A green and straightforward synthesis of 4′-substituted terpyridines

Article abstract of DOI:10.1055/s-2006-942525

A set of 4′-substituted 2,2′:6′,2″-terpyridines has been synthesized in a one-pot procedure under environmentally friendly reaction conditions using PEG and aqueous ammonia as solvents. This procedure features a short synthetic route, short reaction times, easy work-up, and good yields in comparison to conventional methods. The crystallographic data reveal the influence of the 4′-aryl substituent on the molecular structure and π-stacking behavior of the respective terpyridines. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2006-942525

PAPER
2873
A Green and Straightforward Synthesis of 4¢-Substituted Terpyridines
S
ynthesis of
4¢-Ary
n
l
Terpyridin
d
es reas Winter,a Antje M. J. van den Berg,a Richard Hoogenboom,a Guido Kickelbick,b Ulrich S. Schubert*a,c
a
Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven,
The Netherlands
b
c
Institute of Materials Chemistry, Vienna University of Technology, Getreidemarkt 9/165, 1060 Vienna, Austria
Center for Nanoscience, LMU Munich, Geschwister-Scholl-Platz 1, 80333 Munich, Germany
Fax +31(40)2474186; E-mail: u.s.schubert@tue.nl
Received 28 March 2006; revised 3 May 2006
der environmentally friendly conditions still remains a
target in modern organic chemistry. Recently, Hanan and
Wang have introduced a straightforward one-step reaction
of 4¢-substituted terpyridines using potassium hydroxide
Abstract: A set of 4¢-substituted 2,2¢:6¢,2¢¢-terpyridines has been
synthesized in a one-pot procedure under environmentally friendly
reaction conditions using PEG and aqueous ammonia as solvents.
This procedure features a short synthetic route, short reaction times,
easy work-up, and good yields in comparison to conventional meth- and concentrated aqueous ammonia.12 The modest yields
ods. The crystallographic data reveal the influence of the 4¢-aryl
substituent on the molecular structure and p-stacking behavior of
the respective terpyridines.
obtained are competitive with those reported in the litera-
ture, but the employment of very strong bases could not be
avoided.
Key words: green chemistry, heterocycles, ligands, multicompo-
As a part of our work on the development of novel metal-
lopolymers we have chosen poly(ethylene glycol) (PEG)
as a versatile solvent for the efficient synthesis of substi-
tuted and functionalized terpyridine units 1.13 Due to its
non-toxicity, PEG has become a popular reaction medium
in synthetic chemistry over the last number of years.14
Furthermore, this solvent fully meets the demands of
green chemistry,15 as it is highly water-miscible and also
potentially recyclable.
nent reactions, terpyridines
Terpyridine units are found to be among the most widely
used building blocks in supramolecular architectures,1
metallopolymers,2 and molecular devices.3 Furthermore,
they display promising properties in respect of pharma-
ceutical applications, such as anticancer or antimicrobial
agents,4 and in asymmetric catalysis.5
As shown in Scheme 1, the formation of substituted terpy-
ridines 1 was carried out in a straightforward one-pot re-
action. The addition of 2-acetylpyridine to a suspension of
crushed sodium hydroxide in PEG-300 at 0 °C generated
the enolate anion. After ten minutes the aromatic aldehyde
was added and the reaction mixture was kept at this tem-
perature for two hours with occasional stirring. Upon for-
mation of the 1,5-dione, the color changed from yellow to
a reddish brown.
Due to their great importance, many synthetic strategies6
have been published since the pioneering work by
Kröhnke7 and Potts.8 However, most of these methodolo-
gies suffer from a number of limitations and drawbacks.
The Kröhnke protocol often results only in moderate to
low yields and involves the extensive use of toxic and ex-
pensive organic solvents, such as pyridine and organoha-
lides. The Stille coupling reaction involving toxic
organostannanes, for example, is unfavorable from an
ecological point of view.9 In most cases the products have
to be purified extensively by column chromatography as a
number of side products, including 1,5-diones and cyclo-
hexanols, are formed.10 The synthesis of terpyridines, par-
tially under solvent-free conditions, is a promising
approach in the context of green chemistry as waste gen-
eration and the formation of side products are widely
avoided.11 Additionally, unsymmetrical derivatives are
easily accessible via a sequential reaction of the starting
materials. On the other hand, the use of harmful sodium
hydroxide and acetic acid as well as the intermediate
work-up procedures represent major drawbacks of this ap-
proach.
