Polyfused nitrogen heterocycles: XIX. Oxidative imidazo-fusion of 3-benzoylquinoxalin-2-ones with benzylamines in the synthesis of bis(imidazo[1,5-a]quinoxalin-1- and -5-yl) derivatives

Article abstract of DOI:10.1134/S1070428008050187

Oxidative cyclocondensation of bis(3-benzoylquinoxalin-1-yl)alkanes and oxaalkanes with benzylamine and 3-benzoylquinoxalinones with m-xylylenediamine proceeded with the formation of bis-(imidazo[1,5-a]quinoxalinyl) derivatives where the hetaryl fragments were linked by a spacer both through the imidazole and quinoxaline fragments

Full text of DOI:10.1134/S1070428008050187

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2008, Vol. 44, No. 5, pp. 736−740. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © A.A. Kalinin, V.A. Mamedov, 2008, published in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 5, pp. 744−748.
Polyfused Nitrogen Heterocycles: XIX.*
Oxidative Imidazo-Fusion of 3-Benzoylquinoxalin-2-ones
with Benzylamines in the Synthesis
of Bis(imidazo[1,5-a]quinoxalin-1- and -5-yl) Derivatives
A. A. Kalinin and V. A. Mamedov
Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center,
Russian Academy of Sciences, Kazan, 420088 Russia
e-mail: mamedov@iopc.knc.ru
Received July 17, 2007
Abstract—Oxidative cyclocondensation of bis(3-benzoylquinoxalin-1-yl)alkanes and oxaalkanes with benzyl-
amine and 3-benzoylquinoxalinones with m-xylylenediamine proceeded with the formation of bis-(imidazo[1,5-
a]quinoxalinyl) derivatives where the hetaryl fragments were linked by a spacer both through the imidazole and
quinoxaline fragments
DOI: 10.1134/S1070428008050187
X
Derivatives of imidazo[1,5-a]quinoxalines are
used in the synthesis of pharmacologically active
compounds as agonists and antagonists of the receptor
of GABA/diazepine, inhibitors of CAMP and cGMP
phosphodiesterases, agonists of receptors of A1- and
A2a-adenosines [2–8]. Proceeding from quinoxalines 4
types of building up this tricyclic system are possible: by
intramolecular cyclization of functionalized quinoxalines
[9–12], and by reacting quinoxalines derivatives with
synthetic equivalents of one-carbon [13, 14], carbon-
nitrogen-carbon [15–20], and nitrogen-carbon [13, 21,
22] synthons. Although the performance of the first two
types of processes requires functionalized quinoxaline
derivatives that as a rule are prepared by multistage
syntheses, and the third type is experimentally difficult
the designing of the imidazo[1,5-a]quinoxaline system
by these routes is relatively well documented.
N
Ph
N
N
H
O
KSCN,
KNCO
PhCH2NH2
DMSO
Ph
O
Ph
N
N
Cl
O
N
H
N
H
O
X = SH, OH, Ph.
procedure is experimentally simple and provides the
desired tricyclic compounds in high yields.
This study is dedicated to the application of this
method to the synthesis of bisimidazoquinoxalinones,
bisanalogs of fused quinoxalines that as a rule are of
biological activity similar to their monoanalogs [23].
We formerly developed a new assembling procedure
for imidazo[1,5-a]quinoxaline system by introducing a C–
N fragment into the structure of a quinoxaline derivative
[13, 21, 22]. The method is based either on a reaction
of 3-α-chlorobenzylquinoxalines with potassium
thiocyanate or isothiocyanate [13, 21], or on a reaction of
3-benzoylquinoxalines with benzylamines [22] (oxidative
imidazofusion), and it utilizes available reagents. This
Based on the reaction under consideration compounds
with two imidazoquinoxaline fragments can be syn-
thesized using two bifunctional compounds with terminal
benzoylquinoxaline and benzylamine fragments.
A reaction of benzylamine at heating in DMSO
solution with α,ω-bis(3-benzoyl-2-oxoquinoxalin-
* For communication XVIII, see [1].
736

POLYFUSED NITROGEN HETEROCYCLES: XIX.
