Five-membered 2,3-dioxoheterocycles: LXXIII. Synthesis and thermolysis of 3-acylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones

Article abstract of DOI:10.1134/S1070428011020151

Reactions of (Z)-3-(phenacylidene-2-oxo)-3,4-dihydroquinoxalin-2(1H)-ones and (Z)-3-(3,3-dimethyl-2-oxobutylidene)-3,4-dihydroquinoxalin-2(1H)-one with oxalyl chloride led to the formation of 3-acyl-1Hpyrrolo[1,2-a]quinoxaline-1,2, 4(5H)-triones that at the thermal decarbonylation generated acyl(3- oxoquinoxalin-2-yl)ketenes which underwent the intramolecular stabilization giving 3-acylfuro[3,2-b]quinoxalin-2(4H)-ones.

Full text of DOI:10.1134/S1070428011020151

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 2, pp. 253257. Pleiades Publishing, Ltd., 2011.
Original Russian Text  I.V. Mashevskaya, I.G. Mokrushin, K.S. Bozdyreva, A.N. Maslivets, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47,
No. 2, pp. 261266.
Five-membered 2,3-Dioxoheterocycles: LXXIII.*
Synthesis and Thermolysis
of 3-Acylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones
I. V. Mashevskayaa, I. G. Mokrushinb, K. S. Bozdyrevab, and A. N. Maslivetsa,b
aInstitute of Natural Sciences at Perm State University, Perm, Russia
bPerm State University, Perm, 614990 Russia
e-mail: koh2@psu.ru
Received April 6, 2010
Abstract—Reactions of (Z)-3-(phenacylidene-2-oxo)-3,4-dihydroquinoxalin-2(1H)-ones and (Z)-3-(3,3-dimethyl-
2-oxobutylidene)-3,4-dihydroquinoxalin-2(1H)-one with oxalyl chloride led to the formation of 3-acyl-1H-
pyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones that at the thermal decarbonylation generated acyl(3-oxoquinoxalin-
2-yl)ketenes which underwent the intramolecular stabilization giving 3-acylfuro[3,2-b]quinoxalin-2(4H)-ones.
DOI: 10.1134/S1070428011020151
The thermal decarbonylation of 4-acyl-substituted
1H-pyrrole-2,3-diones fused with azaheterocycles at the
[a] side (hetareno[a]-pyrrole-2,3-diones) is a convenient
method for the generation of acyl(imidoyl)ketenes where
the imidoyl fragment is included into the heterocyclic
system [2–5].
the fuzed quinoxalone fragment of the pyrrolo[1,2-a]
quinoxaline-1,2,4(5H)-triones on the stabilization routes
of the quinoxalinylketenes obtained by the thermolysis
of the former we investigated the methods of synthesis
and thermolytic transformations of 3-acyl-1H-pyrrolo-
[1,2-a]quinoxaline-1,2,4(5H)-triones, 5-unsubstituted
analogs of 3-aroyl- and 3-heteroyl-5-phenylpyrrolo[1,2-
a]-quinoxaline-1,2,4-triones [4].
It was formerly established that the thermolysis
of 3-aroyl- and 3-heteroyl-5-phenylpyrrolo[1,2-a]
quinoxalin-1,2,4(5H)-triones resulted in the generation
of aroyl- and heteroyl(3-oxo-4-phenylquinoxalin-2-
yl)ketenes which underwent the stabilization through
[4+2]-cyclodimerization followed by the [1,3]-ac-
ylotropic shift to provide 4-acyl-3-acyloxy-2-(3-oxo-
4-phenyl-2- quinoxalinyl)-6-phenyl-1H-pyrido[1,2-a]
quinoxalin-1,5-diones [4]. Yet even insignificant changes
in the structure of the imidoylketene led to the alteration
of its stabilization paths. For instance, the 4-unsub-
stituted 3-oxoquinoxalin-2-yl(ethoxycarbonyl)ketene
originating from the thermolysis of 5-unsubstituted
3-ethoxycarbonylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-
trione stabilized by the transformation of the quinoxali-
none fragment from the amide into the hydroxyimine
form with the subsequent intramolecular acylation of
the hydroxyimine OH group by the ketene fragment [5].