The 1,5-dione intermediate was then cyclized without pri-
or isolation by adding concentrated aqueous ammonia in-
stead of ammonium acetate.13 Thus, the excess of
inorganic salts was reduced significantly making the reac-
tion sequence even friendlier to the environment. On heat-
ing to 100 °C for two hours 1 precipitated in the form of a
microcrystalline solid. The yields were good and in many
cases higher than those obtained in similar literature pro-
cedures;7,16 the high purity of the crude products could be
1
seen in their H NMR spectra. Further purification of all
compounds could be achieved by recrystallization from
ethanol. The results are summarized in Table 1.
The strategy was also successfully applied to the one-pot
synthesis of bis-terpyridines 2 using aromatic dialde-
hydes. Starting from terephthaldehyde, bis-terpyridine
2a7 was obtained in 51% yield (Scheme 2).
Therefore, the development of simple, efficient, and gen-
eral synthetic routes using readily available reagents un-
In addition to their spectroscopic data, the structures of 1e
and 1j were confirmed by single crystal X-ray diffraction
studies (Figures 1 and 2).17
SYNTHESIS 2006, No. 17, pp 2873–2878
Advanced online publication: 25.07.2006
DOI: 10.1055/s-2006-942525; Art ID: T05406SS
© Georg Thieme Verlag Stuttgart · New York
x
x.
x
x
.
2
0
0
6

2874
A. Winter et al.
PAPER
R
O
R
i) NaOH, PEG300
ii) aq NH3
2
+
O
N
N
1
N
N
NaOH
NH3
O
R
O
O
N
N
R
NaOH
N
O
N
Scheme 1 Generalized mechanism for the synthesis of 4¢-substituted terpyridines 1.
Figure 1 shows the structure of 1e. The three pyridyl rings
are approximately co-planar and the pyridyl nitrogen at-
oms adopt the expected transoid arrangement about the in-
terannular bonds. Both the C–C and C–N bond lengths
within the aromatic rings are normal [1.324(2)–1.394(2)
Å], as are the interannular C–C bond lengths [1.490(2)–
1.493(2) Å] and the C–S bonds [(1.784(2) and 1.7596(18)
Å, respectively]. The planar angles between the central
(N1–C6) and the outer pyridyl rings are 1.96° (C7–C12)
and 1.00° (C13–C18). The planar angle to the substituted
ring (C19–C24) is 8.31°. The S25–C26 bond is co-planar
with the phenyl ring it is attached to. All bond lengths and
angles are similar to the already published structures of 4¢-
(4-amino)-2,2¢:6¢,2¢¢-terpyridine, 4¢-phenyl-2,2¢:6¢,2¢¢-ter-
pyridine, or 4¢-(3,5-diiodo-4-methoxyphenyl)-2,2¢:6¢,2¢¢-
terpyridine.18
Table 1 Yields of the 4¢-Substituted Terpyridines 1
Compound R
Yield (%)a Yield (%)b Mp (°C)
1a
1b
1c
1d
1e
1f
H
25
44
33
47
22
63
46
35
48
13
5320
2316
2016
208
174
157
4-Cl
4-Br
4-OMe
25,16 20 21 165
4-SMe
5022
–
173
189
153
171
176
165
215
4-OBn
1g
1h
1i
4-COOMe
4-CH2OH
4-OCH2CH2OH
2,4,6-(OMe)3
–
–
2623
–
The packing diagram shows columns of the molecules
running parallel to the b-axis formed by p-stacking be-
tween the terpyridyl groups. The distance between the
mean planes through the terpyridyls is 3.492 Å.
1j
1k
Anthracene-9-ylc 17
2712
a Yield of crude precipitated product.
Due to the substitution pattern at the phenyl ring, 1j has a
more twisted conformation for the phenyl ring and the
terpyridine plane (Figure 2). The arrangement of the py-
ridyl nitrogens are the same as in the previous structure
and also the C–C and C–N bond lengths of the aromatic
b Isolated yield of 1 using similar one-pot procedures known in the lit-
erature.
c Anthracene-9-carbaldehyde was used as the aldehyde component.
