Synthesis and redox behavior of azulene-substituted benzene derivatives and η5-cyclopentadienyl)[tetra- and di(6-azulenyl) cyclobutadiene]cobalt complexes

Article abstract of DOI:10.1021/jo010540u

1,2-Di(6-azulenyl)tetraphenylbenzenes and (6-azulenyl)pentaphenylbenzenes were synthesized by Diels-Alder reactions of di(6-azulenyl)acetylenes and 6-(phenylethynyl)azulenes with tetraphenylcyclopentadienone. Cobalt-mediated cyclooligomerization of mono-

Full text of DOI:10.1021/jo010540u

7
090
J . Org. Chem. 2001, 66, 7090-7101
Syn th esis a n d Red ox Beh a vior of Azu len e-Su bstitu ted Ben zen e
5
Der iva tives a n d (η -Cyclop en ta d ien yl)[tetr a - a n d
d i(6-a zu len yl)cyclobu ta d ien e]coba lt Com p lexes
,
†
†
†
†
‡
Shunji Ito,* Haruki Inabe, Tetsuo Okujima, Noboru Morita, Masataka Watanabe,
‡
§
Nobuyuki Harada, and Kimiaki Imafuku
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, J apan,
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University,
Sendai 980-8577, J apan, and Department of Chemistry, Faculty of Science, Kumamoto University,
Kumamoto 860-8555, J apan
ito@funorg.chem.tohoku.ac.jp
Received May 29, 2001
1
,2-Di(6-azulenyl)tetraphenylbenzenes and (6-azulenyl)pentaphenylbenzenes were synthesized by
Diels-Alder reactions of di(6-azulenyl)acetylenes and 6-(phenylethynyl)azulenes with tetraphen-
ylcyclopentadienone. Cobalt-mediated cyclooligomerization of mono- and di(6-azulenyl)acetylenes
5
afforded 1,3,5- and 1,2,4-tri(6-azulenyl)benzene derivatives together with (η -cyclopentadienyl)-
[tetra- and di(6-azulenyl)cyclobutadiene]cobalt complexes. The redox behavior of these novel (6-
azulenyl)benzene derivatives and [tetra- and di(6-azulenyl)cyclobutadiene]cobalt complexes was
examined by cyclic voltammetry (CV). Mono(6-azulenyl)benzenes exhibited a reduction wave upon
CV. In contrast, 1,2-di(6-azulenyl)benzenes showed a two-step reduction wave at the similar
potential region upon CV, which revealed the formation of a dianion stabilized by 6-azulenyl
substituents under electrochemical reduction conditions. Three 6-azulenyl substituents on benzene
in a 1,2,4 relationship also increased electron-accepting properties because of the formation of a
closed-shell dianionic structure, whereas 1,3,5-tri(6-azulenyl)benzenes were reduced stepwise.
In tr od u ction
Sch em e 1
Azulene (C10
H
8
) is a theoretically interesting compound
1
with many unusual properties. The azulene system,
especially, has a tendency to stabilize cations, as well as
anions, owing to its remarkable polarized properties,
which could be utilized to construct advanced materials
for electronic and photonic applications.2 However, to
date, molecules with potentially useful electronic proper-
ties constructed by using azulene derivatives are fairly
scarce. Recently, H u¨ nig et al. proposed a concept of the
violene-cyanine hybrid as stabilized organic electrochro-
as one of a violene-cyanine hybrid in which the two
cyanine-type structures are connected in two positions,
as illustrated in Scheme 2. The compound 1 will provide
-2
a delocalized closed-shell dianion 1RED by an overall
3
mics. The hybrid contains the moieties XdCsY, which
two-electron transfer and could be expected to show
significant changes in the absorption spectra in the
different oxidation states. We have recently developed a
simple route to unknown 1,3,5-tri(1-azulenyl)benzenes by
the tetrachlorosilane-mediated cyclotrimerization of 1-ac-
represent the “cyanine”-type structure in a fully reduced
or oxidized form, as end groups of a violene. The system
provides a highly colored closed-shell form as a cyanine
dye by an overall two-electron transfer, as illustrated in
Scheme 1.
4
ethylazulenes. Hafner et al. reported the ethynylation
Hexa(6-azulenyl)benzene (1) would be a candidate for
a such system. The redox system of 1 could be assumed
of azulenes in a five-membered ring, utilizing Pd-cata-
lyzed cross-coupling reactions of bromo- and iodoazulenes
5
with trimethylsiliylacetylene, and the cyclooligomeriza-
*
To whom correspondence should be addressed. E-mail: ito@funorg.
2
tion of the 1-azulenylacetylenes, catalyzed by CpCo(CO) ,
chem.tohoku.ac.jp. Tel: +81-(0)22-217-7714. Fax: +81-(0)22-217-7714.
†
‡
to afford 1-azulenylbenzene derivatives and (cyclobuta-
Department of Chemistry, Tohoku University.
Institute of Multidisciplinary Research for Advanced Materials,
diene)cobalt complexes.6
Tohoku University.
§
Herein, we report two complementary methods to
prepare novel 6-azulenylbenzene derivatives toward the
Department of Chemistry, Kumamoto University.
(1) Zeller, K.-P. Azulene. In Houben-Weyl; Methoden der Organis-
chen Chemie, 4th ed.; Georg Thieme: Stuttgart, 1985; Vol. V, Part 2C,
7
synthesis of 1. One is the Diels-Alder reaction of di(6-
p 127.
azulenyl)acetylenes and 6-(phenylethynyl)azulenes with
tetraphenylcyclopentadienone to afford 1,2-di- and mono-
(2) See, e.g.: (a) Berresheim, A. J .; M u¨ ller, M.; M u¨ llen, K. Chem.
Rev. 1999, 99, 1747. (b) Martin, R. E.; Diederich, F. Angew. Chem.
Int. Ed. 1999, 38, 1350.
(
3) (a) H u¨ nig, S.; Kemmer, M.; Wenner, H.; Perepichka, I. F.;
B a¨ uerle, P.; Emge, A.; Gescheid, G. Chem.-Eur. J . 1999, 5, 1969. (b)
H u¨ nig, S.; Kemmer, M.; Wenner, H.; Barbosa, F.; Gescheidt, G.;
Perepichka, I. F.; B a¨ uerle, P.; Emge, A.; Peters, K. Chem.-Eur. J .
(4) Sato, K.; Yamashiro, S.; Imafuku, K.; Ito, S.; Morita, N.; Fujimori,
K. J . Chem. Res., Synop. 2000, 334.
(5) Fabian, K. H. H.; Elwahy, A. H. M.; Hafner, K. Tetrahedron Lett.
2000, 41, 2855.
2
000, 6, 2618. (c) H u¨ nig, S.; Perepichka, I. F.; Kemmer, M.; Wenner,
H.; B a¨ uerle, P.; Emge, A. Tetrahedron 2000, 56, 4203.
(6) Elwahy, A. H. M.; Hafner, K. Tetrahedron Lett. 2000, 41, 2859.
1
0.1021/jo010540u CCC: $20.00 © 2001 American Chemical Society
Published on Web 09/26/2001

Azulene-Substituted Benzene Derivatives
J . Org. Chem., Vol. 66, No. 21, 2001 7091
Sch em e 2
Sch em e 3
(6-azulenyl)benzene derivatives 2a , 2b and 3a , 3b, and
the other is the cobalt-mediated cyclooligomerization of
mono- and di(6-azulenyl)acetylenes to give 1,3,5- and
1
5
,2,4-tri(6-azulenyl)benzene derivatives 4a , 4b and 5a ,
b together with [(6-azulenyl)cyclobutadiene]cobalt com-
plexes 6-12. 1,2-Di(1-azulenyl)benzene 2a , 2b would be
a model compound for the formation of a closed-shell
dianionic species by electrochemical reduction. 1,2,4-Tri-
(6-azulenyl)benzene 5a , 5b would be a violene-cyanine
hybrid and would exhibit a two-electron transfer to form
a colored closed-shell dianionic species by electrochemical
reduction. Herein, we also report the redox behavior of
these novel 6-azulenylbenzene derivatives 2-5 together
with those of 6-azulenylacetylenes, diacetylenes, and
cobalt complexes 6-12 examined by cyclic voltammetry
(CV).
Resu lts a n d Discu ssion
Syn th esis of 6-Azu len yla cetylen es. We found an
efficient method of functionalization of azulene in a
seven-membered ring utilizing 6-bromoazulenes 13a and
8
Sch em e 4
1
3b to produce 6-azulenylacetylenes under Sonogash-
9
ira-Hagihara conditions. The Pd-catalyzed cross-cou-
pling reactions of 13a and 13b with trimethylsilylacet-
ylene (TMSA) at room temperature afforded the 6-(tri-
methylsilylethynyl)azulenes 14a and 14b in 86 and 84%
yields, respectively. It is noteworthy that the ethynylation
of azulenes in a seven-membered ring proceeded readily
by using bromides at room temperature. Treatment of
1
4a and 14b with potassium fluoride in DMF or DMF/
by the reaction of 15b with 13b in 96% yield (Scheme 3).
The diacetylenes 17a and 17b were selectively obtained
by the Pd-catalyzed oxidative coupling of 15a and 15b
tetrahydrofuran furnished 6-ethynylazulenes 15a and
1
0
1
5b in 79 and 92% yields, respectively. The cross-
coupling reaction of 15a with 13a using PdCl (PPh as
a catalyst afforded an inseparable mixture (1:2.2) of di-
2
3
)
2
11
in 86 and 58% yields, respectively (Scheme 4).
Diels-Ald er Ap p r oa ch . The Diels-Alder reaction of
6a and 16b with a large excess of tetraphenylcyclopen-
(
(
6-azulenyl)acetylene (16a ) and di(6-azulenyl)diacetylene
17a ). However, we found that the reaction of 15a with
1
tadienone (18) in diphenyl ether at 160 °C under an Ar
atmosphere for 1-2 d and subsequent chromatographic
purification of the reaction mixture on silica gel afforded
1
3a utilizing Pd(PPh
3 4
) as a catalyst exclusively gave the
desired 16a in 98% yield. Similarly, 16b was obtained
2
5
a and 2b in 13 and 90% yields, respectively (Scheme
).
The synthesis of 3a and 3b as outlined in Scheme 6
(
7) A part of this work has been published in a preliminary form:
12
(
a) Ito, S.; Inabe, H.; Okujima, T.; Morita, N.; Watanabe, M.; Imafuku,
K. Tetrahedron Lett. 2000, 41, 8343. (b) Ito, S.; Inabe, H.; Okujima,
T.; Morita, N.; Watanabe, M.; Nobuyuki, H.; Imafuku, K. Tetrahedron
Lett. 2001, 42, 1085.
also commenced with 13a and 13b, respectively. 6-(Phe-
nylethynyl)azulenes 19a and 19b were prepared by the
Sonogashira reaction of 13a and 13b with phenylacety-
lene in 90 and 86% yields, respectively. The Diels-Alder
(
8) McDonald, R. N.; Richmond, J . M.; Curtis, J . R.; Petty, H. E.;
Hoskins, T. L. J . Org. Chem. 1976, 41, 1811.
9) (a) Sonogashira, K. Comprehensive Organic Synthesis; Trost, B.
M., Fleming, I., Eds.; Pergamon Press: Oxford, 1991; Vol. 3, Chapter
.4, p 521. (b) Takahashi, S.; Kuroyama, Y.; Sonogashira, K.; Hagihara,
(
2
N. Synthesis 1980, 627. (c) Sonogashira, K.; Tohda, Y.; Hagihara, N.
Tetrahedron Lett. 1975, 4467.
(11) (a) Rossi, R.; Carpita, A.; Bigelli, C. Tetrahedron Lett. 1985,
26, 523. (b) Takahashi, A.; Endo, T.; Nozoe, S. Chem. Pharm. Bull.
1992, 40, 3181.
(10) (a) Morita, T.; Fujita, T.; Takase, K. Bull. Chem. Soc. J pn. 1980,
5
3
3, 1647. (b) Fujita, T.; Morita, T.; Takase, K. Tetrahedron Lett. 1974,
0, 2585.
(12) Ogliaruso, M. A.; Romanelli, M. G.; Becker, E. I. Chem. Rev.
1965, 65, 261.

