Synthesis of photochromic dithienylethenes having quinoline and Triazolo[4,3-a]quinoline bridges

Article abstract of DOI:10.1134/S1070428007090163

Convenient synthetic approaches to new photochromic dithienylethenes with quinoline and triazolo[4,3-a]quinoline bridging fragments have been developed.

Full text of DOI:10.1134/S1070428007090163

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 9, pp. 1357–1363. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © M.M. Krayushkin, B.V. Lichitskii, D.V. Pashchenko, I.A. Antonov, B.V. Nabatov, A.A. Dudinov, 2007, published in Zhurnal
Organicheskoi Khimii, 2007, Vol. 43, No. 9, pp. 1361–1367.
Dedicated to Full Member of the Russian Academy of Sciences
V.A. Tartakovskii on the 75th anniversary of his birth
Synthesis of Photochromic Dithienylethenes Having Quinoline
and Triazolo[4,3-a]quinoline Bridges
M. M. Krayushkin, B. V. Lichitskii, D. V. Pashchenko, I. A. Antonov,
B. V. Nabatov, and A. A. Dudinov
Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Leninskii pr. 47, Moscow, 119991 Russia
e-mail: mkray@ioc.ac.ru
Received May 28, 2007
Abstract—Convenient synthetic approaches to new photochromic dithienylethenes with quinoline and tri-
azolo[4,3-a]quinoline bridging fragments have been developed.
DOI: 10.1134/S1070428007090163
Most photochromic dihetarylethenes described pre-
viously include five-membered bridging fragments
[1–6]. Obviously, the size of the bridge largely deter-
mines the dihedral and torsion angles between the
heterocyclic fragments and hence photochromic prop-
erties of these compounds. The goal of the present
study was to develop procedures for the synthesis of
photochromic dithienylethenes I and II having quino-
line bridging fragments and their subsequent trans-
formation into dithienyl-substituted triazolo[4,3-a]-
quinolines III and IV.
As reported in [7, 8], diaryl-substituted analogs
of compounds I were synthesized by treatment of
o-aminodiaryl ketones with arylacetyl chlorides and
subsequent cyclization of the amides thus formed to
the corresponding 3,4-diarylquinolin-2-ones in basic
medium. This procedure was successfully extended to
the synthesis of quinolinone derivatives I and II
(Scheme 1). Initial compounds Va and Vb were pre-
pared by tosylation of the corresponding anthranilic
acids [9]. Treatment of Va and Vb with phosphorus
pentachloride gave the corresponding benzoyl chlo-
R
R1
HN
O
N
R2
Me
Me
Me
Me
S
S
S
S
Me Me
Me Me
I
II
R2
R1
O
R
N
HN
N
N
N
N
Me
Me
Me
Me
S
S
S
S
Me Me
Me Me
III
IV
1357

KRAYUSHKIN et al.
1358
Scheme 1.
Ts
Ts
NH
NH
O
NH2
O
Me
Me
(1) PCl5
(2) 2,5-Dimethylthiophene, SnCl4
AcOH, H2SO4
COOH
S
S
R
R
R
Me
Me
Va, Vb
VIa, VIb
VIIa, VIIb
Me
R
O
CH2COCl
Me
S
HN
NH
O
Me
S
O
Me
KOH
S
Me
Me
Me
R
S
S
Me
Me Me
VIIIa, VIIIb
Ia, Ib
R
R
N
N
Cl
H2NNH
POCl3
N2H4 ·H2O
Me
Me
Me
Me
S
S
S
S
Me Me
Me Me
IIc, IId
IIa, IIb
R = H (a, c), Cl (b, d).
rides which were used without additional purification
in Friedel–Crafts acylation of 2,5-dimethylthiophene.
It should be noted that the use of thiophene derivatives
instead of benzene analogs imposes some limitations
on the reagent nature and reaction conditions because
of electron-donor character of the thiophene ring and
instability of thienyl derivatives in acid medium. In
particular, the Friedel–Crafts acylation was performed
in the presence of a relatively weak Lewis acid, tin(IV)
chloride [10]. The use of concentrated sulfuric acid to
remove the tosyl protection (as proposed for benzene
analogs [11]) is inadmissible in reactions with thio-
phene derivatives, for it results in considerable decom-
position of amino ketones VII. We found that a mix-
ture of sulfuric and acetic acids ensures good yields of
key intermediate compounds VII.
of amides VIII in ethanolic potassium hydroxide gave
dithienyl-substituted quinolinones I in good yield.
