A divergent method for preparing 1-aryl- and 1,3-diarylazulenes from ethyl 3-(cyclohepta-1,3,5-trien-1-yl)-3-oxopropionate

Article abstract of DOI:10.1055/s-1999-3546

The 3-aryl substituted 1,2,3,8-tetrahydroazulen-1-ones 3, prepared by the Knoevenagel condensation of ethyl 3-(cyclohepta-1,3,5-trien-1-yl)-3- oxopropionate (6) with arylaldehydes and subsequent Nazarov cyclization, were efficiently transformed into 1-aryl- and 1,3-diarylazulenes in a few steps.

Full text of DOI:10.1055/s-1999-3546

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Mitsunori Oda,* Takanori Kajioka, Kanae Haramoto, Ryuta Miyatake, Shigeyasu Kuroda*
Department of Applied Chemistry, Faculty of Engineering, Toyama University, Gofuku 3190, Toyama 930-8555, Japan
Fax +81(764) 45 6819; Eꢀmail: oda@eng.toyama-u.ac.jp
5HFHLYHGꢁꢂꢃꢁ$SULOꢁꢂꢄꢄꢄ
O
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$EVWUDFWꢉ The 3-aryl substituted 1,2,3,8-tetrahydroazulen-1-ones
ꢁ, prepared by the Knoevenagel condensation of ethyl 3-(cyclohep-
ta-1,3,5-trien-1-yl)-3-oxopropionate (ꢊ) with arylaldehydes and
subsequent Nazarov cyclization, were efficiently transformed into
1-aryl- and 1,3-diarylazulenes in a few steps.
CO2Et
CO2Et
ArCHO, p-TsOH
piperidine
82-93%
Ar
7a-d
6
.H\ ZRUGVꢉ azulenes, azulenones, Nazarov cyclization, dehydroge-
nation
TMSOTf
H3PO4
86-91%
40-74%
HCO2H
Although tetrahydroazulen-1-ones1 can be used as syn-
thetic intermediates for azulenes,2 homoazulenes,3
bridged homotropylium cations,4 and guaiazulene-type
sesquiterpenes,5 there are only a few convenient methods
for their preparation.2,6,7 We reported a synthetic pathway
from 1-acryloylcyclohepta-1,3,5-triene, prepared from
commercially available cyclohepta-1,3,5-triene (ꢀ) in four
steps, to the tetrahydroazulen-1-ones.6 The method in-
volves the Nazarov cyclization8 as a key step for con-
structing the bicyclic carbon framework. Also, we
extended its application to synthesis of the substituted de-
rivatives,7 that makes it possible to obtain 3-aryl-2-ethox-
ycarbonyl-1,2,3,8-tetrahydroazulen-1-ones ꢋ from ꢀ quite
easily. Herein we wish to report the synthesis of 3-aryl-
1,2,3,8-tetrahydroazulen-1-ones ꢁ and their efficient
transformations into 1-aryl- and 1,3-diarylazulenes ꢂ and
ꢇ which may be used to synthesizeꢁpꢀconjugated oligo-
mers and polymers.9 These materials, particularly ones
containing heterols and azulene as a monomeric unit, are
of significant interest because of their electric and optical
properties.10
O
O
COOEt
1N HCl
93%
Ar
Ar
2b, c
3a-d
Ar
= phenyl
= 2-furyl
a
b
c
d
= 2-thienyl
= 2-pyridyl
then hydrolyzed and decarboxylated in methanolic hydro-
chloric acid (70 °C, 5 h) to give ꢁE and ꢁF (Scheme 1).
The 1-arylazulenes ꢂD±G were obtained from the corre-
sponding tetrahydroazulen-1-ones ꢁD±G in moderate to
good yields by a sequence involving reduction with
NaBH4, dehydration with methanesulfonyl chloride and
triethylamine, and dehydrogenation withꢁ Sꢀchloranil
(Scheme 2).
The starting material, ethyl 3-(cyclohepta-1,3,5-trien-1-
yl)-3-oxopropionate (ꢊ), for this work can be prepared
from ꢀ in good yield by the Friedel–Crafts acetylation and
subsequent ethoxycarbonylation.7 Reaction of ꢊ with aryl
aldehydes under the influence of piperidine andꢁSꢀtolue-
nesulfonic acid gave the arylidene derivatives ꢌD±G in
good yields (82-93%).11,12 While heating ꢌD and ꢌG in a
mixture of phosphoric acid and formic acid at 90 °C for 2
h gave the tetrahydroazulen-1-ones ꢁD and ꢁG in moderate
yields, the reaction of ꢌE and ꢌF under the same condi-
tions afforded an intractable reaction mixture, probably
because of the acid-sensitive nature of the electron-rich
heteroles. Thus, ꢁE and ꢁF were obtained from ꢌE and ꢌF
via ꢋE and ꢋF, respectively, in good yields. The Nazarov
cyclization of ꢌE and ꢌF with trimethylsilyl triflate at
room temperature gave the esters ꢋE and ꢋF,13 which were
1) NaBH4
3a-d
2) NEt3 / CH3SO2Cl
3) p-chloranil
Ar
4a-d
Ar
= phenyl
= 2-furyl
4a (73%)
4b (41%)
= 2-thienyl 4c (61%)
= 2-pyridyl 4d (43%)
The new 1-arylazulenes ꢂE±G were fully characterized by
spectroscopic and elemental analyses and the 1-phenyl-
Synthesis 1999, No. 8, 1349–1353 ISSN 0039-7881 © Thieme Stuttgart · New York

ꢀꢁꢇꢍ
M. Oda et al.
3$3(5
azulene (ꢂDꢈ14 was confirmed by comparison with authen- lithium in the addition reaction to the 3-aryl-1,2,3,8-tet-
tic data. It is noteworthy that the dehydration of the inter- rahydroazulen-1-ones.
