Methyl 3-aroyl-4-oxo-1,4-dihydroquinoline-2-carboxylates: Synthesis and molecular and crystal structures

Article abstract of DOI:10.1007/s11172-014-0499-5

Thermal decarbonylation of methyl 1-aryl-3-(het)aroyl-4,5-dioxo-4,5-dihydro-1H-pyrrole-2-carboxylates afforded 8-substituted methyl 3-(het)aroyl-4-oxo-1,4-dihydroquinoline-2-carboxylates. X-ray diffraction studies revealed no hydrogen bonds in the crystals of the compounds obtained. According to spectral data, hydrogen bonding is possible in concentrated solutions of 8-substituted methyl 4-oxo-1,4-dihydroquinoline-2-carboxylates.

Full text of DOI:10.1007/s11172-014-0499-5

Russian Chemical Bulletin, International Edition, Vol. 63, No. 3, pp. 731—738, March, 2014
731
Methyl 3ꢀaroylꢀ4ꢀoxoꢀ1,4ꢀdihydroquinolineꢀ2ꢀcarboxylates:
synthesis and molecular and crystal structures
A. A. Boteva,a O. P. Krasnykh,a I. V. Fefilova,a E. B. Babushkina,b and P. A. Slepukhinc
aPerm National Research Polytechnic University,
29 Komsomol´skii prosp., 614990 Perm, Russian Federation.
Fax: +7 (342) 219 8067. Eꢀmail: anastasiaquinolone@gmail.com
bPerm State Pharmaceutical Academy,
2 ul. Polevaya, 614990 Perm, Russian Federation.
Fax: +7 (342) 233 5501
cI. Ya. Postovskii Institute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences,
22/20 ul. S. Kovalevskoi, 620990 Ekaterinburg, Russian Federation.
Fax: +7 (343) 374 1189. Eꢀmail: slepukhin@ios.uran.ru
Thermal decarbonylation of methyl 1ꢀarylꢀ3ꢀ(het)aroylꢀ4,5ꢀdioxoꢀ4,5ꢀdihydroꢀ1Hꢀpyrꢀ
roleꢀ2ꢀcarboxylates afforded 8ꢀsubstituted methyl 3ꢀ(het)aroylꢀ4ꢀoxoꢀ1,4ꢀdihydroquinolineꢀ
2ꢀcarboxylates. Xꢀray diffraction studies revealed no hydrogen bonds in the crystals of the
compounds obtained. According to spectral data, hydrogen bonding is possible in concentrated
solutions of 8ꢀsubstituted methyl 4ꢀoxoꢀ1,4ꢀdihydroquinolineꢀ2ꢀcarboxylates.
Key words: Nꢀarylimidoylketenes, decarbonylation, 4,5ꢀdioxoꢀ4,5ꢀdihydroꢀ1Hꢀpyrroles,
4ꢀquinolones, hydrogen bonds, Xꢀray diffraction analysis.
Intramolecular cyclizations of Nꢀꢀpyridylꢀ and
Nꢀarylimidoylketenes are known to produce substituted
4ꢀquinolones or their nitrogen analogs.1—3 The reaction
occurs as [4+2] cyclization involving two ꢀelectrons of
the aromatic substituent at the N atom and four ꢀelecꢀ
trons of the imidoylketene fragment followed by migraꢀ
tion of the H atom (Scheme 1). The pathway of the reacꢀ
tion is insensitive to either an acyl group conjugated with
the ketene C=C bond or substituents on the aromatic ring
involved in the cyclization.2
Thermal decarbonylation of methyl 1ꢀarylꢀ3ꢀ(het)ꢀ
aroylꢀ4,5ꢀdioxoꢀ4,5ꢀdihydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylates (1)
through the formation of reactive intermediate Nꢀarylꢀ
imidoylketene (2) provides a convenient route to methyl
3ꢀ(het)aroylꢀ4ꢀoxoꢀ1,4ꢀdihydroquinolineꢀ2ꢀcarboxylꢀ
ates (3) (Scheme 2).
