Synthesis of new aryl(hetaryl)vinyl-substituted benzo[f]quinolines and 4,7-phenanthrolines

Article abstract of DOI:10.1134/S1070428009030154

Previously unknown 1-[2-aryl(quinolin-2-yl)ethenyl]-3-[aryl(quinolin-2-yl)] benzo[f]quinolines and 3-aryl-1-(2-arylethenyl)-4,7-phenanthrolines were synthesized by reactions of 1-methylbenzo[f]quinolines and 1-methyl-4,7- phenanthrolines with substituted

Full text of DOI:10.1134/S1070428009030154

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2009, Vol. 45, No. 3, pp. 434–437. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © N.G. Kozlov, G.N. Lysenko, M.M. Ogorodnikova, K.N. Gusak, 2009, published in Zhurnal Organicheskoi Khimii, 2009, Vol. 45,
No. 3, pp. 444–447.
Synthesis of New Aryl(hetaryl)vinyl-Substituted
Benzo[f]quinolines and 4,7-Phenanthrolines
N. G. Kozlov, G. N. Lysenko, M. M. Ogorodnikova, and K. N. Gusak
Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus,
ul. Surganova 13, Minsk, 220072 Belarus
e-mail: loc@ifoch.bas-net.by
Received March 21, 2008
Abstract—Previously unknown 1-[2-aryl(quinolin-2-yl)ethenyl]-3-[aryl(quinolin-2-yl)]benzo[f]quinolines and
3-aryl-1-(2-arylethenyl)-4,7-phenanthrolines were synthesized by reactions of 1-methylbenzo[f]quinolines and
1-methyl-4,7-phenanthrolines with substituted N-benzylideneanilines and N-(quinolin-2-ylmethylidene)aniline
on heating in dimethylformamide in the presence of potassium hydroxide.
DOI: 10.1134/S1070428009030154
Fused nitrogen-containing heterocycles with aryl-
vinyl or styryl substituents are used as photosensitiz-
ers, cyanine dyes, and medicines [1–5]. Compounds
containing a styrylquinoline fragment attract specific
attention due to strong antibacterial, fungicidal, and
antitumor activity of some representatives [5–7]. The
synthesis of styryl-substituted benzo[f]quinolines and
4,7-phenanthrolines was reported in several publica-
tions [3, 8, 9]; however, the described procedures were
not always satisfactory. For example, the procedure
based on the reaction of methyl-substituted benzo[f]-
quinolines with aromatic aldehydes [8] cannot be ap-
plied to preparation of hetarylvinyl derivatives, for
initial 1-methyl-3-quinolylbenzo[f]quinolines (as free
bases) do not react with aldehydes, while the cor-
responding quaternary salts (in which the methyl group
is activated) undergo decomposition under the pro-
posed conditions. Catalytic condensation of N-aryl-
methylidenenaphthalen-2-amines with substituted ben-
zylideneacetones (4-arylbut-3-en-2-ones), developed
for the synthesis of styryl-substituted benzo[f]quino-
lines [9], is also ineffective as applied to reactions
with quinolyl-substituted Schiff bases. Steric hin-
drances created by the bulky quinoline fragment ham-
per the reaction of Schiff base with unsaturated ketone,
and the yield of the target product decreases. In this
case, hydrolysis of the initial Schiff base and poly-
merization of the carbonyl component become pre-
dominating reaction pathways which lead to the forma-
tion of unidentifiable tarry products.
We were the first to synthesize new aryl(hetaryl)-
vinyl-substituted benzo[f]quinolines and 4,7-phenan-
throlines by reactions of 1-methylbenzo[f]quinolines
and 1-methyl-4,7-phenanthrolines I–VI with Schiff
bases VII–XI derived from aniline. Schiff bases I–VI
were selected as source of aryl(hetaryl)methylidene
fragment, taking into account similarity between the
π-electron systems of the carbonyl and C=N groups, so
that Schiff bases were considered to be heteroanalogs
of carbonyl compounds.
1-Methylbenzo[f]quinolines I–III and 1-methyl-
4,7-phenanthrolines IV–VI were synthesized by con-
densation of N-[aryl(quinolin-2-yl)methylidene]naph-
thalen-2-amines and N-(arylmethylidene)quinolin-6-
amines, respectively with acetone [8]. Benzo[f]quin-
olines I–III were brought into reactions with N-ben-
zylideneaniline (VII), N-(quinolin-2-ylmethylidene)-
aniline (VIII), and N-(4-nitrobenzylidene)aniline (IX).
Analogous reactions of 3-aryl-1-methyl-4,7-phenan-
throlines IV–VI were performed with N-(4-nitroben-
zylidene)aniline (IX), N-(4-bromobenzylidene)aniline
(X), and N-(4-hydroxybenzylidene)aniline (XI)
(Scheme 1). The reactions were carried out by heating
equimolar amounts of compound I–VI and Schiff base
VII–XI in dimethylformamide in the presence of
excess potassium hydroxide. As a result, we isolated
38–61% of the corresponding 1-[2-aryl(quinolin-2-yl)-
ethenyl]-3-[aryl(quinolin-2-yl)benzo[f]quinolines XII–
XV and 1-(2-arylethenyl)-3-aryl-4,7-phenanthrolines
XVI–XVIII. The substituents R and R′ almost did not
434

