Synthesis of novel benzimidazolyl-substituted acrylonitriles and amidino-substituted benzimidazo[1,2-a]quinolines

Article abstract of DOI:10.3390/12081817

A series of novel benzimidazole derivatives 3-10 were synthesized. Benzimidazolyl-substituted acrylonitriles 3 and 4 underwent a photochemical dehydrocyclization reaction to give the corresponding mono- and dicyano-substituted benzimidazo[1,2-a] quinoline

Full text of DOI:10.3390/12081817

Molecules 2007, 12, 1817-1828
molecules
ISSN 1420-3049
© 2007 by MDPI
www.mdpi.org/molecules
Full Paper
Synthesis of Novel Benzimidazolyl-substituted Acrylonitriles
and Amidino-substituted Benzimidazo[1,2-a]Quinolines
Marijana Hranjec and Grace Karminski-Zamola*
Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, Marulićev trg
20, HR-10000 Zagreb, Croatia
* Author to whom correspondence should be addressed; E-mail: gzamola@fkit.hr;
Phone: +385 1 4597 215; Fax: +385 1 4597 224
Received: 28 June 2007; in revised form: 20 July 2007 / Accepted: 20 July 2007 / Published: 13
August 2007
Abstract: A series of novel benzimidazole derivatives 3-10 were synthesized.
Benzimidazolyl-substituted acrylonitriles 3 and 4 underwent a photochemical dehydro-
cyclization reaction to give the corresponding mono- and dicyano-substituted
benzimidazo[1,2-a] quinolines 5 and 6. Pinner reaction of these compounds did not give
the expected mono- and diamidines, but rather only compounds 7-10, with amido groups at
6-position were isolated. A mechanism for the reaction is proposed. Acyclic compounds 3
and 4, as well as cyclic benzimidazo[1,2-a]quinolines 5-8, exhibit interesting spectroscopic
properties and are potential biologically active compounds.
Keywords: Benzimidazoles, acrylonitriles, amidines, benzimidazo[1,2-a]quinolines,
Pinner reaction.
Introduction
Over the past years substituted benzimidazoles and their azino fused derivatives have been one of
the most extensively studied classes of heterocyclic compounds, receiving much attention from
synthetic organic chemists because of their applications in several areas such as optical laser and
polymer dyes, fluorescent tags in DNA sequencing, cosmetic ingredients, etc. [1-2]. Benzimidazoles

Molecules 2007, 12
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also posses broad spectrum of biological properties such as antiviral (anti-HIV), anticancer,
antibacterial, antifungal and many others [3-13]. Benzoannulated benzimidazole analogues such as
benzimidazo[1,2-a]quinolines or benzimidazo[1,2-a]quinazolines, due to their planar chromophore,
have the ability to undergo an intercalation process and thus become inserted between adjacent base
pairs of a DNA molecule [14-15], or have potential applications as fluorescent probes in homogeneous
assays of biological molecules, as well as in optoelectronics [16]. A positive charge is generally
needed for activity and it can be provided by quaternization of nitrogen atom or by introduction of
substituents containing such a positive charge, such as an amidino group. Amidines, the nitrogen
analogues of carboxylic acids, are structural components of numerous compounds of biological
interest, including important medical and biochemical agents [17-19]. Herein we present the synthesis
and preliminary spectroscopic properties of some novel potentially biologically active acyclic and
cyclic benzimidazole derivatives.
Results and Discussion
As part of our medicinal chemistry project aimed at the synthesis of potential biologically active
compounds, we synthesized acyclic benzimidazolyl-substituted acrylonitriles 3-4, as well as their
cyclic derivatives, benzimidazo[1,2-a]quinolines 5-10 (Scheme 1).
Scheme 1.
R
H
NC
N
+
CHO
N
1a,b
2
piperidine
EtOH abs.
R
CN
R
1. HClg,
EtOH abs.
H
R
N
EtOH
hν, I2, O2
N
3 R=H
4 R=CN
2. R-NH2
EtOH abs.
N
N
N
N
5 R=H
CN
6 R=CN
CONH2
7 R=H
8 R=
NH2+Cl-
NH2+Cl-
NH
N
10 R=
NH2
H
N
O
9 R=
N
H+Cl-
Acyclic compounds 3 and 4 were prepared by condensation of the corresponding benzaldehydes
1a,b and benzimidazole-2-acetonitrile 2 (prepared by a previously described method [20]), in absolute
EtOH using piperidine as a catalyst [21-22].