Compounds I were then converted into triazolo[4,3-a]-
quinoline-bridged dithienylethenes. For this purpose,
quinolinones Ia and Ib were treated with phosphoryl
chloride, and 2-chloroquinolines IIa and IIb thus
formed were heated with hydrazine hydrate in butanol
to obtain hydrazinoquinolines IIc and IId. The latter
reacted with formic or acetic acid on heating under
reflux to afford triazolo[4,3-a]quinolines IIIa–IIId.
The reaction of IIc and IId with carbonyldiimidazole
in benzene gave triazoloquinolinones IVa and IVb,
and hydrazine IIc reacted with excess diethyl oxalate
to yield compound IIIe (Scheme 2).
The structure of the isolated compounds was
1
studied by H NMR spectroscopy. Most known dihet-
(2,5-Dimethylthiophen-3-yl)acetic acid was synthe-
sized from 3-acetyl-2,5-dimethylthiophene according
to Willgerodt–Kindler [12] and was treated with oxalyl
chloride to obtain the corresponding acid chloride [13];
the latter was used without additional purification to
acylate amino ketones VII. Intramolecular cyclization
arylethenes are characterized by a low barrier to rota-
tion of the thiophene rings about the bridging frag-
ment, so that their rotation is fairly free [1]. Obviously,
rotation of the thiophene rings in dithienylethenes with
sterically overcrowded bridging moieties should be
hindered, which should be reflected in their NMR
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 9 2007

SYNTHESIS OF PHOTOCHROMIC DITHIENYLETHENES
1359
Scheme 2.
R
R'
COOEt
N
N
N
N
N
N
R'COOH
EtOCOCOOEt
O
IIc, IId
Me
Me
Me
Me
S
S
S
S
Me Me
Me Me
N
N
IIIa–IIId
IIIe
N
N
O
R
HN
N
N
Me
Me
S
S
Me Me
IVa, IVb
II, R = H (c), Cl (d); III, R = H (a, c), Cl (b, d), R′ = Me (a, b), H (c, d); IV, R = H (a), Cl (b).
spectra. In particular, we presumed the occurrence of
atropoisomerism for dithienylethenes having quinoline
and triazoloquinoline bridging fragments. In fact, the
1H NMR spectra of compounds I–IV at room tempera-
ture contained two sets of CH signals in the region
δ 6.20–6.70 ppm and signals from the methyl groups in
the thiophene rings in the region δ 1.90–2.50 ppm; the
other proton signals were not doubled.
Photochromic and fluorescent properties of dithienyl-substituted quinolines and triazoloquinolines I–IV
b
A d
Comp. no.
R
R′
λA,a nm
λB,a nm
DBmax
Irradiation time, min λexcit,c nm
λ , nm IAfl, arb. units
fl
H
330
335
315
325
342
350
315
318
310
320
325
340
350
535
540
590
602
530
~520~
520
530
523
528
530
515
520
0.238
0.162
0.245
0.269
0.016
0.003
0.235
0.096
0.196
0.189
0.350
0.260
0.147
7
5
5
5
9
9
5
5
5
5
8
5
3
340
342
325
330
350
357
325
335
330
343
335
350
354
435
450
445
465
400
400
415
415
420
425
440
425
425
00.80
00.69
Ia
Cl
H
Ib
00.27
IIa
Cl
H
00.37
IIb
IIc
000.122
000.033
00.35
Cl
H
IId
IIIa
IIIb
IIIc
IIId
IIIe
IVa
IVb
Me
Me
H
Cl
H
00.52
00.28
Cl
H
H
00.82
00.62
0e8.48e
H
Cl
13.10
a
λA and λB are the long-wave absorption maxima of the initial (open) and colored (cyclic) forms, respectively.
b
DBmax is the optical density of solution (cell path length 1 cm) after irradiation with filtered light (λ 321 nm) of mercury lamp for indicated
time.
c
d
e
λexcit stands for the excitation wavelength at which the fluorescence emission band has the maximal intensity IAfl.