mediary secondary alcohols with phosphoryl chloride and
pyridine, thionyl chloride and triethylamine, and only ac-
ids, such asꢁSꢀtoluenesulfonic acid or trifluoroacetic acid,
gave lower yields of ꢂ. While Scott et al. reported a one-
In conclusion, we have shown that it is possible to convert
commercially available cyclohepta-1,3,5-triene (ꢀ) into 1-
aryl-1,2,3,8-tetrahydroazulen-1-ones ꢁ in four- or five-
step reactions involving the Nazarov cyclization as a key
pot procedure from 1,2,3,4-tetrahydroazulen-1-one to
step for constructing the bicyclic skeleton and that these
azulene simply by warming with phosphorous pentaoxide
azulenones serve as versatile synthetic intermediates for a
in methanesulfonic acid,2b application of this method for
wide variety of 1-aryl- and 1,3-diarylazulenes. In compar-
ison with other synthetic approaches, our method offers a
divergent way to unsymmetrical 1,3-disubstituted azu-
lenes. Oligomerizations and polymerizations of these azu-
ꢁ resulted in formation of a gummy polymeric material
and none of ꢂ. Furthermore, the Shapiro reaction15 of the
tosylhydrazones of ꢁ and subseqent dehydrogenation with
Rꢀ orꢁSꢀchloranil were carried out; however, the yields of
ꢂ were less than 10%.
lenes are the focus of current investigation.
On the other hand, the 1,2,3,8-tetrahydroazulen-1-ones
Mps were uncorrected. IR spectra were recorded on a JASCO IR-
ꢁD, ꢁF, and ꢁG were reacted with phenyl- or 2-
810 spectrometer; 1H (400 MHz), and 13C (100 MHz) NMR spectra
were recorded on a Jeol A400 spectrometer by use of CDCl3 as sol-
thienyllithium16 to give the intermediary tertiary alcohols
which were treated with a catalytic amount of Pd-C in re-
fluxing diphenyl ether17 to produce the 1,3-diarylazulenes
ꢇH±K as the sole isolable products in 31–68% yields
(Scheme 3). The yields of ꢇH±K are greater than those of
1-methyl- and 1,6-dimethylazulenes which were obtained
by CH3MgCl addition to 1,2,3,4-tetrahydroazulen-1-one
and its 6-methyl derivative and subsequent vapor-phase
reaction with Pd–C, reported by Scott et al.2b The sole pro-
duction of ꢇH±K in the dehydration–dehydrogenation is
contrary to the case in which the secondary alcohols ob-
tained by NaBH4 reduction of ꢁDꢄG gave a mixture of 1-
and 2-arylazulenes under the same reaction conditions of
this dehydration-dehydrogenation reaction. Although a
phenyl group migration of 1- and 2-phenylazulenes above
300 °C has been documented,18 the reluctance of 1,3-dia-
rylazulenes to rearrange under similar conditions has been
disclosed for the first time. Daub et al.9c have recently re-
ported that ꢇH could be synthesized by palladium-cata-
lyzed coupling of phenylboronic acid and a mixture of
vent and TMS as internal standard; Mass spectra were recorded by
Jeol JMSꢀD-300 and JMSꢀGC Mate spectrometers. Ethyl 3-(cyclo-
hepta-1,3,5-trien-1-yl)-3-oxopropionate (ꢊ), ethyl 3-(cyclohepta-
1,3,5-trien-1-yl)-2-arylidene-3-oxopropionates ꢌD, and ꢌE, and 2-
ethoxycarbonyl-3-furyl-1,2,3,8-dihydroazulen-1-ones ꢋE were pre-
pared by the reported method.7 A solution of phenyllithium in cy-
clohexane–diethyl ether was purchased from Aldrich and titrated
before use. A solution of 2-thienyllithium in diethyl ether was pre-
pared from thiophene and BuLi by the literature method.15 A solu-
tion of BuLi in hexane was purchased from Merck and titrated
before use.
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3URFHGXUH
A mixture of ꢊ (20 mmol), the aldehyde (20 mmol), piperidine (0.8
mL), and TsOH (0.02 g) in benzene (20 mL) was refluxed with a
Dean–Stark apparatus until water was not trapped. The mixture was
poured into water and extracted with benzene (3 ¥ 30 mL). The
combined organic layer was washed with brine and dried (MgSO4).
The solvent was removed and the residual oil was purified by silica
gel chromatography (hexane/EtOAc, 8:2) to give ꢌF and ꢌG.
azulene, 1-bromoazulene and 1,3-dibromoazulene, pre- ꢀ(ꢁꢄ(WK\O ꢁꢄꢆF\FORKHSWDꢄꢀꢅꢁꢅꢇꢄWULHQꢄꢀꢄ\OꢈꢄꢋꢄꢆꢋꢄWKLHQ\OꢈPHWK\Oꢄ
HQHꢄꢁꢄR[RSURSLRQDWH ꢆꢌFꢈ
Yield 94%; a pale yellow oil.
IR (liq. film): n = 1720s, 1655s, 1620s, 1250s, 1205s cm-1.
1H NMR: d = 1.21 (t, - = 7.2 Hz, 3H), 2.86 (d, - = 6.8 Hz, 2H), 4.21
(q, - = 7.2 Hz, 2H), 5.68 (dt, - = 8.8, 6.8 Hz, 1H), 5.82 (dd, - = 9.2,
5.6 Hz, 1H), 6.59 (dd, - = 11.2, 6.0 Hz, 1H), 6.84 (dd, - = 11.2, 6.0
Hz, 1H), 7.00 (ddd, - = 4.8, 3.6, 1.6 Hz, 1H), 7.04 (d, - = 5.6 Hz,
1H), 7.23 (d, - = 3.6 Hz, 1H), 7.41 (d, - = 4.8 Hz, 1H), 7.91 (s, 1H).
pared by 1ꢀbromosuccimide bromination of azulene, in
32% yield, along with a 27% yield of 1-phenylazulene.
However, this method is not suitable for synthesizing un-
symmetrical 1,3-disubstituted azulenes. In contrast to
Daub's method, our pathway provides the desired 1,3-dia-
rylazulenes from the ester ꢊ simply by choosing an aryl-
aldehyde for the Knoevenagel condensation and an aryl-
13C NMR: d = 14.1, 25.1, 61.4, 126.0, 127.4, 127.7, 128.6, 129.1,
130.9, 131.3, 133.7, 134.1, 135.8, 136.4, 136.7, 165.0, 194.5.
Ar'
UV-Vis (MeOH): l (loge) = 274 (4.10), 316 (4.31) nm.