Pyrrolediones 1 prepared from methyl (Z)ꢀ2ꢀarylaminoꢀ
4ꢀ(het)arylꢀ4ꢀoxobutꢀ2ꢀenoates (4) and oxalyl chloride
easily and reversibly react with water to give methyl
1ꢀarylꢀ3ꢀ(het)aroylꢀ2,4ꢀdihydroxyꢀ5ꢀoxoꢀ2,5ꢀdihydroꢀ1Hꢀ
pyrroleꢀ2ꢀcarboxylates (5). The spectral and physicochemꢀ
ical characteristics of compounds 1 and 5 agree with the
Scheme 1
1
literature data,2,5 with the exception that their H NMR
spectra feature doublets for the protons of the methyl
groups and those for the protons of the substituents at
the asymmetric C(2) atom of the dihydropyrrole ring
(—COOMe and —OH) and that their 13C NMR spectra
show doublets for the C(2) and C(4) atoms and the carbon
atoms of the oꢀMe and OMe groups. Apparently, the rotaꢀ
tion of the aromatic substituent about the C—N bond in
compounds 5 is hindered by the presence of an orthoꢀ
substituent. This is responsible for the magnetic nonequivꢀ
alence of the protons and the carbon atoms of the aforeꢀ
mentioned groups and, accordingly, for the doubling of
their signals in the 1H and 13C NMR spectra.
X = CH, N; Y = Alk, AlkO, Hal, CN
The commercial success of fluoroquinolones as highly
effective antibacterial drugs as well as the discovery of other
types of activity in 4ꢀquinoloneꢀcontaining compounds
have given impetus to a search for methods of their synꢀ
thesis and investigations of structural factors that ensure
interactions with biological targets.4
Thermal decarbonylation of pyrrolediones 1 at
180—200 C yields methyl 3ꢀ(het)aroylꢀ4ꢀoxoꢀ1,4ꢀdiꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 0731—0738, March, 2014.
1066ꢀ5285/14/6303ꢀ0731 © 2014 Springer Science+Business Media, Inc.

732
Russ.Chem.Bull., Int.Ed., Vol. 63, No. 3, March, 2014
Boteva et al.
Scheme 2
Ar
Ph
Ph
R1
H
Me
Me
Me
R2
H
Me
Me
Me
R3
H
H
H
H
Ar
Ph
R1
Me
R2
H
H
H
H
R3
H
H
Cl
Cl
Ar
R1
Cl
Cl
Cl
R2
R3
Cl
Cl
Cl
a
b
c
d
e
f
g
h
i
j
k
4ꢀEtOC6H4
4ꢀClC6H4
2ꢀThienyl
H
H
H
4ꢀBrC6H4 Me
4ꢀEtOC6H4
4ꢀClC6H4
Ph
Ph
Me
Cl
hydroquinolineꢀ2ꢀcarboxylates (3) as a result of intramoꢀ
lecular cyclization of in situ generated Nꢀarylimidoylꢀ
ketenes. The optimized temperature for the synthesis of
quinolones 3 is 190—220 C. At 155—180 C, the reaction
rate is very low, which substantially extends the reaction
time. Thermolysis above 225 C is often accompanied by
intense tarring of the reaction mixture, thus decreasing
the yields of quinolones 3.
The IR spectra of carboxylates 3 recorded in mineral
oil show absorption bands characteristic of this type
of compounds:2 1628—1610 (C(4)=O), 1690—1655
(COaroyl), 1725—1760 (COester), and 3310—3372 cm–1
(NH stretching).