λBfl is the fluorescence maximum of the initial (open) form.
Concentration 5×10– 5 M.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 9 2007

KRAYUSHKIN et al.
1360
Scheme 3.
hν
Me
Me
Me
hν1
S
S
S
S
Me
Me
Me Me
Me
A
B
All the synthesized quinoline and triazoloquinoline
derivatives were found to possess photochromic prop-
erties in acetonitrile solution at a concentration of
1×10–4 M. Their photoinduced transformations are
thermally irreversible. The initial (open) forms A are
characterized by absorption maxima in the λ range
from 310 to 350 nm (see table). Irradiation of solutions
of these compounds with UV light at λ 321 nm gives
rise to new broad absorption bands in the visible
region with their maxima at λ 515–600 nm, indicating
formation of cyclic structures B [14] (Scheme 3).
A small red shift (Δλ = 5–10 nm) was observed for the
absorption maxima of open and cyclic forms of
7-chloroquinoline and 8-chlorotriazoloquinoline deriv-
atives as compared to their unsubstituted analogs. In
addition, the optical densities of solutions of cyclic
forms of chloro-substituted compounds (except for
IIb) at the absorption maximum (DBmax) were lower
than those for the corresponding unsubstituted deriva-
tives (see table).
The open forms exhibit a weak fluorescence with
the emission maxima located in the λ range from 400
to 465 nm. The fluorescence spectra were measured
both before and after UV irradiation (λexcit 325–
360 nm). UV irradiation resulted in reduced fluores-
cence intensity, the shape and position of the fluores-
cence bands remaining almost unchanged. These find-
ings suggest that the cyclic forms show no fluores-
cence. The fluorescence intensity of 7-chloroquinoline
derivatives (except for IIb) are lower, while the fluo-
rescence intensity of 8-chlorotriazoloquinoline deriva-
tives is considerably higher, than the corresponding
parameters of their unsubstituted analogs. It should
also be noted that the fluorescence intensity of tria-
zoloquinolinones IVa and IVb is higher by more than
order of magnitude than the fluorescence intensity of
the other compounds.
EXPERIMENTAL
The 1H NMR spectra were recorded on Bruker AM-
300 (300 MHz) and Bruker WM-250 (250 MHz) spec-
trometers from solutions in DMSO-d6 and CDCl3. The
melting points were determined on a Boetius hot stage
and were not corrected. The progress of reactions and
the purity of products were monitored by TLC on
Silica gel 60 F254 plates (Merck) using ethyl acetate–
hexane as eluent. The electronic absorption and fluo-
rescence spectra were measured on an SF-256 UVI
two-channel spectrophotometer (LOMO) and Flyuorat-
02 Panorama spectrofluorimeter (Lyumeks). Solutions
were irradiated using an OI-18A luminescent lighter
(LOMO) equipped with a DRK-120 mercury lamp and
a composite optical filter; acetonitrile was used as sol-
vent; concentration 1×10–4 M. Samples were placed in
10-mm quartz cells; and measurements were per-
formed under the following conditions: monochroma-
tor step 1 nm, split width 3 nm, averaging by 3–
5 points at each step.
2-(4-Methylphenylsulfonylamino)benzoic acid
(Va) was synthesized according to the procedure de-
scribed in [10]. Yield 60%, mp 227–229°C; published
data [11]: mp 230°C.
4-Chloro-2-(4-methylphenylsulfonylamino)ben-
zoic acid (Vb) was prepared according to [14]. Yield
56%, mp 204–206°C; published data [15]: mp 203°C.