O
N
N
N
N
O
i) NaOH, PEG300
ii) aq NH3
+
4
N
N
N
2a
O
Scheme 2 Synthesis of bis-terpyridine 2a.
Synthesis 2006, No. 17, 2873–2878 © Thieme Stuttgart · New York

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Synthesis of 4¢-Aryl Terpyridines
2875
Figure 1 Molecular structure and packing diagram obtained from
single-crystal X-ray diffraction analysis of 1e. Crystal data:
C22H17N3S, M = 355.45 gmol–1, monoclinic, P2(1)/c, Z = 4, T = 295
K,
a = 19.2602(14),
b = 5.3143(4),
c = 17.3778(13)
Å,
b = 91.685(2)°, U = 1777.9(2) Å3, Dc = 1.328 gcm–3.
Figure 2 Molecular structure and packing diagram obtained from
single crystal X-ray diffraction analysis of 1j. Crystal data:
C24H21N3O3, M = 399.44 gmol–1, monoclinic, P2(1)/c, Z = 4, T = 295
K, a = 15.892(3), b = 9.9542(16), c = 14.332(2) Å, b = 115.123(3)°,
U = 2052.8(6) Å3, Dc = 1.292 gcm–3.
rings are within their normal ranges [1.335(3)–1.397(2)
Å] as are the interannular C–C bond lengths [1.486(2)–
1.496(2) Å]. The C–O bonds of the substituents also span
the expected range [1.3664(18)–1.425(2) Å]. The whole
molecule is more twisted compared to the preceding one;
the planar angles between the central (N1–C6) and the
outer pyridyl rings are 12.11° (C7–C12) and 6.39° (C13–
C18). The substituted phenyl ring (C19–C24) is complete-
ly out of plane with an angle of 76.63°. The reason for this
distortion is most likely the steric demand of the two ortho
methoxy substituents. A similar distortion due to ortho
substituents was already observed in the structures of 4¢-
(2,5-dimethoxyphenyl)-2,2¢:6¢,2¢¢-terpyridine and 4¢-mes-
ityl-2,2¢:6¢,2¢¢-terpyridine.19 All methoxy groups are co-
planar with the plane of the phenyl ring. Contrary to 1e,
In conclusion, the strategy presented here is a straightfor-
ward method to synthesize 4¢-substituted terpyridines 1
and bis-terpyridines 2 under mild conditions in short reac-
tion times in a one-pot reaction. The products obtained
represent versatile building blocks for novel metallopoly-
mers and supramolecular architectures.
All chemicals were reagent grade and were used as received. IR
spectra were recorded on a Perkin-Elmer 160 Fourier transform in-
frared spectrometer. 1H and 13C NMR spectroscopy was carried out
packing occurs in 1j not via the terpyridyl groups but via on a Varian Gemini 300 MHz spectrometer at 298 K using TMS as
internal standard and CDCl3 as solvent. Elemental analyses were
obtained on a EuroVector EuroEA3000 elemental analyzer.
the phenyl substituents along the b-axis. The distance be-
tween the mean planes through the phenyl substituents is
3.633 Å.
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PAPER
Terpyridines 1; General Procedure
4¢-(4-Benzyloxyphenyl)-2,2¢:6¢,2¢¢-terpyridine (1f)
2-Acetylpyridine (5 g, 41.2 mmol) was added to a stirred suspen-
sion of crushed NaOH (1.65 g, 41.2 mmol) in PEG-300 (30 mL) at
0 °C. After 10 min the corresponding aldehyde (20.6 mmol) was
added and the reaction mixture was kept at 0 °C for 2 h. In those cas-
es where the suspension became too viscous, manual stirring was
carried out occasionally. Then a concentrated solution of aq NH3
(25 mL) was added and the suspension was heated at 100 °C for 2
h. During this time product formed as a yellowish precipitate. The
product was isolated by vacuum filtration and washed with H2O (50
mL) and cold EtOH (10 mL). The crude product was recrystallized
from EtOH and then fully characterized.
Yield: 63%.
IR (KBr): 2934, 1577, 1553, 1531, 1422, 1399, 1207, 1054, 997,
876, 805 cm–1.
