Synthesis of photochromic 5,6-diaryl-2-chloropyridine-3,4-dicarbonitriles from 3,4-diaryl-4-oxobutane-1,1,2,2-tetracarbonitriles

Full text of DOI:10.1134/S1070428014090231

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2014, Vol. 50, No. 9, pp. 1372–1374. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © M.Yu. Belikov, M.Yu. Ievlev, O.V. Ershov, K.V. Lipin, S.A. Legotin, O.E. Nasakin, 2014, published in Zhurnal Organicheskoi
Khimii, 2014, Vol. 50, No. 9, pp. 1387–1388.
SHORT
COMMUNICATIONS
Synthesis of Photochromic 5,6-Diaryl-2-chloropyridine-
3,4-dicarbonitriles from 3,4-Diaryl-4-oxobutane-
1,1,2,2-tetracarbonitriles
M. Yu. Belikova, M. Yu. Ievleva, O. V. Ershova, K. V. Lipina, S. A. Legotinb, and O. E. Nasakina
a I.N. Ul’yanov Chuvash State University, Moskovskii pr. 15, Cheboksary, 428015 Russia
e-mail: belikovmil@mail.ru
b National University of Science and Technology MISIS, Leninskii pr. 4, Moscow, 119049 Russia
Received April 24, 2014
DOI: 10.1134/S1070428014090231
1,2-Diarylethenes constitute one of the most prom-
ising classes of organic photochromes due to high
thermal stability of their photoinduced forms and resis-
tance to photodegradation, and they can be used in data
recording and storage systems, as well as in other
fields [1–3].
We now propose a new synthetic approach to
photochromic diarylethenes, which is based on the
reaction of tetracyanoethylene with ketones as key
intermediate step. Tetracyanoethylation of ketones has
been well documented; however, there are almost no
published data on reactions of aryl arylmethyl ketones
with tetracyanoethylene. Adducts of tetracyanoethyl-
ene with ketones of the general formula R(CO)CH2R′
were used as starting compounds to obtain hetero-
cycles containing an RC=CR′ fragment [4–10].
Analogous reactions with aryl arylmethyl ketones
Ar(CO)CH2Ar could give rise to various 1,2-diaryl-
ethenes as new potential photochromes.
We were the first to react tetracyanoethylene with
1,2-diarylethanones Ia and Ib in the presence of
a catalytic amount of hydrochloric acid. As a result, we
isolated 3,4-diaryl-4-oxobutane-1,1,2,2-tetracarboni-
triles IIa and IIb. The substrates were deoxybenzoin
(Ia), the parent compound of the 1,2-diarylethanone
series, and 1,2-bis(2,5-dimethylthiophen-3-yl)ethanone
(Ib). The latter was selected taking into account that
diarylethenes containing thienyl substituents are most
promising from the viewpoint of the design of prac-
tically useful photochromic devices [1]. Ketone Ib was
synthesized in a number of steps starting from hexane-
2,5-dione [11].
Treatment of compounds IIa and IIb with acetyl
chloride in isopropyl alcohol led to the formation of
5,6-diaryl-2-chloropyridine-3,4-dicarbonitriles IIIa
and IIIb. The closest analogs of structures IIIa and
IIIb are diaryl-substituted quinoline derivatives [12].
Compounds IIIa and IIIb turned out to display
photochromic properties in ethanol solution. UV ir-
radiation of their solutions in ethanol at λ 365 nm gave
rise to photoinduced form, while the reverse trans-
formation was induced by the action of full-spectrum
visible light.
NC
CN
CN
O
O
HCl
NC
+
CN
CN
Ar
CN
Ar
Ar
CN
Ar
IIa, IIb
Ia, Ib
4-Oxo-3,4-diphenylbutane-1,1,2,2-tetracarbo-
nitrile (IIa). Deoxybenzoin (Ia), 1.00 g (5.1 mmol),
was dissolved in 20 mL of 1,4-dioxane, 0.64 g
(5 mmol) of tetracyanoethylene and two drops of con-
centrated aqueous HCl were added, and the resulting
yellow solution was stirred for 2–3 min at 35–40°C
until tetracyanoethylene dissolved completely. The
CN
Ar
CN
AcCl, i-PrOH
Ar
N
Cl
IIIa, IIIb
Ar = Ph (a), 2,5-dimethylthiophen-3-yl (b).
1372