N-[2-(2,5-Dimethylthiophen-3-ylcarbonyl)phen-
yl]-4-methylbenzenesulfonamide (VIa). 2-(4-Methyl-
phenylsulfonylamino)benzoic acid (Va), 0.29 g
(1 mmol), was added to a suspension of 0.24 g
(1.15 mmol) of phosphorus pentachloride in 3 ml of
methylene chloride, and the mixture was heated for
30 min under reflux. 2,5-Dimethylthiophene, 0.112 g
(1 mmol), was then added, a solution of 1.15 g
(4.4 mmol) of tin(IV) chloride in 3 ml of methylene
chloride was added dropwise, and the mixture was
heated for 6 h under reflux, cooled, and poured into
50 ml of water. The organic layer was separated, the
aqueous layer was extracted with methylene chloride
(2×10 ml), the extracts were combined with the organ-
Thus we have developed convenient synthetic ap-
proaches to new photochromic dithienylethenes I–IV
having quinoline and triazoloquinoline bridging frag-
ments. The proposed procedures are characterized by
mild conditions and good yields, and they seem to be
quite acceptable from the preparative viewpoint.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 9 2007

SYNTHESIS OF PHOTOCHROMIC DITHIENYLETHENES
1361
ic phase, washed with a solution of sodium hydrogen
carbonate (3×20 ml) and water, and dried over sodium
sulfate, the solvent was removed under reduced pres-
sure, and the residue was recrystallized from ethanol.
ylene chloride (2×15 ml), the extracts were combined,
washed with a saturated solution of sodium hydrogen
carbonate (4×15 ml) and water (2×20 ml), and dried
over sodium sulfate, and the solvent was removed
under reduced pressure. Yield 0.96 g (87%). Oily sub-
1
Yield 299 mg (62%), mp 123–125°C. H NMR spec-
1
trum (DMSO-d6), δ, ppm: 2.2–2.4 s (9H, CH3), 6.45 s
(1H, 4′-H), 7.2–7.6 m (8H, Harom), 9.95 s (1H, NH).
Found, %: C 62.41; H 5.02; N 3.85; S 16.52.
C20H19NO3S2. Calculated, %: C 62.31; H 4.97; N 3.63;
S 16.63.
stance. H NMR spectrum (CDCl3), δ, ppm: 2.3–2.5 s
(12H, CH3), 3.6 s (2H, CH2), 6.6 s (1H, 4′-H), 6.7 s
(1H, 4″-H), 7.1 m (1H, Harom), 7.55 m (2H, Harom),
8.75 s (1H, Harom), 10.7 s (1H, NH). Found, %:
C 65.92; H 5.58; N 3.80; S 16.85. C21H21NO2S2. Cal-
culated, %: C 65.77; H 5.52; N 3.65; S 16.72.
N-[5-Chloro-2-(2,5-dimethylthiophen-3-ylcar-
bonyl)phenyl]-4-methylbenzenesulfonamide (VIb)
was synthesized in a similar way. Yield 260 mg (62%),
N-[5-Chloro-2-(2,5-dimethylthiophen-3-ylcar-
bonyl)phenyl](2,5-dimethylthiophen-3-yl)acetamide
(VIIIb) was synthesized in a similar way. Yield 84%,
1
mp 108–110°C. H NMR spectrum (DMSO-d6), δ,
1
ppm: 2.2–2.4 s (9H, CH3), 6.45 s (1H, 4′-H), 7.15–
7.6 m (7H, Harom), 10.15 s (1H, NH). Found, %:
C 57.41; H 4.30; Cl 8.56; N 3.45; S 15.55.
C20H18ClNO3S2. Calculated, %: C 57.20; H 4.32;
Cl 8.44; N 3.34; S 15.27.
mp 120–122°C (from ethanol). H NMR spectrum
(CDCl3), δ, ppm: 2.3–2.55 s (12H, CH3), 3.6 s (2H,
CH2), 6.55 s (1H, 4′-H), 6.65 s (1H, 4″-H), 7.05 d (1H,
6-H, J6,5 = 8 Hz), 7.05 d (1H, Harom, J5,6 = 8 Hz), 8.75 s
(1H, 5-H), 10.85 s (1H, NH). Found, %: C 60.48;
H 4.90; Cl 8.65; N 3.45; S 15.37. C21H20ClNO2S2.
Calculated, %: S 60.35; H 4.82; Cl 8.48; N 3.35;
S 15.34.
