220
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 1, January, 2008
Kalinin and Mamedov
quinoxalinꢀ3ꢀyl)pyrrole (3b). A solution of compound 1b (0.32 g,
1.5 mmol) and benzylamine (0.17 g, 1.7 mmol) in DMSO (10 mL)
was stirred for 6 h at 140—150 °C, cooled, and poured in water. The
crystals formed were filtered off, washed with water, dried, and
purified by column chromatography on silica gel (eluent: dichloroꢀ
methane). The yield of compound 3а was 35 mg (11%), of compoꢀ
und 3b, 60 mg (16%).
2,5ꢀBis(1ꢀethylꢀ2ꢀoxoꢀ1,2ꢀdihydroquinoxalinꢀ3ꢀyl)pyrrole
(3а), m.p. 270—272 °C. IR, ν/cm–1: 412, 475, 652, 741, 815, 1040,
1092, 1115, 1159, 1181, 1252, 1290, 1483, 1578, 1603, 1644, 3327.
1H NMR, δ: 1.34 (t, 6 Н, Me, J = 7.0 Hz); 4.41 (q, 4 Н, CH2, J =
7.0 Hz); 7.40 (s, 2 Н, Н(3), H(4)); 7.42 (ddd, 2 Н, Н(6) quinox.,
J = 8.4 Hz, J = 8.0 Hz, J = 1.3 Hz); 7.60 (ddd, 2 Н, Н(7) quinox.,
J = 8.4 Hz, J = 8.0 Hz, J = 1.3 Hz); 7.67 (d, 2 Н, Н(8) quinox., J =
8.0 Hz); 7.85 (dd, 2 Н, Н(5) quinox., J = 8.0 Hz, J = 1.3 Hz). MS
EI, m/z (Irel (%)): 412 [M + 1]+• (29), 411 (100) [M]+•, 382 (7),
368 (11), 354 (12), 313 (14), 299 (11), 264 (9), 239 (10), 236 (14).
Found (%): C, 70.11; H, 5.09; N, 17.13. С24H21N5O2. Calculated
(%): C, 70.06; H, 5.14; N, 17.02.
1ꢀBenzylꢀ2,5ꢀbis(1ꢀethylꢀ2ꢀoxoꢀ1,2ꢀdihydroquinoxalinꢀ3ꢀ
yl)pyrrole (3b), m.p. 286—288 °C. IR, ν/cm–1: 477, 551, 586, 874,
1038, 1090, 1192, 1293, 1382, 1536, 1579, 1601, 1654. 1H NMR, δ:
1.24 (t, 6 Н, Me, J = 7.1 Hz); 4.29 (q, 4 Н, CH2СН3, J = 7.1 Hz);
6.35 (s, 2 Н, СН2Ph); 6.82 (d, 2 Н, Н(оꢀPh), J = 8.4 Hz); 7.00 (dd,
1 Н, Н(рꢀPh), J = 7.4 Hz, J = 6.9 Hz); 7.08 (dd, 2 Н, Н(mꢀPh), J =
7.62 Hz, J = 7.4 Hz); 7.32—7.40 (m, 2 Н, quinox.); 7.52 (s, 2 Н,
Н(3), H(4)); 7.52—7.58 (m, 4 Н, quinox.); 7.64 (d, 2 Н, quinox.,
J = 7.6 Hz). MS EI, m/z (Irel (%)): 501 (100) [M]+•, 472 (89), 444
(10), 425 (13), 424 (38), 412 (21), 366 (7), 340 (11), 328 (20), 300
(7), 251 (8), 199 (16), 170 (9), 156 (8), 130 (8), 91 (35), 86 (24), 44
(42), 28 (33). Found (%): C, 74.35; H, 5.48; N, 14.04. С31H27N5O2.
Calculated (%): C, 74.23; H, 5.43; N, 13.96.
dazo[1,5ꢀa]quinoxalinꢀ4(5H)ꢀone system (2a), whereas
the reactions, leading to 2,5ꢀbis(1ꢀethylꢀ2ꢀoxoꢀ1,2ꢀ
dihydroquinoxalinꢀ3ꢀyl)pyrrole (3а), 1ꢀbenzylꢀ2,5ꢀbis(1ꢀ
ethylꢀ2ꢀoxoꢀ1,2ꢀdihydroquinoxalinꢀ3ꢀyl)pyrrole (3b),
and 5ꢀethylꢀ1ꢀphenylimidazo[1,5ꢀa]quinoxalinꢀ4ꢀone
(2b), compete when 3ꢀacetylꢀ1ꢀethylquinoxalinꢀ2ꢀone
(1b) is used instead of 1а.