1H NMR: d = 8.74 (d, J = 4.6 Hz, 2 H, 6,6¢¢-H), 8.69 (s, 2 H, 3¢,5¢-
H), 8.59 (d, J = 7.9 Hz, 2 H, 3,3¢¢-H), 8.02 (dd, J = 7.9, 6.2 Hz, 2 H,
4,4¢¢-H), 7.81 (dd, J = 6.2, 4.6 Hz, 2 H, 5,5¢¢-H), 7.42–7.61 (m, 7 H,
Ar), 6.95 (d, J = 8.2 Hz, 2 H, Ar), 5.07 (s, 2 H, OCH2Ph).
13C NMR: d = 158.7 (Ar), 156.4 (2¢,6¢-C), 155.6 (2,2¢¢-C), 148.2
(6,6¢¢-C), 143.2 (4¢-C), 136.6 (4,4¢¢-C), 135.4 (Ph), 133.2 (Ar),
131.4 (Ar), 128.2 (Ph), 127.5 (Ph), 127.2 (Ph), 124.4 (5,5¢¢-C),
120.9 (3,3¢¢-C), 119.1 (3¢,5¢-C), 115.9 (Ar), 68.2 (OCH2Ph).
4¢-Phenyl-2,2¢:6¢,2¢¢-terpyridine (1a)20
Yield: 25%.
IR (KBr): 1583, 1567, 1550, 1468, 1392, 993, 892, 796 cm–1.
Anal. Calcd for C28H21N3O: C, 80.94; H, 5.09; N, 10.11. Found: C,
81.11; H, 4.97; N, 10.21.
1H NMR: d = 8.81 (d, J = 4.8 Hz, 2 H, 6,6¢¢-H), 8.69 (s, 2 H, 3¢,5¢-
H), 8.66 (d, J = 7.9 Hz, 2 H, 3,3¢¢-H), 8.11 (dd, J = 7.9, 6.6 Hz, 2 H,
4,4¢¢-H), 7.89 (dd, J = 6.6, 4.8 Hz, 2 H, 5,5¢¢-H), 7.49–7.62 (m, 5 H,
Ar).
Methyl 4-(2,2¢:6¢,2¢¢-Terpyridin-4¢-yl)benzoate (1g)
Yield: 46%.
IR (KBr): 3013, 2922, 1583, 1549, 1522, 1469, 1453, 1407, 1365,
1212, 1187, 1017, 986, 855 cm–1.
1H NMR: d = 8.75 (d, J = 5.9 Hz, 6,6¢¢-H), 8.72 (s, 2 H, 3¢,5¢-H),
8.63 (d, J = 7.7 Hz, 2 H, 3,3¢¢-H), 8.07 (dd, J = 7.7, 5.9 Hz, 2 H,
4,4¢¢-H), 7.76–7.85 (m, 4 H, 5,5¢¢-H, Ar), 7.33 (d, J = 7.5 Hz, 2 H,
Ar), 3.85 (s, 3 H, COOCH3).
13C NMR: d = 162.4 (COOMe), 156.6 (2¢,6¢-C), 155.7 (2,2¢¢-C),
148.6 (6,6¢¢-C), 148.1 (4¢-C), 144.5 (Ar), 136.8 (4,4¢¢-C), 133.6
(Ar), 131.0 (Ar), 129.7 (Ar), 124.2 (5,5¢¢-C), 121.3 (3,3¢¢-C), 118.8
(3¢,5¢-C), 52.0 (CH3).
Anal. Calcd for C21H15N3: C, 81.53; H, 4.89; N, 13.58. Found: C,
81.55; H, 4.85; N, 13.60.
4¢-(4-Chlorophenyl)-2,2¢:6¢,2¢¢-terpyridine (1b)21
Yield: 44%.
IR (KBr): 1585, 1567, 1546, 1469, 1441, 1411, 1383, 1091, 1012,
826, 789 cm–1.
1H NMR: d = 8.82 (d, J = 5.0 Hz, 2 H, 6,6¢¢-H), 8.69 (s, 2 H, 3¢,5¢-
H), 8.66 (d, J = 7.9 Hz, 2 H, 3,3¢¢-H), 8.09 (dd, J = 7.9, 6.7 Hz, 2 H,
4,4¢¢-H), 8.02 (d, J = 8.7 Hz, 2 H, Ar), 7.64 (d, J = 8.7 Hz, 2 H, Ar),
7.53 (dd, J = 6.7, 5.0 Hz, 2 H, 5,5¢¢-H).