1) PhLi or 2-thienyllithium
3a, c, d
MS (EI): P/] (%) = 300 (M+, 28), 254 (66), 226 (14), 198 (15), 186
(20), 149 (24), 137 (13), 118 (100), 90 (51), 65 (23).
2) Pd-C / Ph2O
HRMS calcd. for C17H16O3S P/]ꢁ300.0820; found 300.0775.
Ar
5e-h
ꢀ(ꢁꢄ(WK\O ꢁꢄꢆF\FORKHSWDꢄꢀꢅꢁꢅꢇꢄWULHQꢄꢀꢄ\OꢈꢄꢋꢄꢆꢋꢄS\ULG\OꢈPHWK\Oꢄ
HQHꢄꢁꢄR[RSURSLRQDWH ꢆꢌGꢈ
Ar = Ar' = phenyl
5e (68%)
5f (31%)
Ar = phenyl, Ar' = 2-furyl
Yield 86%; an orange oil.
Ar = phenyl, Ar' = 2-thienyl 5g (42%)
Ar = Ar' = 2-thienyl 5h (38%)
IR (liq. film): n = 1715s, 1660s, 1255s, 1210s, 760s cm-1.
1H NMR: d = 1.24 (t, - = 7.2 Hz, 3H), 2.87 (d, - = 6.8 Hz, 2H), 4.25
(q, - = 7.2 Hz, 2H), 5.65 (dt, - = 9.6, 6.8 Hz, 1H), 6.22 (dd, - = 9.6,
5.6 Hz, 1H), 6.52 (dd, - = 11.2, 6.0 Hz, 1H), 6.74 (dd, - 11.2, 5.6
Synthesis 1999, No. 8, 1349–1353 ISSN 0039-7881 © Thieme Stuttgart · New York

3$3(5
A Divergent Method for Preparing 1-Aryl- and 1,3-Diarylazulenes
ꢀꢁꢇꢀ
Hz, 1H), 6.85 (d, - = 6.0 Hz, 1H), 7.15 (ddd, - = 7.6, 4.8, 0.8 Hz,
1H), 7.35 (dm, - = 7.6 Hz, 1H), 7.64 (dt, - = 7.6, 1.6 Hz, 1H), 7.74
(s, 1H), 8.44 (dm, - = 4.0 Hz, 1H).
13C NMR: d = 14.0, 25.4, 61.6, 123.8, 125.7, 125.9, 127.0, 129.1,
132.1, 133.1, 135.2, 135.5, 136.5, 139.6, 149.4, 151.5, 164.9, 193.9.
purified by silica gel chromatography (hexane/EtOAc, 8:2) to give
ꢋF.
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GURD]XOHQꢄꢀꢄRQH ꢆꢋFꢈ
Yield 91%; yellow prisms; mp 66-67 °C.
UV-Vis (MeOH): l (loge) = 256sh (4.10), 295 (4.20), 453 (1.82)
IR (KBr): n = 1730s, 1690s, 1610s, 1540s, 1250s, 1150s, 720s cm-1.
nm.
1H NMR: d = 1.30 (t, - = 7.2 Hz, 3H), 2.79 (dd, - = 14.4, 6.4 Hz,
1H), 2.84 (dd, - = 14.4, 6.4 Hz, 1H), 3.56 (d, - = 2.8 Hz, 1H), 4.22
(m, 2H), 4.80 (d, - = 2.8 Hz, 1H), 5.69 (dt, - = 10.0, 6.4 Hz, 1H),
6.18 (dd, - = 10.0, 6.0 Hz, 1H), 6.50 (d, - = 11.2 Hz, 1H), 6.76 (dd,
- = 11.2, 6.0 Hz, 1H), 6.85 (dd, - = 3.6, 1.2 Hz, 1H), 6.94 (dd,
- = 4.8, 3.6 Hz, 1H), 7.21 (dd, - 4.8, 1.2 Hz, 1H).
MS (EI): P/] (%) = 295 (M+, 11), 248 (19), 221 (24), 217 (100), 193
(50), 145 (56), 91 (50).
HRMS calcd. for C18H17NO3 m/z 295.1209; found 295.1209.
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DQG )RUPLF $FLGꢎ 7\SLFDO 3URFHGXUH
13C NMR: d = 14.2, 22.2, 44.4, 61.9, 63.3, 125.1, 125.6, 127.0,
127.1, 127.9, 128.0, 130.6, 137.9, 143.7, 164.5, 168.0, 198.0.
A solution of ꢌ (10.0 mmol) in phosphoric acid (85%, 40 mL) and
formic acid was stirred at 90 °C for 2 h, and then was poured into
H2O and extracted with Et2O (3 ¥ 100 mL). The combined organic
layer was washed with sat. NaHCO3 and brine, and was dried
(MgSO4). The solvent was removed and the residue was purified by
chromatography on silica gel (hexane/EtOAc, 8:2) to give ꢁD and
ꢁG.
UV-Vis (MeOH): l (loge) = 228 (4.28), 308 (3.75) nm.
MS (EI): P/] (%) = 300 (M+, 100), 225 (12), 226 (55), 198 (32), 165
(26), 115 (18), 60 (81).
Anal. Calc. for C17H16O3S: C, 67.98; H, 5.87. Found: C, 67.86; H,
5.37.
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Yield 74%; colorless oil.
IR (liq. film): n = 1690s, 700s cm-1.
1H NMR: d = 2.48 (dd, - = 18.8, 2.4 Hz, 1H), 2.71 (dd, - = 14.4, 6.0
Hz, 1H), 2.93 (dd, - = 14.4, 6.8 Hz, 2H), 3.03 (dd, - = 18.8, 6.8 Hz,
1H), 4.05 (d, - = 6.8 Hz, 1H), 5.69 (dt, - = 10.0, 6.4 Hz, 1H), 6.15
(dd, - = 9.6, 6.0 Hz, 1H), 6.35 (d, - = 11.2 Hz, 1H), 6.67 (dd,
- = 11.2, 6.0 Hz, 1H), 7.08 (d, - = 7.2 Hz, 2H), 7.24 (t, - = 7.6 Hz,
1H), 7.31 (t, - = 7.6 Hz, 2H).