737
1-yl)alkanes and -oxaaalkanes (I) easily obtained by
reacting 3-benzoylquinoxalin-2-ones with various α,ω-
dibromoalkanes and oxaalkane [24] led to the formation
of crystalline compounds whose IR spectrum contained a
single absorption band of νC=O in the region 1645–1655
cm–1. The presence in the electron ionization mass spectra
of molecular ions [M]+ 744 of compound IIa, [M]+ 756
of compound IIb, and [M]+ 788 of compound IIc, and
in the 1H NMR spectra of proton signals from aromatic
fragments alongside the proton signals of methylene
groups indicates the formation of α,ω-bis-(4-oxo-1,3-
diphenylimidazo[1,5-a]-quinoxalin-5-yl)alkanes and
-oxaalkanes (II).
procedure makes it possible to obtain bisimidazo-
quinoxalines linked by a spacer at the position 1.
A reaction of m-xylylenediamine (IV) with various
N-alkylbenzoylquinoxalinones III results in the
fusion of imidazole rings and in the formation of
m-bisheterylbenzenes V as the main products and
formylphenylimidazo[1,5-a]quinoxalinones VI as the
side reaction products.
Ph
N
O
N
R
_
O
NH2
NH2
Ph
IV
IIIa IIId
N
Ph
DMS
N
N
N
N
Ph
O
O
N
_
N
O
O
O
O
Ph
O
Ph
N
PhCH2NH2
DMS
N
N
N
P
h
X
X
O
N
R
N
R
N
N
N
N
N
R
O
O
_
VIa−VId
Va Vd
Ph
Ph
N
R = Me (a), Et (b), Pr (c), Bn (d).
Ph
_
Ia Ic
_
IIa IIc
The latter compounds form apparently from initially
arising aminomethylphenylimidazoquinoxalines VII that
under the reaction conditions are oxidized to imines VIII
followed by hydrolysis to aldehydes VI.
X = CH2OCH2 (a), (CH2)4 (b), CH2OCH2CH2OCH2 (c).
The alteration of the character of N4 atom in going into
N10 atom from pyridine character in initial compounds I
to pyrrole one in reaction products II is revealed in the
1H NMR spectra by the upfield shift of all protons from
the quinoxaline system of compounds II (to the region
6.9–7.6 ppm) compared to the signals of the quinoxaline
protons of initial compounds I observed in the region
7.4–8.0 ppm.
H N
2
N
DMS
III+ IV
N
N
Ph
O
R
VII
Unlike benzoylquinoxalinone [22] that treated with
equimolar amount of benzylamine easily transformed
into 1,3-diphenylimidazo[1,5-a]quinoxalin-4(1H)-one
benzoylquinoxalinonopodands required a longer reaction
time and benzylamine excess to obtain the corresponding
bis(imidazo[1,5-a]-quinoxalinyl) derivatives.
HN
N
N
N
VI
Ph
The second approach to the synthesis of bisimidazo-
quinoxalines is based on the method we have former-ly
developed involving a reaction of compounds con-taining
two aminomethyl moieties in a benzene ring. The
O
R
VIII
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KALININ, MAMEDOV
738
1,5-Bis(4-oxo-1,3-diphenylimidazo[1,5-a]-
quinoxalin-5-yl)-3-oxapentane (IIa). Yield 48%,
mp 174–176°C (DMSO). IR spectrum, ν, cm–1: 694,
750, 781, 1053, 1108, 1180, 1255, 1300, 1324, 1337,
1447, 1485, 1503, 1610, 1655. 1H NMR spectrum, δ,
ppm: 3.85 t (4H, OCH2, J 5.46 Hz), 4.39 t (4H,
NCH2, J 5.46 Hz), 6.87 d.d (2H, H8quinoxaline, J 8.10,
7.56 Hz), 7.10 d (2H, H9quinoxaline, J 8.34 Hz), 7.15 d.d
The structure of compounds V was established from
IR, H NMR, and mass spectra and from the data of
1
ele-mental analysis. The IR spectra of compounds V
lack absorption bands ν(COket) in the region 1675–1690
cm–1. In the electron ionization mass spectra molecular
ions are present [M]+ 624, 680, 776 of compounds Va,
1
Vc, and Vd respectively. In the H NMR spectrum 22
signals of aromatic protons are observed. The protons
of the m-phenylene fragment appear separately from the
other aromatic protons signals in weaker field (7.9–8.1
ppm) as a singlet of H2, a doublet (H4 and H6, J 7.8
Hz), and a doublet of doublets (H5, J 7.6, 7.6 Hz). They
have intensity corresponding to a half of that of the
phenyl rings protons and of quinoxaline systems. In the
upfield region similar to compounds II appears a signal
of H8 proton of the quinoxaline system as a doublet of
doublets (J ~8.0, ~7.6 Hz) at ~7.00 ppm. The formation
of compounds VIa–VId was revealed by the electron
ionization mass spectra, and compound VIa was isolated
and characterized. The IR spectrum of imidazoquinoxaline
VIa contained absorption bands of two carbonyl groups
with ν(COamide) 1648 and ν(COald) 1693 cm–1. In the
1H NMR spectrum the protons of 1,3-disubstituted
benzene fragment appeared as four and not three signals
characteristic of the 1H NMR spectrum of compound Va;
two of the signals, the singlet from proton H6 at 8.29 ppm
and the doublet (J 7.56 Hz) from proton H4 at 8.18 ppm,
are located more downfield due to the stronger electron-
withdrawing effect of the aldehyde group. The aldehyde
group signal appears at 10.14 ppm.