Molecules 2007, 12
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In the photochemical dehydrocyclization reaction of 3 and 4 (ethanolic solution, c = 1.3 × 10-3 mol
dm-3) cyclic bezimidazo[1,2-a]quinolines 5 and 6 were prepared [23]. Irradiation was performed for
about 12-15 h with a 400-W high-pressure mercury lamp using a Pyrex filter under oxidative
conditions, with a small amount of iodine as a catalyst. The photochemical dehydrocyclization reaction
was followed by UV/Vis spectroscopy. Cyclic derivatives were obtained in good yields (40-50%). In
1
the H-NMR spectra of both cyclic compounds it was noted that the cyclization reactions lead to a
downfield shift of the signal of the ethylenic proton and most other protons. The proton of the NH
group of the benzimidazole ring, as well as one proton of the phenyl ring disappeared, which also
1
confirmed the cyclic nature of the products. In the H-NMR spectra of acyclic compound 4 two
doublets at 8.11 and 8.04 ppm, corresponding to four phenyl protons, were observed, while in the
spectra of compound 6, due to the cyclization reaction, two doublets and one singlet for three phenyl
protons were observed.
Compound 5 had been previously prepared by classic thermal cyclization [24]. In the Pinner
reaction [25-26], carried out under acidic conditions and using absolute EtOH as well as carbitol as
solvents, compounds 7-10 were prepared. The formation of the imino-ester was confirmed by the
disappearance of a nitrile band at ~2200 cm-1 in the IR spectrum. Attempts to prepare monoamidino-
(amidino group at position 6) or diamidino (amidino groups at positions 2 and 6)-substituted
benzimidazo[1,2-a]quinolines were not successful. Instead of the desired 6-amidino-benzimidazo[1,2-
a]quinolines, the benzimidazo[1,2-a]quinoline-6-carboxamide 7 was unexpectedly isolated [27]. After
isolation and identification of the crude imino-ester by NMR and MS, we confirmed that the amido
group at the 6-position is formed immediately in the first phase of Pinner reaction. In 1H-NMR spectra
of compound 7 two novel singlets can be observed for the amide protons. From the Pinner reaction of
dicyano-substituted benzimidazo[1,2-a]quinoline 6 only 2-amidino-substituted-benzimidazo[1,2-a]-
quinoline-6-carboxamides 8-10 were isolated. Their structures were confirmed by their NMR and MS
1
spectra. In the H-NMR spectrum, singlets for amidine protons can be observed in the 11.63 - 9.60
ppm region. The presence of the corresponding amidine group in compounds 8, 9 and 10 lead to
downfield shifts of most proton signals. In the IR spectrum of amidino compounds 8, 9 and 10, bands
in the ~3500 cm-1 region can be observed.
It appears that the cyano groups at position 2 and 6 reacted quite differently under the “Pinner”
conditions used. The cyano group at the 2-position of the cyclic benzimidazo[1,2-a]quinoline 6 gave in
the first phase an imino-ester, while in the second phase, after reaction with corresponding amine, an
amidino-substituted group is obtained. The cyano groups at the 6-position of the cyclic
benzimidazo[1,2-a]quinolines 5 and 6 gave, in the second phase of the Pinner reaction, an
unsubstituted amido group instead of corresponding amidine. The amido group at the 6-position is also
formed immediately in the first phase of Pinner reaction. The proposed mechanism of the above-
mentioned reaction is presented in Scheme 2. The intermediate protonated imino-ester, formed at the
6-position, underwent an SN-transformation by ethanol giving an amide.
In order to study the spectroscopic properties of substitued benzimidazo[1,2-a]quinolines 5-8 and
their acyclic precursors 3-4, a preliminary investigation of their UV/Vis, fluorescence emission and
excitation spectra, recorded in EtOH, was undertaken. The results are shown in Figures 1-2 and
summarized in Table 1.

