Straightforward method for synthesis of highly alkyl-substituted naphthacene and pentacene derivatives by homologation [7]

Full text of DOI:10.1021/ja003130g

12876
J. Am. Chem. Soc. 2000, 122, 12876-12877
Scheme 1. Preparation of Odd-Numbered Ring Compounds
Straightforward Method for Synthesis of Highly
Alkyl-Substituted Naphthacene and Pentacene
Derivatives by Homologation
Tamotsu Takahashi,* Masanori Kitamura, Baojian Shen, and
Kiyohiko Nakajima†
Catalysis Research Center and
Graduate School of Pharmaceutical Sciences
Hokkaido UniVersity
CREST, Science and Technology Corporation (JST)
Sapporo 060-0811, Japan
Department of Chemistry, Aichi UniVersity of Education
Igaya, Kariya 448-8542, Japan
ReceiVed August 22, 2000
π-Conjugated compounds such as polyphenylenes, poly-
acetylenes, polythiophenes, and polyacenes have attracted much
attention as organic conductive materials.1 Among them, poly-
acenes have a very low band gap (0.1-0.5 eV)2 compared with
polyacetylenes (1.4 eV), and polythiophenes (1.71 eV).1,2 There-
fore, polyacenes have been widely recognized as a promising and
useful organic conductive material.2 In fact, recently, pentacene
has been shown to be useful for organic solar batteries or
semiconductors.3 However, the established methods for synthesis
of polyacenes have several critical problems. First, available
acenes are very limited. Until now, heptacene has been the longest
known member of acenes.1a Second, acenes such as pentacene
have very poor solubility in organic solvents.1a It is well-known
that these problems can be solved by introducing alkyl substituents
into the π-conjugated aromatic compounds.4 However, there is
no systematic general method for the synthesis of highly alkyl-
substituted acenes.5 Diels-Alder-type reaction of furans or dienes
has been known for the construction of the rings.6 Dodecameth-
ylnaphthacene could be prepared on the basis of the Diels-Alder
reaction of furans with benzynes.7 However, similar attempts to
prepare alkyl-substituted pentacene derivatives have not been
successful.7 Here we would like to report a general and straight-
forward method for the synthesis of highly alkyl-substituted
pentacenes and naphthacenes by homologation (eq 1).
dimethyl acetylenedicarboxylate (DMAD) in the presence of
CuCl8 or NiX2(PPh3)2 (X ) Cl or Br).9 First, we tried to prepare
linear polycyclic compounds starting from the highly alkyl-
substituted phthalates 1 by homologation. Homologation of linear
polycyclic compounds is shown in Scheme 1. Reduction of 1 with
LiAlH4 gave 2, and bromination of 2 afforded bis(bromomethyl)-
benzene derivatives 3. Coupling reaction of 3 with alkynyllithium
produced diynes 4. Intramolecular cyclization of diynes 4 with
Cp2ZrBu210 in situ provided zirconacyclopentadienes 5. Copper-
mediated coupling reaction of 5 with DMAD gave dihydroanthra-
cene derivatives 6. Repetition of the same procedures (i)-(v) from
1 to 6 for the transformation of 6 to 8 provided the five-ring
compound 8. This homologation afforded odd-numbered ring
compounds such as three-ring 6, five-ring 8 (via 7), and even
seven-ring compounds 10 (from 8 via 9) without any problem of
purification.
As for even-numbered ring compounds, tetrahydronaphthalene
derivatives 12 prepared from diynes 11 were used as the starting
compounds. The same procedures shown in Scheme 1 and Scheme
2 were applied to preparation of four-ring compounds 13b and
six-ring compounds 14b.
Recently, we reported the formation of highly alkyl-substituted
phthalates 1 by the reaction of zirconacyclopentadienes with
† Aichi University of Education.