SYNTHESIS OF NEW ARYL(HETARYL)VINYL-SUBSTITUTED BENZO[f]QUINOLINES
435
Scheme 1.
Me
R
R'
R
N
KOH, DMF
N
+
PhN=CHR'
+
PhNH2
X
X
I–VI
VII–IX
XII–XVIII
R'
R
R
O
N
N
+
Me
R'
XIX, XX
XXI, XXII
XII, XV
I–III, XII–XV, X = CH; IV–VI, XVI–XVIII, X = N; I, XII, XIX, R = Ph; II, XIII, XIV, R = quinolin-2-yl; III, IV, XV, XVI, XX,
R = 4-O2NC6H4; V, XVII, R = 4-BrC6H4; VI, XVIII, R = 2-HOC6H4; VII, XIII, R′ = Ph; VIII, XII, XIV, XXI, R′ = quinolin-2-yl;
IX, XV, XVI, XXII, R′ = 4-O2NC6H4; X, XVII, R′ = 4-BrC6H4; XI, XVIII, R′ = 2-HOC6H4.
affect the yield of the target products. The poor yield
of 1-[2-(2-hydroxyphenyl)ethenyl]-3-(2-hydroxyphen-
yl)-4,7-phenanthroline (XVIII, 38%) is likely to be
related to steric effect of the ortho-hydroxy group in
the benzene ring of Schiff base XI.
[8, 10]. The spectra contain three bands in the UV
region: β (257–265 nm), r (271–303 nm), and α (330–
378 nm). The β and r bands are displaced toward
longer wavelengths relative to the corresponding bands
in the spectra of the initial methyl-substituted com-
pounds [8, 10], and the intensity of the α-band strongly
increases. This pattern results from extension of the
conjugated bond system due to introduction of addi-
tional chromophore (ethenyl group conjugated with the
aromatic substituent R′). Apart from absorption bands
belonging to the benzo[f]quinoline core, quinolyl-
substituted derivatives XIII and XIV showed three
fairly strong maxima at λ 316–320, 329–330, and 344–
345 nm, which should be attributed to the quinolyl
substituent [11].
It should be noted that we succeeded in synthesiz-
ing only 1-[2-(quinolin-2-yl)ethenyl]-3-phenylbenzo-
[f]quinoline (XII) and 1-[2-(4-nitrophenyl)ethenyl]-3-
(4-nitrophenyl)benzo[f]quinoline (XV) by an alterna-
tive method, condensation of N-benzylidenenaphtha-
len-2-amine (XIX) and N-(4-nitrobenzylidene)naph-
thalen-2-amine (XX), respectively, with 4-(quinolin-2-
yl)but-3-en-2-one (XXI) and 4-(4-nitrophenyl)but-3-
en-2-one (XXII). However, the yields of XIII and XV
were lower (42–54%) than in the reactions of I and III
with the corresponding Schiff bases.
In the mass spectra of XII–XVIII, the most abun-
dant were the corresponding molecular ions [M]+.
Their fragmentation involved expulsion of neutral
HCN molecules at different decomposition steps,
which is typical of fused nitrogen-containing hetero-
cycles. The mass spectra of XII and XV–XVIII con-
tained medium-intensity peaks from the [M – R]+ ions
(Irel = 22–31%). The presence of [M – NO]+ and
[M – NO2]+ ion peaks confirmed the structure of nitro-
substituted compounds XV and XVI. The intensity
ratio in the molecular ion cluster, as well as the pres-
ence of [M – Br]+ ion peak, was consistent with the
presence of a bromine atom in molecule XVII.
The structure of newly synthesized compounds
XII–XVIII was confirmed by elemental analysis and
IR, UV, and 1H NMR spectra. The IR spectra of benzo-
[f]quinoline and 4,7-phenanthroline derivatives XII–
XVIII contain absorption bands at 3080–3000, 1595–
1575, and 1480–1450 cm–1, which are typical of
stretching and bending vibrations of C–H and C–C
bonds in the azaphenanthrene ring system. Stretching
vibrations of the exocyclic C=C bond give rise to ab-
sorption at 1630–1600 cm–1, and stretching and bend-
ing vibrations of the corresponding =C–H bonds ap-
pear at 2990–2920 and 1300–1295 and 990–975 cm–1,
respectively. Nitro derivatives XV and XVII displayed
strong absorption bands due to stretching vibrations of
the nitro group (1590–1585 and 1355–1340 cm–1).
1
The H NMR spectra of XII–XVIII were inter-
preted using the data reported previously for 1-methyl-
3-arylbenzo[f]quinolines and 3-aryl-1-phenyl-4,7-
phenanthrolines [10, 12]. Ethenyl derivatives XII–
XVIII displayed two doublets from protons at the
The electronic absorption spectra of XII–XVIII are
typical of benzo[f]quinolines and 4,7-phenanthrolines
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 3 2009