(Z)-3-(2-Oxophenacylidene)-3,4-dihydroquinoxalin-
2(1H)-ones Ia–Ig and (Z)-3-(3,3-dimethyl-2-oxobutyl-
idene)-3,4-dihydroquinoxalin-2(1H)-one (Ih) were
obtained reacting the esters of acylpyruvic acids with
O-phenylenediamine by the known method [6, 7] (see
the scheme).
Compounds Ia–Ig are bright yellow crystalline sub-
stances of high melting points, readily soluble in DMF
and DMSO, sparingly soluble in the common organic
solvents, insoluble in water and alkanes.
IR spectra of compounds Ia–Ig contain absorption
bands of the stretching vibrations of the group N1H
(3120–3170 cm–1), of N4H group involved into an in-
tramolecular hydrogen bond of the H-chelate type (wide
band at 3020–3060 cm–1), of amide carbonyl C2=O
(1673–1688 cm–1), of the aroyl carbonyl group involved
into the intramolecular hydrogen bond (wide band at
1603–1611 cm–1).
In order to examine the effect of the structure of
_________
* For Communication LXXII, see [1].
253

MASHEVSKAYA et al.
254
Scheme.
H
H
N
NH2
NH2
N
O
O
O
O
(COCl)2
RCOCH2COCOOMe
N
H
N
IIa_IIh
R
Ia_Ih
O
R
O
H
N
O
N
N
OH
N
O
O
O

O
N
H
_CO
N
R
R
R
VIa_VIh
C
O
C
O
IVa_IVh
O
IIIa_IIIh
R = Ph (a), п-MeC6H4 (b), п-EtOC6H4 (c), п-FC6H4 (d), п-ClC6H4 (e), п-BrC6H4 (f), п-NO2C6H4 (g), t-Bu (h).
In the 1H NMR spectra of compounds Ia–Ig apart the
to the reaction with air moisture.
signals of the aromatic protons and the groups linked to
the aromatic rings a singlet was observed of the vinyl
proton (6.80–6.87 ppm), a singlet of the proton of N1H
group (11.97–12.18 ppm), and the singlet of the proton
of N4H group involved into the intramolecular hydrogen
bond, downfield at 13.58–13.81 ppm. In the group of the
aromatic protons the doublet of two ortho-protons of the
benzene ring of the ArCO group is shifted downfield to
7.90–8.22 ppm.
IR spectra of compounds IIa–IIg contain absorption
bands of the stretching vibrations of group N5H (3120–
3180 cm–1), of lactam carbonyl C1=O (1754–1774 cm–1),
of keto group C2=O (1715–1740 cm–1), of amide carbonyl
C4=O in the region 1670–1696 cm–1, and of the aroyl
carbonyl group of the side chain (1615–1635 cm–1). The
range of the stretching vibrations of the carbonyl groups
of the pyrroledione ring and also the higher frequency of
ν(CO) of the lactam carbonyl compared with that of the
keto group in the ring are consistent with the published
data for these groups in the IR spectra of monocyclic
1H-pyrrole-2,3-diones [8].
In the 1H NMR spectra of compounds IIa–IIg apart
the signals of the aromatic protons and the groups linked
to the aromatic rings a singlet was observed of the proton
of the N5H group in the region 11.60–11.90 ppm. In the
group of the aromatic protons the doublet of two ortho-
protons of the benzene ring of the ArCO group is shifted
downfield to 8.03–8.32 ppm, and the multiplet of the pro-
ton H9 deshielded due to the interaction with the oxygen
of the carbonyl group C1=O appears at 8.36–8.40 ppm.
The spectral characteristics of compounds Ia–Ig show
that they exist in the crystalline state and in solution in
the form with the exo-located double bond and a strong
intramolecular hydrogen bond of the H-chelate type be-
tween the N4H and aroyl group, therefore they are present
in the form of Z-isomers characteristic of compounds of
this class [8].