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$FLGꢎ 7\SLFDO 3URFHGXUH
A solution of ꢋ (5.00 mmol) in a mixure of 1N HCl (100 mL) and
CH3OH (100 mL) was refluxed for 5 h, and then the solvent was re-
moved. The residue was poured into H2O and extracted with Et2O
(3 ¥ 30 mL). The combined organic layer was washed with sat.
NaHCO3 and brine, and was dried (MgSO4). The solvent was re-
moved and the residue was purified by column chromatography on
silica gel (hexane/ EtOAc, 8:2) to give ꢁE and ꢁF.
13C NMR: d = 21.9, 45.4, 46.6, 127.1, 127.5, 127.79 (2C), 127.84,
128.9, 133.2, 136.7, 142.2, 165.9, 206.7.
ꢆ±ꢈꢄꢁꢄꢆꢋꢄ)XU\OꢈꢄꢀꢅꢋꢅꢁꢅꢏꢄWHWUDK\GURD]XOHQꢄꢀꢄRQH ꢆꢁEꢈ
Yield 93%; a pale yellow oil.
UV-Vis (MeOH): l (loge) = 216 (4.31), 296 (3.78) nm.
MS (EI):ꢁP/] (%) = 222 (M+, 100), 179 (49).
IR (liq. film): n = 1710s, 1620s, 1280s, 750s, 710s cm-1.
1H NMR: d = 2.667 (dd, - = 18.8, 2.4 Hz, 1H), 2.670 (dd, - = 13.8,
5.6 Hz, 1H), 2.90 (dd, - = 14.4, 6.8 Hz, 1H), 2.92 (dd, - = 18.8, 7.2
Hz, 1H), 4.17 (dd, - = 7.2, 2.4 Hz, 1H), 5.65 (dt, - = 10.0, 6.4 Hz,
1H), 6.08 (dd, - = 2.8, 0.8 Hz, 1H), 6.16 (d, - = 10.0, 6.0 Hz, 1H),
6.31 (dd, - = 2.8, 2.0 Hz, 1H), 6.56 (d, - = 11.2 Hz, 1H), 6.74 (dd,
- = 11.6, 6.06 Hz, 1H), 7.34 (dd, - = 2.0, 0.8 Hz, 1H).
HRMS calcd. for C16H14O m/z 222.1045; found 222.1064.
ꢆ±ꢈꢄꢁꢄꢆꢋꢄ3\ULG\OꢈꢄꢀꢅꢋꢅꢁꢅꢏꢄWHWUDK\GURD]XOHQꢄꢀꢄRQH ꢆꢁGꢈ
Yield 40%; yellow needles; mp = 60-61 °C.
IR (KBr): n = 1675s, 750s cm-1.
1H NMR: d = 2.70 (dd, - = 18.8, 2.4 Hz, 1H), 2.72 (dd, - = 14.4, 6.0
Hz, 1H), 2.93 (dd, - = 14.4, 6.8 Hz, 1H), 3.02 (dd, - = 18.8, 7.2 Hz,
1H), 4.27 (dm, - = 5.2 Hz, 1H), 5.68 (dt, - = 10.0, 6.4 Hz, 1H), 6.15
(dd,ꢁ - = 10.0, 6.0 Hz, 1H), 6.38 (d, - = 11.2 Hz, 1H), 6.68 (dd,
- = 11.2, 6.0 Hz, 1H), 7.05 (dt, - = 7.6, 1.2 Hz, 1H), 7.18 (ddd,
- = 7.6, 5.2, 1.2 Hz, 1H), 7.64 (td, - = 7.6, 2.0 Hz, 1H), 8.56 (dm,
- = 4.8 Hz, 1H).
13C NMR: d = 21.9, 38.7, 42.7, 106.3, 110.3, 127.3, 127.7, 127.8,
132.8, 136.8, 142.1, 154.2, 162.8, 205.7.
UV-Vis (MeOH): l (loge) = 221 (4.34), 303 (3.68) nm.
MS (EI): m/z (%) = 212 (M+, 100), 183 (14), 170 (16), 155 (18),
141 (52), 128 (14), 115 (34).
HRMS calcd. for C14H12O2 m/z 212.0837, found 212.0857.
13C NMR: d = 22.0, 44.6, 47.6, 122.0, 122.1, 127.4, 127.8, 127.9,
133.4, 136.8, 136.9, 149.8, 161.3, 164.6, 206.4.
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Yield 93%; an yellow oil.
UV-Vis (MeOH): l (loge) = 257sh (3.74), 264 (3.79), 270 (3.76),
IR (liq. film): n = 1700s, 1620s, 1280s, 700s cm-1.
302 (3.62) nm.
1H NMR: d = 2.58 (dd, - = 18.8, 2.4 Hz, 1H), 2.68 (dd, - = 14.4, 6.0
Hz, 1H), 2.92 (dd, - = 14.4, 6.0 Hz, 1H), 3.06 (dd, - = 18.8, 7.6 Hz,
1H), 4.37 (dm, - = 7.2 Hz, 1H), 5.66 (dt, - = 10.0, 6.0 Hz, 1H), 6.16
(dd, - = 10.0, 6.4 Hz, 1H), 6.51 (d, - = 11.2 Hz, 1H), 6.72 (dd,
- = 11.2, 6.0 Hz, 1H), 6.82 (dm, - = 3.2 Hz, 1H), 6.93 (dd, - = 5.2,
3.2 Hz, 1H), 7.18 (dm, - = 5.2 Hz, 1H).
MS (EI):ꢁP/] (%) = 223 (M+, 26), 194 (78), 180 (100).
Anal. Calc. for C15H13NO: C, 80.69; H, 5.87; N, 6.27. Found: C,
81.01; H, 5.98; N, 6.17.
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13C NMR: d = 21.6, 40.4, 49.9 124.4, 124.8, 127.0, 127.4, 127.7,
127.8, 132.5, 137.0, 145.7, 164.7, 205.6.
Trimethylsilyl triflate (10.5 mmol) was added dropwise to a solu-
tion of ꢌ (10.0 mmol) in CH2Cl2 (100 mL) at r.t. This mixture was
stirred at the same temperature for 0.5 to 2 h under N2, and then was
poured into sat. NaHCO3 (150 mL) and extracted with CH2Cl2
(3 ¥ 100 mL). The combined organic layer was washed with brine.