Anal. Calcd for C23H17N3O2: C, 75.19; H, 4.66; N, 11.44. Found: C,
74.98; H, 4.53; N, 11.31.
[4-(2,2¢:6¢2¢¢-Terpyridin-4¢-yl)phenyl]methanol (1h)24
Yield: 35%.
Anal. Calcd for C21H14ClN3: C, 73.36; H, 4.10; N, 12.22. Found: C,
73.41; H, 4.08; N, 12.25.
IR (KBr): 3398, 2951, 1567, 1542, 1512, 1444, 1423, 1387, 1234,
1109, 1005, 945, 817, 756 cm–1.
4¢-(4-Bromophenyl)-2,2¢:6¢,2¢¢-terpyridine (1c)20
Yield: 33%.
1H NMR: d = 8.77 (d, J = 6.2 Hz, 2 H, 6,6¢¢-H), 8.72 (s, 2 H, 3¢,5¢-
H), 8.62 (d, J = 8.2 Hz, 2 H, 3,3¢¢-H), 7.95 (dd, J = 8.2, 6.5 Hz, 2 H,
4,4¢¢-H), 7.77 (dd, J = 6.5, 6.2 Hz, 2 H, 5,5¢¢-H), 7.69 (d, J = 8.1 Hz,
2 H, Ar), 6.93 (d, J = 8.1 Hz, 2 H, Ar), 4.43 (s, 2 H, OCH2Ph), 2.56
(br s, 1 H, OH).
IR (KBr): 1584, 1567, 1550, 1490, 1408, 889, 789 cm–1.
1H NMR: d = 8.80 (d, J = 5.1 Hz, 2 H, 6,6¢¢-H), 8.72 (s, 2 H, 3¢,5¢-
H), 8.64 (d, J = 8.1 Hz, 2 H, 3,3¢¢-H), 8.02 (dd, J = 8.1, 6.9 Hz, 2 H,
4,4¢¢-H), 7.92 (d, J = 8.4 Hz, 2 H, Ar), 7.81 (d, J = 8.4 Hz, 2 H, Ar),
7.55 (dd, J = 6.9, 5.1 Hz, 2 H, 5,5¢¢-H).
Anal. Calcd for C22H17N3O: C, 77.86; H, 5.05; N, 12.38. Found: C,
77.71; H, 5.12; N, 12.43.
Anal. Calcd for C21H14BrN3: C, 64.96; H, 3.68; N, 10.78. Found: C,
65.04; H, 3.71; N, 10.81.
2-[4-(2,2¢:6¢,2¢¢-Terpyridin-4¢-yl)phenoxy]ethanol (1i) 23
Yield: 48%.
4¢-(4-Methoxyphenyl)-2,2¢:6¢,2¢¢-terpyridine (1d)21
Yield: 47%.
IR (KBr): 1581, 1566, 1546, 1467, 1402, 990, 888, 791 cm–1.
IR (KBr): 3446, 1594, 1572, 1533, 1451, 1412, 1392, 1212, 1097,
998, 833, 779 cm–1.
1H NMR: d = 8.77 (d, J = 5.9 Hz, 2 H, 6,6¢¢-H), 8.74 (s, 2 H, 3¢,5¢-
H), 8.64 (d, J = 8.2 Hz, 2 H, 3,3¢¢-H), 7.92 (m, 4 H, 4,4¢¢-H, Ar), 7.41
(dd, J = 6.7, 5.9 Hz, 2 H, 5,5¢¢-H), 7.04 (d, J = 7.5 Hz, 2 H, Ar), 4.17
(t, J = 4.8 Hz, 2 H, OCH2CH2OH), 4.06 (t, J = 4.8 Hz, 2 H,
OCH2CH2OH), 3.61 (br s, 1 H, OH).