(2-Aminophenyl)(2,5-dimethylthiophen-3-yl)-
methanone (VIIa). Compound VIa, 0.03 g
(0.078 mmol), was dissolved in 0.5 g of acetic acid,
0.5 g of sulfuric acid was added, and the mixture was
stirred for 6 h at 50–60°C. The mixture was then
poured into 5 ml of water and extracted with diethyl
ether (2×5 ml), and the extracts were washed with
water (2×5 ml) and evaporated. Yield 140 mg (77%),
3,4-Bis(2,5-dimethylthiophen-3-yl)-1H-quinolin-
2-one (Ia). A solution of 0.96 g (2.5 mmol) of com-
pound VIIIa in 10 ml of a 1 N alcoholic solution of
potassium hydroxide was heated for 1 h under reflux.
The mixture was cooled, 0.65 g of acetic acid and
10 ml of water were added, and the precipitate was
filtered off and dried. Yield 0.737 g (80%), mp 248–
1
oily substance. H NMR spectrum (CDCl3), δ, ppm:
2.4–2.45 s (6H, CH3), 6.05 br.s (2H), 6.55 m (1H,
H
arom), 6.65 s (1H, Harom), 6.65 m (1H, Harom) 6.70 s
1
249°C. H NMR spectrum (DMSO-d6), δ, ppm: 1.85 s
(1H, 4′-H), 7,25 m (1H, Harom) 7.5 m (1H, Harom).
Found, %: C 67.59; H 5.70; N 6.15; S 13.99.
C13H13NOS. Calculated, %: C 67.50; H 5.66; N 6.06;
S 13.86.
(3H, CH3), 1.85–1.95 s (6H, CH3), 2.0 s (3H, CH3),
2.15–2.25 s (6H, CH3), 2.35 s (6H, CH3), 6.15–6.55 m
(2H, 4′-H), 7.05–7.65 m (4H, Harom), 11.95 s (1H, NH).
Found, %: C 69.12; H 5.28; N 3.90; S 17.75.
C21H19NOS2. Calculated, %: C 69.01; H 5.24; N 3.83;
S 17.54.
(2-Amino-4-chlorophenyl)(2,5-dimethylthiophen-
3-yl)methanone (VIIb) was synthesized in a similar
1
way. Yield 80%, oily substance. H NMR spectrum
7-Chloro-3,4-bis(2,5-dimethylthiophen-3-yl)-1H-
quinolin-2-one (Ib) was synthesized in a similar way.
(CDCl3), δ, ppm: 2.35–2.45 s (6H, CH3), 6.0 br.s (2H),
6.55 d (1H, 6-H, J6,5 = 8 Hz), 6.65 s (1H, Harom), 6.70 s
(1H, 4′-H), 7.4 d (1H, 5-H, J5,6 = 8 Hz). Found, %:
C 58.88; H 4.48; Cl 13.25; N 5.45; S 12.17.
C13H12ClNOS. Calculated, %: C 58.75; H 4.55;
Cl 13.34; N 5.27; S 12.06.
N-[2-(2,5-Dimethylthiophen-3-ylcarbonyl)phen-
yl](2,5-dimethylthiophen-3-yl)acetamide (VIIIa).
A solution of 0.55 g (3 mmol) of (2,5-dimethylthio-
phen-3-yl)acetyl chloride in 5 ml of methylene chlo-
ride was added to a solution of 0.66 g (2.87 mmol) of
compound VIIa in 15 ml of methylene chloride. The
mixture was stirred for 3 h at room temperature,
poured into 50 ml of water, and extracted with meth-
1
Yield 84%, mp 130–132°C. H NMR spectrum
(DMSO-d6), δ, ppm: 1.8–2.0 s (6H, CH3), 2.07 s (3H,
CH3), 2.35 s (3H, CH3), 2.45 s (3H, CH3), 2.55 s (3H,
CH3), 6.1–6.5 m (2H, 4′-H), 7.0–7.5 m (3H, Harom),
12.5 s (1H, NH). Found, %: C 63.18; H 4.60; Cl 8.95;
N 3.45; S 16.17. C21H18ClNOS2. Calculated, %:
C 63.06; H 4.54; Cl 8.86; N 3.50; S 16.03.
2-Chloro-3,4-bis(2,5-dimethylthiophen-3-yl)-
quinoline (IIa). A mixture of 0.43 g (1.18 mmol) of
compound Ia and 6 g (39 mmol) of phosphoryl chlo-
ride was heated for 12 h under reflux. Excess POCl3
was removed under reduced pressure, 15 ml of water
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 9 2007

KRAYUSHKIN et al.