The reaction of (Z)-3-(2-oxophenacylidene)-3,4-
dihydroquinoxalin-2(1H)-ones Ia–Ig with oxalyl chloride
at boiling in anhydrous chloroform over 1–2 h (till the
end of HCl liberation) afforded in virtually quantitative
yields 3-aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-tri-
ones IIa–IIg. Pyrroloquinoxalinetriones IIa–IIg are dark
violet (nearly black) crystalline substances of high melt-
ing point, melting with decomposition, readily soluble
in DMF and DMSO, sparingly soluble in the common
organic solvents, insoluble in alkanes. They react with
water and alcohols and suffer decoloration at storage due
The heating of 3-aroylsubstituted pyrroloquinoxa-
linetriones IIa–IIg and 3-pivaloylpyrrolo-[1,2-a]qui-
noxaline-1,2,4(5H)-trione (IIh) [7] in an inert aprotic
solvent (DowthermA) at 190–195°C for 1–5 min (till the
disappearance of the violet color of the initial pyrrolo-
quinoxalinetriones) furnished in good yields 3-aroyl- and
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 2 2011

FIVE-MEMBERED 2,3-DIOXOHETEROCYCLES: LXXIII.
255
30 ml of dioxane was boiled for 30 min (TLC monitoring),
the solvent was removed, the residue was recrystallized
from dioxane. Yield 99%, mp 266–267°C [6]. IR spec-
trum, ν, cm–1: 3160 (N1H), 3070 br (N4H), 1688 (C2=O),
1611 br (COPh). 1H NMR spectrum, δ, ppm: 6.83 s (1H,
C3=CH), 7.14–7.61 group of signals (7H, C6H3 + H5-8),
7.99 d [2H, 2HO(PhCO), J 8.7 Hz], 12.05 s (N1H), 13.68 s
(N4H). Found, %: C 72.77; H 4.60; N 10.63. C16H12N2O2.
Calculated, %: C 72.72; H 4.58; N 10.60.
3-pivaloylfuro[3,2-b]-quinoxaline-2(4H)-ones IIIa–IIIh.
After the thermolysis in the reaction mixture according
to TLC monitoring initial quinoxalones Ia–Ih are pres-
ent in trace amounts as impurities. They apparently form
by hydrolysis of pyrroloquinoxalinetriones IIa–IIh with
residual water present in the dried solvent. Compounds
IIIa–IIIh are light-yellow crystalline substances of
high melting point, melting with decomposition, read-
ily soluble in DMF and DMSO, sparingly soluble in the
common organic solvents, insoluble in water and alkanes.
Compounds Ib–Ig were similarly obtained.
In the IR spectra of compounds IIIa–IIIh the fol-
lowing absorption bands are observed: the wide band of
the stretching vibrations of the NH group (3170–3290
cm–1), of lactone group C2=O (1775–1787 cm–1), of aroyl
carbonyl group from the side chain (1654–1664 cm–1 for
compounds IIIa–IIIg), of pivaloyl carbonyl group (1680
cm–1 for compound IIIh).
(Z)-3-[2-(4-Methylphenyl)-2-oxoethylidene]-3,4-
dihydroquinoxalin-2(1H)-one (Ib). Yield 98%, mp 229–
230°C. IR spectrum, ν, cm–1: 3170 (N1H), 3030 br (N4H),
1680 (C2=O), 1607 br (COC6H4). 1H NMR spectrum, δ,
ppm: 2.39 s (3H, Me), 6.81 s (1H, C3=CH), 7.12–7.57
group of signals [6H, 2Hm(COC6H4) + H5–8], 7.90 d [2H,
2HO(COC6H4), J 8.2 Hz], 12.02 s (N1H), 13.63 s (N4H).
Found, %: C 73.35; H 5.03; N 10.09. C17H14N2O2. Cal-
culated, %: C 73.37; H 5.07; N 10.07.