(2H, H7quinoxaline, J 7.86, 7.32 Hz), 7.37 d.d (2H, Hp1-Ph
,
J 7.32, 6.54 Hz), 7.41 d.d (4H, Hm1-Ph, J 7.32, 7.08 Hz),
7.57 d (2H, H6quinoxaline, J 8.88 Hz), 7.60 d (4H, H°1-Ph,
J 7.08 Hz), 7.64 d.d (2H, Hp3-Ph, J 7.62, 6.78 Hz), 7.65 d
(4H, Hm3-Ph, J 7.62 Hz), 8.12 d (4H, H3°-Ph, J 7.56 Hz).
Mass spectrum, m/z (Irel, %): 746 (2), 745 (6), 744 [M]+
(11), 757 (8), 407 (8), 381 (28), 363 (44), 337 (100), 260
(10), 234 (18), 219 (24), 205 (32), 102 (38). Found, %:
C 77.32; H 4.95; N 11.36. C48H36N6O3. Calculated, %:
C 77.40; H 4.87; N 11.28.
1,6-Bis(4-oxo-1,3-diphenylimidazo[1,5-a]-
quinoxalin-5-yl)hexane (IIb). Yield 77%, mp 271–
273°C (DMSO). IR spectrum, ν, cm–1: 694, 704, 747,
781, 1050, 1121, 1250, 1300, 1335, 1395, 1447, 1485,
1503, 1611, 1655. 1H NMR spectrum, δ, ppm: 1.45–
1.55 m [4H, (CH2)2(CH2)2(CH2)2], 1.65–1.75 m [4H,
CH2CH2(CH2)2CH2CH2], 4.24 t (4H, NCH2, J 7.47 Hz),
6.97 d.d (2H, H8quinoxaline, J 8.34, 8.10 Hz), 7.19 d.d (2H,
H9quinoxaline, J 8.37, 1.29 Hz), 7.43–7.47 m (4H, H7quinoxaline
and Hp3-Ph), 7.44 d.d (4H, Hm3-Ph, J 7.56, 7.32 Hz), 7.57 d
pm
(2H, H6quinoxaline, J 8.10 Hz), 7.60–7.68 m (6H, H
),
,
1 -Ph
7.72 d.d (4H, H°1-Ph, J 7.56, 1.56 Hz), 8.14 d.d (4H, H3°-Ph,
J 7.68, 1.32 Hz). Mass spectrum, m/z (Irel, %): 757 (7),
756 [M]+ (11), 420 (32), 406 (44), 378 (50), 364 (57),
337 (70), 322 (16), 205 (16). Found, %: C 79.46; H 5.28;
N 11.21. C50H40N6O2. Calculated, %: C 79.34; H 5.33;
N 11.10.
EXPERIMENTAL
Melting points were measured on a Boёtius heating
block. IR spectra of compounds synthesized were recoded
on a Fourier spectrometer Bruker Vector-22 from mulls
in mineral oil. 1H NMR spectra were registered on a spec-
trometerAvance-600 at operating frequency 600.00 MHz
from solutions in DMSO-d6. Mass spectra of electron
ionization were taken on a quadrupole mass spectrometer
TRACE MS, sample admission was performed directly
through a system with water cooling.