7
092 J . Org. Chem., Vol. 66, No. 21, 2001
Ito et al.
1
4
Sch em e 5
16a and 16b in the presence of cobalt carbonyl and
dichlorobis(benzonitrile)palladium15 following literature
procedures did not afford satisfactory results. The forma-
tion of the cobalt complexes 6a and 6b by the reactions
2
of 16a and 16b in the presence of CpCo(CO) is similar
to the results obtained by Hafner et al. with the use of
di(1-azulenyl)acetylenes.6
2
Similarly, the reaction of 14b with CpCo(CO) afforded
5
a mixture (1:4.1) of the cis- and trans-(η -cyclopentadi-
enyl)[bis(1,3-diethoxycarbonyl-6-azulenyl)bis(trimethyl-
silyl)cyclobutadiene]cobalt complexes (7 and 8) in 82%
yields, which were separable by gel permeation chroma-
tography (GPC) with chloroform (Scheme 8). The regio-
chemistry of 7 and 8 could not be determined by NMR
spectroscopy. Suitable crystals of the major isomer 8 for
X-ray structure determination were obtained by slow
evaporation of the solution in dichloromethane/hexane,
and the molecular structure was determined by X-ray
crystallography. Thus, the relative stereochemistry of the
major isomer 8 was established as a trans-cobalt complex.
Sch em e 6
7
b
The ORTEP plot of 8 has been reported elsewhere.
A
synopsis of some key structural features of 8 is provided
in Figure 1. Recently, Sekiguchi et al. reported the X-ray
structure of cis-diphenyl-substituted (cyclobutadiene)-
cobalt complex 20, which exhibited an almost square
structure as confirmed by the internal bond angles (89.5,
9
0.2, 90.3, and 90.4°) (Chart 1.).16 However, the four-
membered ring in 8 is almost planar and forms a
rhombus structure.
The reaction of 19b with CpCo(CO)
2
also afforded a
mixture (1:1.1) of the cis- and trans-(η -cyclopentadienyl)-
bis(1,3-diethoxycarbonyl-6-azulenyl)di(phenyl)cyclobuta-
diene]cobalt complexes (9 and 10) in 94% yields (Scheme
). These regioisomers were separable by GPC with
5
[
8
Sch em e 7
chloroform. The regiochemistries of 9 and 10 were
tentatively assigned by the comparison of the chemical
1
shifts of their azulene and benzene ring protons in
H
NMR spectra. The aromaticity of azulene is considerably
smaller than that of benzene. Thus, the anisotropy effect
1
7
of the azulene ring is less than that of the benzene ring.
Therefore, the protons on the azulene ring in the trans-
configuration 10 (H4′,8′ ) 9.36 and H5′,7′ ) 7.76 ppm) must
be much more shielded than those of the cis-configuration
9
(H4′,8′ ) 9.47 and H5′,7′ ) 7.94 ppm) because the azulene
rings in the trans-configuration are interposed by two
phenyl groups. The comparison of the chemical shift of
the phenyl groups led to the same conclusion (9, 7.45,
reaction of 19a and 19b with a large excess of 18 in
diphenyl ether for 5 d afforded 3a and 3b in 32 and 93%
yields, respectively. The spectral features of these azu-
lene-substituted benzenes 2a , 2b, 3a , and 3b are in
agreement with the structures of these products. These
compounds are remarkably stable, showing no decom-
position even after several weeks at room temperature.
Met a l-Med ia t ed Cyclooligom er iza t ion . Attempts
made toward the cyclooligomerization of 16a and 16b in
7
.29, and 7.35; 10, 7.65, 7.41, and 7.45 ppm). In these
three reactions, azulene-substituted benzene derivatives
could not be obtained even in trace amounts. The
exclusive formation of the (cyclobutadiene)cobalt com-
plexes 6-10 would be attributable to the steric effect
among the aromatic rings and/or the trimethylsilyl
groups.
In contrast to the exclusive formation of the (cyclo-
butadiene)cobalt complexes 6-10, the cyclooligomeriza-
tion of 15a using CpCo(CO) afforded 1,3,5- and 1,2,4-
2
2
the presence of CpCo(CO) in refluxing 1,4-dioxane did
not yield hexa(6-azulenyl)benzene (1) but exclusively
5
gave (η -cyclopentadienyl)[tetra(6-azulenyl)cyclobutadi-
tri(6-azulenyl)benzenes 4a and 5a in 0.5 and 0.3% yields,
ene]cobalt complexes 6a and 6b in 43 and 81% yields,
5
respectively, along with (η -cyclopentadienyl)[1,2-bis(6-
respectively (Scheme 7).13 The spectral features of 6a and
6
b are in agreement with the structures of these prod-
(
14) Herwig, P.; Kayser, C. W.; M u¨ llen, K.; Spiess, H. W. Adv. Mater.
Weinheim, Ger.) 1996, 8, 510.
15) Keegstra, A.; Feyter, S. D.; Schryver, F. C.; M u¨ llen, K. Angew.
ucts. Attempts made toward the cyclooligomerization of
(
(
(
13) For CpCo(CO)
e.g.: (a) Vollhart, K. P. C. Angew. Chem. Int. Ed. Engl. 1984, 23, 539.
b) Vollhart, K. P. C. Acc. Chem. Res. 1977, 10, 1.
2
-mediated cyclooligomerization of alkynes, see,
Chem. Int. Ed. Engl. 1996, 35, 774.
(16) Matsuo, T.; Mizue, T.; Sekiguchi, A. Chem. Lett. 2000, 896.
(17) Esquivel, D. M. S.; De Giambiagi, M. S.; Giambiagi, M.; Makler,
S. Chem. Phys. Lett. 1979, 64, 131.
(

Azulene-Substituted Benzene Derivatives
J . Org. Chem., Vol. 66, No. 21, 2001 7093
Sch em e 8
(part a of Figure 2). These results clearly show the
presence of the 1,2-disubstitution pattern in the cyclo-
butadiene ring in 11a and 11b.19
The cis-configuration of 11a and 11b was also con-
1
3
firmed by the preparation and observation of the
C
satellite signals of the trans-isomer 12. The deprotection
of the trimethylsilyl groups of 8 was furnished by
treatment with tetrabutylammonium fluoride in tetrahy-
drofuran in 53% yield (Scheme 10). In contrast to 11a
1
3
1
and 11b, the C satellite signals of 12 ( J CH ) 189 Hz)
F igu r e 1. Some key structural features in the cyclobutadiene
ring of 8.
in the 1H NMR spectrum exhibited a large coupling
constant between the cyclobutadiene protons (8.1 Hz),
which consists of the 1,3-disubstitution of the cyclobuta-
diene ring.19 The signals were also identified definitely
by a 2D HMQC spectrum measured under nondecoupling
conditions. The coupling constants could be determined
Ch a r t 1
1
by both normal H NMR spectrum and the 2D HMQC
spectrum. The use of a 2D HMQC spectrum under
nondecoupling conditions for the definite observation of
1
3
C satellite signals could be a powerful method for the
analysis of the stereochemistry of highly symmetrical
compounds. The details of this method will be reported
elsewhere.20
azulenyl)cyclobutadiene]cobalt (11a ) (19%). The cyclo-
The formation of both the benzene derivatives 4a , 4b
and 5a , 5b could not be explained by the single inter-
mediate 21 in this reaction, because the intermediate 21
could not afford 4a and 4b by further reaction with 15a
and 15b. The formation of 4a , 4b and 5a , 5b is assumed
by the existence of 22 as an intermediate in this reac-
tion.21 The exclusive formation of the cis-cobalt complexes
2
oligomerization of 15b using CpCo(CO) afforded similar
results to give a mixture (2.5:1) of 1,3,5- and 1,2,4-tri(6-
azulenyl)benzenes 4b and 5b in 21% yields together with
5
(
η -cyclopentadienyl)[1,2-bis(1,3-diethoxycarbonyl-6-azu-
lenyl)cyclobutadiene]cobalt (11b) (47%). The products 4b
and 5b were separable by repeated silica gel preparative
TLC with ethyl acetate/hexane (Scheme 9). The benzene
derivatives 4a , 4b and 5a , 5b were stable and fully
characterized by spectroscopic data as described in the
Experimental Section.
1
1a and 11b in this reaction exhibits the existence of 21
as an intermediate and the relatively high reactivity of
the intermediate 22 toward 15a and 15b, when compared
with reductive elimination to give trans-cobalt complexes
(Chart 2).
The cis-configuration of the cobalt complexes 11a and
1
3
1
1b was confirmed by the measurement of the
C
1
Red ox Beh a vior s of Azu len e-Su bstitu ted Ben -
satellite signals of cyclobutadiene protons in the H NMR
spectrum. The signals provide very useful information
+
zen e Der iva tives. The redox potentials (V vs Ag/Ag )
of the azulene-substituted benzenes and the (cyclobuta-
diene)cobalt complexes measured by CV are summarized
in Table 1. Mono(6-azulenyl)benzenes 3a and 3b showed
a reversible one-electron transfer at -2.06 and -1.63 V
upon CV, respectively. The less negative reduction po-
tentials of 3b compared with those of 3a are attributable
to the stabilization of anions by the ethoxycarbonyl
groups substituted in the five-membered ring. In contrast
for the analysis of stereochemistry in highly symmetrical
compounds such as 11a and 11b.18 The signals of 11b
observed in the cyclobutadiene proton region in CDCl
3
are shown in Figure 2b. In the case of 11b, one of the
signals is in the lower slope of the cyclopentadienyl
proton signal. For the definite assignment of the signals,
we utilized a 2D heteronuclear multiple-quantum coher-
ence (HMQC) spectrum measured under nondecoupling
conditions. The 2D spectrum in the region is shown in
Figure 3. A slice of the 2D spectrum in the region
(19) (a) Drage, J . S.; Vollhardt, K. P. C. Organometallics 1982, 1,
1545. (b) Fritch, J . R.; Vollhardt, K. P. C. Organometallics 1982, 1,
590. (c) Brune, H. A.; Wolff, H. P.; H u¨ ther, H. Z. Naturforsch., B:
Chem. Sci.1968, 23B, 1184.
1
unequivocally exhibited the signals (11a , J CH ) 188 Hz;
1
1
1b, J CH ) 189 Hz) with a negligibly small coupling
constant (<1 Hz) between the cyclobutadiene protons
(20) To be published.
(21) 3,4-Di(6-azulenyl) metallacycle could also be expected as an
intermediate in this reaction. However, 3,4-disubstitution is in a poor
position to minimize sterics: Wakatsuki, Y.; Nomura, O.; Kitaura, K.;
Morokuma, K.; Yamazaki, H. J . Am. Chem. Soc. 1983, 105, 1907.
(
18) Harada, N.; Li, H.-Y.; Koumura, N.; Abe, T.; Watanabe, M.;
Hagiwara, M. Enantiomer 1997, 2, 349.