After drying (Na2SO4) and removal of the solvent, the residue was
UV-Vis (MeOH): l (loge) = 225 (4.34), 303 (3.77) nm.
MS (EI): P/] (%) = 228 (M+, 100), 185 (25), 144 (11). 115 (14), 60
(42).
HRMS calcd. for C14H12OS m/z 228.0609; found 228.0576.
Synthesis 1999, No. 8, 1349–1353 ISSN 0039-7881 © Thieme Stuttgart · New York

ꢀꢁꢇꢋ
M. Oda et al.
3$3(5
7UDQVIRUPDWLRQ RI ꢁꢄ$U\OꢄꢀꢅꢋꢅꢁꢅꢏꢄWHWUDK\GURD]XOHQꢄꢀꢄRQHV ꢆꢁꢈ
LQWR ꢁꢄ$U\OD]XOHQHV ꢆꢂꢈꢎ 7\SLFDO 3URFHGXUH
Anal. Calc. for C14H10S: C, 79.96; H, 4.79. Found: C, 79.88; H,
4.93.
A solution of ꢁ (1.00 mmol) in MeOH (10 mL) was added dropwise
to a suspension of NaBH4 (1.20 mmol) in MeOH (5 mL) at 0 °C.
This mixture was stirred at the same temp. for 1 h, and then was
poured into sat. NaHCO3 and extracted with Et2O (3 ¥ 30 mL). The
combined organic layer was washed with brine and was dried
(MgSO4). The solvent was removed and the residue was dissolved
in CH2Cl2 (20 mL). To this solution at 0 °C was added Et3N (6.00
mmol), followed by dropwise addition of methanesulfonyl chloride
(1.20 mmol). This reaction solution was stirred at r.t. for 3 h. Then,
Sꢀchloranil (1.20 mmol) was added to this mixture which was fur-
ther stirred at r.t. for 10 to 15 h. The resulted dark-colored reaction
mixture was poured into water and extracted with CH2Cl2 (3 ¥ 20
mL). The combined organic layer was washed with brine and was
dried (MgSO4). The solvent was removed and the residue was puri-
fied by column chromatography on silica gel (hexane or hexane/
EtOAc, 8:2) to give ꢂD±ꢂG.
ꢀꢄꢆꢋꢄ3\ULG\OꢈD]XOHQH ꢆꢂGꢈ
Yield 43%; a purple oil.
IR (liq. film): n = 1590s, 1515s, 1480s, 1400s, 780s cm-1.
1H NMR: d = 7.14 (dd, - = 4.8, 4.0 Hz, 1H), 7.22 (t, - = 9.6 Hz, 1H),
7.31 (t, - = 9.6 Hz, 1H), 7.42 (d, - = 4.0 Hz, 1H), 7.65 (t, - = 9.6 Hz,
1H), 7.73 (dm, - = 3.6 Hz, 2H), 8.25 (d, - = 4.0 Hz, 1H), 8.37 (d,
- = 9.6 Hz, 1H), 8.74 (dm, - = 5.2 Hz, 1H), 9.56 (d, - = 9.6 Hz, 1H).
13C NMR: d = 117.8, 120.2, 123.1, 124.1, 125.2, 128.0, 136.30,
136.34, 136.7, 137.5, 137.7, 138.6, 143.2, 149.4, 156.6.
UV-Vis (hexane): l (loge) = 217sh (4.20), 232 (4.28), 243 (4.27),
294 (4.43), 311 (4.43), 317sh (4.39), 324 (4.35), 379 (4.11), 398sh
(3.87), 547sh (2.41), 564sh (2.45), 590 (2.52), 613sh (2.44), 646sh
(2.42), 684sh (1.99), 703 (1.84), 718 (1.98) nm.
MS (EI): P/] (%) = 205 (M+, 54), 204 (100), 60 (33).
ꢀꢄ3KHQ\OD]XOHQH ꢆꢂDꢈ
Yield 73%; blue leaflets; mp 56-57 °C (lit. 58 °C).
HRMS calcd. for C15H11N P/] 205.0892, found 205.0896.
1H NMR: d = 7.15 (t, - = 10.0 Hz, 1H), 7.16 (t, - = 10.0 Hz, 1H),
7.35 (tm, - = 7.6 Hz, 1H), 7.44 (d, - = 4.0 Hz, 1H), 7.50 (tm, - = 7.6
Hz, 2H), 7.60 (t, - = 10.0 Hz, 1H), 7.62 (dm, - = 7.6 Hz, 2H), 8.03
(d, - = 4.0 Hz, 1H), 8.36 (d, - = 10.0 Hz, 1H), 8.56 (d, - = 10.0 Hz,
1H).
13C NMR: d = 117.4, 123.0, 123.3, 126.3, 128.6, 129.8, 131.3,
135.2, 135.6, 137.1, 137.3, 137.5, 138.2, 141.7.
7UDQVIRUPDWLRQ RI ꢁꢄ$U\OꢄꢀꢅꢋꢅꢁꢅꢏꢄWHWUDK\GURD]XOHQꢄꢀꢄRQHV ꢆꢁꢈ
LQWR ꢀꢅꢁꢄ'LDU\OD]XOHQHV ꢆꢇꢈꢎ 7\SLFDO 3URFHGXUH
A solution of either PhLi or 2-thienyllithium (1.05 mmol) in cyclo-
hexane-diethyl ether or THF was added to a solution of ꢁ (1.00
mmol) in THF (15 mL) at 0 °C. This mixture was stirred at r.t. for 1
h under N2, and then was poured into H2O and extracted with Et2O
(3 ¥ 30 mL). The combined organic layer was washed with brine
and was dried (MgSO4). The solvent was removed and the residue
was dissolved in diphenyl ether (5 mL). To this solution was added
a catalytic amount of 5% Pd–C (0.05 g), and this mixture was re-
fluxed on an oil bath for 1 h under N2. After being cooled to r.t., the
resulted mixture was filtrated to remove solids. Then, the solvent
was evaporated under reduced pressure and the residue was purified
by column chromatography on silica gel (hexane) to give ꢇH±ꢇK.