1,8-Bis(4-oxo-1,3-diphenylimidazo[1,5-a]-
quinoxalin-5-yl)-3,5-dioxaoctane (IIc). Yield 60%,
mp 216–218°C (DMSO). IR spectrum, ν, cm–1: 670,
695, 744, 777, 1005, 1033, 1101, 1124, 1178, 1246,
1257, 1300, 1326, 1352, 1393, 1445, 1485, 1504, 1591,
1
1609, 1645. H NMR spectrum, δ, ppm: 3.59 C (4H,
OCH2CH2O), 3.73 t (4H, OCH2CH2N, J 6.04 Hz),
α,ω-Bis(4-oxo-1,3-diphenylimidazo[1,5-a]-
quinoxalin-5-yl)alkanes and -oxaalkanes II. A
solution of 0.34 mmol of compound I and 1.4 mmol of
benzylamine in 6 ml of DMSO was stirred at 140–150°C
for 8 h, then it was cooled and poured into water. The
separated crystals were filtered off, washed with water,
and dried.
4.33 t (4H, NCH2, J 6.04), 6.88 d.d (2H, H8quinoxaline
,
J 7.40, 7.36 Hz), 7.12 d (2H, H9quinoxaline, J 8.04 Hz),
7.28 d.d (2H, H7quinoxaline, J 8.04, 7.36 Hz), 7.32–7.70 m
pm
,
(18H, H6quinoxaline, 3-C6H5; H
), 8.11 d (4H, H3°-Ph,
1 -Ph
J 6.68 Hz). Mass spectrum, m/z (Irel, %): 788 [M]+ (5),
452 (5), 425 (7), 394 (7), 364 (37), 337 (100), 322 (5),
234 (11), 219 (25), 205 (15). Found, %: C 76.27; H 5.23;
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 5 2008

POLYFUSED NITROGEN HETEROCYCLES: XIX.
739
(10), 680 [M]+ (24), 638 (6), 596 (8), 375 (10), 304 (16),
298 (36), 246 (25), 233 (29), 219 (49), 205 (100), 190
(18). Found, %: C 77.48; H 5.27; N 12.46. C44H36N6O2.
Calculated, %: C 77.63; H 5.33; N 12.34.
N 10.56. C50H40N6O4. Calculated, %: C 76.12; H 5.11;
N 10.65.
1,3-Bis(5-alkyl-4-oxo-3-phenylimidazo[1,5-a]-
quinoxalin-1-yl)benzenes (V). A solution of 0.9 mmol
of compound III and 0.66 mmol of compound IV
in 6 ml of DMSO was stirred at 140–150°C for 24 h,
then it was cooled and poured into water, extracted with
CH2Cl2 (3×10 ml), washed with water, the solvent was
evaporated, and the residue was subjected to column
chromatography on silica gel (eluent CH2Cl2–EtOH,
200:1).
1,3-Bis(5-benzyl-4-oxo-3-phenylimidazo[1,5-a]-
quinoxalin-1-yl)benzene (Vd). Yield 32%, mp 143–
145°C. IR spectrum, ν, cm–1: 458, 670, 782, 960, 1028,
1076, 1128, 1257, 1300, 1401, 1485, 1495, 1592, 1612,
1656. 1H NMR spectrum, δ, ppm: 5.40 C (4H, CH2),
7.02 d.d (2H, H8quinoxaline, J 7.92, 7.86 Hz), 7.20–7.50 m
(22H, H6,7q,9uinoxaline, Hm,p , CH2Ph), 7.88 d.d (1H, H5,
3-Ph
J 7.92, 7.44 Hz), 8.05 d (2H, H4,6, J 7.44 Hz), 8.15 c (1H,
H2), 8.16 d (4H, HP°h,J 7.44 Hz). Mass spectrum, m/z (Irel,
%): 776 [M]+ (2), 685 (6), 233 (3), 205 (7). Found, %:
C 80.47; H 4.71; N 10.75. C52H36N6O2. Calculated, %:
C 80.39; H 4.67; N 10.82.