The 1H NMR spectra of compounds 3a—j in DMSOꢀd6
(Table 1) contain the signals for aromatic protons, a sinꢀ
glet at  3.74—3.77 for the protons of the methoxycarbonꢀ
Table 1. 1H NMR spectra of compounds 3a (DMSOꢀd6,  J/Hz)
Compound OМе (с)
Н(6)
H(7)
Н(3´), (5´)
Н(4´) (м)
Н(2´), (6´)
Н(5)
NH
3аb
3b
3c
3d
3e
3f
3.75
3.74
3.74
3.77
3.75
3.77
3.75
3.74
3.77
7.43—7.46
(m)
7.31
(br.d, J = 7.5)
7.29
(br.d, J = 5.5)
7.32
(d, J = 7.5)
7.36—7.39
(m)
8.00
(d, J = 8.0)
—
7.47—7.50
(m)
7.48—7.51
(m)
6.99
(d, J = 9.0)
7.56 (d,
J = 6.8, J = 2.0)
7.49—7.52
(m)
7.70—7.74
(m, 4 Н)
7.48—7.52
(m)
7.49—7.52
(m)
7.57 (d,
7.60—7.63
7.81—7.83
(m)
7.78
(d, J = 7.0)
7.73
8.07 (d,
J = 6.5, J = 1.0)
7.87
(br.d, J = 7.5)
7.88
(br.d, J = 5.5)
7.89
(d, J = 7.5)
7.98
(d, J = 6.0)
7.96
(d, J = 6.0)
8.06
12.40
7.61—7.64
10.70
10.65
10.78
10.87
10.95
11.08
11.23
11.29
—
—
—
—
(d, J = 9.0)
7.79 d,
(J = 6.8, J = 2.0)
7.79—7.81
(m)
7.67
(d, J = 7.0)
7.67
(d, J = 7.0)
7.88
7.62—7.65
—
7.37—7.40
(m)
7.70—7.74
(m)
7.80
(d, J = 8.0)
7.83
3g
3h
3j
—
7.62—7.65
7.62—7.66
—
(br.s)
8.08
(br.s)
8.07
(br.s)
8.22
(d, J = 2.5)
8.22
—
—
(d, J = 7.5)
7.85 (d,
(br.s)
J = 7.0, J = 2.0)
J = 7.0, J = 2.0)
(d, J = 2.5)
a The signals pertaining to the substituent R are given in text.
b The spectrum also contains a signal at  7.78—7.80 (m, 1 H, H(8)).

4ꢀQuinolones: synthesis and crystal structure
Russ.Chem.Bull., Int.Ed., Vol. 63, No. 3, March, 2014
733
yl group, and a broadened singlet at  10.65—11.29 for the
NH proton. For 8ꢀunsubstituted analogs, the last signal is
shifted downfield2 ( 12.40 for 3a).
shifted by 20—40 cm–1 to the higher frequencies comꢀ
pared to their spectra in Nujol. The absorption band due
to ester CO group is shifted to the lower frequencies by
10—20 cm–1 (see Table 2). In more dilute chloroform
solutions (0.5 mmol L–1), the bands of neither the ester
nor aroyl CO groups are shifted compared to more conꢀ
centrated solutions. Therefore, the carbonyl O atom of the
ester group and the endocyclic amino group seem to be
linked by no intermolecular hydrogen bonds in the crysꢀ
tals of compounds 3a—f. According to spectroscopic data,
the formation of such intermolecular hydrogen bonds is
possible in concentrated solutions (by analogy with methyl
1,4ꢀdihydroquinolineꢀ2ꢀcarboxylates studied earlier2).
However, the above comparison of the absorption freꢀ
quencies of the aroyl CO group and C(4)=O in solutions
and in the crystals precludes any conclusion about their
participation in hydrogen bonding.
Earlier,6 4ꢀquinolones have been reported to dimerize
in solutions by means of ꢀhydrogen bonding; those bonds
are weakened by a substituent in position 8. Because of
this, the signals for the NH proton in the 1H NMR spectra
of 8ꢀsubstituted 4ꢀquinolones are shifted upfield and the
stretching vibrations at 3000 cm–1 in their IR spectra beꢀ
come more intense.
Based on the spectral characteristics2 of 8ꢀunsubstiꢀ
tuted compounds 3, we have hypothesized that their molꢀ
ecules in the crystals may be linked by strong intermolecuꢀ
lar hydrogen bonds between the C(4)=O group of one
molecule and the NH group of another. Later,7 such bonds
have been detected in 2ꢀarylꢀ4ꢀquinolones by Xꢀray
diffraction.