The NMR spectra of compounds IIIa–IIIh apart the
signals of the aromatic protons and the groups linked to
the aromatic rings contain the proton singlet of the N4H
group in the region 13.73–14.30 ppm. In the group of the
aromatic protons the doublet of the proton H8 is shifted
downfield due to the deshielding because of the interac-
tion with the atom N9 (8.18–8.24 ppm).
(Z)-3-[2-Oxo-2-(4-ethoxyphenyl)ethylidene]-3,4-
dihydroquinoxalin-2(1H)-one (Ic). Yield 92%, mp 238–
239°C. IR spectrum, ν, cm–1: 3120 (N1H), 3020 br (N4H),
1676 (C2=O), 1610 br (COC6H4). 1H NMR spectrum, δ,
ppm: 2.39 s (3H, Me), 6.81 s (1H, C3=CH), 7.12–7.57
group of signals [6H, 2Hm(COC6H4) + H5–8], 7.90 d [2H,
2HO(COC6H4), J 8.2 Hz], 11.97 s (N1H), 13.58 s (N4H).
Found, %: C 70.16; H 5.25; N 9.11. C18H16N2O3. Calcu-
lated, %: C 70.12; H 5.23; N 9.09.
Evidently the thermolysis of pyrroloquinoxalinetrio-
nes IIa–IIh led to the decarbonylation and the generation
of acyl(3-oxoquinoxalin-2-yl)ketenes IVa–IVh undergo-
ing the stabilization by the conversion of the quinoxalone
fragment from the amide into the hydroxyimine form
Va–Vh with the subsequent intramolecular acylation of
the hydroxyimine OH group with the ketene fragment.
This reaction is a convenient method of the regioselec-
tive construction of the functionally-substituted system
of furo[3,2-b]quinoxaline.
(Z)-3-[2-Oxo-2-(4-fluorophenyl)ethylidene]-3,4-
dihydroquinoxalin-2(1H)-one (Id). Yield 89%, mp 257–
258°C. IR spectrum, ν, cm–1: 3140 (N1H), 3030 br (N4H),
1
1674 (C2=O), 1610 br (COC6H4). H NMR spectrum,
δ, ppm: 6.80 s (1H, C3=CH), 7.12–7.54 group of signals
[6H, 2Hm(COC6H4) + H5–8], 8.06 d [2H, 2HO(COC6H4),
J 8.7 Hz], 12.06 s (N1H), 13.62 s (N4H). Found, %:
C 68.05; H 3.97; F 6.70; N 9.95. C16H11FN2O2. Calcu-
lated, %: C 68.08; H 3.93; F 6.73; N 9.92.
EXPERIMENTAL
IR spectra of compounds obtained were recorded on
a spectrophotometer FSM-1201. 1H and 13C NMR spec-
tra were registered on a spectrometer Bruker AM-400
[operating frequencies 400 (1H) and 100 (13C) MHz] in
DMSO-d6, internal reference TMS. The homogeneity of
compounds synthesized was tested by TLC on Silufol
plates, eluents benzene–ethyl acetate, 5:1, ethyl acetate,
development in iodine vapor or under UV irradiation.
(Z)-3-[2-Oxo-2-(4-chlorophenyl)ethylidene]-3,4-
dihydroquinoxalin-2(1H)-one (Ie). Yield 94%, mp 271–
272°C. IR spectrum, ν, cm–1: 3170 (N1H), 3030 br (N4H),
1
1684 (C2=O), 1608 br (COC6H4). H NMR spectrum,
δ, ppm: 6.80 s (1H, CH), 7.15–7.60 group of signals
[6H, 2Hm(COC6H4) + H5–8], 8.00 d [2H, 2HO(COC6H4),
J 8.6 Hz], 12.07 s (N1H), 13.65 s (N4H). Found, %:
C 64.37; H 3.74; Cl 11.85; N 9.32. C16H11ClN2O2. Cal-
culated, %: C 64.33; H 3.71; Cl 11.87; N 9.36.