KOZLOV et al.
436
50 mmol of powdered potassium hydroxide in 40 ml of
dimethylformamide was heated to 80–90°C under
vigorous stirring and was stirred for 1.5–2.0 h at that
temperature. The mixture was cooled to room tem-
perature, and 50 ml of water and 35 ml of 10% hydro-
chloric acid were added. The precipitate was filtered
off, washed with water until neutral washings and with
methanol, and recrystallized from propan-2-ol–toluene
(1:2) (XII–XIV) or DMF (XV–XVIII).
exocyclic double bond in the region δ 7.54–7.80 (XII–
XV) or 8.07–8.30 ppm (XVI–XVIII). The coupling
constant J is equal to 15.6–16.2 Hz, indicating trans
3
orientation of these protons. Arylvinyl-substituted
4,7-phenanthrolines XVI–XVIII are poorly soluble in
organic solvents; therefore, their 1H NMR spectra were
recorded from solutions in CF3COOD, and all signals
were displaced downfield relative to the corresponding
signals of their analogs whose spectra were measured
in CDCl3 [12]. The downfield shift results from
protonation of the ring nitrogen atoms by strong acid.
The effects of bromine atom and hydroxy and nitro
groups extends primarily to protons in the phenyl ring
containing these substituents. On the other hand, the
2-H and 10-H signals of ortho-hydroxyphenyl-substi-
tuted phenanthroline XVIII are displaced appreciably
downfield, as compared to analogous compounds XVI
and XVII. The 2-H proton is deshielded due to elec-
tron-withdrawing effect of the oxygen atom in the
hydroxy group in the 3-phenyl substituent. Steric effect
of the ortho-hydroxy group forces the 2-hydroxyaryl-
vinyl fragment out from conjugation with the phenan-
throline core, so that the 10-H proton is shielded to
a lesser extent.
b. A mixture of 5 mmol of N-benzylidenenaphtha-
len-2-amine (XIX) or N-(4-nitrobenzylidene)naphtha-
len-2-amine (XX) and 5 mmol of 4-(quinolin-2-yl)but-
3-en-2-one (XXI) or 4-(4-nitrophenyl)but-3-en-2-one
(XXII), respectively, in 10 ml of ethanol containing
1 ml of concentrated hydrochloric acid was heated for
1 h in a sealed ampule. The precipitate was filtered off,
treated with aqueous ammonia, washed with water, and
recrystallized from propan-2-ol–toluene (XII) or di-
methylformamide (XV).
3-Phenyl-1-[2-(quinolin-2-yl)ethenyl]benzo[f]-
quinoline (XII). Yield 46% (a), 42% (b), mp 172–
173°C. UV spectrum, λmax, nm (logε): 260 (4.69), 271
1
(4.72), 338 (4.40). H NMR spectrum, δ, ppm: 7.19–
8.63 m and 8.82 m (18H, Harom), 7.62 d and 7.80 d
3
(2H, CH=CH, J = 15.8 Hz). Found, %: C 88.02;
EXPERIMENTAL
H 4.73; N 6.51. C30H20N2. Calculated, %: C 88.24;
H 4.90; N 6.86.
The UV spectra were recorded on a Specord UV-
Vis spectrophotometer from solutions in ethanol with
a concentration c of 10–4 M. The IR spectra were
measured in KBr on a Nicolet Protégé-460 spectrom-
eter with Fourier transform. The NMR spectra were
obtained on Bruker AC-500 (500 MHz) and Tesla
BS-567 instruments (100 MHz) using CDCl3 and
CF3COOD as solvents and tetramethylsilane as in-
ternal reference. The mass spectra (electron impact,
70 eV) were run on a Finnigan MAT Incos 50 spec-
trometer and on a Hewlett–Packard 5890/5972 GC–
MS system (HP-5MS capillary column, 30 m ×
0.25 mm, film thickness 0.25 μm; injector temperature
250°C). The melting points were determined using
a Kofler hot stage.
1-(2-Phenylethenyl)-3-(quinolin-2-yl)benzo[f]-
quinoline (XIII). Yield 58%, mp 209–210°C. UV
spectrum, λmax, nm (logε): 257 (4.63), 287 (4.64), 316
1
(4.62), 329 (4.53), 344 (4.45), 374 (3.88). H NMR
spectrum, δ, ppm: 7.24–8.81 m (20H, Harom, CH=CH).
Found, %: C 87.93; H 4.69; N 6.67. C30H20N2. Calcu-
lated, %: C 88.24; H 4.90; N 6.86.
3-(Quinolin-2-yl)-1-[2-(quinolin-2-yl)ethenyl]-
benzo[f]quinoline (XIV). Yield 61%, mp 199–200°C.
UV spectrum, λmax, nm (logε): 265 (4.76), 285 (4.79),
315 (4.59), 330 (4.62), 345 (4.60), 378 (4.06).
1H NMR spectrum, δ, ppm: 7.29–8.84 m (21H,
19Harom, CH=CH). Found, %: C 85.24; H 4.63; N 9.41.
C31H21N3. Calculated, %: C 85.52; H 4.83; N 9.66.
Initial 1-methylbenzo[f]quinolines I–III and
1-methyl-4,7-phenanthrolines IV–VI were synthesized
according to the procedure reported in [8].
3-(4-Nitrophenyl)-1-[2-(4-nitrophenyl)ethenyl]-
benzo[f]quinoline (XV). Yield 60% (a), 54% (b),
mp 299–300°C. UV spectrum, λmax, nm (logε): 265
1
1-[2-Aryl(quinolin-2-yl)ethenyl]-3-[aryl(quino-
lin-2-yl)]benzo[f]quinolines XII–XV and 3-aryl-1-
(2-arylethenyl)-4,7-phenanthrolines XVI–XVIII
(general procedure). a. A mixture of 5 mmol of
compound I–VI, 5 mmol of Schiff base VII–XI, and
(4.56), 299 (4.62), 342 (4.43). H NMR spectrum, δ,
ppm: 7.34 m, 7.42 d, 7.79 m, 8.04 d, 8.12 d (15H,
3
3
H
arom, J = 8.8 Hz); 7.54 d, 7.72 d (2H, CH=CH, J =
15.6 Hz). Found, %: C 72.22; H 3.73; N 9.29.
C27H17N3O4. Calculated, %: C 72.48; H 3.80; N 9.40.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 3 2009