1H NMR: d = 8.79 (d, J = 4.2 Hz, 2 H, 6,6¢¢-H), 8.71 (s, 2 H, 3¢,5¢-
H), 8.35 (d, J = 8.8 Hz, 2 H, 3,3¢¢-H), 8.06 (dd, J = 8.8, 7.4 Hz, 2 H,
4,4¢¢-H), 7.92 (d, J = 8.1 Hz, 2 H, Ar), 7.51 (dd, J = 7.4, 4.2 Hz, 2
H, 5,5¢¢-H), 7.11 (d, J = 8.1 Hz, 2 H, Ar), 3.85 (s, 3 H, OCH3).
Anal. Calcd for C22H17N3O: C, 77.86; H, 5.05; N, 12.38. Found: C,
77.81; H, 4.99; N, 12.44.
Anal. Calcd for C23H19N3O2: C, 74.78; H, 5.18; N, 11.37. Found: C,
74.83; H, 5.24; N, 11.31.
4¢-(4-Methylsulfanylphenyl)-2,2¢:6¢,2¢¢-terpyridine (1e)22
4¢-(2,4,6-Trimethoxyphenyl)-2,2¢:6¢,2¢¢-terpyridine (1j)
Yield: 22%.
Yield: 13%.
IR (KBr): 1584, 1561, 1547, 1467, 1398, 989, 826 cm–1.
IR (KBr): 1585, 1565, 1542, 1466, 1439, 1389, 1206, 1102, 1009,
833 cm–1.
1H NMR: d = 8.78 (d, J = 6.7 Hz, 2 H, 6,6¢¢-H), 8.70 (s, 2 H, 3¢,5¢-
H), 8.69 (d, J = 8.2 Hz, 2 H, 3,3¢¢-H), 7.92 (dd, J = 8.2, 6.7 Hz, 2 H,
1H NMR: d = 8.82 (d, J = 5.1 Hz, 2 H, 6,6¢¢-H), 8.75 (s, 2 H, 3¢,5¢-
H), 8.56 (d, J = 8.1 Hz, 2 H, 3,3¢¢-H), 7.86–7.95 (m, 4 H, 4,4¢¢-H,
Ar), 7.33–7.51 (m, 4 H, 5,5¢¢-H, Ar), 2.56 (s, 3 H, SCH3).
Anal. Calcd for C22H17N3S: C, 74.34; H, 4.82; N, 11.82. Found: C,
74.39; H, 4.86; N, 11.85.
Synthesis 2006, No. 17, 2873–2878 © Thieme Stuttgart · New York

PAPER
Synthesis of 4¢-Aryl Terpyridines
2877
4,4¢¢-H), 7.53 (dd, J = 8.2, 6.7 Hz, 2 H, 5,5¢¢-H), 6.24 (s, 2 H, Ar),
Housecroft, C. E.; Moukhtar, E.; Schofield, E. R. Chem.
Commun. 2002, 284. (h) Gohy, J.-F.; Lohmeijer, B. G. G.;
Schubert, U. S. Chem. Eur. J. 2003, 9, 3472.
3.87 (s, 3 H, OCH3), 3.71 (s, 6 H, OCH3).
13C NMR: d = 160.8 (Ar), 157.9 (2¢,6¢-C), 156.4 (Ar), 154.4 (2,2¢¢-
C), 149.1 (4¢-C), 148.7 (6,6¢¢-C), 136.2 (4,4¢¢-C), 123.5 (3,3¢¢-C),
122.9 (5,5¢¢-C), 120.9 (3¢,5¢-C), 90.2 (Ar), 55.4 (OCH3), 54.9
(OCH3).
(3) (a) Encinas, S.; Flamigni, L.; Barigeletti, F.; Constable, E.
C.; Housecroft, C. E.; Schofield, E. R.; Figgemeier, E.;
Fenske, D.; Neuberger, M.; Vos, J. G.; Zehnder, M. Chem.
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Alcock, N. W.; Pikramenou, Z.; Hannon, M. J.; Kurth, D. G.
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Ziessel, R. Chem. Commun. 1996, 1707.
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Cho, W.-J.; Choi, H.; Lee, C.-S.; Kim, J.-A.; Jeong, T. C.;
Chang, C.; Lee, E.-S. Bioorg. Med. Chem. Lett. 2001, 11,
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Jahng, Y.; Park, J. G.; Jeong, T. C.; Cho, W.-J.; Choi, S.-U.;
Lee, C. O.; Lee, S.-Y.; Lee, C.-S.; Lee, E.-S. Bioorg. Med.