ꢀꢄꢆꢋꢄ)XU\OꢈD]XOHQH ꢆꢂEꢈ
Yield 41%; a green oil.
IR (liq. film): n = 1580s, 1400, 740s cm-1.
1H NMR: d = 6.47 (m, 1H), 6.59 (d, - = 3.2 Hz, 1H), 6.97 (t, - = 9.6
Hz, 1H), 7.05 (t, - = 9.6 Hz, 1H), 7.29 (d, - = 3.6 Hz, 1H), 7.43 (t,
- = 9.6 Hz, 1H), 7.49 (dd, - = 1.6, 0.8 Hz, 1H), 8.08 (d, - = 4.0 Hz,
1H), 8.13 (d, - = 9.6 Hz, 1H), 8.86 (d, - = 9.6 Hz, 1H).
13C NMR: d = 105.4, 111.4, 118.2, 119.8, 123.5m 123.6, 133.4,
135.1, 136.2, 137.1, 138.4, 141.1, 142.3, 152.6.
ꢀꢅꢁꢄ'LSKHQ\OD]XOHQH ꢆꢇHꢈ
Yield 68%; mp 117-118 °C (lit. 100-102 °C).
1H NMR: d = 7.12 (t, - = 10.0 Hz, 2H), 7.37 (tm, - = 7.6 Hz, 2H),
7.51 (tm, - = 7.6 Hz, 4H), 7.58 (t, - = 10.0 Hz, 1H), 7.65 (dm,
- = 7.6 Hz, 4H), 8.12 (s, 1H), 8.55 (d, - = 10.0 Hz, 2H).
13C NMR: d = 123.5, 126.5, 128.7, 129.9, 130.6, 136.2, 136.7,
137.17, 137.22, 139.0.
UV-Vis (hexane): l (loge) = 243 (4.43), 288 (4.38), 299sh (4.34),
309 (4.37), 321 (4.32), 328sh (4.27), 335 (4.17), 363sh (3.78), 385
(3.97), 401 (3.90), 407 (3.91), 586sh (2.35), 610sh (2.39), 637
(2.42), 675sh (2.31), 702sh (2.26), 751sh (1.83), 798 (1.62) nm.
MS (EI): P/] (%) = 194 (M+, 76), 165 (100).
ꢁꢄ3KHQ\OꢄꢀꢄꢆꢋꢄIXU\OꢈD]XOHQH ꢆꢇIꢈ
Yield 31%; a green oil.
IR (liq. film): n = 1575s, 770s, 740s, 710s cm-1.
ꢂE◊ꢀꢅꢁꢅꢇꢄWULQLWUREHQ]HQH &RPSOH[
Black leaflets, mp 102-104 °C.
1H NMR: d = 6.55 (ddd, - = 3.2, 1.6, 0.8 Hz, 1H), 6.68 (d, - = 3.2
Hz, 1H), 7.07 (t, - = 9.6 Hz, 1H), 7.13 (t, - = 9.6 Hz, 1H), 7.36 (tm,
- = 7.6 Hz, 1H), 7.49 (tm, - = 8.0 Hz, 2H), 7.56 (m, 4H), 8.21 (s,
1H), 8.43 (d, - = 9.6 Hz, 1H), 8.92 (d, - = 9.6 Hz, 1H).
13C NMR: d = 105.9, 111.5, 119.0, 123.8, 124.1, 126.6, 128.6,
129.9, 131.3, 134.8, 135.1, 136.3, 136.9 (2C), 137.7, 139.3, 141.4,
152.3.
Anal. Calc. for C20H13N3O7: C, 58.97; H, 3.22; N, 10.32. Found: C,
59.01; H, 3.26; N, 10.23.
ꢀꢄꢆꢋꢄ7KLHQ\OꢈD]XOHQH ꢆꢂFꢈ
Yield 61%; greenish blue plates; mp 34-35 °C.
IR (KBr): n = 790s, 740s, 690s cm-1.
1H NMR: d = 7.14 (t, - = 9.6 Hz, 1H), 7.17 (dd, - = 5.2, 3.6 Hz, 1H),
7.18 (t, - = 9.6 Hz, 1H), 7.28 (dd, - = 3.6, 1.2 Hz, 1H), 7.34 (dd,
- = 5.2, 1.2 Hz, 1H), 7.39 (d, - = 3.6 Hz, 1H), 7.59 (t, - 9.6 Hz,
1H), 8.04 (d, - = 3.6 Hz, 1H), 8.30 (d, - = 9.6 Hz, 1H), 8.74 (d,
- = 9.6 Hz, 1H).
13C NMR: d = 117.8, 123.5, 123.58, 123.63, 124.4, 124.5, 127.7,
135.0, 135.7, 137.3, 137.4, 138.5, 139.7, 142.2.
UV-Vis (hexane): l (loge) = 222 (4.23), 256sh (4.28), 276sh (4.48),
292 (4.51), 300sh (4.48), 330 (4.25), 394 (3.88), 414sh (3.80),
600sh (2.33), 651 (2.42), 720sh (2.25), 812sh (1.64) nm.
MS (EI): P/] (%) = 270 (M+, 100), 239 (35), 165 (15).
ꢇI◊ꢀꢅꢁꢅꢇꢄWULQLWUREHQ]HQH &RPSOH[
Black leaflets; mp 106-107 °C.
UV-Vis (hexane): l (loge) = 204 (4.30), 248 (4.37), 295sh (4.39),
305 (4.43), 327sh (4.15), 382 (3.84), 414sh (3.16), 618 (2.44),
675sh (2.31), 757sh (1.72) nm.
Anal. Calc. for C26H17N3O7: C, 64.60; H, 3.54; N, 8.69. Found: C,
64.38; H, 3.57; N, 8.76.
MS (EI): P/] (%) = 210 (M+, 100), 165 (20), 76 (36), 69 (53), 64
(79), 60 (68), 54 (40).
ꢁꢄ3KHQ\OꢄꢀꢄꢆꢋꢄWKLHQ\OꢈD]XOHQH ꢆꢇJꢈ
Yield 42%, green plates, mp 88-89 °C.