1,3-Bis(5-methyl-4-oxo-3-phenylimidazo[1,5-a]-
quinoxalin-1-yl)benzene (Va). Yield 31%, mp 321–
323°C. IR spectrum, ν, cm–1: 695, 750, 1104, 1259, 1303,
1
1333, 1348, 1396, 1502, 1591, 1656. H NMR spectrum,
δ, ppm: 3.60 s (6H, CH3), 7.11 d.d.d (2H, H8quinoxaline.
,
J 8.16, 7.64 Hz), 7.35–7.50 m (10H, H7,9qunoxaline, HmP,ph),
7.58 d (2H, H6quinoxaline, J 7.80 Hz), 7.89 m.d (1H, H5,
J 7.86, 7.56 Hz), 8.03 d (2H, H4,6, J 7.86 Hz), 8.12 s (1H,
5-Methyl-1-(3-formylphenyl)-3-phenylimidazo-
[1,5-a]quinoxalin-4-one (VIa). Yield 8%, mp 237–
239°C. IR spectrum, ν, cm–1: 672, 696, 755, 804, 979,
1055, 1105, 1192, 1301, 1332, 1400, 1483, 1613, 1648,
H2), 8.16 d (4H, H° , J 7.08 Hz). Mass spectrum, m/z (Irel,
Ph
1
1693. H NMR spectrum, δ, ppm: 3.63 s (3H, CH3),
%): 625 (40), 624 [M]+ (86), 521 (30), 381.1 (32), 337.0
(62), 312.2 (12), 273.0 (18), 233.1 (30), 218.8 (100),
205.0 (34), 150.8 (24), 106 (32), 97 (42), 94 (50), 54
(56). Found, %: C 76.85; H 4.61; N 13.32. C40H28N6O2.
Calculated, %: C 76.91; H 4.52; N 13.45.
7.03 d.d (1H, H8, J 8.10, 7.56 Hz), 7.21 d (1H, H9,
J 8.34 Hz), 7.39–7.50 m (4H, H7, HmP,ph), 7.59 d (1H, H6,
J 8.34 Hz), 7.86 d.d (1H, H5phenylene, J 7.80, 7.62 Hz),
8.09 d (1H, H6phenylene, J 7.86 Hz), 8.18 d (1H, H4phenylene
,
J 7.56 Hz), 8.18 d (2H, HP°h, J 7.56 Hz), 8.29 C (1H,
H2phenylene), 10.14 C (1H, CHO). Mass spectrum, m/z (Irel,
%): 380 (24), 379 [M]+ (94), 276 (100), 219 (68), 218 (18),
152 (14), 124 (34). Found, %: C 75.79; H 4.61; N 11.25.
C24H17N3O2. Calculated, %: C 75.98; H 4.52; N 11.07.
1,3-Bis(5-ethyl-4-oxo-3-phenylimidazo[1,5-a]-
quinoxalin-1-yl)benzene (Vb). Yield 43%, mp 322–
324°C. IR spectrum, ν, cm–1: 695, 715, 728, 823, 859,
926, 1111, 1184, 1253, 1301, 1400, 1446, 1500, 1588,
1
1609, 1653. H NMR spectrum, δ, ppm: 1.28 t (3H,
The study was carried out under a financial support
of the Russian Foundation for Basic Research (grant no.
07-03-00613-a) and of a grant of the President of the
Russian Federation”Young Candidates of Sciences and
their Scientific Supervisors” (grant MK-801.2006.3).
CH3, J 7.11 Hz), 4.29 q (2H, CH2, J 7.11 Hz), 7.09 d.d
(2H, H8quinoxaline., J 8.34, 7.56 Hz), 7.35–7.50 m (10H,
H7,q9uinoxaline, Hm,p), 7.62 d (2H, H6quinoxaline, J 8.10 Hz),
Ph
7.88 d.d (1H, H5, J 7.56, 7.56 Hz), 8.03 d (2H, H4,6,
J 7.80 Hz), 8.11 s (1H, H2), 8.17 d (4H, HP°h, J 7.08 Hz).
Found, %: C 77.35; H 4.81; N 12.75. C42H32N6O2.
Calculated, %: C 77.28; H 4.94; N 12.87.
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1144, 1181, 1228, 1252, 1298, 1485, 1591, 1611, 1662.
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