spectrum could be obtained; IR (ATR): n=1612
(w), 1426 (w), 1324 (s), 1163 (m), 1106 (s), 1066 (s), 949 (m),
814 (m), 744 cmÀ1 (w); MS (EI, 70 eV): m/z (%)=759 (M+,
100), 740 (8), 614 (70), 600 (13), 588 (15), 455 (9); HR-MS
(EI, 70 eV): m/z=759.178068, calcd. for C41H25F12N:
759.17899.
4H, J=16.1 Hz, CH), 7.20 (d, 8H, J=7.8 Hz, CH), 7.44 (d,
3 3
4H, J=15.9 Hz, CH), 7.46 (d, 8H, J=7.8 Hz, CH), 7.79 (s,
2H, CH); 13C NMR (75 MHz, CDCl3): d=21.3, (CH3),
124.6, 125.4, 126.6, 129.5, 131.1 (CH), 134.8, 135.4, 137.7
(C); IR (ATR): n=2921 (w), 2849 (w), 1685 (w), 1625 (w),
1460 (w), 1377 (w), 1299 (w), 1151 (w), 1080 (w), 955 (m),
769 (s), 623 cmÀ1 (m); MS (EI, 70 eV): m/z (%)=542 (M+,
100), 437 (79), 345 (17), 332 (47), 319 (5), 195 (47); HR-MS
(EI, 70 eV): m/z=542.29652, calcd. for C42H38: 542.29680.
1,2,4,5-Tetrakis(2-thiophenstyryl)benzene (5l): According
to the general procedure compound 5l was isolated as
a brown solid; yild: 96 mg (63%); decomposition at ~2908C.
1H NMR (300 MHz, CDCl3): d=7.09 (d, 4H, 3J=16.1 Hz,
CH), 7.29–7.40 (m, 16H, CH), 7.71 (s, 2H, CHAr); 13C NMR
(75 MHz, CDCl3): d=122.7 (CH), 124.4 (CHAr), 125.0,
125.3, 126.1, 126.3 (CH), 135.1, 140.3 (C); IR (ATR): n=
2956 (m), 2917 (m), 2849 (m), 1726 (w), 1603 (w), 1511 (w),
1460 (w), 1260 (m), 1090 (m), 1018 (m), 957 (m), 798 (s),
520 cmÀ1 (m); MS (EI, 70 eV): m/z (%)=510 (M+, 100), 497
(12), 440 (11), 425 (8), 413 (55), 379 (10), 329 (17), 316 (34),
303 (11).
2,3,5,6-Tetrakis(4-fluorostyryl)pyridine (5d): According to
the general procedure compound 5d was isolated as
a yellow solid; yield: 146 mg (88%); mp 236–2388C. Due to
the low solubility of this compound we were unable to
obtain NMR-spectra; IR (ATR): n=3043 (w), 1701 (w),
1598 (m), 1507 (s), 1421 (w), 1225 (s), 1156 (s), 1094 (w),
961 (m), 817 (s), 726 (m), 523 , cmÀ1 (s); MS (EI, 70 eV):
m/z (%)=559 (M+, 100), 464 (87), 450 (15), 438 (12), 355
(12), 342 (6); HR-MS (EI, 70 eV): m/z=559.191142, calcd.
for C37H25N1F4: 559.19176.
2,3,5,6-Tetrakis(4-methylstyryl)pyridine (5e): According
to the general procedure compound 4f was isolated as
a yellow solid; yield: 163 mg (99%); mp 2458C. 1H NMR
3
(300 MHz, CDCl3): d=2.41 (s, 12H, CH3), 7.06 (d, 2H, J=
16.3 Hz, CH), 7.22 (d, 4H, 3J=8.1 Hz, CH), 7.23 (d, 4H,
3J=8.1 Hz, CH), 7.44 (d, 2H, J=16.6 Hz, CH), 7.48 (d, 4H,
3
3J=8.1 Hz, CH), 7.48 (d, 2H, J=15.4 Hz, CH), 7.56 (d, 4H,
3
Acknowledgements
3J=8.1 Hz, CH), 7.93 (d, 2H, J=15.4 Hz, CH), 7.96 (s, 1H,
3
CHPyr); 13C NMR (75 MHz, CDCl3): d=21.3, 21.4 (CH3),
123.2, 123.4, 126.6, 127.3, 129.4, 129.5 (CH), 129.9 (C), 131.5,
131.9, 134.3 (CH), 134.4, 134.5, 138.0, 138.2, 150.8 (C); IR
(ATR): n=2913 (w), 1694 (w), 1621 (w), 1503 (m), 1419
(m), 1306 (w), 1178 (m), 1107 (w), 960 (s), 798 (s), 521 cmÀ1
(s); MS (EI, 70 eV): m/z (%)=543 (M+, 100), 452 (69), 438
(19), 426 (12), 347 (11), 334 (6); HR-MS (EI, 70 eV):
m/z=543.291351, calcd. for C41H37N: 543.29205.
Financial support by the Volkswagenstiftung and by the State
of Mecklenburg-Vorpommern is gratefully acknowledged.
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FULL PAPERS
Tetraalkynylated and Tetraalkenylated Benzenes and
Pyridines: Synthesis and Photophysical Properties
11
Adv. Synth. Catal. 2013, 355, 1 – 11
Peter Ehlers, Ani Hakobyan, Antje Neubauer,
Stefan Lochbrunner, Peter Langer*
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