7
094 J . Org. Chem., Vol. 66, No. 21, 2001
Ito et al.
Sch em e 9
dence of the formation of the radical anion and/or dianion
-
2
2
RED due to the instability of these species.
Acetylenes 16a and 16b are also examples of such two-
electron redox systems stabilized by two 6-azulenyl
substituents as illustrated in Scheme 12. In contrast to
the poor reversibility of 2a and 2b, acetylenes 16a and
1
6b exhibited good reversibility (16a , E1/2 ) -1.41 and
-
1.61 V; 16b, E1/2 ) -0.96 and -1.15 V, respectively)
7
a
upon CV. The potentials are less negative than those
of 6-phenylethynylazulenes 19a (-1.66 V) and 19b
(-1.29 V), respectively. Thus, the two 6-azulenyl sub-
stituents on acetylene also increase electron-accepting
properties. Diacetylenes 17a and 17b also exhibited a
reversible two-step reduction wave (17a , E1/2 ) -1.37 and
-
1.50 V; 17b, E1/2 ) -0.98 and -1.09 V, respectively)
upon CV. The potentials are almost comparable with
those of 16a and 16b, respectively. Thus, the redox
system of 17a and 17b could also be depicted to be a
violene like that of 16a and 16b.
1
,3,5-Tri(6-azulenyl)benzene (4a ) exhibited a quasi-
reversible broad reduction wave, centered at around
1.90 V, upon CV. The wave was identified as three
-
waves that were barely separated, at -1.75, -1.87, and
-2.00 V, by differential pulse voltammetry (DPV). In
contrast to the three-step reduction of 4a , 1,2,4-tri(6-
azulenyl)benzene (5a ) showed a two-step reduction wave
upon CV, i.e., a two-electron reduction wave at -1.74 V
and a one-electron transfer at -2.15 V. The waves
F igu r e 2. (a) Slice of 2D HMQC spectrum in the cyclobuta-
1
3
diene proton region and (b) C satellite signals of the protons
1
measured by H NMR spectrum of 11b.
to the redox behavior of 3a and 3b, the benzene deriva-
tive 2b exhibited a barely separated two-step reduction
wave at E1/2 ) -1.57 and -1.72 V upon CV.7a The
compound 2a also showed a similar two-electron transfer
at -2.00 and -2.20 V. The first reduction potentials and
even the second ones of 2a and 2b are almost comparable
with those of 3a and 3b, respectively. Therefore, the two
exhibited good reversibility at the scan rate of 100 mV
-1
s
. 1,3,5- and 1,2,4-tri(6-azulenyl)benzene derivatives 4b
and 5b also exhibited similar reduction waves upon CV,
as shown in Figure 4. Therefore, the three 6-azulenyl
substituents on benzene in a 1,2,4 relationship also
increased electron-accepting properties because of the
6
-azulenyl substituents on a benzene ring in a 1,2
-2
formation of a closed-shell dianionic structure 5RED
.
relationship have increased the electron-accepting prop-
erties, because of the formation of a closed-shell dianionic
Consequently, the redox system of 5a and 5b could be
illustrated as a violene-cyanine hybrid and could exhibit
a significant color change with a different oxidation state
-
2
structure 2RED . Thus, the redox system of 2a and 2b
can be depicted to be a violene 23 as illustrated in Scheme
(Scheme 13). The three 6-azulenyl substituents on ben-
2
2
1
1. Unfortunately, the reduction waves of 2a and 2b
zene in a 1,3,5 relationship cannot take such a closed-
shell dianionic structure. Thus, the three azulene rings
of 4a and 4b were reduced stepwise. Although good
reversibility was observed upon CV, measurement of the
UV-vis spectroscopy of 5b under electrochemical reduc-
tion conditions did not afford any evidence of the forma-
showed poor reversibility; they exhibited low stabilities
-
2
of the expected radical anion and dianion 2RED under
the electrochemical reduction conditions. Although we
tried the electrochemical reduction of 2b under UV-vis
(UV-visible) monitoring, we could not obtain any evi-
2
-
tion of dianion 5RED . These results would exhibit the
low stability of the dianion species under the conditions
of the UV-vis measurement.
(
22) (a) Deuchert, K.; H u¨ nig, S. Angew. Chem. Int. Ed. Engl. 1978,
1
7, 875. (b) H u¨ nig, S.; Ort, B. Liebigs Ann. Chem. 1984, 1959. (c) H u¨ nig,
S.; Ort, B. Liebigs Ann. Chem. 1984, 1936.

Azulene-Substituted Benzene Derivatives
J . Org. Chem., Vol. 66, No. 21, 2001 7095
F igu r e 3. 2D HMQC spectrum of 11b measured under nondecoupling conditions.
Sch em e 10
Ch a r t 2
R ed ox Beh a vior of Azu len e-Su b st it u t ed Cyclo-
bu ta d ien ecoba lt Com p lexes. The voltammogram of 6a
was characterized by two quasi-reversible waves at -1.61
and -1.79 V and the next two irreversible waves at -1.91
and -2.09 V upon CV. The cobalt complex 6b exhibited
a quasi-reversible one-electron transfer at less negative
potentials compared with those of 6a , but the next
irreversible two- or three-electron transfer blended into
one broad wave centered at -1.42 V. The less negative
reduction potentials of 6b compared with those of 6a are
attributable to the stabilization by the ethoxycarbonyl
groups substituted on the five-membered rings. The
voltammetric behavior of 6a and 6b indicates that the
ions of higher charge in the cobalt complexes are con-
siderably less stable under the reduction conditions.

7
096 J . Org. Chem., Vol. 66, No. 21, 2001
Ito et al.
Ta ble 1. Red ox P oten tia lsa of th e Com p ou n d s 2-12
mediated cyclooligomerization of mono- and di(6-azule-
nyl)acetylenes also afforded novel 1,3,5- and 1,2,4-tri(6-
azulenyl)benzenes together with (η -cyclopentadienyl)-
[tetra- and di(6-azulenyl)cyclobutadiene]cobalt complexes.
We could not detect the radical anion and/or dianion of
the azulene-substituted benzene derivatives by UV-vis
spectroscopy due to the instability of these species.
However, redox behaviors examined by CV of these
compounds represented the presumed multielectron re-
dox properties under the electrochemical conditions used.
E1ox
E2ox
E1red
E2red
E3red
sample
5
2
2
3
3
4
4
5
5
6
a b
(0.81)
(-2.00)
(-1.57)
-2.06
(-2.20)
(-1.72)
b
b
a
b
a
b
a
b
b
(0.88)
(0.73)
(0.78)
(0.71)
b
-1.63
b
c
c
c
c
(-2.00)c
(-1.56)c
(1.23)
(1.29)
(0.91)
(-1.75)
(-1.38)
-1.74 (2e)
-1.31 (2e)
-1.61
(-1.87)
(-1.46)
-2.15
-1.63
-1.79
b
b
b
a
(-1.91)f
(-2.09)
e
(1.13)
6
7
8
9
1
1
b
(1.19)
(0.88)
(0.87)
(0.84)
(0.87)
(0.58)
(1.52)
(1.48)
(1.52)
(1.43)
(1.45)
(0.83)
-1.24
-1.37
-1.38
-1.33
-1.33
-1.72
(-1.42)d
-1.53
-1.53
-1.48
-1.49
-1.84
Exp er im en ta l Section
6
-(Tr im eth ylsilyleth yn yl)a zu len e (14a ). TMSA (737 mg,
.50 mmol) was added to a solution of 13a (1.05 g, 5.07 mmol),
PPh (135 mg, 0.515 mmol), CuI (100 mg, 0.525 mmol), and
PdCl (PPh (177 mg, 0.252 mmol) in triethylamine (30 mL)
(-2.26)
(-2.26)
(-2.28)
7
0
1a
3
e
3 2
)
(1.00)
2
1
1
1b
2
(0.82)
(0.80)
(1.45)
(1.33)
-1.34 (2e)
-1.33
(-2.23)
-1.51
and toluene (60 mL). The resulting mixture was stirred at
room temperature for 2.5 h under an Ar atmosphere. The
reaction mixture was poured into a 10% NH
extracted with CH Cl . The organic layer was washed with
water and dried over MgSO . After the solvent was removed
4
Cl solution and
a
The redox potentials were measured by CV (0.1 M Et4NClO4
in benzonitrile, Pt electrode, scan rate ) 100 mV s-1, and Fc/Fc
0.15 V). In the case of irreversible waves, which are shown in
parentheses, Eox and Ered were calculated as Epa (anodic peak
potential) - 0.03 and Epc (cathodic peak potential) + 0.03 V,
respectively. The potentials were measured in 0.1 M Bu4NBF4
+
2
2
4
)
under reduced pressure, the residue was purified by column
chromatography on silica gel with hexane to afford 14a (978
mg, 86%): blue plates; mp 62-63 °C (MeOH/water); MS (70
b
+
+
c
eV) m/z (relative intensity) 224 (M , 100); IR (KBr disk) νmax
tetrahydrofuran solution (Fc/Fc ) 0.19 V). The values are peak
-1
d
2 2
2153 (CtC) cm ; UV-vis (CH Cl ) λmax, nm (log ꢀ) 237 (4.09),
potentials measured by DPV. The value represents two or three
electrons in one broad wave. E3 value. f E4 value.
e
ox
red
301 (4.88), 305 (4.84), 346 (3.78), 356 (3.96), 363 (3.90), 373
1
(
4.23), 618 (2.56), 671 (2.47), 748 (2.01); H NMR (400 MHz,
CDCl ) δ ) 8.22 (d, J ) 10.6 Hz, 2H, H4′,8′), 7.89 (t, J ) 3.8
Hz, 1H, H2′), 7.38 (d, J ) 3.8 Hz, 2H, H1′,3′), 7.36 (d, J ) 10.6
3
The electrochemical reduction of the cis-cobalt complex
showed a barely separated two-step reduction wave at
1/2 ) -1.37 and -1.53 V, which exhibited good revers-
ibility at the scan rate of 100 mV s (Figure 5a). The
trans-cobalt complex 8 also showed a similar two-step
reduction wave at E1/2 ) -1.38 and -1.53 V, which also
exhibited good reversibility under the same conditions
7
E
13
3
Hz, 2H, H5′,7′), 0.31 (s, 9H, 1-TMS); C NMR (100 MHz, CDCl )
δ ) 139.9 (C3′a,8′a), 137.7 (C2′), 135.0 (C4′,8′), 131.2 (C6′), 126.2
-
1
(C5′,7′), 119.0 (C1′,3′), 109.1 (C ), 96.9 (C ), -0.1 (1-TMS). Anal.
2
1
Calcd for C15H16Si: C, 80.30; H, 7.19. Found: C, 80.13; H, 7.47.
Diet h yl 6-(Tr im et h ylsilylet h yn yl)a zu len e-1,3-d ica r -
boxyla te (14b). The same procedure as was used for the
preparation of 14a was adopted. The reaction of 13b (1.76 g,
(
part b of Figure 5). The cobalt complexes 9-12 also
5
0
.01 mmol) with TMSA (760 mg, 7.74 mmol), PPh
3
(132 mg,
(176
showed similar reversible two-electron transfers upon
CV, as summarized in Table 1. Formally, the reduction
of 7-12 corresponds to the formation of a rare type of
.503 mmol), CuI (103 mg, 0.541 mmol), and PdCl (PPh )
2
3 2
mg, 0.251 mmol) in triethylamine (40 mL) and toluene (110
mL) for 1.5 h followed by column chromatography on silica
gel with CH Cl afforded 14b (1.55 g, 84%): purple needles;
2
0-electron cobalt complex.23
2
2
The electrochemical oxidation of 6b exhibited two
mp 170-174 °C (ethyl acetate); MS (70 eV) m/z (relative
+
intensity) 368 (M , 100); IR (KBr disk) νmax 2139 (CtC), 1680
irreversible waves at 1.19 and 1.52 V upon CV. The
electrochemical oxidation of 7-10, 11b, and 12 also
exhibited the similar two irreversible waves at 0.80-0.88
and 1.33-1.52 V upon CV. The electrochemical oxidation
of 6a and 11a showed three irreversible waves at 0.58-
.13 V owing to the lower oxidation potentials of the
substituted azulenes. These results are summarized in
Table 1. The first irreversible wave of 6b, 7-10, 11b, and
2 is probably due to the Co(I) oxidation and the second
-
1
(
(
(
1
4
CdO) cm ; UV-vis (CH Cl ) λmax, nm (log ꢀ) 234 (4.50), 274
2 2
1
4.18), 329 (4.88), 359 (4.28), 368 (4.32), 540 (2.79); H NMR
400 MHz, CDCl ) δ ) 9.63 (d, J ) 11.1 Hz, 2H, H4′,8′), 8.77 (s,
H, H2′), 7.84 (d, J ) 11.1 Hz, 2H, H5′,7′), 4.43 (q, J ) 7.1 Hz,
H, 1′,3′-COOEt), 1.45 (t, J ) 7.1 Hz, 6H, 1′,3′-COOEt), 0.32
(s, 9H, 1-TMS); C NMR (100 MHz, CDCl
COOEt), 143.8 (C2′), 143.5 (C3′a,8′a), 137.5 (C4′,8′), 135.9 (C6′),
33.5 (C5′,7′), 116.9 (C1′,3′), 107.4 (C ), 101.2 (C ), 60.1 (t, 1′,3′-
COOEt), 14.5 (q, 1′,3′-COOEt), -0.3 (1-TMS). Anal. Calcd for
Si: C, 68.45; H, 6.56. Found: C, 67.86; H, 6.25.
-Eth yn yla zu len e (15a ). A solution of KF (610 mg, 10.5
mmol) in water (3 mL) was added to a solution of 14a (1.15 g,
.13 mmol) in DMF (40 mL). After the mixture was stirred at
3
1
3
1
3
) δ ) 164.8 (s, 1′,3′-
1
2
1
1
21 24 4
C H O
one is attributable to the redox reaction of 6-azulenyl
groups, based on analogy with those of 6a and 11a and
6
those of 6b, 7-10, 11b, and 12. The relatively less
5
ox
positive E
2
value of 12 (1.33 V) could be rationalized
room temperature for 3 h, the reaction mixture was poured
into water and extracted with hexane. The organic layer was
washed with water, dried over MgSO , and concentrated under
4
by the contribution of the conjugation between two
-azulenyl groups and the cyclobutadiene ring due to the
least steric hindrance among these compounds.
Con clu sion . We have demonstrated the Pd-catalyzed
ethynylation of azulenes in a seven-membered ring using
bromoazulenes. We have demonstrated an efficient prepa-
ration of novel 6-azulenylbenzene derivatives by the
reaction of 6-azulenylacetylenes with 18. The cobalt-
6
reduced pressure. The residue was purified by recrystallization
from MeOH/water to afford 15a (613 mg, 79%): blue plates;
+
mp 82-84 °C; MS (70 eV) m/z (relative intensity) 152 (M ,
-1
1
00); IR (KBr disk) νmax 3305 (CtCH), 2103 (CtC) cm ; UV-
vis (CH
353 (3.76), 368 (3.84), 616 (2.54), 670 (2.46), 745 (2.04);
NMR (400 MHz, CDCl
2 2
Cl ) λmax, nm (log ꢀ) 234 (4.05), 293 (4.86), 338 (3.62),
1
H
3
) δ ) 8.22 (d, J ) 10.5 Hz, 2H, H4′,8′),
7
7
.89 (t, J ) 3.8 Hz, 1H, H2′), 7.38 (d, J ) 3.8 Hz, 2H, H1′,3′),
1
3
.35 (d, J ) 10.5 Hz, 2H, H5′,7′), 3.26 (s, 1H, H
) δ ) 140.0 (C3′a,8′a), 138.1 (C2′), 134.9 (C4′,8′), 130.7
(C6′), 126.2 (C5′,7′), 119.2 (C1′,3′), 87.6 (C ), 78.9 (C ). Anal. Calcd
for C12 : C, 94.70; H, 5.30. Found: C, 94.54; H, 5.36.
2
); C NMR (100
(23) Little is known about the reduction potentials of (cyclobutadi-
MHz, CDCl
3
ene)cobalt complexes: (a) Brotin, T.; Posp ´ı sil, L.; Fiedler, J .; King, B.
T.; Michl, J . J . Phys. Chem. B 1998, 102, 10062. (b) Iyoda, M.; Sultana,
F.; Sasaki, S.; Butensch o¨ n, H. Tetrahedron Lett. 1995, 36, 579.
1
2
H
8