1362
was added to the residue, and the mixture was kept for
12 h. The precipitate was filtered off and thoroughly
washed with water. Yield 0.275 g (61%), mp 103–
(3H, CH3), 2.3 s (3H, CH3), 2.35 s (6H, CH3), 3.1 s
(3H, CH3), 6.25–6.6 m (2H, 4′-H), 7.35–7.6 m (2H,
Harom), 7.75 s (1H, Harom), 8.4 m (1H, Harom). Found, %:
1
105°C. H NMR spectrum (DMSO-d6), δ, ppm: 1.85–
C 68.78; H 5.12; N 10.48; S 15.83. C23H21N3S2. Calcu-
lated, %: C 68.45; H 5.25; N 10.41; S 15.89.
2.1 s (6H, CH3), 2.3–2.4 s (6H, CH3), 6.4–6.5 br.s (2H,
4′-H), 7.45 m (1H, Harom), 7.65 m (1H, Harom), 7.85 m
(1H, Harom), 8.05 m (1H, Harom). Found, %: C 65.88;
H 4.80; Cl 9.35; N 3.55; S 16.85. C21H18ClNS2. Calcu-
lated, %: C 65.69; H 4.73; Cl 9.23; N 3.65; S 16.70.
8-Chloro-4,5-bis(2,5-dimethylthiophen-3-yl)-1-
methyl[1,2,4]triazolo[4,3-a]quinoline (IIIb) was syn-
thesized in a similar way. Yield 65%, mp 173–175°C.
1H NMR spectrum (CDCl3), δ, ppm: 1.9–2.1 s (6H,
CH3), 2.3–2.5 s (6H, CH3), 3.3 s (3H, CH3), 6.2–6.6 m
(2H, 4′-H), 7.2–7.65 m (2H, Harom), 8.25 s (1H, Harom).
Found, %: C 63.12; H 4.72; Cl 8.15; N 9.38; S 14.42.
C23H20ClN3S2. Calculated, %: C 63.07; H 4.60;
Cl 8.09; N 9.59; S 14.64.
2,7-Dichloro-3,4-bis(2,5-dimethylthiophen-3-yl)-
quinoline (IIb) was synthesized in a similar way.
1
Yield 59%, mp 95–97°C. H NMR spectrum (CDCl3),
δ, ppm: 1.9–2.2 s (6H, CH3), 2.3–2.5 s (6H, CH3),
6.25–6.35 m (2H, 4′-H), 7.4–7.55 m (2H, Harom), 8.1 s
(1H, Harom). Found, %: C 60.38; H 4.25; Cl 16.75;
N 3.45; S 15.38. C21H17Cl2NS2. Calculated, %:
C 60.28; H 4.10; Cl 16.95; N 3.35; S 15.33.
4,5-Bis(2,5-dimethylthiophen-3-yl)[1,2,4]triazolo-
[4,3-a]quinoline (IIIc). A mixture of 100 mg
(0.26 mmol) of compound IIc and 2 ml of formic acid
was heated for 7 h under reflux. The mixture was
evaporated, 5 ml of water was added to the residue,
and the mixture was extracted with benzene. The
extract was dried over MgSO4, and the solvent was
removed under reduced pressure. Yield 105 mg (65%),
[3,4-Bis(2,5-dimethylthiophen-3-yl)quinolin-2-
yl]hydrazine (IIc). A mixture of 0.46 g (1.2 mmol) of
compound IIa, 4 ml of hydrazine hydrate, and 6 ml of
butanol was heated for 48 h under reflux. The mixture
was evaporated to dryness on a rotary evaporator, and
the residue was recrystallized from 2 ml of ethanol.
1
mp 167–169°C. H NMR spectrum (CDCl3), δ, ppm:
1
1.85–2.4 s (24H, CH3), 6.3–6.6 m (2H, 4′-H), 7.3–
7.85 m (3H, Harom), 8.5 s (1H, Harom), 10.0 s (1H, CH).
Found, %: C 62.22; H 4.30; Cl 8.25; N 9.78; S 15.42.
C22H18ClN3S2. Calculated, %: C 62.32; H 4.28;
Cl 8.36; N 9.91; S 15.12.