(1) For a review, see: (a) Roncali, J. Chem. ReV. 1997, 97, 173-205 and
references therein. (b) Bloor, D. In ComprehensiVe Polymer Science; Allen,
G., Bevington, J. C., Eds.; Pergamon Press: Elmsford, New York, 1986;
Vol. 2, p 687.
(2) (a) Tanaka, K. Ohzeki, K.; Nankai, S.; Yamabe, T.; Shirakawa, H. J.
Phys. Chem. Solids 1983, 44, 1069. (b) Bre´das, J. L.; Chance, T. T.; Baughman,
R. H.; J. Chem. Phys. 1982, 76, 3673. (c) Pomerantz, M.; Cardona, R.; Rooney,
P. Macromolecules 1989, 22, 304. (d) Kao, J.; Lilly, A. C., Jr. J. Am. Chem.
Soc. 1987, 109, 4149.
(3) (a) Scho¨n, J. H.; Kloc, C.; Bucher, E.; Batlogg, B. Nature 2000, 403,
408-410. (b) Dimitrakopoulos, C. D.; Purushothaman, S.; Kymissis, J.;
Callegari, A.; Shaw, J. M. Science 1999, 283, 822-824. (c) Nelson, S. F.;
Lin, Y.-Y.; Gundlach, D. J.; Jackson, T. N. Appl. Phys. Lett. 1998, 72, 1854-
1856. (d) Signerski, R.; Jarosz, G.; Godlewski, J. Synth. Met. 1998, 94, 135-
137. (e) Videlot, C.; Fichou, D.; Garnier, F. J. Chim. Phys. 1998, 95, 1335-
1338. (f) Lin, Y.-Y.; Gundlach, D. J.; Nelson, S. F.; Jackson, T. N. IEEE
Trans. Electron. DeVices 1997, 44, 1325-1331.
(4) Allinson, G.; Bushby, R. J.; Jesudason, M. V.; Paillaud, J. L.; Taylor,
N. J. Chem. Soc., Perkin Trans. 2 1997, 147-156.
(5) For the preparation of pentacene and naphthacene, see: (a) Harwig, P.
T.; Mu¨llen, K. AdV. Mater. 1999, 11, 480-483. (b) Luo, J.; Hart, H. J. Org.
Chem. 1987, 52, 4833-4836 and references therein. (c) Netka, J.; Crump, S.
L.; Rickborn, B. J. Org. Chem. 1986, 51, 1189-1199. (d) Goodings, E. P.;
Mitchard, D. A.; Owen, G. J. Chem. Soc., Perkin Trans. I 1972, 1310-1314.
Preparation of alkyl-substituted naphthacenes and pentacenes
was performed in a similar way using substituted naphthalene
dimethoxycarbonyl compounds 15b and substituted anthracene
dimethoxycarbonyl compounds 19b, respectively, which were
prepared by oxidation of 12 and 6, with DDQ or chloranil
(Scheme 3). The compounds 15 and 19 were treated with the
(6) (a) Benkhoff, J.; Boese, R.; Kla¨rner, F. G. Liebigs Ann./Recl. 1997,
501-516. (b) Pascal, R. A., Jr.; McMillan, W. D.; Van Engen, D.; Eason, R.
G. J. Am. Chem. Soc. 1987, 109, 4660-4665.
(7) (a) Hart, H.; Ruge, B. Tetrahedron Lett. 1977, 3143-3146. (b) Hart,
H.; Lai, C.; Nwokogu, G. C.; Shamouilian, S. Tetrahedron 1987, 432, 5203-
5224
(8) (a) Takahashi, T.; Xi, Z.; Yamazaki, A.; Liu, Y.; Nakajima, K.; Kotora,
M. J. Am. Chem. Soc. 1998, 120, 1672. (b) Takahashi, T.; Kotora, M.; Xi, Z.
J. Chem. Soc., Chem. Commun. 1995, 361-362.
(9) Takahashi, T.; Tsai, F.-Y.; Li, Y.; Nakajima, K.; Kotora, M. J. Am.
Chem. Soc. 1999, 121, 11093.