Azulene-Substituted Benzene Derivatives
J . Org. Chem., Vol. 66, No. 21, 2001 7097
Sch em e 11
Sch em e 12
Sch em e 13
by column chromatography on silica gel with CH
2
Cl
2
afforded
1
0
1
1
5b (375 mg, 92%): purple needles; mp 175-176 °C dec (lit.
+
64-165 °C); MS (70 eV) m/z (relative intensity) 296 (M , 100);
IR (KBr disk) νmax 3235 (CtCH), 2093 (CtC), 1688 (CdO)
cm ; UV-vis (CH
-
1
2
Cl
2
) λmax, nm (log ꢀ) 233 (4.47), 274 (4.24),
1
3
21 (4.88), 346 (4.06), 354 (4.13), 378 (3.75), 541 (2.75);
H
NMR (400 MHz, CDCl
3
) δ ) 9.64 (d, J ) 11.1 Hz, 2H, H4′,8′),
8
7
6
1
1
.79 (s, 1H, H2′), 7.85 (d, J ) 11.2 Hz, 2H, H5′,7′), 4.43 (q, J )
.1 Hz, 4H, 1′,3′-COOEt), 3.48 (s, 1H, H
H, 1′,3′-COOEt); 13C NMR (100 MHz, CDCl
′,3′-COOEt), 144.1 (C2′), 143.6 (C3′a,8′a), 137.5 (C4′,8′), 134.7 (C6′),
33.5 (C5′,7′), 117.1 (C1′,3′), 86.2 (C ), 82.3 (C ), 60.2 (t, 1′,3′-
: C,
2
), 1.45 (t, J ) 7.1 Hz,
3
) δ ) 164.7 (s,
1
2
COOEt), 14.5 (q, 1′,3′-COOEt). Anal. Calcd for C18
16 4
H O
7
2.96; H, 5.44. Found: C, 72.91; H, 5.52.
3 4
Di(6-a zu len yl)a cetylen e (16a ). Pd(PPh ) (298 mg, 0.258
mmol) was added to a degassed solution of 13a (1.03 g, 4.97
mmol), 15a (761 mg, 5.00 mmol), PPh (134 mg, 5.11 mmol),
3
and CuI (108 mg, 5.67 mmol) in triethylamine (40 mL) and
toluene (200 mL). The resulting mixture was stirred at room
temperature for 18 h under an Ar atmosphere. The reaction
F igu r e 4. Cyclic voltammograms of (a) 4b and (b) 5b in THF
+
-
containing n-Bu
4
N BF
4
(0.1 M) as a supporting electrolyte.
mixture was poured into a 10% NH
with CH Cl . The organic layer was washed with water, dried
over MgSO , and concentrated under reduced pressure. The
residue was purified by recrystallization from CH Cl /hexane
4
Cl solution and extracted
Dieth yl 6-Eth yn yla zu len e-1,3-d ica r boxyla te (15b). The
same procedure as was used for the preparation of 15a was
adopted. The treatment of a solution of 14a (505 mg, 1.37
mmol) in THF (27 mL) and DMF (15 mL) with a solution of
KF (159 mg, 2.72 mmol) in water (0.5 mL) for 50 min followed
2
2
4
2
2
to afford 16a (1.35 g, 98%): green plates; mp 240-250 °C dec
+
(1,4-dioxane); MS (70 eV) m/z (relative intensity) 278 (M , 100);