Molecules 2007, 12
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Scheme 2.
- H+
R
C
O
NH2
R
C
N
+ C2H5OH
R
C
O
NH2
C2H5
C2H5
O
H
C2H5
- H+
O
+
O
C2H5
C2H5
R
NH2
Table 1. Electronic absorption and fluorescence data of compounds 3-8 in EtOH.
ε x 103
(dm3mol-1 cm-1)
Int
Comp. λmax/nm
λemiss/nm λexc/nm
(arb. un.)
355
21.7
8.4
352
3
445
280
28.6
280
371
17.6
12.1
6.4
367
4
490
274
570.0
278
387
350
5
6
7
8
351
270
9.9
469
507
467
507
268
245
370
274
247
345
268
240
368
272
249
864.5
126.3
469.5
121.1
35.5
370
276
7.9
32.5
375
344
267
7.8
4.6
28.9
374
276
8.1
35.2
Acyclic compound 3 showed an absorption maximum at 355 nm, while dicyano-substituted acyclic
compound 4 showed it at 371 nm (batochromic effect). At 280 and 278 nm both compounds showed
another absorption band. Cyclic compounds 5-8, as it can be visualized in Figure 1, showed several
absorption bands. Di-substituted benzimidazo[1,2-a]quinolines 6 and 8 showed one absorption band in

Molecules 2007, 12
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370 and 374 nm, while mono-substituted benzimidazo[1,2-a]quinolines 5 and 7 showed two
absorption bands from 344 nm to 387 nm.
Figure 1. UV/Vis absorption spectra of compounds 3-8 in EtOH (c = 2×10-5 mol dm-3).
0.7
0.6
3
0.5
4
5
0.4
6
7
0.3
8
0.2
0.1
0.0
250
300
350
400
450
Wavelenght / nm
Figure 2. Fluorescence emission spectra of compounds 3-8 in EtOH, excited at λabs.max
according to data given in Table 1 (c = 6.7×10-7 mol dm-3).
900
3
800
4
700
5
6
600
7
500
8
400
300
200
100
0
400
450
500
550
600
Wavelenght / nm
All the studied compounds showed a single emission band. Acyclic compound 3 exhibited very low
fluorescence intensity, while compound 4 exhibited much higher fluorescence intensity and showed a
bathochromic shift. Cyclic compound 5 exhibited 30 times higher fluorescence intensity than its
acyclic precursor 3. Interestingly, dicyano-substituted benzimidazo[1,2-a]quinoline 6 exhibited ~4.5