(10) Negishi, E.; Cederbaum, F. E.; Takahashi, T. Tetrahedron Lett. 1986,
27, 2829.
10.1021/ja003130g CCC: $19.00 © 2000 American Chemical Society
Published on Web 12/05/2000

Communications to the Editor
J. Am. Chem. Soc., Vol. 122, No. 51, 2000 12877
Scheme 2. Further Homologation of 6 to 10
Scheme 3. Preparation of a Naphthacene Derivative and a
Pentacene Derivative by Homologation
Figure 1. Perspective view of 18b.
Figure 2. Perspective view of 21a.
in 71 and 33% yield, respectively. The structure of 18b, and 21a
were determined by X-ray analysis as shown in Figures 1 and 2.
The naphthacene derivative 18b was a red compound, and its
13C NMR spectrum showed nine sp2 carbons of the naphthacene
ring in the range of 122-138 ppm. The pentacene derivative 22b
was deep-blue and soluble in organic solvents such as THF,
CHCl3, benzene, hexane, ether, AcOEt, and acetone. The 1H NMR
spectrum of 22b showed characteristic two singlets at 9.06 and
9.17 ppm assigned to protons attached to C5, C7, C12, C14 of
the pentacene ring. In its 13C NMR spectrum, eleven sp2 carbons
are observed in the range of 120-138 pm.
same reagents (i), (ii), (iii), (iv), and (v) as for the conversion of
1 to 6 to give the corresponding intermediates 17 and 21,
respectively. Alternatively, 21a could be prepared from 8a with
chloranil (R ) Et, isolated yield 40%). The oxidation of 17 and
21 with DDQ afforded naphthacene 18b11 and pentacene 22b12
In conclusion, this homologation procedure provides a general
and straightforward method for synthesis of soluble acenes, and
will expand the chemistry of these important compounds.
(11) 18b: 1H NMR (CDCl3, Me4Si) δ 1.19 (t, J ) 7.3 Hz, 6H), 1.23 (t,
J ) 7.3 Hz, 6H), 1.92-1.86 (m, 8H), 3.26 (t, J ) 8.1 Hz, 4H), 3.72 (t, J )
8.1 Hz, 4H), 3.94 (s, 6H), 7.46 (dd, J ) 3.2, 7.0 Hz, 2H), 8.31 (dd, J ) 3.2,
7.0 Hz, 2H), 9.19 (s, 2H); 13C NMR (CDCl3, Me4Si) δ 14.81, 14.89, 24.67,
24.89, 30.73, 32.72, 52.25, 122.65, 125.12, 125.39, 126.67, 128.44, 128.77,
129.63, 134.16, 137.87, 169.58.
Supporting Information Available: Experimental details and spec-
troscopic characterization of new compounds and crystallographic data,
positional and thermal parameters, and lists of bond lengths and angles
for 18b and 21a (PDF). This material is available free of charge via the
Internet at http://pubs.acs.org.
(12) 22b: 1H NMR (CDCl3, Me4Si) δ 1.15 (t, J ) 7.2 Hz, 6H), 1.20 (t,
J ) 7.3 Hz, 6H), 1.27 (t, J ) 7.5 Hz, 6H), 1.29 (t, J ) 7.4 Hz, 6H), 1.62-
1.68 (m, 4H), 1.85-2.07 (m, 12H), 2.78 (t, J ) 7.5 Hz, 4H), 3.22-3.26 (m,
8H), 3.90 (bs, 4H), 3.94 (s, 6H), 9.06 (s, 2H), 9.17 (s, 2H); 13C NMR (CDCl3,
Me4Si) δ 14.85, 15.05, 15.13, 24.36, 24.60, 24.87, 25.11, 31.33, 31.76, 32.67,
32.85, 52.26, 120.08, 122.74, 126.23, 127.57, 127.76, 128.35, 129.91, 133.37,
133.76, 136.77, 138.13, 169.65.
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