(Z)-3-(2-Oxo-2-phenylethyl idene)-3,4-dihydroqui-
noxalin-2(1H)-one (Ia). Asolution of 0.01 mol of methyl
benzoylpyruvate and 0.01 mol of o-phenylenediamine in
(Z)-3-[2-(4-Bromophenyl)-2-oxoethylidene]-3,4-
dihydroquinoxalin-2(1H)-one (If). Yield 89%, mp 279–
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 2 2011

MASHEVSKAYA et al.
256
280°C. IR spectrum, ν, cm–1: 3150 (N1H), 3040 br (N4H),
1673 (C2=O), 1607 br (COC6H4). 1H NMR spectrum, δ,
ppm: 6.80 s (1H, C3=CH), 7.13–7.74 group of signals
[6H, 2Hm(COC6H4) + H5–8], 7.92 d [2H, 2HO(COC6H4),
J 8.6 Hz], 12.09 s (N1H), 13.66 s (N4H). Found, %:
C 56.07; H 3.20; Br 23.30; N 8.14. C16H11BrN2O2. Cal-
culated, %: C 56.00; H 3.23; Br 23.28; N 8.16.
(N5H). Found, %: C 66.28; H 3.85; N 7.70. C20H14N2O5.
Calculated, %: C 66.30; H 3.89; N 7.73.
3-(4-Fluorobenzoyl)pyrrolo[1,2-a]quinoxaline-
1,2,4(5H)-trione (IId). Yield 93%, mp 258–259°C.
IR spectrum, ν, cm–1: 3120 (N5H), 1760 (C1=O), 1730
(C2=O), 1670 (C4=O), 1610 (C3C=O). 1H NMR spectrum,
δ, ppm: 7.10–8.09 group of signals [7H, H6–8 + C6H4],
8.37 m (1H, H9), 11.80 s (1H, N5H). Found, %: C 64.25;
H 2.68; F 5.61; N 8.30. C18H9FN2O4. Calculated, %:
C 64.29; H 2.70; F 5.65; N 8.33.
(Z)-3-[2-(4-Nitrophenyl)-2-oxoethylidene]-3,4-
dihydroquinoxalin-2(1H)-one (Ig). Yield 80%, mp 298–
299°C. IR spectrum, ν, cm–1: 3170 (N1H), 3060 br (N4H),
1684 (C2=O), 1603 br (COC6H4). 1H NMR spectrum, δ,
ppm: 6.87 s (1H, C3=CH), 7.17–7.61 group of signals
(4H, H5–8), 8.22 d [2H, 2HO(COC6H4), J 8.7 Hz], 8.34 d
[2H, 2Hm(COC6H4), J 8.7 Hz], 12.18 s (N1H), 13.81 s
(N4H). Found, %: C 62.11; H 3.61; N 13.55. C16H11N3O4.
Calculated, %: C 62.14; H 3.58; N 13.59.
3-(4-Chlorobenzoyl)pyrrolo[1,2-a]quinoxaline-
1,2,4(5H)-trione (IIe). Yield 89%, mp 248–250°C.
IR spectrum, ν, cm–1: 3170 (N5H), 1774 (C1=O),
1
1737 (C2=O), 1696 (C4=O), 1620 (C3C=O). H NMR
spectrum, δ, ppm: 7.14–7.83 group of signals [5H, H6–
8+2Hm(COC6H4)], 8.10 d [2H, 2HO(COC6H4), J 8.5 Hz],
8.39 m (1H, H9), 11.82 s (1H, N5H). Found, %: C 61.26;
H 2.53; Cl 11.12; N 7.91. C18H9ClN2O4. Calculated, %:
C 61.29; H 2.57; Cl 10.05; N 7.94.