Molecules 2007, 12
1822
times lower fluorescence intensity than its acyclic precursor 4. Compound 6 also exhibited ~7 times
lower fluorescence intensity than the monocyano-substituted benzimidazo[1,2-a]quinoline 5. As it can
be visualized from Figure 2, benzimidazo[1,2-a]quinoline-6-carboxamide 7 exhibited ~2 times lower
fluorescence intensity than 6-cyano-benzimidazo[1,2-a]quinoline 5. The fluorescence intensity of 2-
carboxamidine-benzimidazo[1,2-a]quinoline-6-carboxamide hydrochloride (8) is similar to that of
compound 6. Excitation spectra of all studied compounds are in good agreement with their absorption
spectra.
Conclusions
We have prepared benzimidazolyl substituted acrylonitriles 3-4, which were converted into
corresponding benzimidazo[1,2-a]quinolines 5-6 by a photochemical dehydrocyclization reaction.
From the Pinner reaction of compounds 5 and 6 we did not obtain the desired mono- and diamidino-
substituted benzimidazo[1,2-a]quinolines. The cyano group at the 6-position of both cyclic compounds
5 and 6 gave an unsubstituted amido group, instead of an amidine group. An amido group was formed
in the first phase of the Pinner reactions. All the prepared compounds, especially the cyclic
benzimidazo[1,2-a]quinolines 5-8, are potential biologically active compounds and may be expected to
be DNA intercalators, which will be investigated during the course of our ongoing work in this area.
Acknowledgements
This study was supported by grant (No: 125-0982464-1356) from the Ministry of Science and
Technology of the Republic of Croatia.
Experimental
General
Melting points were determinated on a Koffler hot stage microscope and are uncorrected. IR
1
spectra were recorded on Perkin-Elmer 297 spectrophotometer with KBr disks. H- and 13C-NMR
spectra were recorded in DMSO-d6 on a Varian Gemini 300 or Bruker Avance DPX 300 spectrometers
using TMS as an internal standard. Mass spectra were recorded on an Agilent 1100 series LC/MSD
Trap SL. Elemental analysis for carbon, hydrogen and nitrogen were performed on a Perkin-Elmer,
Series II, CHNS Analyzer 2400. Where analyses are indicated only as symbols of elements, analytical
results obtained are within 0.4% of the theoretical values. All compounds were routinely checked by
TLC with Merck silica gel 60F-254 glass plates. The electronic absorption spectra were obtained on
Varian Cary 100 spectrometer and fluorescence emission spectra were recorded on Varian Eclipse
fluorimeter, in both cases using quartz cuvettes (1 cm).

Molecules 2007, 12
1823
General method for preparation of 3 and 4.