In dilute solutions, 8ꢀunsubstituted methyl 1,4ꢀdiꢀ
hydroquinolineꢀ2ꢀcarboxylates were expected2 to be staꢀ
bilized by intramolecular hydrogen bonds between the
endocyclic amino group and the carbonyl O atom of the
ester group, which is suggested by the lower frequency of
the absorption of the ester CO group in the IR spectra of
solutions of these compounds compared to their spectra in
crystals. For 8ꢀsubstituted quinolones in both the crystalꢀ
line state and solutions, intramolecular hydrogen bonding
through the NH group seems to be the only possible one
because the substituent in position 8 precludes intermoꢀ
lecular hydrogen bonding.
An Xꢀray diffraction study of compound 3f containing
the methyl group in position 8 revealed no hydrogen bonds
in its crystal (Fig. 1).
The main geometrical parameters of structure 3f are
very close to standard values for such substituted heteroꢀ
cycles.8 The quinolone ring is virtually planar; the bromoꢀ
benzoyl fragment is nearly perpendicular to the plane of
the heterocycle (the torsion angle C(6)C(10)C(9)O(4) is
99.1(2)). Note that the rotation of the aroyl group, which
disrupts the conjugation between the above fragments, can
be due to two types of intermolecular contacts in the crysꢀ
…
tal packing. First, this is the Br O contact between the
To study the nature of hydrogen bonding in 8ꢀsubstiꢀ
tuted methyl 1,4ꢀdihydroquinolineꢀ2ꢀcarboxylates 3, we
recorded their IR spectra in solutions (Table 2).
In the spectra of 0.005 M solutions of compounds 3a—f
in CHCl3, the absorption band due to the NH group is
Br(1) atom and the oxo group of the quinolone ring
([–0.5 + x, 1 – y, –0.5 + z]; Br(1) O(3), 3.052(2) Å).
…
This distance is shorter by about 0.3 Å than the sum of the
van der Waals radii of the corresponding atoms (according
to Bondi´s compilation), which indicates a specific interꢀ
molecular interaction between them. Nevertheless, the
C(14)=O(3) and C(3)—Br(1) bond lengths (1.230(2) and
1.894(2) Å, respectively) do not differ appreciably from
standard values. Second, this is the contact between the
endocyclic NH group and the O atom of the aroyl group.
The distance between the N(1) atom and the nearest carꢀ
bonyl O atom of the aroyl group ([2 – x, –y, 1 – z];
Table 2. IR spectra of compounds 3
Comꢀ
pound
/cm–1
ArCO
NH
1—
3372
3350*
3396
3310*
3396
COOМе
C(4)=O, C=C
3a
3b
3c
3d
1746*
1734
1750*
1730
1745*
1732
1676* 1620*, 1610* sh
1682 1616
1692* 1625*, 1600*
1682 1618
1655* 1610*, 1620*
1682 1620, 1604
…
N(1) O(4), 3.096(2) Å) is long, and the corresponding
O(3)
C(12)
O(4)
C(9)
C(17)
C(11)
C(15)
C(13)
C(16)
C(25)
C(14)
3400*, 3370* 1760*, 1740*, 1680* 1620*, 1595*
1725*
C(10)
N(1)
3396
3360*
3396
3368*
3392
1732
1740*
1732
1744*
1734
1682
1680* 1588*
1680
1680* 1624*, 1610*
1684
1622
C(23)
C(19)
3e
3f
Br(1)
O(2)
1622, 1612
C(7)
C(6)
C(13)
C(26)
C(21)
1624
O(1)
C(22)
Note. The IR spectra were recorded in mineral oil (asterisked
values) and CHCl3. The concentration of compounds 3a—f in
Fig. 1. Structure 3f with atomic displacement ellipsoids (p = 50%)
(Xꢀray diffraction data).
CHCl3 is 5 mmol L–1
.