3-Benzoylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-
trione (IIa). To a dispersion of 0.01 mol of compound
Ia in 50 ml of anhydrous chloroform was added drop-
wise 0.011 mol of freshly distilled oxalyl chloride, the
mixture was heated at 40–50°C for 10 min, boiled for
100 min, cooled, the precipitate was filtered off and
washed with anhydrous hexane (2 × 10 ml). Yield 92%,
mp 220–221°C (decomp). IR spectrum, ν, cm–1: 3175
(N5H), 1769 (C1=O), 1730 (C2=O), 1682 (C4=O), 1630
(C3C=O). 1H NMR spectrum, δ, ppm: 7.05–7.85 group of
signals (5H, C6H3 + H6–8), 8.03 d [2H, 2HO(COC6H4)],
8.36 m (1H, H9), 11.60 s (1H, N5H). Found, %: C 67.90;
H 3.13; N 8.81. C18H10N2O4. Calculated, %: C 67.93;
H 3.17; N 8.80.
3-(4-Bromobenzoyl)pyrrolo[1,2-a]quinoxaline-
1,2,4(5H)-trione (IIf). Yield 79%, mp 255–257°C.
IR spectrum, ν, cm–1: 3170 (N5H), 1770 (C1=O),
1
1740 (C2=O), 1680 (C4=O), 1615 (C3C=O). H NMR
spectrum, δ, ppm: 7.06–7.80 group of signals [5H, H6–
8+2Hm(COC6H4)], 8.01 d [2H, 2HO(COC6H4), J 8.7 Hz],
8.37 m (1H, H9), 11.78 s (1H, N5H). Found, %: C 54.40;
H 2.23; Br 20.07; N 7.09. C18H9BrN2O4. Calculated, %:
C 54.43; H 2.28; Br 20.12; N 7.05.
3-(4-Nitrobenzoyl)pyrrolo[1,2-a]quinoxaline-
1,2,4(5H)-trione (IIg). To a solution of 0.01 mol of
compound Ig in 50 ml of anhydrous O 1,2-dichloroethene
was added 0.011 mol of freshly distilled oxalyl chloride,
the mixture was heated at 40–50°C for 10 min, boiled for
100 min, cooled, the precipitate was filtered off, washed
with anhydrous hexane (2×10 ml), and dried in air for
3 min. Yield 86%, mp 290–292°C (decomp). IR spectrum,
ν, cm–1: 3180 (N5H), 1780 (C1=O), 1732 (C2=O), 1693
Compounds IIb–IIg were similarly obtained.
3-[(4-Methyl)benzoyl]pyrrolo[1,2-a]quinoxaline-
1,2,4(5H)-trione (IIb). Yield 93%, mp 238–240°C.
IR spectrum, ν, cm–1: 3180 (N5H), 1765 (C1=O), 1722
(C2=O), 1688 (C4=O), 1625 (C3C=O). 1H NMR spectrum,
δ, ppm: 2.39 s (3H, Me), 7.17–7.77 group of signals
[5H, H6–8+2Hm (COC6H4)], 7.97 d [2H, 2H0(COC6H4),
J 7.93 Hz], 8.38 m (1H, H9), 11.75 s (N1H). Found, %:
C 68.63; H 3.60; N 8.41. C19H12N2O4. Calculated, %:
C 68.67; H 3.64; N 8.43.
1
(C4=O), 1618 (C3C=O). H NMR spectrum, δ, ppm:
7.09–7.30 group of signals (3H, H6–8), 8.32 m (4H, C6H4),
8.40 m (1H, H9), 11.90 s (1H, N5H). Found, %: C 59.50;
H 2.47; N 11.54. C18H9N3O6. Calculated, %: C 59.51;
H 2.50; N 11.57.
3-(4-Ethoxybenzoyl)pyrrolo[1,2-a]quinoxaline-
1,2,4(5H)-trione (IIc). Yield 86%, mp 218–220°C.