Synthesis 1999, No. 8, 1349–1353 ISSN 0039-7881 © Thieme Stuttgart · New York

3$3(5
A Divergent Method for Preparing 1-Aryl- and 1,3-Diarylazulenes
ꢀꢁꢇꢁ
IR (kBr): n = 855s, 790s, 760s, 735s, 700s cm-1.
b) Denmark, S. &RPSUHKHQVLYHꢁ2UJDQLFꢁ6\QWKHVLV, Vol. 5,
Trost, B. M.; Fleming, I. Ed.; Pergamon: Oxford, 1991; ch.
6.3, p 751.
1H NMR: d = 7.11 (t, - = 10.0 Hz, 1H), 7.15 (t, - = 10.0 Hz, 1H),
7.19 (dd, - = 5.2, 3.6 Hz, 1H), 7.31 (dd, - = 3.6, 1.2 Hz, 1H), 7.37
(m, 2H), 7.50 (t, - = 7.6 Hz, 2H), 7.57 (t, - = 10.0 Hz, 1H), 7.62
(dm, - = 7.6 Hz, 2H), 8.14 (s, 1H), 8.49 (d, - = 9.2 Hz, 1H), 8.74 (d,
- = 9.6 Hz, 1H).
13C NMR: d = 122.7, 123.8, 124.0, 124.7, 124.9, 126.6, 127.7,
128.7, 129.9, 130.9, 136.28, 136.30, 136.4, 136.8, 137.2, 137.3,
139.2, 139.3.
c) Santelli-Rouvier, C.; Santelli, M. 6\QWKHVLV ꢀꢃꢏꢁ, 429.
(9) a) Bargon, J.; Mohmand, S.; Waltman, R. J. 0ROꢅꢁ&U\VWꢅꢁ/LTꢅꢁ
&U\VWꢅ ꢀꢃꢏꢁ, ꢄꢉ, 279.
b) Yamamoto, T.; Zhou, Z.-h.; Kanbara, T.; Shimura, M.;
Kizu, K.; Maruyama, T.; Nakamura, Y.; Fukuda, T.; Lee, B.-
L.; Ooba, N.; Tomaru, S.; Kurihara, T.; Kaino, T.; Kubota, T.;
Sasaki, S. -ꢅꢁ$Pꢅꢁ&KHPꢅꢁ6RFꢅ ꢀꢃꢃꢊ, ꢂꢂꢋ, 10389.
c) Porsch, M.; Sigl-Seifert, G.; Daub, J. $GYꢅꢁ0DWHUꢅ ꢀꢃꢃꢌ, ꢋ,
635.
UV-Vis (hexane): l (loge) = 203 (4.42), 233 (4.22), 295 (4.45),
335sh (4.12), 388 (3.82), 594sh (2.32), 635 (2.39), 690 (2.29), 775
(1.74) nm.
MS (EI):ꢁP/] (%) = 286 (M+, 100), 239 (11).
(10) a) +DQGERRNꢁRIꢁ&RQGXFWLQJꢁ3RO\PHUV, Vols. I and II,
Skotheim, T. A. Ed., Marcel Dekker: New York, 1986.
b) Bradley, D. D. C.; Mori, H. (OHFWURQLFꢁ3URSHUWLHVꢁRIꢁ
&RQMXJDWHGꢁ3RO\PHUVꢁ,,,, Kuzmany,H., Mehring, M., Roth, S.
Eds.; Springer: Berlin, 1989.
Anal. Calc. for C20H14S: C, 83.88; H, 4.93. Found: C, 84.28; H,
5.08.
c) Yamamoto, T. J. 6\QWKꢅꢁ2UJꢅꢁ&KHPꢅ, Jpn. ꢀꢃꢃꢇ, ꢌꢉ, 999.
d) Garnier, F. $FFꢅꢁ&KHPꢅꢁ5HVꢅ ꢀꢃꢃꢃ, ꢉꢈ, 209.
e) Bredas, J.-L.; Cornil, J.; Beljonne, D.; Santos, D. A. D.;
Shuac, Z. $FFꢅꢁ&KHPꢅꢁ5HVꢅ ꢀꢃꢃꢃ, ꢉꢈ, 267.
ꢀꢅꢁꢄ'LꢆꢋꢄWKLHQ\OꢈD]XOHQH ꢆꢇKꢈ
Yield 38%, green plates, mp 132-133 °C.
IR (liq. film): n = 840s, 730s, 690s cm-1.
1H NMR: d = 7.16 (t, - = 9.6 Hz, 2H), 7.19 (dd, - = 5.2, 3.2 Hz, 2H),
7.29 (dd, - = 3.2, 1.2 Hz, 2H), 7.38 (dd, - = 5.2, 1.2 Hz, 2H), 7.59
(t, - = 9.6 Hz, 1H), 8.16 (s, 1H), 8.70 (t, - = 9.6 Hz, 2H).
(11) a) Jones, G. 2UJDQLFꢁ5HDFWLRQV, Vol. 15; Wiley: New York,
1967; p 204.
b) Tietze, F. L.; Beifuss, U. &RPSUHKHQVLYHꢁ2UJDQLFꢁ
6\QWKHVLV, Vol. 2, Trost, B. M.; Fleming, I. Ed.; Pergamon:
Oxford, 1991; ch. 1.11, p 341.
13C NMR: d = 123.0, 124.3, 124.9, 125.1, 127.8, 136.4, 137.0,
137.3, 138.8, 139.6.
(12) The stereochemical relationship between the ester and aryl
groups in ꢌ was determined to be trans, as seen in the other
derivatives (see, ref 6). Similar results were reported in the
Knoevenagel condensation of ethyl 3-oxo-3-
phenylpropionate with benzaldehyde, though the reaction of
methyl acetoacetate was known to give a mixture of
geometrical isomers; see following references and those cited
therein.
UV-Vis (hexane): l (loge) = 206 (4.43), 239 (4.32), 289sh (4.50),
297 (4.53), 345sh (4.16), 395 (3.91), 646 (2.46), 700sh (2.35),
798sh (1.75) nm.
MS (EI): m/z (%) = 292 (M+, 100), 258 (11).