7
098 J . Org. Chem., Vol. 66, No. 21, 2001
Ito et al.
CH
2
Cl
2
, washed with water, dried over MgSO
4
, and concen-
trated under reduced pressure. The residue was purified by
recrystallization from toluene to afford 17a (171 mg, 86%):
green needles; mp 200-210 °C dec (toluene); MS (70 eV) m/z
+
(
(
4
relative intensity) 302 (M , 100); UV-vis (CH
2
Cl
2
) λmax, nm
log ꢀ) 248 (4.39), 296 (4.76), 316 (4.78), 335 (4.70), 395 (4.65),
25 (4.73), 636 (2.94); H NMR (500 MHz, CDCl
1
3
) δ ) 8.25 (d,
J ) 10.4 Hz, 4H, H4′,8′), 7.92 (t, J ) 3.7 Hz, 2H, H2′), 7.42 (d,
1
3
J ) 3.7 Hz, 4H, H1′,3′), 7.40 (d, J ) 10.4 Hz, 4H, H5′,7′);
C
NMR (125 MHz, CDCl
(
(
3
) δ ) 140.2 (C3′a,8′a), 138.6 (C2′), 134.8
C
C
4′,8′), 130.2 (C6′), 126.3 (C5′,7′), 119.5 (C1′,3′), 87.8 (C1,4), 76.0
1
2,3). Anal. Calcd for C24
H
14‚ /
2
H
2
O: C, 92.58; H, 4.86.
Found: C, 92.23; H, 4.70.
Bis(1,3-dieth oxycar bon yl-6-azu len yl)diacetylen e (17b).
The same procedure as was used for the preparation of 17a
was adopted. The reaction of 15b (100 mg, 0.337 mmol) with
PdCl
triethylamine (0.15 mL) at 60 °C for 1 h under an O
atmosphere afforded 17b (58 mg, 58%): green needles; mp
300 °C (1,4-dioxane); MS (70 eV) m/z (relative intensity) 590
2 3 2
(PPh ) (10 mg, 0.014 mmol), CuI (2 mg, 0.01 mmol), and
2
>
+
-1
(
M , 100); IR (KBr disk) νmax 1694 (CdO) cm ; UV-vis
(CHCl ) λmax, nm (log ꢀ) 361 (4.79), 380 (4.80), 402 (4.73),
36 (4.79), 558 (3.26); H NMR (500 MHz, CDCl
(
4
2 2
)
1
3
) δ ) 9.70 (d,
J ) 11.1 Hz, 4H, H4′,8′), 8.84 (s, 2H, H2′), 7.91 (d, J ) 11.1 Hz,
4
7
H, H5′,7′), 4.45 (q, J ) 7.1 Hz, 8H, 1′,3′-COOEt), 1.46 (t, J )
.1 Hz, 12H, 1′,3′-COOEt); C NMR (125 MHz, CDCl , 50 °C)
3
13
δ ) 164.7 (s, 1′,3′-COOEt), 144.7 (C2′), 143.9 (C3′a,8′a), 137.4
(
(
C
C
4′,8′), 133.8 (C6′), 133.4 (C5′,7′), 117.8 (C1′,3′), 87.6 (C1,4), 78.4
2,3), 60.3 (t, 1′,3′-COOEt), 14.5 (q, 1′,3′-COOEt). Anal. Calcd
for C36
H
30
O
8
2
‚2H O: C, 69.00; H, 5.47. Found: C, 69.21; H, 5.55.
1
,2-Di(6-a zu len yl)tetr a p h en ylben zen e (2a ). A solution
of 16a (277 mg, 1.00 mmol) and 18 (2.70 g, 7.02 mmol) in
diphenyl ether (30 mL) was stirred at 160 °C for 41 h under
an Ar atmosphere. Column chromatography on silica gel with
hexane, followed with 80% CH
CHCl afforded 2a (80 mg, 13%): blue crystals; mp >300 °C
toluene/hexane); MS (FAB) m/z 634 (M ); UV-vis (CH
max, nm (log ꢀ) 237 (4.76), 283 (5.02), 352 (4.14), 578 (2.81);
2 2
Cl /hexane, and GPC with
3
+
(
2 2
Cl )
λ
F igu r e 5. Cyclic voltammograms of (a) cis-cobalt complex 7
and (b) trans-cobalt complex 8 in benzonitrile containing
1
H NMR (600 MHz, CDCl ) δ ) 7.82 (d, J ) 10.4 Hz, 4H, H4′,8′),
3
7
7
6
H
.64 (t, J ) 3.7 Hz, 2H, H2′), 7.05 (d, J ) 3.7 Hz, 4H, H1′,3′),
+
-
Et
4
N ClO
4
(0.1 M) as a supporting electrolyte.
.00 (d, J ) 10.4 Hz, 4H, H5′,7′), 6.88-6.83 (m, 10H, H2′′′-6′′′),
.80 (d, J ) 7.1 Hz, 4H, H2′′,6′′), 6.78 (dd, J ) 7.3, 7.1 Hz, 4H,
1
3
UV-vis (CH
2
Cl
2
) λmax, nm (log ꢀ) 255 (4.33), 288 (4.45), 309
3
3′′,5′′), 6.74 (t, J ) 7.3 Hz, 2H, H4′′); C NMR (150 MHz, CDCl )
1
(
4.66), 326 (4.86), 421 (4.72), 628 (2.91); H NMR (500 MHz,
δ ) 149.9 (C6′), 142.5 (C1,2), 140.9 (C3,6, C4,5, or C1′′′), 140.2 (C3,6
C4,5, or C1′′′), 140.0 (C3,6, C4,5, or C1′′′), 139.8 (C1′′), 138.8 (C3′a,8′a),
,
CDCl
3
) δ ) 8.29 (d, J ) 10.5 Hz, 4H, H4′,8′), 7.92 (t, J ) 3.7
Hz, 2H, H2′), 7.47 (d, J ) 10.5 Hz, 4H, H5′,7′), 7.42 (d, J ) 3.7
136.3 (C2′), 134.2 (C4′,8′), 131.3 (C2′′′,6′′′), 131.2 (C2′′,6′′), 127.4
(C5′,7′), 126.8 (C3′′,5′′), 126.7 (C3′′′,5′′′), 125.6 (C4′′), 125.4 (C4′′′), 117.5
(C1′,3′). Anal. Calcd for C34H30: C, 94.60; H, 5.40. Found: C,
1
3
Hz, 4H, H1′,3′); C NMR (125 MHz, CDCl
3
) δ ) 139.9 (C3′a,8′a),
38.1 (C2′), 135.0 (C4′,8′), 131.6 (C6′), 126.1 (C5′,7′), 119.2 (C1′,3′),
6.1 (C1,2). Anal. Calcd for C22 14: C, 94.93; H, 5.07. Found:
1
9
H
94.19; H, 5.58.
C, 94.44; H, 5.01.
1,2-Bis(1,3-d ieth oxyca r bon yl-6-a zu len yl)tetr a p h en yl-
ben zen e (2b). A solution of 16b (802 mg, 1.42 mmol) and 18
(3.80 g, 9.88 mmol) in diphenyl ether (30 mL) was stirred at
160 °C for 24 h under an Ar atmosphere. Column chromatog-
raphy on silica gel with hexane, followed with 5% ethyl acetate/
Bis(1,3-d ieth oxyca r bon yl-6-a zu len yl)a cetylen e (16b).
The same procedure as was used for the preparation of 16a
was adopted. The reaction of 13b (633 mg, 1.80 mmol) with
1
5b (524 mg, 1.77 mmol), Pd(PPh
PPh (47 mg, 0.16 mmol), and CuI (34 mg, 0.18 mmol) in
triethylamine (10 mL) and toluene (80 mL) for 1.5 h followed
by column chromatography on silica gel with CHCl afforded
6b (961 mg, 96%): green needles; mp 272-278 °C dec (1,4-
3 4
) (107 mg, 0.093 mmol),
3
CH
2 2 3
Cl , and GPC with CHCl afforded 2b (1.18 g, 90%): pink
crystals; mp >300 °C (toluene/hexane); MS (FAB) m/z 922
+
-1
3
(M ); IR (KBr disk) νmax 1690 (CdO) cm ; UV-vis (CH
2 2
Cl )
1
λ
1
max, nm (log ꢀ) 234 (4.97), 272 (4.72), 302 (4.87), 510 (3.13);
H NMR (600 MHz, CDCl ) δ ) 9.23 (d, J ) 11.1 Hz, 4H, H4′,8′),
3
+
dioxane); MS (70 eV) m/z (relative intensity) 566 (M , 100);
IR (KBr disk) νmax 1694 (CdO) cm ; UV-vis (CH
nm (log ꢀ) 237 (4.74), 266 (4.49), 360 (4.82), 378 (4.81), 401
-
1
2
Cl
2
) λmax
,
8.60 (s, 2H, H2′), 7.52 (d, J ) 11.1 Hz, 4H, H5′,7′), 6.91-6.85
(m, 10H, H2′′′-6′′′), 6.84 (d, J ) 7.1 Hz, 4H, H2′′,6′′), 6.79 (dd, J )
7.2, 7.1 Hz, 4H, H3′′,5′′), 6.75 (t, J ) 7.2 Hz, 2H, H4′′), 4.36-
4.28 (m, 8H, 1′,3′-COOEt), 1.36 (t, J ) 7.1 Hz, 12H, 1′,3′-
1
(
9
1
4.74), 425 (4.85), 551 (3.29); H NMR (400 MHz, CDCl
3
) δ )
.70 (d, J ) 11.1 Hz, 4H, H4′,8′), 8.82 (s, 2H, H2′), 7.95 (d, J )
1.1 Hz, 4H, H5′,7′), 4.45 (q, J ) 7.1 Hz, 8H, 1′,3′-COOEt), 1.47
COOEt); 13C NMR (150 MHz, CDCl
) δ ) 164.9 (s, 1′,3′-
3
1
3
(
t, J ) 7.1 Hz, 12H, 1′,3′-COOEt); C NMR (100 MHz, CDCl
3
)
COOEt), 153.4 (C6′), 143.3 (C2′), 142.6 (C3′a,8′a), 141.9 (C4,5),
140.9 (C1,2), 140.2 (C3,6), 139.5 (C1′′′), 138.8 (C1′′), 136.7 (C4′,8′),
134.4 (C5′,7′), 131.2 (C2′′,6′′), 131.1 (C2′′′,6′′′), 127.2 (C3′′,5′′), 126.8
(C3′′′,5′′′), 126.1 (C4′′), 125.7 (C4′′′), 116.2 (C1′,3′), 59.9 (t, 1′,3′-
δ ) 164.7 (s, 1′,3′-COOEt), 144.5 (C2′), 143.6 (C3′a,8′a), 137.5
(
C
4′,8′), 134.6 (C6′), 133.3 (C5′,7′), 117.4 (C1′,3′), 97.0 (C1,2), 60.3
t, 1′,3′-COOEt), 14.5 (q, 1′,3′-COOEt). Anal. Calcd for
: C, 72.07; H, 5.34. Found: C, 71.89; H, 5.58.
Di(6-a zu len yl)d ia cetylen e (17a ). PdCl (PPh (18 mg,
.026 mmol), CuI (5 mg, 0.03 mmol), and triethylamine (0.6
(
C
34
H
30
O
8
50 8
COOEt), 14.5 (q, 1′,3′-COOEt). Anal. Calcd for C62H O : C,
80.67; H, 5.46. Found: C, 80.31; H, 5.93.
6-(P h en yleth yn yl)a zu len e (19a ). Phenylacetylene (2.30
g, 22.5 mmol) was added to a solution of 13a (3.10 g, 15.0
2
3
)
2
0
mL) were added to a solution of 15a (200 mg, 1.31 mmol) in
toluene (2.6 mL). The resulting mixture was stirred at room
mmol), PPh
and PdCl (PPh
mL) and toluene (40 mL). The resulting mixture was stirred
3
(392 mg, 1.49 mmol), CuI (286 mg, 1.50 mmol),
temperature for 1 h under an O
mixture was poured into a 5% NH
2
atmosphere. The reaction
Cl solution, extracted with
2
3 2
)
(528 mg, 0.752 mmol) in triethylamine (40
4