IR spectrum, ν, cm–1: 3130 (N5H), 1765 (C1=O), 1740
3-Benzoylfuro[3,2-b]quinoxalin-2(4H)-one (IIIa). A
solution of 2.5 mmol of compound IIa in 8 ml of Dow-
thermAwas heated on a metal bath at 195–200°C for 1.5
mandH (till the disappearance of the bright violet color of
initial compound IIa). The reaction mixture was cooled,
the separated precipitate was filtered off. Yield 95%, mp
1
(C2=O), 1679 (C4=O), 1635 (C3C=O). H NMR spec-
trum, δ, ppm: 1.35 t (3H, CH2CH3, J 7.0 Hz), 4.14 q
(2H, CH2CH3, J 7.0 Hz), 7.00 d [2H, 2Hm (COC6H4),
J 8.7 Hz], 7.11–7.22 group of signals (3H, H6–8), 8.0 d
[H, 2HO(COC6H4), J 8.7 Hz], 8.38 m (1H, H9), 11.74 s
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 2 2011

FIVE-MEMBERED 2,3-DIOXOHETEROCYCLES: LXXIII.
257
274–275°C (ethyl acetate). IR spectrum, ν, cm–1: 3170 br
(NH), 1776 (C2=O), 1656 (COPh). 1H NMR spectrum, δ,
ppm: 7.50–7.87 group of signals (8H, H5–7+ Ph), 8.21 d
(1H, H8, J 8.2 Hz), 14.05 s (1H, N4H). 13C NMR spec-
trum, δ, ppm: 91.7 (C3), 118.6–142.0 (CAr, C9a), 154.7
(C3a), 164.0 (C2), 188.5 (COPh). Found, %: C 70.30;
H 3.43; N 9.62. C17H10N2O3. Calculated, %: C 70.34;
H 3.47; N 9.65.
1H NMR spectrum, δ, ppm: 7.56–7.88 group of signals
(7H, H5-7+ C6H4CO), 8.21 d (1H, H8, J 8.2 Hz), 14.12 s
(1H, N4H). Found, %: C 55.28; H 2.43; Br 21.60; N 7.55.
C17H9BrN2O3. Calculated, %: C 55.31; H 2.46; Br 21.64;
N 7.59.
3-(4-Nitrobenzoyl)furo[3,2-b]quinoxalin-2(4H)-
one (IIIg). Yield 69%, mp 278–279°C. IR spectrum,
ν, cm–1: 3267 (NH), 1786 (C2=O), 1657 (COC6H4).
1H NMR spectrum, δ, ppm: 7.58–8.37 group of sig-
nals (7H, H5-7+ C6H4CO), 8.23 d (1H, H8, J 8.3 Hz),
14.30 s (1H, N4H). Found, %: C 60.87; H 2.69; N 12.50.
C17H9N3O4. Calculated, %: C 60.90; H 2.71; N 12.53.
Compounds IIIb–IIIh were similarly obtained.
3-(4-Methylbenzoyl)furo[3,2-b]quinoxalin-2(4H)-
one (IIIb). Yield 93%, mp 239–240°C. IR spectrum,
ν, cm–1: 3190 br (NH), 1787 (C2=O), 1657 (COC6H4).
1H NMR spectrum, δ, ppm: 2.40 s (3H, Me), 7.30–7.87
group of signals (7H, H5–7+ C6H4CO), 8.19 d (1H, H8,
J 8.2 Hz), 14.00 s (1H, N4H). Found, %: C 71.01; H 3.93;
N 9.20. C18H12N2O3. Calculated, %: C 71.05; H 3.97;
N 9.21.
3-Pivaloylfuro[3,2-b]quinoxalin-2(4H)-one (IIIh).
Yield 61%, mp 239–240°C. IR spectrum, ν, cm–1: 3180
(NH), 1781 (C2=O), 1680 (COCMe3). 1H NMR spectrum,
δ, ppm: 1.33 s (9H, CMe3), 7.55 m (3H, H5–7), 8.24 d (1H,
H8, J 8.4 Hz), 13.73 s (1H, N4H). Found, %: C 66.60;
H 5.19; N 10.32. C15H14N2O4. Calculated, %: C 66.66;
H 5.22; N 10.36.