734
Russ.Chem.Bull., Int.Ed., Vol. 63, No. 3, March, 2014
Boteva et al.
was refluxed for 2 h (with special care taken to prevent ingress of
atmospheric moisture) and then concentrated by half. The preꢀ
cipitate of compound 1b that formed was filtered off and
washed with chloroform. Yield 7.55 g (92%), m.p. 132—134 C
(decomp.). IR, /cm–1: 1780 (C(5)=O); 1754 (COO); 1714
(C(4)=O); 1636 (PhCO); 1600 (C=C). Found (%): C, 69.32;
H, 4.51; N, 3.82. C21H17NO5. Calculated (%): C, 69.41; H, 4.72;
N, 3.85. The mother liquor was concentrated, and the residue
was recrystallized from chloroform—hexane (4 : 1) to give comꢀ
pound 5b. Yield 0.43 g (5%), m.p. 154—156 C (decomp.). IR,
/cm–1: 3410, 3340 (OH); 1745 (COO); 1720, 1680 (C(5)=O);
1645 (PhCO); 1600 (C=C). 1H NMR (CDCl3), : 1.97, 2.17
(both s, 3 H, C(2)Me); 2.27, 2.31 (both s, 3 H, C(3)Me); 3.62,
3.80 (both s, 3 H, OMe); 4.60, 4.81 (both s, 1 H, C(2)OH); 6.65
(d, 1 H, H(4), J = 7.8 Hz); 7.09—7.23 (m, 2 H, H(4´), H(5));
7.44—7.46 (m, 2 H, H(3´), H(5´)); 7.55—7.58 (m, 1 H, H(6));
7.89—7.92 (m, 2 H, H(2´), H(6´)). 1H NMR (DMSOꢀd6), :
1.93, 2.27 (both s, 3 H, C(2)Me); 2.10, 2.30 (both s, 3 H,
C(3)Me); 3.59, 3.76 (both s, 3 H, OMe); 6.67 (d, 1 H, H(6),
J = 8.0 Hz); 7.13—7.26 (m, 2 H, H(4), H(5)); 7.50—7.54 (m, 2 H,
H(3´), H(5´)); 7.61—7.64 (m, 1 H, H(4´)); 7.79—7.83 (m, 2 H,
H(2´), H(6´)). 13C NMR (DMSOꢀd6), : 13.96, 14.84 (oꢀMe);
20.12 (mꢀMe); 52.44, 52.82 (OMe); 87.83, 88.83 (C(2)); 119.99,
119.14 (C(3)); 125.42, 125.82, 126.03, 127.26, 128.14, 128.92,
129.86, 130.24, 132.31, 132.69, 132.74, 132.82, 135.49, 137.11,
137.59, 137.70, 137.84 (Ar); 151.69 (C(5)); 164.16 (COO);
168.18, 169.02 (C(4)); 188.49 (COPh). Found (%): C, 66.02;
H, 4.97; N, 3.60. C21H19NO6. Calculated (%): C, 66.13; H, 5.02;
N, 3.67.
Methyl 1ꢀ(2,3ꢀdimethylphenyl)ꢀ3ꢀ(4ꢀethoxybenzoyl)ꢀ4,5ꢀdiꢀ
oxoꢀ4,5ꢀdihydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (1c) and methyl 1ꢀ(2,3ꢀ
dimethylphenyl)ꢀ3ꢀ(4ꢀethoxybenzoyl)ꢀ2,4ꢀdihydroxyꢀ5ꢀoxoꢀ2,5ꢀ
dihydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (5c). Compound 1c was obꢀ
tained in a similar way from enamine 4c (3.50 g, 9.9 mmol) and
oxalyl chloride (1.32 g, 10.4 mmol). Yield 2.49 g (62%), m.p.
148—150 C. IR, /cm–1: 1770 (C(5)=O); 1750 (COO); 1735
(C(4)=O); 1635 (ArCO); 1600 (C=C). 1H NMR (CDCl3),
: 1.44 (t, 3 H, Me, J = 6.9 Hz); 2.17 (s, 3 H, Me); 2.34 (s, 3 H,
Me); 3.68 (s, 3 H, OMe); 4.12 (q, 2 H, CH2, J = 6.9 Hz); 6.94
(d, 2 H, H(3´), H(5´), J = 9.0 Hz); 6.99 (d, 1 H, H(4), J = 7.8 Hz);
7.13—7.19 (m, 1 H, H(5)); 7.24—7.27 (m, 1 H, H(6)); 7.85 (d, 2 H,
H(2´), H(6´), J = 9.0 Hz). Found (%): C, 67.88; H, 5.25;
N, 3.35. C23H21NO6. Calculated (%): C, 67.80; H, 5.20; N, 3.44.