Structures of compounds 2a, 3а, and 3b were estabꢀ
lished by spectroscopy methods (IR spectroscopy, 1Н
NMR spectroscopy, mass spectrometry), and additionꢀ
ally by Xꢀray analysis for compounds 3а and 3b. The
formation of compound 2b (in ~10% yield) was deterꢀ
1
mined from the Н NMR spectrum of the reaction mixꢀ
ture by the presence of indicative signals1 of Н(8) proton
(6.87 dd, 1 Н, J = 8.4 Hz, J = 8.4 Hz) and of the protons
of the methyl group 2.79 (s, CH3).
The pyrrole ring is formed not only in the reaction of
3ꢀacetylꢀ1ꢀethylquinoxalinꢀ2ꢀone (1b) with benzylamine,
but also with other suppliers of the nitrogen atom, such as
mꢀbis(aminomethyl)benzene, other primary amines, and
NH4OAc, which will be reported in one of our next paꢀ
pers, where the Xꢀray data will be presented and suggesꢀ
tions on the mechanism of the pyrrole ring formation will
be considered.
IR spectra were recorded on a Bruker Vectorꢀ22 spectrometer in
Nujol. 1H NMR spectra were recorded on a Bruker MSLꢀ400
spectrometer relatively to the residual signals of the solvent (DMSOꢀ
d6). Mass spectra (electron ionization) were recorded on a Finnigan
TRACE MS ThermoQuest instrument (Bace MS).
3ꢀMethylꢀ1ꢀphenylimidazo[1,5ꢀa]quinoxalinꢀ4(5Н)ꢀone
(2a). A solution of 3ꢀacetylquinoxalinꢀ2(1Н)ꢀone (1a) (0.14 g,
0.75 mmol) and benzylamine (0.11 g, 1 mmol) in DMSO (5 mL)
was stirred for 5 h at 140—150 °C, cooled, and poured in water. The
crystals formed were filtered off, washed with water, dried, and
purified by column chromatography on silica gel (eluent: chloroꢀ
form). The yield was 60 mg (30%), m.p. 290—292. IR, ν/cm–1: 469,
584, 670, 697, 838, 1122, 1253, 1332, 1409, 1504, 1573, 1618, 1673,
2500ꢀ3220. 1H NMR, δ: 2.63 (s, 3 Н, Me); 6.87 (ddd, 1 Н, Н(8),
J = 8.5 Hz, J = 7.3 Hz, J = 1.6 Hz); 7.01 (d, 1 Н, Н(6), J = 8.5 Hz);
7.26 (ddd, 1 Н, Н(7), J = 8.1 Hz, J = 7.3 Hz, J = 1.2 Hz); 7.29 (dd,
1 Н, Н(9), J = 8.1 Hz, J = 1.6 Hz); 7.58—7.67 (m, 5 Н, Ph). MS,
m/z (Irel (%)): 276 (26) [M + 1]+•, 275 [M]+• (100), 274 (28), 234
(26), 206 (6), 172 (36), 144 (42), 143 (39), 118.1 (22), 104 (8), 90
(14), 81 (32), 69 (40). Found (%): C, 74.25; H, 4.82; N, 15.15.
С17H13N3O.. Calculated (%): C, 74.17; H, 4.76; N, 15.26.
This work was financially supported by the Russian
Foundation for Basic Research (Project Nos 07ꢀ03ꢀ
00613ꢀа and 05ꢀ03ꢀ33008ꢀа) and by the Russian Federaꢀ
tion President Council for Grants (Program for the State
Support of Leading Scientific Schools and Young Scienꢀ
tists, Grant MKꢀ801.2006.3).
References
1. V. A. Mamedov, A. A Kalinin, E. A. Gorbunova, I. Bayer, W. D.
Habicher, Zh. Org. Khim., 2004, 40, 1082 [Russ. J. Org. Chem.,
2004, 40 (Engl. Transl.)].
2,5ꢀBis(1ꢀethylꢀ2ꢀoxoꢀ1,2ꢀdihydroquinoxalinꢀ3ꢀyl)pyrrole
Received June 14, 2007;
(3а) and 1ꢀbenzylꢀ2,5ꢀbis(1ꢀethylꢀ2ꢀoxoꢀ1,2ꢀdihydroꢀ
in revised form November 16, 2007
Kalinin