SYNTHESIS OF PHOTOCHROMIC 5,6-DIARYL-2-CHLOROPYRIDINE-3,4-...
1373
mixture was left to stand for 2–3 days in a closed
vessel at room temperature, and the presence of tetra-
cyanoethylene was checked by the hydroquinone test
(formation of a blue complex). When the reaction was
complete, the mixture was diluted with a fivefold
volume of water and stirred until a uniform suspension
was obtained. The precipitate was filtered off and
washed on a filter with water and cold propan-2-ol.
Yield 1.12 g (68%), mp 140–141°C (decomp.); pub-
lished data [13]: mp 141–142°C. IR spectrum, ν, cm–1:
2246 (C≡N), 1696 (C=O). UV spectrum: λmax 242 nm
C 72.19; H 3.25; N 13.39. C19H10ClN3. Calculated, %:
C 72.27; H 3.19; N 13.31. M 315.06.
2-Chloro-5,6-bis(2,5-dimethylthiophen-3-yl)-
pyridine-3,4-dicarbonitrile (IIIb) was synthesized in
a similar way from 0.96 g (0.5 mmol) of compound
IIb. Yield 0.146 g (76%), mp 142–143°C. IR spec-
trum: ν 2229 cm–1 (C≡N). UV spectrum, λmax, nm (ε):
1
305 (8362), 377 (6122). H NMR spectrum
(DMSO-d6), δ, ppm: 1.99 s, 2.24 s, 2.28 s, and 2.38 s
(3H each, CH3); 6.15 s and 6.61 s (1H each, 4′-H).
Mass spectrum, m/z 383 [M]+. Found, %: C 59.36;
H 3.676; N 10.99. C19H14ClN3S2. Calculated, %:
C 59.44; H 3.68; N 10.95. M 383.03.
1
(ε = 12476). H NMR spectrum (acetone-d6), δ, ppm:
5.77 s (1H, CHPh), 6.01 s (1H, CHCN), 7.46–7.69 m
(8H, Harom), 8.07 d (2H, Harom, J = 7.9 Hz). Found, %:
C 74.13; H 3.79; N 17.19. C20H12N4O. Calculated, %:
C 74.06; H 3.73; N 17.27.
The progress of reactions and the purity of products
were monitored by TLC on Silufol UV-254 plates;
spots were visualized under UV light, by treatment
with iodine vapor, or by heating. The IR spectra were
recorded on an FSM-1202 spectrometer with Fourier
transform from samples dispersed in mineral oil. The
1H NMR spectra were measured on a Bruker DRX-500
spectrometer at 500.13 MHz using tetramethylsilane as
internal reference. The UV spectra were recorded from
solutions in ethanol (c = 5×10–5 M) on an SF-2000
spectrophotometer. The elemental compositions were
determined on a £aboratorni Přistroje analyzer. The
mass spectra (electron impact, 70 eV) were obtained
on a Finnigan MAT INCOS-50 spectrometer.
3,4-Bis(2,5-dimethylthiophen-3-yl)-4-oxobutane-
1,1,2,2-tetracarbonitrile (IIb). 1,2-Bis(2,5-dimethyl-
thiophen-3-yl)ethanone (Ib), 1.08 g (4.1 mmol), was
dissolved in 20 mL of 1,4-dioxane, 0.51 g (4 mmol) of
tetracyanoethylene and two drops of concentrated
aqueous HCl were added, and the dark brown mixture
was stirred for 5–7 min at 35–40°C until tetracyano-
ethylene dissolved completely. The mixture was then
left to stand for 8–9 h in a closed vessel at room
temperature, and the presence of tetracyanoethylene
was checked by the hydroquinone test (formation of
a blue complex). When the reaction was complete, the
mixture was treated as described above in the synthesis
of IIa. Yield 1.32 g (82%), mp 85–86°C (decomp.). IR
spectrum, ν, cm–1: 2249 (C≡N), 1699 (C=O). UV spec-
This study was performed under financial support
by the President of the Russian Federation (project
no. MK-97.2014.3.
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