Compound 5c. Yield 0.5 g (12%), m.p. 121—122 C (deꢀ
comp.). IR, /cm–1: 3390, 3260 (OH); 1745 (COO); 1705, 1675
(C(5)=O); 1620 (ArCO); 1600 (C=C). 1H NMR (DMSOꢀd6),
: 1.36 (t, 3 H, Me, J = 7.0 Hz); 1.93, 2.26 (both s, 3 H, C(2)Me);
2.09, 2.29 (both s, 3 H, C(3)Me); 3.59, 3.76 (both s, 3 H, OMe);
4.12 (q, 2 H, CH2, J = 7.0 Hz); 6.67 (d, 1 H, H(6), J = 8.0 Hz);
7.03 (d, 2 H, H(3´), H(5´), 3J = 9.0 Hz); 7.13—7.17 (m, 1 H,
H(5)); 7.20—7.26 (m, 1 H, H(4)); 7.82 (dd, 2 H, H(2´), H(6´),
3J = 8.8 Hz, 4J = 2.0 Hz). 13C NMR (DMSOꢀd6), : 14.48,
14.78 (oꢀMe); 20.07 (mꢀMe); 52.33, 52.72 (OMe); 63.50 (CH2);
87.93, 88.90 (C(2)); 119.51, 119.66 (C(3)); 125.40, 125.50,
125.96, 127.25, 129.76, 129.99, 130.16, 131.48, 131.61, 132.38,
132.81, 135.49, 137.12, 137.64, 137.88 (Ar); 150.32 (C(5));
164.27 (COO); 168.25, 169.09 (C(4)); 186.68, 186.90 (ArCO).
Found (%): C, 64.55; H, 5.46; N, 3.42. C23H23NO7. Calculatꢀ
ed (%): C, 64.93; H, 5.45; N, 3.29.
angle NHO is too acute (125(1)) to form a normal hydroꢀ
gen bond. In this case, one can assume the presence of
only a dipolar coupling that is crucial for the conformaꢀ
tion of the aroyl group relative to the plane of the heteroꢀ
cycle. The methoxycarbonyl group is slightly turned with
respect to the plane of the heterocycle (the torsion angle
O(1)C(21)C(6)N(1) is –15.6(2)) and is not involved in
specific interactions.
Experimental
The IR spectra of the compounds obtained were recorded on
a SpecordꢀM80 instrument in mineral oil. For compounds 3a—f,
both mineral oil and chloroform solutions (C3a—f = 0.5 and
5 mmol L–1) were used. 1H NMR spectra were recorded on
BSꢀ567A (100 MHz, HMDS as an internal standard), Bruker
AMꢀ300, Bruker DRXꢀ400, and Bruker Avanceꢀ500 spectromeꢀ
ters (SiMe4 as an internal standard). 13C NMR spectra were
recorded on a Bruker Avanceꢀ500 spectrometer.
The progress of the reactions was monitored and the purity
of the compounds obtained was checked by TLC on Sorbfil plates.