Azulene-Substituted Benzene Derivatives
J . Org. Chem., Vol. 66, No. 21, 2001 7099
at room temperature for 5 h under an Ar atmosphere. The
(C3,5), 140.1 (C1′′′′), 139.9 (C1′′′), 139.6 (C2,6), 139.3 (C1′′), 136.4
(C4′,8′), 135.1 (C5′,7′), 131.3 (C2′′,6′′), 131.2 (C2′′′,6′′′ and C2′′′′,6′′′′), 127.1
(C3′′,5′′), 126.7 (C3′′′,5′′′ and C3′′′′,5′′′′), 125.8 (C4′′), 125.5 (C4′′′), 125.4
(C4′′′′), 115.5 (C1′,3′), 59.9 (t, 1′,3′-COOEt), 14.5 (q, 1′,3′-COOEt).
reaction mixture was poured into a 10% NH
extracted with toluene. The organic layer was washed with
water, dried over MgSO , and concentrated under reduced
4
Cl solution and
4
pressure. The residue was purified by column chromatography
on silica gel with toluene to afford 19a (3.07 g, 90%): blue
plates; mp 174-175 °C (toluene); MS (70 eV) m/z (relative
Anal. Calcd for C52
H, 6.06.
40 4
H O : C, 85.69; H, 5.53. Found: C, 85.05;
Rea ction of 16a w ith Cp Co(CO)
mg, 2.00 mmol) and CpCo(CO) (721 mg, 4.00 mmol) in 1,4-
dioxane (170 mL) was refluxed for 30 h. Column chromatog-
raphy on silica gel with 50% CH Cl /hexane afforded 6a (296
mg, 43%): brown crystals; mp >300 °C (toluene/hexane); MS
2
. A solution of 16a (558
+
-1
intensity) 228 (M , 100); IR (KBr disk) νmax 2203 (CtC) cm
Cl
2.03), 617 (2.58); H NMR (400 MHz, CDCl
;
2
UV-vis (CH
2
2
) λmax, nm (log ꢀ) 302 (4.67), 388 (4.44), 447
1
(
3
) δ ) 8.25 (d, J )
0.4 Hz, 2H, H4′,8′), 7.88 (t, J ) 3.5 Hz, 1H, H2′), 7.57 (m, 2H,
2′′,6′′), 7.42 (d, J ) 3.5 Hz, 2H, H5′,7′), 7.38 (d, J ) 10.4 Hz,
2
2
1
H
2
+
(FAB) m/z 680 (M ); UV-vis (CH
(4.68), 307 (5.04), 395 (4.54); H NMR (400 MHz, CDCl
2
Cl
2
) λmax, nm (log ꢀ) 246
) δ )
1
3
1
H, H1′,3′), 7.38-7.36 (m, 3H, H3′′,4′′,5′′); C NMR (100 MHz,
CDCl ) δ ) 139.7 (C3′a,8′a), 137.6 (C2′), 135.0 (C4′,8′), 132.3 (C6′),
31.9 (C2′′,6′′), 128.8 (C4′′), 128.5 (C3′′,5′′), 125.9 (C5′,7′), 122.8 (C1′′),
19.0 (C1′,3′), 93.9 (C ). Anal. Calcd for C18 12: C,
4.70; H, 5.30. Found: C, 94.73; H, 5.35.
Diet h yl 6-(P h en ylet h yn yl)a zu len e-1,3-d ica r b oxyla t e
19b). The same procedure as was used for the preparation of
9a was adopted. The reaction of 13b (9.19 g, 26.2 mmol) with
phenylacetylene (3.99 g, 39.1 mmol), PdCl (PPh (912 mg,
.30 mmol), PPh (688 mg, 2.62 mmol), and CuI (497 mg, 2.61
mmol) in triethylamine (100 mL) and toluene (100 mL) for 20
h followed by column chromatography on silica gel with CH
Cl afforded 19b (8.34 g, 86%): purple needles; mp 160 °C
toluene); MS (70 eV) m/z (relative intensity) 372 (M , 100);
3
3
8.05 (d, J ) 10.5 Hz, 8H, H4′,8′), 7.91 (t, J ) 3.8 Hz, 4H, H2′),
7.46 (d, J ) 10.4 Hz, 8H, H5′,7′), 7.33 (d, J ) 3.8 Hz, 8H, H1′,3′),
1
1
9
), 91.9 (s, C
2
H
4.78 (s, 5H, Cp); 13C NMR (100 MHz, CDCl
3
) δ ) 145.7 (C6′),
1
139.0 (C3′a,8′a), 136.9 (C2′), 134.8 (C4′,8′), 124.7 (C5′,7′), 119.1 (C1′,3′),
84.9 (Cp), 82.1 (C1,2,3,4). Anal. Calcd for C49
84.23; H, 5.05. Found: C, 83.77; H, 5.03.
Rea ction of 16b w ith Cp Co(CO)
mg, 1.59 mmol) and CpCo(CO) (491 mg, 2.73 mmol) in 1,4-
dioxane (700 mL) was refluxed for 40 h. To the mixture,
additional CpCo(CO) (286 mg, 1.59 mmol) was added, and
the mixture was further refluxed for 43 h. Column chroma-
tography on silica gel with 3% ethyl acetate/CH Cl afforded
H
2
33Co‚H O: C,
(
1
2
. A solution of 16b (900
2
3
)
2
2
1
3
2
2
-
2
2
2
+
(
6b (804 mg, 81%): brown crystals; mp >300 °C (toluene/
-
1
+
IR (KBr disk) νmax 1693 (CdO) cm ; UV-vis (CH
nm (log ꢀ) 237 (4.54), 270 (4.13), 313 (4.40), 350 (4.68), 392
2
Cl
2
) λmax
,
hexane); MS (FAB) m/z 1256 (M ); IR (KBr disk) νmax 1694
-
1
2 2
(CdO) cm ; UV-vis (CH Cl ) λmax, nm (log ꢀ) 242 (5.04), 268
1
1
(4.47), 458 (2.57), 536 (2.91); H NMR (400 MHz, CDCl
3
) δ )
(4.84), 337 (4.95), 365 (4.95), 383 (4.94), 418 (4.65); H NMR
(600 MHz, CDCl ) δ ) 9.52 (d, J ) 10.9 Hz, 8H, H4′,8′), 8.86 (s,
9
1
3
)
1
1
1
.69 (d, J ) 10.3 Hz, 2H, H4′,8′), 8.79 (s, 1H, H2′), 7.92 (d, J )
3
0.3 Hz, 2H, H5′,7′), 7.63-7.61 (m, 2H, H2′′,6′′), 7.43-7.42 (m,
H, H3′′,4′′,5′′), 4.44 (q, J ) 7.1 Hz, 4H, 1′,3′-COOEt), 1.46 (t, J
4H, H2′), 7.90 (d, J ) 10.9 Hz, 8H, H5′,7′), 4.91 (s, 5H, Cp), 4.42
(q, J ) 7.1 Hz, 16H, 1′,3′-COOEt), 1.44 (t, J ) 7.1 Hz, 24H,
1
3
13
7.1 Hz, 6H, 1′,3′-COOEt); C NMR (150 MHz, CDCl
64.8 (s, 1′,3′-COOEt), 143.5 (C2′), 143.2 (C3′a,8′a), 137.4 (C4′,8′),
36.4 (C6′), 133.2 (C5′,7′), 132.1 (C3′′,5′′), 129.5 (C4′′), 128.6 (C2′′,6′′),
3
) δ )
3
1′,3′-COOEt); C NMR (150 MHz, CDCl ) δ ) 164.8 (s, 1′,3′-
COOEt), 148.7 (C6′), 143.6 (C2′), 142.7 (C3′a,8′a), 137.3 (C4′,8′),
131.0 (C5′,7′), 117.6 (C1′,3′), 85.5 (Cp), 81.6 (C1,2,3,4), 60.2 (t, 1′,3′-
22.0 (C1′′), 116.9 (C1′,3′), 95.4 (C
2
), 92.7 (C
1
), 60.1 (t, 1′,3′-
: C,
COOEt), 14.6 (q, 1′,3′-COOEt). Anal. Calcd for C73
O: C, 68.75; H, 5.30. Found: C, 69.08; H, 5.26.
Rea ction of 14b w ith Cp Co(CO) . A solution of 14b (478
mg, 1.30 mmol) and CpCo(CO) (402 mg, 2.23 mmol) in 1,4-
dioxane (130 mL) was refluxed for 24 h. To the mixture,
additional CpCo(CO) (400 mg, 2.22 mmol) was added, and
the mixture was further refluxed for 40 h. Column chroma-
tography on silica gel with CHCl afforded a mixture (1:4.1)
of 7 and 8 (456 mg, 82%). The products 7 and 8 were separated
by GPC with CHCl . 7: reddish brown crystals; mp 161-167
°C (hexane); MS (70 eV) m/z (relative intensity) 860 (M , 100);
65
H O16Co‚
COOEt), 14.5 (q, 1′,3′-COOEt). Anal. Calcd for C24
7.40; H, 5.41. Found: C, 77.10; H, 5.20.
6-Azu len yl)p en ta p h en ylben zen e (3a ). A solution of 19a
685 mg, 3.00 mmol) and 18 (8.01 g, 20.8 mmol) in diphenyl
H
20
O
4
H
2
7
2
(
2
(
ether (30 mL) was stirred at 140 °C for 5 d under an Ar
atmosphere. Column chromatography on silica gel with hex-
2
ane, followed with CH
2
Cl
2
/hexane (1:1), and GPC with CHCl
3
3
afforded 3a (559 mg, 32%): blue crystals; mp >300 °C
+
(
toluene); MS (70 eV) m/z (relative intensity) 584 (M , 100);
UV-vis (CH Cl ) λmax, nm (log ꢀ) 239 (4.68), 299 (4.68), 335
3.84), 351 (3.88), 368 (3.42), 578 (3.50), 618 (3.43), 686 (2.96);
3
+
2
2
-
1
(
IR (KBr disk) νmax 1694 (CdO) cm ; UV-vis (CH
2 2
Cl ) λmax,
1
H NMR (600 MHz, CDCl ) δ ) 7.87 (d, J ) 10.5 Hz, 2H, H4′,8′),
3
nm (log ꢀ) 238 (4.81), 271 (4.72), 314 (4.73), 363 (4.66), 378
1
7
6
6
.70 (t, J ) 3.7 Hz, 1H, H2′), 7.12 (d, J ) 3.7 Hz, 2H, H1′,3′),
(4.64), 434 (4.30); H NMR (400 MHz, CDCl
11.3 Hz, 4H, H4′,8′), 8.77 (s, 2H, H2′), 7.76 (d, J ) 11.3 Hz, 4H,
5′,7′), 4.88 (s, 5H, Cp), 4.41 (q, J ) 7.2 Hz, 8H, 1′,3′-COOEt),
1.43 (t, J ) 7.2 Hz, 12H, 1′,3′-COOEt), 0.30 (s, 18H, 1,2-TMS);
3
) δ ) 9.48 (d, J )
.94 (d, J ) 10.5 Hz, 2H, H5′,7′), 6.88 (d, J ) 7.2 Hz, 4H, H2′′,6′′),
.87-6.83 (m, 15H, H2′′′-6′′′ and H2′′′′-6′′′′), 6.78 (dd, J ) 7.2, 7.2
H
1
3
Hz, 4H, H3′′,5′′), 6.73 (t, J ) 7.2 Hz, 2H, H4′′); C NMR (150
1
3
MHz, CDCl
(
3
) δ ) 150.7 (C6′), 143.2 (C
1
), 140.7 (C
4
or C1′′′′), 140.5
3
C NMR (100 MHz, CDCl ) δ ) 165.1 (s, 1′,3′-COOEt), 152.6
C
3,5 or C1′′′), 140.4 (C or C1′′′′), 140.3 (C3,5 or C1′′′), 140.0 (C1′′),
4
(C6′), 142.4 (C4′,8′ and C3′a,8′a), 136.9 (C2′), 131.4 (C5′,7′), 116.8
(C1′,3′), 91.6 (C3,4), 82.4 (Cp), 72.5 (C1,2), 60.0 (t, 1′,3′-COOEt),
1
39.7 (C2,6), 138.8 (C3′a,8′a), 136.0 (C2′), 134.2 (C4′,8′), 131.4
2′′′,6′′′), 131.3 (C2′′,6′′ and C2′′′′,6′′′′), 127.6 (C5′,7′), 126.7 (C3′′,5′′),
26.6 (C3′′′,5′′′ and C3′′′′,5′′′′), 125.5 (C4′′), 125.3 (C4′′′ and C4′′′′), 117.2
(C
14.6 (q, 1′,3′-COOEt), 2.0 (1,2-TMS). Anal. Calcd for C47
Si Co‚H O: C, 64.22; H 6.31. Found: C, 64.38; H, 6.07. 8:
reddish brown prisms; mp 286-288 °C (CH Cl /hexane); MS
(70 eV) m/z (relative intensity) 860 (M , 100); IR (KBr disk)
53 8
H O -
1
2
2
(C
1′,3′). Anal. Calcd for C46
H
32: C, 94.48; H, 5.52. Found: C,
2
2
+
9
3.88; H, 5.84.
-
1
(
1,3-Diet h oxyca r b on yl-6-a zu len yl)p en t a p h en ylb en -
ν
max 1692 (CdO) cm ; UV-vis (CH
2 2
Cl ) λmax, nm (log ꢀ) 238
zen e (3b). A solution of 19b (729 mg, 1.96 mmol) and 18 (5.28
g, 13.7 mmol) in diphenyl ether (40 mL) was stirred at 160 °C
for 5 d under an Ar atmosphere. Column chromatography on
(4.80), 271 (4.67), 317 (4.67), 366 (4.61), 378 (4.62), 455 (4.51);
1
H NMR (400 MHz, CDCl ) δ ) 9.56 (d, J ) 11.1 Hz, 4H, H4′,8′),
3
8.75 (s, 2H, H2′), 7.82 (d, J ) 11.1 Hz, 4H, H5′,7′), 4.88 (s, 5H,
Cp), 4.44 (q, J ) 7.1 Hz, 8H, 1′,3′-COOEt), 1.46 (t, J ) 7.1 Hz,
12H, 1′,3′-COOEt), 0.29 (s, 18H, 1,3-TMS); 13C NMR (100 MHz,
CDCl ) δ ) 165.2 (s, 1′,3′-COOEt), 155.2 (C6′), 142.5 (C3′a,8′a),
3
142.1 (C2′), 136.5 (C4′,8′), 131.3 (C5′,7′), 116.6 (C1′,3′), 92.7 (C2,4),
82.4 (Cp), 72.8 (C1,3), 60.0 (t, 1′,3′-COOEt), 14.6 (q, 1′,3′-
2 2
silica gel with hexane, followed with CH Cl /hexane (1:1), and
GPC with CHCl
300 °C (CH Cl
3
afforded 3b (1.32 g, 93%): pink needles; mp
+
>
2
2
/hexane); MS (FAB) m/z 728 (M ); IR (KBr
-
1
disk) νmax 1694 (CdO) cm ; UV-vis (CH
2
Cl
2
) λmax, nm (log ꢀ)
1
2
36 (4.85), 270 (4.55), 320 (4.56), 503 (2.90); H NMR (600
MHz, CDCl
3
) δ ) 9.27 (d, J ) 11.1 Hz, 2H, H4′,8′), 8.64 (s, 1H,
COOEt), 1.7 (1,3-TMS). Anal. Calcd for C47
C, 64.22; H, 6.31. Found: C, 64.06; H, 6.26.
H
53
O
8
Si
2
2
Co‚H O:
H
2′), 7.50 (d, J ) 11.1 Hz, 2H, H5′,7′), 6.90-6.84 (m, 15H, H2′′′-6′′′
and H2′′′′-6′′′′), 6.83 (d, J ) 7.0 Hz, 4H, H2′′,6′′), 6.78 (dd, J ) 7.2,
Rea ction of 19b w ith Cp Co(CO)
mg, 2.00 mmol) and CpCo(CO) (720 mg, 4.00 mmol) in 1,4-
dioxane (170 mL) was refluxed for 18 h. Column chromatog-
raphy on silica gel with ethyl acetate/CHCl afforded a mixture
(1:1.1) of 9 and 10 (817 mg, 94%). The products 9 and 10 were
2
. A solution of 19b (745
7
7
.0 Hz, 4H, H3′′,5′′), 6.74 (t, J ) 7.2 Hz, 2H, H4′′), 4.35 (q, J )
.1 Hz, 4H, 1′,3′-COOEt), 1.40 (t, J ) 7.1 Hz, 6H, 1′,3′-COOEt);
2
1
3
C NMR (150 MHz, CDCl
3
) δ ) 165.1 (s, 1′,3′-COOEt), 155.3
), 141.5 (C ), 140.8
3
(C
6′), 142.8 (C3′a,8′a), 142.7 (C2′), 141.7 (C
1
4