Yield 0.220 g (50%), mp 164–166°C. H NMR spec-
trum (DMSO-d6), δ, ppm: 1.9 s (3H, CH3), 2.0 s (3H,
CH3), 2.3 s (6H, CH3), 4.5 br.s (2H, NH2), 6.3–6.5 m
(2H, 4′-H), 6.6–6.8 br.s (1H, NH2), 7.1–7.2 m (2H,
Harom), 7.65 s (1H, Harom). Found, %: C 66.58; H 5.65;
N 11.22; S 16.73. C21H21N3S2. Calculated, %: C 66.46;
H 5.58; N 11.07; S 16.90.
8-Chloro-4,5-bis(2,5-dimethylthiophen-3-yl)-
[1,2,4]triazolo[4,3-a]quinoline (IIId) was synthesized
in a similar way. Yield 60%, mp 173–175°C. 1H NMR
spectrum (CDCl3), δ, ppm: 1.9–2.5 s (24H, CH3),
6.25–6.6 m (2H, 4′-H), 7.25–7.65 m (2H, Harom), 8.05 s
(1H, Harom), 9.3 s (1H, CH). Found, %: C 67.72;
H 4.90; N 10.70; S 16.42. C22H19N3S2. Calculated, %:
C 67.83; H 4.92; N 10.79; S 16.46.
[7-Chloro-3,4-bis(2,5-dimethylthiophen-3-yl)-
quinolin-2-yl]hydrazine (IId) was synthesized in
1
a similar way. Yield 76%, mp 175–177°C. H NMR
spectrum (DMSO-d6), δ, ppm: 1.9–2.05 s (12H, CH3),
2.25–2.35 s (12H, CH3), 4.5 br.s (2H, NH2), 6.25–
6.4 m (2H, 4′-H), 6.6–6.8 br.s (1H, NH), 7.1–7.2 m (2H,
Harom), 7.65 s (1H, Harom). Found, %: C 60.82; H 4.70;
Cl 8.75; N 10.25; S 15.28. C21H20ClN3S2. Calculated,
%: C 60.93; H 4.87; Cl 8.56; N 10.15; S 15.49.
Ethyl 4,5-bis(2,5-dimethylthiophen-3-yl)[1,2,4]-
triazolo[4,3-a]quinoline-1-carboxylate (IIIe). A mix-
ture of 190 mg (0.5 mmol) of compound IIc and 3 ml
of diethyl oxalate was heated for 20 h under reflux.
The mixture was evaporated, and the residue was re-
crystallized from 2 ml of ethanol. Yield 74 mg (35%),
4,5-Bis(2,5-dimethylthiophen-3-yl)-1-methyl-
[1,2,4]triazolo[4,3-a]quinoline (IIIa). A mixture of
152 mg (0.4 mmol) of compound IIc and 2 ml of ace-
tic acid was heated for 7 h under reflux. The mixture
was then evaporated, 5 ml of water was added to the
residue, the mixture was extracted with benzene (2×
5 ml), the extracts were combined and dried over
MgSO4, and the solvent was removed under reduced
pressure. Yield 96 mg (58%), mp 236–238°C. 1H NMR
spectrum (CDCl3), δ, ppm: 1.85 s (3H, CH3), 1.9 s
(3H, CH3), 1.95 s (3H, CH3), 2.1 s (3H, CH3), 2.25 s
1
mp 142–144°C. H NMR spectrum (DMSO-d6), δ,
ppm: 1.9–2.15 s (12H, CH3), 2.3–2.45 s (12H, CH3),
6.3–6.65 m (2H, 4′-H), 7.5 m (1H, Harom), 7.65 m (1H,
Harom), 7.8 m (1H, Harom), 8.55 m (1H, Harom). Found,
%: C 65.21; H 5.14; N 8.85; S 14.03. C25H23N3O2S2.
Calculated, %: C 65.05; H 5.02; N 9.10; S 13.89.
4,5-Bis(2,5-dimethylthiophen-3-yl)[1,2,4]triazolo-
[4,3-a]quinolin-1(2H)-one (IVa). A solution of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 9 2007

SYNTHESIS OF PHOTOCHROMIC DITHIENYLETHENES
1363
3. Uchida, K., Kido, Y., Yamaguchi, T., and Irie, M., Bull.
Chem. Soc. Jpn., 1998, vol. 71, p. 1101.