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Anal. Calcd for C24H21N3O3: C, 72.16; H, 5.30; N, 10.52. Found: C,
72.09; H, 5.26; N, 10.44.
4¢-(Anthracen-9-yl)-2,2¢:6¢,2¢¢-terpyridine (1k)12
Yield: 17%.
IR (KBr): 1583, 1571, 1542, 1465, 1438, 1407, 1377, 1105, 1015,
996, 821, 794 cm–1.
1H NMR (300 MHz, CDCl3): d = 8.82 (d, J = 7.9 Hz, 2 H, 6,6¢¢-H),
8.66 (d, J = 7.9 Hz, 2 H, 3,3¢¢-H), 8.63 (s, 2 H, 3¢,5¢-H), 8.55 (s, 1 H,
10-HAnth), 8.09 (d, J = 8.6 Hz, 2 H, 1,8-HAnth), 7.95 (t, J = 7.5 Hz, 2
H, 4,¢¢-H), 7.73 (d, J = 8.6 Hz, 2 H, 2,7-HAnth), 7.49 (t, J = 7.2 Hz, 2
H, 3,6-HAnth), 7.36–7.39 (m, 4 H, 5,5¢¢-H, 3,6-HAnth).
Anal. Calcd for C29H19N3: C, 85.06; H, 4.68; N, 10.26. Found: C,
85.11; H, 4.62; N, 10.27.
1,4-Di(2,2¢:6¢,2¢¢-terpyridin-4¢-yl)benzene (2a)23,25
Yield: 51%.
IR (KBr): 1583, 1567, 1550, 1468, 1392, 993, 892, 796 cm–1.
1H NMR (300 MHz, CDCl3): d = 8.81 (s, 4 H, 3¢,5¢-H), 8.77 (d,
J = 5.6 Hz, 4 H, 6,6¢¢-H), 8.70 (d, J = 8.0 Hz, 4 H, 3,3¢¢-H), 8.07 (s,
4 H, Ar), 7.90 (dd, J = 8.0, 5.9 Hz, 4 H, 4,4¢¢-H), 7.38 (dd, J = 5.9,
5.6 Hz, 4 H, 5,5¢¢-H).
(5) Chelucci, G.; Thummel, R. P. Chem. Rev. 2002, 102, 3129.
(6) Heller, M.; Schubert, U. S. Eur. J. Org. Chem. 2003, 947.
(7) Kröhnke, F. Synthesis 1976, 1.
(8) Potts, K. T.; Cipullo, M. J.; Ralli, P.; Theodoridis, G. J. Org.
Anal. Calcd for C36H24N6: C, 79.98; H, 4.47; N, 15.55. Found: C,
80.09; H, 4.28; N, 15.63.
Chem. 1982, 47, 3027.
(9) (a) Schubert, U. S.; Eschbaumer, C. Org. Lett. 1999, 1,
1027. (b) Lehmann, U.; Henze, O.; Schlüter, A. D. Chem.
Eur. J. 1999, 5, 854. (c) Lehmann, U.; Schlüter, A. D. Eur.
J. Org. Chem. 2000, 3483. (d) Fallahpour, R.-A. Synthesis
2000, 1665. (e) Heller, M.; Schubert, U. S. Synlett 2002,
751. (f) Heller, M.; Schubert, U. S. J. Org. Chem. 2002, 67,
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Acknowledgment
We thank the Nederlandse Organisatie voor Wetenschappelijk
Onderzoek (through VICI award) and the Fonds der Chemischen
Industrie for financial support.
(10) (a) Constable, E. C.; Handel, R.; Housecroft, C. E.;
Neuberger, M.; Schofield, E. R.; Zehnder, M. Polyhedron
2004, 23, 135. (b) Vatsadze, S. Z.; Nuriev, V. N.;
Leshcheva, I. F.; Zyk, N. V. Russ. Chem. Bull. 2004, 53, 911.
(11) Cave, G. W. V.; Raston, C. L. Chem. Commun. 2000, 2199.
(12) Wang, J.; Hanan, G. S. Synlett 2005, 1251.
(13) Smith, C. B.; Raston, C. L.; Sobolev, A. N. Green Chem.
2005, 650.
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