7
100 J . Org. Chem., Vol. 66, No. 21, 2001
Ito et al.
separated by GPC with CHCl
3
. 9: reddish brown crystals; mp
1H NMR (600 MHz, CDCl
3
) δ ) 9.88 (d, J ) 11.0 Hz, 6H, H4′,8′),
+
2
90-296 °C (1,4-dioxane); MS (FAB) m/z 868 (M ); IR (KBr
8.87 (s, 3H, H2′), 8.06 (d, J ) 11.0 Hz, 6H, H5′,7′), 8.05 (s, 3H,
-
1
disk) νmax 1688 (CdO) cm ; UV-vis (CH
2
2
Cl
2
) λmax, nm (log ꢀ)
H2,4,6), 4.45 (q, J ) 7.1 Hz, 12H, 1′,3′-COOEt), 1.46 (t, J ) 7.1
13
39 (4.89), 271 (4.69), 319 (4.78), 365 (4.63), 380 (4.63), 414
3
Hz, 18H, 1′,3′-COOEt); C NMR (150 MHz, CDCl ) δ ) 164.9
1
(4.37), 458 (4.32); H NMR (600 MHz, CDCl
3
) δ ) 9.47 (d, J )
(s, 1′,3′-COOEt), 152.8 (C6′), 145.6 (C1,3,5), 144.0 (C2′), 142.9
(C3′a,8′a), 138.6 (C4′,8′), 130.6 (C5′,7′), 129.3 (C2,4,6), 117.1 (C1′,3′),
30.2 (t, 1′,3′-COOEt), 14.6 (q, 1′,3′-COOEt). Anal. Calcd for
1
H
H
4
1
1.1 Hz, 4H, H4′,8′), 8.80 (s, 2H, H2′), 7.94 (d, J ) 11.1 Hz, 4H,
5′,7′), 7.45 (d, J ) 7.1 Hz, 4H, H2′′,6′′), 7.35 (t, J ) 7.5 Hz, 2H,
4′′), 7.29 (dd, J ) 7.5, 7.1 Hz, 4H, H3′′,5′′), 4.75 (s, 5H, Cp),
C
54
H
48
O
12‚H
2
O: C, 71.51; H, 5.56. Found: C, 71.39; H, 5.59.
.42 (q, J ) 7.1 Hz, 8H, 1′,3′-COOEt), 1.44 (t, J ) 7.1 Hz, 12H,
5b: pink crystals; mp 150-153 °C (ethyl acetate/hexane); MS
13
+
-1
′,3′-COOEt); C NMR (150 MHz, CDCl
3
) δ ) 165.1 (s, 1′,3′-
(FAB) m/z 888 (M ); IR (KBr disk) νmax 1694 (CdO) cm ; UV-
vis (CH Cl ) λmax, nm (log ꢀ) 237 (4.97), 271 (4.75), 337 (5.02),
515 (3.40); H NMR (600 MHz, CDCl
COOEt), 152.8 (C6′), 142.5 (C2′ and C3′a,8′a), 137.2 (C4′,8′), 133.6
2
2
1
(
(
C
C
1′′), 130.9 (C5′,7′), 129.4 (C2′′,6′′), 128.5 (C3′′,5′′), 127.6 (C4′′), 117.0
1′,3′), 84.4 (Cp), 80.3 (C3,4), 77.6 (C1,2), 60.1 (t, 1′,3′-COOEt),
3
) δ ) 9.88 (d, J ) 11.0
Hz, 2H, H4′′′,8′′′), 9.59 (d, J ) 11.0 Hz, 2H, H4′′,8′′), 9.58 (d, J )
11.0 Hz, 2H, H4′,8′), 8.87 (s, 1H, H2′′′), 8.79 (s, 2H, H2′ and H2′′),
8.05 (d, J ) 11.0 Hz, 2H, H5′′′,7′′′), 7.92 (dd, J ) 7.9, 1.9 Hz, 1H,
1
7
4.6 (q, 1′,3′-COOEt). Anal. Calcd for C53
0.35; H, 5.46. Found: C, 70.51; H, 5.24. 10: reddish brown
H
45
O
8
2
Co‚2H O: C,
crystals; mp >300 °C (ethyl acetate/hexane); MS (FAB) m/z
H
5
), 7.91 (d, J ) 1.9 Hz, 1H, H
3
), 7.77 (d, J ) 7.9 Hz, 1H, H
6
),
+
-1
8
68 (M ); IR (KBr disk) νmax 1690 (CdO) cm ; UV-vis (CH
Cl ) λmax, nm (log ꢀ) 240 (4.92), 267 (4.73), 333 (4.71), 362 (4.69),
78 (4.68), 448 (4.58); H NMR (600 MHz, CDCl
2
-
7.70 (d, J ) 11.0 Hz, 2H, H5′′,7′′), 7.68 (d, J ) 11.0 Hz, 2H,
2
H5′,7′), 4.46 (q, J ) 7.1 Hz, 4H, 1′′′,3′′′-COOEt), 4.39 (q, J ) 7.1
1
3
3
) δ ) 9.36 (d,
Hz, 8H, 1′,3′- and 1′′,3′′-COOEt), 1.48 (t, J ) 7.1 Hz, 6H, 1′′′,3′′′-
COOEt), 1.42 (t, J ) 7.1 Hz, 6H, 1′,3′- or 1′′,3′′-COOEt), 1.41
J ) 11.1 Hz, 4H, H4′,8′), 8.73 (s, 2H, H2′), 7.76 (d, J ) 11.1 Hz,
1
3
4
2
H, H5′,7′), 7.65 (d, J ) 6.9 Hz, 4H, H2′′,6′′), 7.45 (t, J ) 7.5 Hz,
H, H4′′), 7.41 (dd, J ) 7.5, 6.9 Hz, 4H, H3′′,5′′), 4.76 (s, 5H,
(t, J ) 7.1 Hz, 6H, 1′,3′- or 1′′,3′′-COOEt); C NMR (150 MHz,
CDCl
COOEt), 152.7 (C6′′), 152.6 (C6′), 152.5 (C6′′′), 144.3 (C
(C2′ or C2′′), 143.9 (C2′ or C2′′), 143.8 (C2′′′), 143.5 (C ), 143.1 (C
142.9 (C3′′′a,8′′′a), 142.8 (C3′a,8′a and C3′′a,8′′a), 138.6 (C4′′′,8′′′), 138.0
(C4′,8′ and C4′′,8′′), 132.6 (C5′,7′ and C5′′,7′′), 132.1 (C
130.5 (C5′′′,7′′′), 129.1 (C ), 117.1 (C1′,3′ or C1′′,3′′), 117.0 (C1′,3′, C1′′,3′′
3
) δ ) 164.9 (s, 1′′′,3′′′-COOEt), 164.8 (s, 1′,3′- and 1′′,3′′-
), 144.0
),
Cp), 4.40 (q, J ) 7.1 Hz, 8H, 1′,3′-COOEt), 1.43 (t, J ) 7.1 Hz,
4
1
1
1
1
2H, 1′,3′-COOEt); 13C NMR (150 MHz, CDCl
′,3′-COOEt), 153.5 (C6′), 142.5 (C3′a,8′a), 142.1 (C2′), 137.1 (C4′,8′),
33.1 (C1′′), 130.6 (C2′′,6′′), 129.8 (C5′,7′), 128.9 (C3′′,5′′), 128.2 (C4′′),
16.6 (C1′,3′), 84.2 (Cp), 80.3 (C2,4), 77.8 (C1,3), 60.0 (t, 1′,3′-
3
) δ ) 165.1 (s,
2
1
6
3
), 131.5 (C ),
5
,
COOEt), 14.6 (q, 1′,3′-COOEt). Anal. Calcd for C53
H
45
O
8
Co:
and/or C1′′′,3′′′), 60.2 (t, 1′′′,3′′′-COOEt), 60.1 (t, 1′,3′- and 1′′,3′′-
C, 73.27; H, 5.22. Found: C, 72.95; H, 5.33.
COOEt), 14.6 (q, 1′′′,3′′′-COOEt), 14.5 (q, 1′,3′- and 1′′,3′′-
1
Rea ction of 15a w ith Cp Co(CO)
g, 6.57 mmol) and CpCo(CO) (1.22 g, 6.78 mmol) in 1,4-
dioxane (400 mL) was refluxed for 43 h. Column chromatog-
raphy on silica gel with 50% CH Cl /hexane and GPC with
CHCl afforded 4a (5 mg, 0.5%), 5a (3 mg, 0.3%), and 11a (274
mg, 19%). 4a : MS (70 eV) m/z (relative intensity) 456 (M ,
2
. A solution of 15a (1.00
COOEt). Anal. Calcd for C54
Found: C, 72.14; H, 5.48. 11b: brown crystals; mp 254 °C
(ethyl acetate/hexane); MS (FAB) m/z 716 (M ); IR (KBr disk)
H
48
O
12‚ /
2
H
2
O: C, 72.23; H, 5.50.
2
+
-
1
2
2
ν
max 1686 (CdO) cm ; UV-vis (CH
(4.83), 265 (4.63), 313 (4.61), 361 (4.72), 377 (4.69); H NMR
(600 MHz, CDCl
2 2
Cl ) λmax, nm (log ꢀ) 240
1
3
+
3
) δ ) 9.51 (d, J ) 11.1 Hz, 4H, H4′,8′), 8.76 (s,
1
1
6
7
00); H NMR (600 MHz, CDCl
3
) δ ) 8.46 (d, J ) 10.4 Hz,
2H, H2′), 7.80 (d, J ) 11.1 Hz, 4H, H5′,7′), 4.92 (s, 2H, H3,4),
H, H4′,8′), 7.96 (s, 3H, H2,4,6), 7.95 (t, J ) 3.7 Hz, 3H, H2′),
.53 (d, J ) 10.4 Hz, 6H, H5′,7′), 7.46 (d, J ) 3.7 Hz, 6H, H1′,3′);
C NMR (150 MHz, CDCl
4.80 (s, 5H, Cp), 4.43 (q, J ) 7.1 Hz, 8H, 1′,3′-COOEt), 1.45 (t,
J ) 7.1 Hz, 12H, 1′,3′-COOEt); 13C NMR (150 MHz, CDCl
) δ
3
1
3
3
) δ ) 150.1 (C6′), 146.4 (C1,3,5), 139.1
) 165.0 (s, 1′,3′-COOEt), 154.2 (C6′), 142.1 (C2′ and C3′a,8′a),