3-(4-Ethoxybenzoyl)furo[3,2-b]quinoxalin-2(4H)-
one (IIIc). Yield 95%, mp 246–247°C. IR spectrum,
ν, cm–1: 3290 br (NH), 1775 (C2=O), 1658 (COC6H4).
1H NMR spectrum, δ, ppm: 1.37 t (3H, Me, J 7.0 Hz),
4.14 q (2H, CH2O, J 7.0 Hz), 7.03–7.92 group of sig-
nals (7H, H5–7+ C6H4CO), 8.18 d (1H, H8, J 8.3 Hz),
13.92 s (1H, N4H). Found, %: C 68.22; H 4.20; N 8.34.
C19H14N2O3. Calculated, %: C 68.26; H 4.22; N 8.38.
ACKNOWLEDGMENTS
The study was carried out under the financial support
of the Russian Foundation for Basic Research (grant
no. 08-03-01032).
REFERENCES
3-(4-Fluorobenzoyl)furo[3,2-b]quinoxalin-2(4H)-
one (IIId). Yield 89%, mp 258–259°C. IR spectrum,
ν, cm–1: 3216 (NH), 1775 (C2=O), 1658 (COC6H4).
1H NMR spectrum, δ, ppm: 7.34–7.96 group of signals
(7H, H5–7+ C6H4CO), 8.21 d (1H, H8, J 8.3 Hz), 14.06 s
(1H, N4H). Found, %: C 66.20; H 2.91; F 6.14; N 9.04.
C17H9FN2O3. Calculated, %: C 66.23; H 2.94; F 6.16;
N 9.08.
1. Dmitriev, M.V., Silaichev, P.S., and Maslivets, A.N. Zh.
Org. Khim., 2011, vol. 47, p. 94.
2. Aliev, Z.G., Krasnykh, O.P., Maslivets, A.N., And-
reichikov, Yu.S., and Atovmyan, L.O., Izv. Akad. Nauk,
Ser. Khim., 1993, p. 1633.
3. Aliev, Z.G., Krasnykh, O.P., Maslivets, A.N., And-
reichikov, Yu.S., and Atovmyan, L.O., Izv. Akad. Nauk,
Ser. Khim., 1999, p. 2154.
3-(4-Chlorobenzoyl)furo[3,2-b]quinoxalin-2(4H)-
one (IIIe). Yield 95%, mp 257–259°C. IR spectrum,
ν, cm–1: 3282 (NH), 1797 (C2=O), 1654 (COC6H4).
1H NMR spectrum, δ, ppm: 7.56–7.89 group of signals
(7H, H5–7+ C6H4CO), 8.21 d (1H, H8, J 8.3 Hz), 14.12 s
(1H, N4H). Found, %: C 62.85; H 2.74; Cl 10.89; N 8.61.
C17H9ClN2O3. Calculated, %: C 62.88; H 2.79; Cl 10.92;
N 8.63.
4. Bozdyreva, K.S., Cmirnova, I.V., and Maslivets, A.N., Zh.
Org. Khim., 2005, vol. 41, p. 1101.
5. Maslivets, A.N., Golovnina, O.V, Krasnykh, O.P., and
Aliev, Z.G., Khim. Geterotsikl. Soedin., 2000, p. 418.
6. Andreichikov, Yu.S., Pitirimova, S.G., Saraeva, R.F.,
Gein, V.L., Plakhina, G.D., and Voronova, L.A. Khim.
Geterotsikl. Soedin., 1978, p. 407.
7. Bozdyreva, K.S.,Aliev, Z.G., and Maslivets,A.N., Zh. Org.
Khim., 2008, vol. 44, p. 612.
3-(4-Bromobenzoyl)furo[3,2-b]quinoxalin-2(4H)-
one (IIIf). Yield 90%, mp 271–272°C. IR spectrum,
ν, cm–1: 3285 (NH), 1778 (C2=O), 1664 (COC6H4).
8. Maslivets, A.N., Cmirnova, L.I., and Andreichikov, Yu.S.,
Zh. Org. Khim., 1992, vol. 28, p. 2141.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 2 2011