4. Krayushkin, M.M., Ivanov, S.N., Martynkin, A.Yu.,
Lichitskii, B.V., Dudinov, A.A., and Uzhinov, B.M., Izv.
Ross. Akad. Nauk, Ser. Khim., 2001, p. 2315.
5. Krayushkin, M.M., Ivanov, S.N., Martynkin, A.Yu.,
Lichitskii, B.V., Dudinov, A.A., Vorontsova, L.G., Stari-
kova, Z.A., and Uzhinov, B.M., Izv. Ross. Akad. Nauk,
Ser. Khim., 2002, p. 1588.
6. Krayushkin, M.M., Ivanov, S.N., Lichitskii, B.V., Dudi-
nov, A.A., Vorontsova, L.G., Starikova, Z.A., and Mar-
tynkin, A.Yu., Russ. J. Org. Chem., 2004, vol. 40, p. 79.
130 mg (0.8 mmol) of 1,1′-carbonyldiimidazole in
2 ml of benzene was added to 30 mg (0.08 mmol) of
compound IIc, and the mixture was heated for 6 h
under reflux and evaporated. The residue was dis-
solved in chloroform, the solution was thoroughly
washed with water (3×10 ml) and dried over MgSO4,
and the solvent was removed under reduced pressure.
1
Yield 19 mg (59%), mp >300°C. H NMR spectrum
(DMSO-d6), δ, ppm: 1.9 s (3H, CH3), 1.95 s (3H,
CH3), 2.0 s (3H, CH3), 2.1 s (3H, CH3), 2.25 s (3H,
CH3), 2.3 s (3H, CH3), 2.35 s (6H, CH3), 6.2–6.6 m
(2H, 4′-H), 7.15–7.4 m (2H, Harom), 7.6 m (1H, Harom),
9.05 m (1H, Harom), 12.5 s (1H, NH). Found, %:
C 67.92; H 4.79; N 10.58; S 16.63. C22H19N3S2. Calcu-
lated, %: C 67.83; H 4.92; N 10.79; S 16.46.
7. Peifer, C., Kinkel, K., Abadleh, M., Schollmeyer, D.,
and Laufer, S., J. Med. Chem., 2007, vol. 50, p. 1213.
8. Croisy-Delcey, M., Croisy, A., Carez, D., Huel, C.,
Chiaroni, A., Ducrot, P., Bissagni, E., Jin, L., and Le-
clercq, G., Bioorg. Med. Chem., 2000, vol. 8, p. 2629.
9. Theeraladanon, C., Arisawa, M., Nishida, A., and Naka-
gawa, M., Tetrahedron, 2004, vol. 60, p. 3017.
10. Buu-Hoi, H., Recl. Trav. Chim. Pays–Bas, 1949, vol. 68,
p. 441.
8-Chloro-4,5-bis(2,5-dimethylthiophen-3-yl)-
[1,2,4]triazolo[4,3-a]quinolin-1(2H)-one (IVb) was
synthesized in a similar way. Yield 65%, mp 305–
1
307°C (sublimes). H NMR spectrum (DMSO-d6), δ,
ppm: 1.9–2.15 s (6H, CH3), 2.2–2.5 s (6H, CH3), 6.2–
11. Organic Syntheses, Noland, W.E., Ed., New York:
Wiley, 1963, collect. vol. 4, p. 34.
6.6 m (2H, 4′-H), 7.1–7.5 m (2H, Harom), 9.05 s (1H,
Harom), 12.6 s (1H, NH). Found, %: C 62.52; H 4.47;
12. Press, J.B. and McNally, J., J. Heterocycl. Chem., 1988,
vol. 25, p. 1571.
Cl 8.57; N 9.77; S 15.42. C22H18ClN3S2. Calculated,
%: C 62.32; H 4.28; Cl 8.36; N 9.91; S 15.12.
13. Mrozek, T., Goerner, H., and Daub, J., Chem. Europ. J.,
2001, vol. 7, p. 1028.
REFERENCES
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p. 8096.
15. Loseva, M.V., Krasovitskii, B.M., and Bolotin, B.M.,
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