SYNTHESIS OF NEW ARYL(HETARYL)VINYL-SUBSTITUTED BENZO[f]QUINOLINES
437
3-(4-Nitrophenyl)-1-[2-(4-nitrophenyl)ethenyl]-
4,7-phenanthroline (XVI). Yield 49%, mp 336–
337°C. UV spectrum, λmax, nm (logε): 250 (4.48), 303
This study was performed under financial support
by the Byelorussian Republican Foundation for Basic
Research (project no. Kh07-007).
1
(4.49), 330 (4.32). H NMR spectrum, δ, ppm: 8.00 d,
3
8.40 d, 8.63 d (8H, Harom, J = 8.3 Hz); 8.07 d, 8.30 d
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3
3
(2H, CH=CH, J = 16.1 Hz); 8.47 d.d (1H, 9-H, J =
8.8, 4J = 4.4 Hz); 8.84 s (1H, 2-H); 9.02 d, 9.09 d (2H,
5-H, 6-H, J = 9.1 Hz); 9.48 d (1H, 8-H, J = 4.4 Hz);
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3
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yl]-4,7-phenanthroline (XVII). Yield 52%, mp 262–
263°C. UV spectrum, λmax, nm (logε): 232 (4.41), 256
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ppm: 7.64 d, 7.78 d, 7.98 d, 8.08 m (10H, Harom, J =
3
3
8.4, CH=CH, J = 16.0 Hz); 8.48 d.d (1H, 9-H, J =
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3
3
5-H, 6-H, J = 9.1 Hz); 9.40 d (1H, 8-H, J = 4.8 Hz);
10.28 d (1H, 10-H, 3J = 8.0 Hz). Found, %: C 60.45;
H 2.89; Br 30.73; N 5.26. C26H16Br2N2. Calculated, %:
C 60.47; H 3.10; Br 31.01; N 5.43.
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3-(2-Hydroxyphenyl)-1-[2-(2-hydroxyphenyl)-
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mp 297–298°C. UV spectrum, λmax, nm (logε): 260
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1
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3
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3
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3
3
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 3 2009