(C
3′a,8′a), 137.4 (C2′), 135.9 (C4′,8′), 128.3 (C2,4,6), 123.4 (C5′,7′),
18.8 (C1′,3′). HRMS calcd for C36 24 456.1878, found 456.1880.
a : MS (70 eV) m/z (relative intensity) 456 (M , 90); H NMR
) δ ) 8.44 (d, J ) 10.5 Hz, 2H, H4′′′,8′′′), 8.16
d, J ) 10.5 Hz, 4H, H4′,8′ and H4′′,8′′), 7.93 (t, J ) 3.7 Hz, 1H,
2′′′), 7.84 (d, J ) 2.0 Hz, 1H, H ), 7.84 (t, J ) 3.7 Hz, 2H, H2′
and H2′′), 7.79 (dd, J ) 8.0, 2.0 Hz, 1H, H ), 7.67 (d, J ) 8.0
Hz, 1H, H ), 7.51 (d, J ) 10.5 Hz, 2H, H5′′′,7′′′), 7.45 (d, J ) 3.7
Hz, 2H, H1′′′,3′′′), 7.30 (d, J ) 3.7 Hz, 4H, H1′,3′ and H1′′,3′′), 7.20
d, J ) 10.5 Hz, 2H, H5′′,7′′), 7.18 (d, J ) 10.5 Hz, 2H, H5′,7′);
137.4 (C4′,8′), 128.5 (C5′,7′), 117.0 (C1′,3′), 81.9 (Cp), 78.9 (C1,2),
1
5
(
(
H
61.9 (C3,4), 60.0 (t, 1′,3′-COOEt), 14.6 (q, 1′,3′-COOEt). Anal.
+
1
1
Calcd for C41
H
37
O
8
Co‚ /
2
H
2
O: C, 67.86; H, 5.28. Found: C,
600 MHz, CDCl
3
67.60; H, 5.32.
5
(η -Cyclop en ta d ien yl)[1,3-bis(1,3-d ieth oxyca r bon yl-6-
4
a zu len yl)cyclobu ta d ien e]coba lt (12). A solution of n-Bu -
H
3
5
NF (1.0 M, 0.8 mL) in THF was added to a solution of 8 (69
mg, 0.080 mmol) in the same solvent (2 mL). The mixture was
stirred at room temperature for 30 min. The reaction mixture
6
(
was poured into water and extracted with CH . The organic
2
Cl
2
1
3
C NMR (150 MHz, CDCl
or C6′′), 149.7 (C6′′′), 144.9 (C
3a′′′,8a′′′), 139.0 (C3a′′,8a′′), 138.9 (C3a′,8a′), 137.3 (C2′′′), 137.2 (C2′
and C2′′), 135.9 (C4′′′,8′′′), 135.4 (C4′,8′ and C4′′,8′′), 131.5 (C
3
) δ ) 150.3 (C6′ or C6′′), 150.1 (C6′
4
layer was washed with water, dried over MgSO , and concen-
4
), 144.5 (C ), 143.7 (C ), 139.1
2
1
trated under reduced pressure. The residue was purified by
column chromatography on silica gel with 5% ethyl acetate/
(C
6
), 131.2
CH
2 2
Cl to afford 12 (30 mg, 53%): brown crystals; mp >300
+
(
(
C
C
3
), 128.0 (C
5
), 125.6 (C5′′,7′′), 125.5 (C5′,7′), 123.2 (C5′′′,7′′′), 118.7
°C (ethyl acetate); MS (70 eV) m/z (relative intensity) 716 (M ,
-
1
1′′′,3′′′), 118.5 (C1′,3′ or C1′′,3′′), 118.4 (C1′,3′ or C1′′,3′′). HRMS calcd
100); IR (KBr disk) νmax 1688 (CdO) cm ; UV-vis (CH
2 2
Cl )
for C36
H
24 456.1878, found 456.1888. 11a : brown crystals; mp
λmax, nm (log ꢀ) 240 (4.81), 268 (4.64), 341 (4.61), 362 (4.64),
+
1
1
75-180 °C (hexane); MS (FAB) m/z 428 (M , 100); UV-vis
3
465 (4.71); H NMR (600 MHz, CDCl ) δ ) 9.50 (d, J ) 11.1
(CH
2
Cl
2
1
) λmax, nm (log ꢀ) 237 (4.55), 295 (4.82), 329 (4.60), 394
) δ ) 8.12 (d, J ) 10.5 Hz,
Hz, 4H, H4′,8′), 8.72 (s, 2H, H2′), 7.53 (d, J ) 11.1 Hz, 4H, H5′,7′),
5.56 (s, 2H, H2,4), 4.65 (s, 5H, Cp), 4.43 (q, J ) 7.1 Hz, 8H,
(4.35); H NMR (400 MHz, CDCl
3
1
3
4
4
H, H4′,8′), 7.84 (t, J ) 3.7 Hz, 2H, H2′), 7.37 (d, J ) 10.5 Hz,
H, H5′,7′), 7.29 (d, J ) 3.7 Hz, 4H, H1′,3′), 4.77 (s, 5H, Cp), 4.73
1′,3′-COOEt), 1.45 (t, J ) 7.1 Hz, 12H, 1′,3′-COOEt); C NMR
(150 MHz, CDCl
3
) δ ) 165.1 (s, 1′,3′-COOEt), 153.8 (C6′), 142.0
(C3′a,8′a), 141.6 (C2′), 137.6 (C4′,8′), 125.7 (C5′,7′), 116.9 (C1′,3′), 81.8
region (C1,3) confirmed by a 2D
1
3
(
(
(
s, 2H, H3,4); C NMR (100 MHz, CDCl
3′a,8′a), 135.7 (C2′), 135.1 (C4′,8′), 121.9 (C5′,7′), 118.7 (C1′,3′), 81.5
Cp), 80.3 (C1,2), 59.9 (C3,4). Anal. Calcd for C29
21Co‚1/
3
) δ ) 149.6 (C6′), 138.5
C
(Cp), a signal in CDCl
3
H
2
H
2
O:
heteronuclear multiple-bond correlation (HMBC) spectrum,
60.0 (t, 1′,3′-COOEt), 57.9 (C2,4), 14.6 (q, 1′,3′-COOEt). Anal.
C, 79.63; H, 5.07. Found: C, 80.04; H, 5.12.
Rea ction of 15b w ith Cp Co(CO) . A solution of 15b (593
mg, 2.00 mmol) and CpCo(CO) (360 mg, 2.00 mmol) in 1,4-
dioxane (170 mL) was refluxed for 44 h. Column chromatog-
raphy on silica gel with 10% ethyl acetate/CH Cl afforded a
mixture (2.5:1) of 4b and 5b (125 mg, 21%) and 11b (334 mg,
7%). The products 4b and 5b were separated by silica gel
2
Calcd for C41
H, 5.26.
H
37
O
8
2
Co‚H O: C, 67.03; H, 5.35. Found: C, 67.09;
2
X-r a y Cr ysta llogr a p h ic Da ta for 8. Data and diffraction
parameters were obtained for a crystal with dimensions of 0.07
× 0.15 × 0.20 mm using a Rigaku/MSC mercury CCD
diffractometer with Mo KR radiation (λ ) 0.710 69 Å) at -103
°C. Crystal system: triclinic. Space group: P 1h . Unit cell
dimensions: a ) 9.634(3) Å, b ) 10.536(2) Å, c ) 22.457(4) Å,
R ) 91.034(8)°, â ) 90.12(1)°, γ ) 106.414(2)°, V ) 2186.3(9)
2
2
4
preparative TLC with 30% ethyl acetate/hexane. 4b: pink
crystals; mp >300 °C (ethyl acetate/hexane); MS (FAB) m/z
+
-1
8
Cl
2
88 (M ); IR (KBr disk) νmax 1694 (CdO) cm ; UV-vis (CH -
2
3
-3
-1
) λmax, nm (log ꢀ) 237 (4.94), 273 (4.68), 333 (5.18), 517 (3.36);
Å , and Z ) 2. Dcalcd ) 1.308 g cm . µ (Mo KR) ) 5.00 cm .

Azulene-Substituted Benzene Derivatives
J . Org. Chem., Vol. 66, No. 21, 2001 7101
F(000) ) 908. 2θ range for data collection ) 0.0-55.0°. Number
of measured reflections ) 15 735. Independent reflections )
were performed using the software package of Molecular
Structure Corporation (Crystal Structure Analysis Package,
Molecular Structure Corporation, 1985 and 1999).
8
675 (Rint ) 0.027). Final R ) 0.056, R
observed reflections (I > 2σ (I
.10. ∆Fmax and ∆Fmin are 0.37 and -0.43 e-
Refinement method: full matrix least-squares. All calculations
w
) 0.169 for 5956
0
0
)). Parameters ) 523. GOF )
-3
1
Å
, respectively.
J O010540U