A solution of equimolar amounts of corresponding benzaldehydes 1a,b and benzimidazole-2-
acetonitrile 2 in absolute EtOH (15 mL) was refluxed in the presence of piperidine (0.03 mL) for 4 h.
The dark yellow product which separated on cooling was filtered off, washed with petroleum ether and
EtOH and recrystallized from EtOH to give the products.
2-(1H-benzimidazol-2-yl)-3-acrylonitrile (3)
Compound 3 was prepared as described above from benzaldehyde (1.35 g, 12.72 mmol) and
benzimidazole-2-acetonitrile 2 (2.00 g, 12.72 mmol), to obtain after recrystallization from EtOH a
yellow powder (2.52 g, yield 80%); mp = 217–218 °C; IR (KBr) υ/cm-1: 3249, 2225, 1621, 1600;
1H-NMR (δ/ppm): 13.20 (brs, 1H, NHbenzimidazole), 8.34 (s, 1H), 8.00 (d, 2H, J = 8.80Hz, Harom.), 7-63-
7.61 (m, 2H, Harom.), 7.60 (d, 1H, J = 7.72Hz, Harom.), 7.57 (d, 2H, J = 8.77Hz, Harom.), 7.30-7.24 (m,
13
2H, Harom.); C-NMR (δ/ppm): 147.89 (s), 145.86 (d), 139.69 (s), 133.17 (s), 132.14 (d), 130.00 (d,
2C), 129.76 (d, 3C), 123.54 (d), 122.87 (s), 120.99 (d), 118.65 (d), 116.66 (s), 102.90 (s); MS m/z 246
(M+1); Anal. Calc. for C16H11N3: C 78.35%, H 4.52%, N 17.13%; found: C 78.13%, H 4.75%, N
17.29%.
2-(1H-benzimidazol-2-yl)-3-(4-cyanophenyl)-acrylonitrile (4)
Compound 4 was prepared from 4-cyanobenzaldehyde (1.60 g, 12.72 mmol) and benzimidazole-2-
acetonitrile 2 (2.00 g, 12.72 mmol), using the described general method, to give, after recrystallization
from EtOH, a yellow powder (2.60 g, yield 75%); mp = 290–291 °C; IR (KBr) υ/cm-1: 3332, 2225,
1
2214, 1641, 1619; H-NMR (δ/ppm): 13.32 (s, 1H, NHbenzimidazole), 8.40 (s, 1H), 8.11 (d, 2H, J =
8.64Hz, Harom.), 8.04 (d, 2H, J = 8.52Hz, Harom.), 7.68 (brs, 1H, Harom.), 7.63 (d, 1H, J = 7.70Hz, Harom.),
7.27 (brs, 2H, Harom.); 13C-NMR (δ/ppm): 147.28 (s), 147.27 (s), 143.68 (d), 137.44 (s), 133.48 (d, 2C),
130.42 (d, 2C), 118.79 (s), 124.55 (d), 123.18 (d), 119.20 (d), 118.79 (s), 116.07 (s), 113.58 (s), 112.09
(d), 105.99 (s); MS m/z 271 (M+1); Anal. Calc. for C17H10N4: C 75.54%, H 3.73%, N 20.73%; found: C
75.77%, H 3.98%, N 20.44%.
General method for preparation of 5 and 6
A solution of 2-(1H-benzimidazol-2-yl)-3-acrylonitrile 3 or 2-(1H-benzimidazol-2-yl)-3-(4-cyano
phenyl)acrylonitrile 4 and small amount of iodine (5%) in EtOH (c = 1.3 × 10-3 moldm-3) was
irradiated at room temperature with a 400-W high-pressure mercury lamp, using a Pyrex filter, for
about 12-15 h, until the UV spectra shown that the dehydrocyclization reaction was finished. Air was
bubbled through the solution, which was then concentrated under reduced pressure to give the product.