Anal. Calc. for C18H14S2: C, 73.94; H, 4.14. Found: C, 74.18; H,
4.37.
a) Kingsbury, C. A.; Draney, D.; Sopchik, A.; Rissler, W.;
Durham, D. -ꢅꢁ2UJꢅꢁ&KHPꢅ ꢀꢃꢌꢊ, ꢊꢂ, 3863.
b) Postma, J; Arens J. 5HFOꢅꢁ7UDYꢅꢁ&KLPꢅꢁ3D\Vꢀ%DV ꢀꢃꢇꢊ, ꢍꢌ,
1385.
$FNQRZOHGJHPHQW
This work was financially supported by a Grant-in-Aid Scientific
Research (No. 09640631) from the Ministry of Education, Science,
Sports, and Culture, Japan.
(13) The - between the protons at the 2 and 3 positions of ꢋF is
2.8 Hz, suggesting a WUDQV-arrangement. See ref 6 and the
following references.
a) Marino, J. P.; Linderman, R. J. -ꢅꢁ2UJꢅꢁ&KHPꢅ ꢀꢃꢏꢀ, ꢊꢌ,
3696.
5HIHUHQFHV
b) Sakai, T.; Miyata, K.; Takeda, A. &KHPꢅꢁ/HWWꢅ ꢀꢃꢏꢇ, 1137.
c) Andrews, J. F. P.; Regan, A. C. 7HWUDKHGURQꢁ/HWWꢅ ꢀꢃꢃꢀ, ꢉꢈ,
7731.
(1) Oda, M.; Kuroda, S. Recent. Res. Devel. in Pure & Applied
Chem. ꢀꢃꢃꢏ, 2, 145.
(2) a) Scott, L. T. J. &KHPꢅꢁ6RFꢅꢆꢁ&KHPꢅꢁ&RPPXQꢅ ꢀꢃꢌꢁ, 882.
b) Scott, L. T.; Minton, M. A.; Kirms, M. A. -ꢅꢁ$Pꢅꢁ&KHPꢅꢁ6RFꢅꢁ
ꢀꢃꢏꢍ, ꢂꢇꢈ, 6311.
(3) a) Scott, L. T.; Brunsvold, W. R.; Kirms, M. A.; Erden, I.
$QJHZꢅꢁ&KHPꢅꢁꢀꢃꢏꢀ, ꢄꢉ, 282; $QJHZꢅꢁ&KHPꢅꢆꢁ,QWꢅꢁ(Gꢅꢁ(QJOꢅꢁ
ꢀꢃꢏꢀ, 20, 284.
(14) Nozoe, T.; Takase, K.; Fukuda, S. %XOOꢅꢁ&KHPꢅꢁ6RFꢅꢁ-SQꢅ ꢀꢃꢌꢀ,
ꢊꢊ, 2210.
(15) Shapiro, R. H.ꢁ2UJDQLFꢁ5HDFWLRQV, Vol. 23; Wiley: New York,
1976; p 405.
(16) Ramanathan, V.; Levine, R. -ꢅꢁ2UJꢅꢁ&KHPꢅꢁꢀꢃꢊꢋ, ꢈꢍ, 1667.
(17) We have already reported that a thermolytic method with Pd-
C in refluxing diphenyl ether is effective to prepare some
azulene derivatives, see: Kuroda, S.; Hirooka, S.; Iwaki, H.;
Ikeda, M.; Nakao, T. Ogisu, M. Yasunami, M.; Takase, K.
Chem. Lett. ꢀꢃꢏꢊ, 2039. Kuroda S.; Hirooka, S.; Oda, M.;
Iwaki, H.; Teranishi, S.; Matsushita, N.; Hongou, T.; Ikeda,
M.; Hayashi, S.; Miyatake, R.; Izawa, M.; Yamada, M.;
Shimao, I. %XOOꢅꢁ&KHPꢅꢁ6RFꢅꢁ-SQꢅ ꢀꢃꢃꢏ, ꢍꢂ, 459.
(18) Zeller, K.-P. 0HWKRGHQꢁ'HUꢁ2UJDQLVFKHQꢁ&KHPLH (Houben-
Weyl), Bd. 5, 2c; Carbocyclische p-Elektronen-Systeme
Kropf, H. Ed.; Thieme: Stuttgart, 1985; p. 127.
b) Scott, L. T.; Brunsvold, W. R.; Kirms, M. A.; Erden, I. -ꢅꢁ
$Pꢅꢁ&KHPꢅꢁ6RFꢅ ꢀꢃꢏꢀ, ꢂꢇꢉ, 5216.
(4) a) Scott, L. T.; Hashimi, M. M. 7HWUDKHGURQ ꢀꢃꢏꢊ, ꢊꢈ, 1823.
b) Scott, L. T.; Oda, M. &KHPꢅꢁ/HWWꢅ ꢀꢃꢏꢊ, 1759.
(5) a) Kennedy, M.; McKervey, M. A. -ꢅꢁ&KHPꢅꢁ6RFꢅꢆꢁ&KHPꢅꢁ
&RPPXQꢅ ꢀꢃꢏꢏ, 1028, and 1030.
b) Duddeck, H.; Furguson, G.; Kaitner, B.; Kennedy, M.;
McKervey, M. A. -ꢅꢁ&KHPꢅꢁ6RFꢅꢁ3HUNLQꢁ7UDQVꢅꢁ1 ꢀꢃꢃꢍ, 907.
(6) Oda, M.; Yamazaki, T.; Kajioka, T.; Miyatake, R.; Kuroda, S.
/LHELJVꢁ$QQꢅ ꢀꢃꢃꢌ, 2563.
(7) Kajioka, T.; Oda, M.; Yamada, S.; Miyatake, R.; Kuroda, S.
6\QWKHVLVꢁꢀꢃꢃꢃ, 184.
(8) Habermas, K. L.; Denmark, S.; Jones, T. K. 2UJDQLFꢁ
5HDFWLRQV, Vol. 45, Paquette, L. A. Ed.; Wiley: New York,
1994; p 1.
Article Identifier:
1437-210X,E;1999,0,08,1349,1353,ftx,en;F12599SS.pdf
Synthesis 1999, No. 8, 1349–1353 ISSN 0039-7881 © Thieme Stuttgart · New York