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GAVRISHOVA et al.
Here Het is quinolin-2-yl (I), 7-chloroquinolin-2-yl
(II), benzo[f]quinolin-3-yl (III), and 2,2'-bipyridin-6-
yl (IV).
quinoline, and 3-(4-hydroxystyryl)benzo[f]quinoline
the reaction mixture was treated with aqueous ethanol,
after which the undissolved residue was filtered off
and washed with acetone (3 ml) and ethanol (3 × 5 ml).
The reaction was run in a DAEWOO-KOR-
4115SA domestic microwave oven (power 600 W). In
synthesis of I we used different amounts of 2-methyl-
quinoline (from 0.286 to 1.43 g) and different 2-
methylquinoline to 4-hydroxybenzaldehyde ratios. This
compound was obtained in a maximal (90%) yield
under twofold excess of the aldehyde, which avoids its
secondary reaction with two 2-methylquinoline
molecules.
For isolation of 6-(4-hydroxystyryl)-2,2'-bipyridine
the reaction mixture was extracted with a hot diethyl
ether–heptane mixture. The precipitate obtained upon
cooling of the extract was recrystallized from a diethyl
ether–heptane mixture (1 : 5).
2-(4-Hydroxystyryl)quinoline (I). Yield 90%,
light-yellow crystals, mp 268°C (from isopropanol)
1
(mp 268–270°C according to [4]). H NMR spectrum,
In the 1H NMR spectra of I–IV the signals from the
olefin protons of the styryl moiety at 7–8 ppm take the
form of doublets with the vicinal coupling constant of
16–18 Hz, indicating the trans configuration of the
double bond. The IR spectra of these compounds
exhibit absorption bands at 968–982 cm–1, associated
with out-of-plane bending vibrations of C–H bonds
attached to the C=C bond, which confirms the trans
configuration of the double bond. Also, the IR spectra
contain characteristic absorption bands of the –OH
groups at 2430–3090 cm–1, indicating strong hydrogen
bonding between the hydroxy group and the nitrogen
atom of the heterocycle.
δ, ppm: 6.76 d (2H, J = 8.4 Hz, o-C6H4), 7.18 d (1H,
J = 16.2 Hz, =CH–), 7.47–7.55 m (3H, m-C6H4,
quinoline-6), 7.66–7.72 m (2H, –CH=, quinoline-7),
7.78 d (1H, J = 8.6 Hz, quinoline-3), 7.88 d (1H, J =
8.0 Hz, quinoline-5), 7.92 d (1H, J = 8.4 Hz,
quinoline-8), 8.26 d (1H, J = 8.6 Hz, quinoline-4),
10.25 br. s (1H, OH). IR spectrum, ν, cm–1: 1636
(νC=C), 968 (out-of-plane δ trans-HC=C–H), 2430–
3090 (OH). UV spectrum (in ethanol), λmax, nm: 293,
359.
2-(4-Hydroxystyryl)-7-chloroquinoline (II). Yield
72%, yellow crystals, mp 266–267°C (from
1
isopropanol). H NMR spectrum, δ, ppm: 6.81 d (2H,
J = 8.6 Hz, o-C6H4), 7.22 d (1H, J = 16.3 Hz, =CH–),
7.50–7.58 m (3H, m-C6H4, quinoline-3), 7.75 d (1H,
J = 16.3 Hz, –CH=), 7.83 d (1H, J = 7.8 Hz, quinoline-6),
7.93–7.97 m (2H, quinoline-8,5), 8.32 d (1H, J =
8.6 Hz, quinoline-4), 9.85 br. s (1H, OH). IR spectrum,
ν, cm–1: 1636 (νC=C), 968 (out-of-plane δ trans-HC=C–H),
2430–3090 (OH). UV spectrum (in ethanol), λmax, nm:
218, 233, 287, 367. Found, %: C 72.28, H 4.18, N
4.81. Calculated %: C 72.47, H 4.29, N 4.97.
EXPERIMENTAL
1
The H NMR spectra were recorded on Bruker
Avance III spectrometers (500 MHz; DMSO-d6;
internal standard TMS; chemical shifts reported using
δ values). The IR absorpion spectra (KBr pellets) were
taken on a Fourier-transform Spectrum BX-2 spectro-
meter. The melting points of the compounds syn-
thesized were determined using a Koffler apparatus at
the heating rate of 4 deg min–1. The TLC analyses
were carried out with ALUGRAM SIL G/UV254 plates
(visualization with UV light).
3-(4-Hydroxystyryl)benzo[f]quinoline (III). Yield
56%, light-yellow crystals, mp 299–300°C (from
1
ethanol). H NMR spectrum, δ, ppm: 6.84 d (2H, J =
8.4 Hz, o-C6H4), 7.31 d (1H, J = 16.1 Hz, =CH–), 7.59
d (2H, J = 8.4 Hz, m-C6H4), 7.68 t (1H, J = 7.6 Hz,
benzoquinoline), 7.74 t (1H, J = 7.3 Hz, benzo-
quinoline), 7.79 d (1H, J = 16.1 Hz, –CH=), 7.89 d
(1H, J = 9.1 Hz, benzoquinoline), 7.92 d (1H, J =
8.8 Hz, benzoquinoline), 8.04 d (1H, J = 7.7 Hz,
benzoquinoline), 8.09 d (1H, J = 9.1 Hz, benzoquino-
line), 8.82 d (1H, J = 7.7 Hz, benzoquinoline), 9.17 d
(1H, J = 8.5 Hz, benzoquinoline), 9.78 s (1H, OH). IR
spectrum, ν, cm–1: 1638 (νC=C), 982 (out-of-plane δ
trans-HC=C–H), 2430–3090 (OH). UV spectrum (in
ethanol), λmax, nm: 240, 279, 296, 332, 344, 362, 379.
A test tube containing 2.0 mmol of methyl-
quinoline, benzo[f]quinoline, or bipyridyl, and 4 mmol
of 4-hydroxybenzaldehyde was placed into a glass
beaker filled with water and irradiated in a domestic
microwave oven (power 600 Wt) 3–5 times for 3 min
at 30-s intervals (total irradiation time 9–15 min). The
course of the reaction was monitored by the TLC
technique (eluent acetone–hexane 1 : 1). We used dif-
ferent procedures for isolation of 4-hydroxy-
styrylquinolines and bipyridines. In the case of 2-(4-
hydroxystyryl)quinoline, 2-(4-hydroxystyryl)-7-chloro-
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 84 No. 3 2011