Molecules 2007, 12
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Benzimidazo[1,2-a]quinoline-6-carbonitrile (5)
Compound 5 was prepared using above described method from 2-(1H-benzoimidazol-2-yl)-3-
acrylonitrile 3 (1.40 g, 5.71 mmol) after irradiation for 12 h, to give a yellow powder (0.67 g, yield
1
50%); mp = 256–258 °C (Lit [24] mp = 261 °C); IR (KBr) υ/cm-1: 3056, 2225, 1608, 1572; H-NMR
(δ/ppm): 8.77 (d, 1H, J = 8.40Hz, Harom.), 8.74 (s, 1H, Hquinoline), 8.66 (d, 1H, J = 8.10Hz, Harom.), 8.06
(d, 1H, J = 7.68Hz, Harom.), 7.95 (d, 1H, J = 8.00Hz, Harom.), 7.93 (t, 1H, J = 8.10Hz, Harom.), 7.59 (t,
13
1H, J = 7.44Hz, Harom.), 7.55-7.51 (m, 2H, Harom.); C-NMR (δ/ppm): 144.44 (s), 143.74 (s), 140.67
(d), 135.80 (s), 133.65 (d), 131.21 (s), 125.19 (d), 123.64 (d), 121.20 (s), 120.26 (d), 115.97 (s), 115.38
(s), 114.86 (d); MS m/z 244 (M+1); Anal. Calc. for C16H9N3: C 79.00%, H 3.73%, N 17.27%; found: C
79.17%, H 3.89%, N 17.60%.
Benzimidazo[1,2-a]quinoline-2,6-dicarbonitrile (6)
Compound 6 was prepared using the above described method from 2-(1H-benzimidazol-2-yl)-3-(4-
cyano phenyl)-acrylonitrile 4 (1.04 g, 3.86 mmol) to give after irradiation for 15 h a yellow powder
(0.42 g, yield 40%); mp >295 °C; IR (KBr) υ/cm-1: 3058, 2231, 2224, 1609, 1600; 1H-NMR (δ/ppm):
8.99 (s, 1H), 8.75 (d, 1H, Harom., J = 8.34Hz), 8.73 (s, 1H, Hquinoline), 8.17 (d, 1H, J= 8.10Hz, Harom.),
7.93 (d, 1H, J = 8.10Hz, Harom.), 7.89 (d, 1H, J = 7.86Hz, Harom.), 7.53-7.47 (m, 2H, Harom.); 13C-NMR
(δ/ppm): 144.10 (s), 143.97 (s), 139.97 (d), 135.80 (s), 132.51 (d), 130.83 (s), 128.47(d), 126.03 (d),
124.82 (s), 124.78 (d), 120.85 (d), 119.96 (d), 118.44 (s), 115.74 (d), 115.35 (s), 115.28 (s), 104.62 (s);
MS m/z 269 (M+1); Anal. Calc. for C17H8N4: C 76.11%, H 3.08%, N 20.88%; found: C 75.87%, H
3.10%, N 21.14%.
General method for preparation of benzimidazo[1,2-a]quinoline-6-carboxamide 7 and
2-amidino-benzimidazo[1,2-a]quinoline-6-carboxamides 8-10
A stirred suspension of compounds 5 and 6 in absolute EtOH was cooled in an ice-salt bath and
then saturated with HCl gas. The flask was then tightly stoppered and the mixture was maintained at
room temperature for 20 days until the nitrile band disappeared (monitored by IR analysis at 2200
cm-1). The reaction mixture was purged with N2 gas and diluted with diethyl ether (50 mL). The crude
imidate was filtered off and was immediately suspended in absolute EtOH (10 mL). The corresponding
amine was added and the mixture was stirred for one to three days at room temperature. The crude
product was then filtered off and washed with diethyl ether.
Benzimidazo[1,2-a]quinoline-6-carboxamide (7)
Compound 7 was obtained from 5 (0.20 g, 0.82 mmol) as the main product of the above described
Pinner reaction, instead of the corresponding amidine, as a light yellow powder (0.07 g, yield 35%);
1
mp >295 °C; IR (KBr) υ/cm-1: 3180, 1719, 1644, 1621, 1571; H-NMR (δ/ppm): 9.89 (brs, 1H), 8.91
(d, 1H, J = 8.49 Hz, Harom.), 8.80 (s, 1Hquinoline), 8.77 (d, 1H, J = 8.30Hz, Harom.), 8.30 (d, 1H, J =
7.80Hz, Harom.), 8.19 (brs, 1H), 8.03 (d, 1H, J = 7.80Hz, Harom.), 7.97 (d, 1H, J = 8.20Hz, Harom.), 7.68-

Molecules 2007, 12
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7.55 (m, 2H, Harom.); 13C-NMR (δ/ppm): 163.86 (s), 146.46 (s), 143.21 (s), 136.03 (s), 135.93 (d),
132.96 (d), 132.13 (d), 130.56 (s), 125.63 (d), 125.54 (d), 123.93 (d), 122.28 (s), 120.68 (s), 120.24
(d), 116.23 (d), 115.42 (d); MS m/z 262 (M+1); Anal. Calc. for C16H11N3O: C 73.55%, H 4.24%, N
16.08%; found: C 73.81%, H 4.55%, N 16.14%.
2-Carboxamidine-benzimidazo[1,2-a]quinoline-6-carboxamide hydrochloride (8)
Compound 8 was prepared as a yellow powder (0.11 g, yield 43%) using above described Pinner
method from 6 (0.20 g, 0.75 mmol) and NH3 gas; mp >295 °C; IR (KBr) υ/cm-1: 3480, 3220, 1715,
1
1655, 1627, 1589; H-NMR (δ/ppm): 9.92 (s, 1H), 9.60 (brs, 4H, Hamidine), 9.14 (s, 1H), 8.89 (s, 1H),
8.77 (d, 1H, J = 7.60Hz), 8.56 (d, 1H, J = 8.65Hz), 8.20 (s, 1H), 8.11 (d, 1H, J = 7.65Hz), 8.03 (d, 1H,
J = 8.60Hz), 7.72-7.65 (m, 2H); 13C-NMR (δ/ppm): 164.01 (s), 162.11 (s), 146.26 (s), 144.23 (s),
136.33 (d), 136.02 (s), 132.99 (d), 131.01 (s), 129.68 (s), 127.02 (d), 125.89 (s), 125.67 (d), 124.12 (d),
122.56 (s), 120.51 (d), 118.76 (d), 116.28 (d); MS m/z 304 (M+1); Anal. Calc. for C17H14 N5OCl: C
60.09%, H 4.15%, N 20.61%; found: C 60.24%, H 4.33%, N 20.88%.
2-(1H-imidazol-2-yl)-benzimidazo[1,2-a]quinoline-6-carboxamide Hydrochloride (9)
Compound 9 was prepared as a yellow powder (0.180 g, yield 66%) from 6 (0.20 g, 0.75 mmol) and
ethylenediamine (0.121 mL, 1.80 mmol) using above described Pinner method; mp >295 °C; IR (KBr)
υ/cm-1: 3456, 3212, 1730, 1651, 1634, 1593; 1H-NMR (δ/ppm): 11.29 (s, 2H, Hamidine), 9.78 (s, 1H),
9.09 (s, 1H), 9.06 (d, 1H, J = 7.45Hz), 8.87 (s, 1H), 8.44 (d, 1H, J = 8.40Hz), 8.37 (s, 1H), 8.20 (d, 1H,
J = 8.37Hz), 8.06 (d, 1H, J = 7.50Hz), 7.71-7.64 (m, 2H), 4.11 (brs, 2H, CH2), 3.09 (brs, 2H, CH2); 13C
NMR (δ/ppm): 163.98 (s), 162.14 (s), 145.96 (s), 144.40 (s), 136.88 (s), 136.34 (d), 133.10 (d), 131.33
(s), 129.61 (s), 127.41 (d), 126.10 (s), 125.89 (d), 124.24 (d), 122.44 (s), 120.58 (d), 118.76 (d), 116.02
(d), 46.45 (t), 39.88 (t); MS m/z 330 (M+); Anal. Calc. for C19H16N5OCl: C 62.38%, H 4.41%,
N19.14%; found: C 62.54%, H 4.26%, N 18.89%.
N-Morpholin-4-yl-benzimidazo[1,2-a]quinoline-6-carboxamide hydrochloride (10)
Compound 10 was prepared as a yellow powder (0.20 g, yield 63 %) from 6 (0.20 g, 0.75 mmol)
and 4-aminomorpholine (0.360 mL, 1.80 mmol) using above described Pinner method; mp >295 °C;
IR (KBr) υ/cm-1: 3480, 3256, 1726, 1639, 1624, 1591; 1H-NMR (δ/ppm): 11.63 (s, 1H, Hamidine), 10.20
(s, 1H, Hamidine), 9.82 (s, 1H), 9.45 (s, 1H, Hamidine), 9.08 (s, 1H), 8.92 (d, 1H, J = 7.10Hz), 8.86 (s, 1H),
8.54 (d, 1H, J = 8.16Hz), 8.32 (s, 1H), 8.10 (d, 1H, J = 7.11Hz), 7.98 (d, 1H, J = 8.25Hz), 7.69-7.64
(m, 2H), 3.83 (brs, 4H, 2CH2), 3.20 (brs, 2H, 2CH2); 13C-NMR (δ/ppm): 163.54 (s), 161.84 (s), 145.87
(s), 144.08 (s), 135.10 (s), 135.03 (d), 132.36 (d), 130.23 (s), 129.63 (s), 126.31 (d), 125.76 (s), 125.20
(d), 124.53 (d), 122.75 (s), 120.08 (d), 116.55 (d), 116.13 (d), 66.01 (t, 2C), 54.42 (t, 2C); MS m/z 389
(M+1); Anal. Calc. for C21H21N6O2Cl: C 59.36%, H 4.98%, N 19.78%; found: C 59.56%, H 5.11%, N
20.03%.

Molecules 2007, 12
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