An Xꢀray diffraction study of structure 3f (C19H14BrNO4,
M = 400.22) was carried out on an Xcalibur 3 diffractometer
equipped with a CCD detector according to a standard proceꢀ
dure ((Mo), graphite monochromator, 295(2) K,  and  scan
modes, scan step 0.5, frame exposure time 10 s). A colorless
crystal stub (0.212×0.169×0.108 mm) of quinolone 3f was used
for Xꢀray diffraction. Single crystals of compound 3f were obꢀ
tained by crystallization from acetonitrile. The crystals are monoꢀ
clinic, space group P2/n. The unit cell parameters are as follows:
a = 12.1557(13) Å, b = 9.5382(12) Å, c = 14.2910(11) Å,
3
 = 91.591(7), V = 1656.3(3) Å , Z = 4, dcalc = 1.605 g cm–3
,
F(000) = 808. For 2.85 <  < 31.79, 26 645 reflections were
collected. The number of unique reflections was 5235 (Rint
=
= 0.0283), including 2976 reflections with I  2(I). The ranges
of the Miller indices were –17  h  17, –14  k  13, and
–20  l  20. An absorption correction was applied analytically
using a multifaceted crystal model9 ( = 2.50614 mm–1). The
structure was solved by the direct methods with the SHELXS97
program10 and refined anisotropically by the fullꢀmatrix leastꢀ
squares method on F2 (for nonꢀhydrogen atoms) with the
SHELXL97 program11 for 242 parameters. The hydrogen atoms
were located geometrically and refined with parentꢀdependent
thermal parameters. The final R factors are R1 = 0.0293 and
R2 = 0.0566 (for reflections with I > 2(I)) and R1 = 0.0701 and
R2 = 0.0592 (for all reflections); S = 1.000. The maximum and
minimum peaks of the residual electron density are 0.261 and
–0.544 e Å–3, respectively.
Comprehensive crystallographic data were deposited with
the Cambridge Structural Database (CCDC No. 763936) and
can be retrieved free of charge from www.ccdc.cam.ac.uk/
data_request/cif.
Compounds 1a and 5a were synthesized as described
earlier.2,5
Methyl 3ꢀbenzoylꢀ1ꢀ(2,3ꢀdimethylphenyl)ꢀ4,5ꢀdioxoꢀ4,5ꢀdiꢀ
hydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (1b) and methyl 3ꢀbenzoylꢀ1ꢀ
(2,3ꢀdimethylphenyl)ꢀ2,4ꢀdihydroxyꢀ5ꢀoxoꢀ2,5ꢀdihydroꢀ1Hꢀpyrꢀ
roleꢀ2ꢀcarboxylate (5b). Enamine 4b (7 g, 23 mmol) was disꢀ
solved in anhydrous CHCl3 (60 mL), and oxalyl chloride
(2.02 mL, 24 mmol) was added dropwise. The reaction mixture
Methyl 3ꢀ(4ꢀchlorobenzoyl)ꢀ1ꢀ(2,3ꢀdimethylphenyl)ꢀ4,5ꢀdiꢀ
oxoꢀ4,5ꢀdihydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (1d) and methyl 3ꢀ(4ꢀ
chlorobenzoyl)ꢀ1ꢀ(2,3ꢀdimethylphenyl)ꢀ2,4ꢀdihydroxyꢀ5ꢀoxoꢀ

4ꢀQuinolones: synthesis and crystal structure
Russ.Chem.Bull., Int.Ed., Vol. 63, No. 3, March, 2014
735
2,5ꢀdihydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (5d). Compound 1d was
obtained in a similar way from enamine 4d (5 g, 14.5 mmol) and
oxalyl chloride (1.94 g, 15.3 mmol). Yield 5.11 g (88%), m.p.
86—88 C. IR, /cm–1: 1775 (C(5)=O); 1740 (COO); 1725
(C(4)=O); 1645 (ArCO); 1590 (C=C). Found (%): C, 63.09;
H, 4.10; Cl, 8.70; N, 3.48. C21H16ClNO5. Calculated (%):
C, 63.40; H, 4.05; Cl, 8.91; N, 3.52.
Compound 5d. Yield 0.63 g (10%), m.p. 157—158 C (deꢀ
comp.). IR, /cm–1: 3390, 3340 (OH); 1750 (COO); 1720, 1680
(C(5)=O); 1650 (ArCO); 1600 (C=C). 1H NMR (CDCl3),
: 1.98, 2.16 (both s, C(2)Me); 2.27, 2.31 (both s, 3 H, C(3)Me);
3.67, 3.83 (both s, 3 H, OMe); 4.57, 4.78 (both s, 1 H, OH); 6.66
(d, 1 H, H(4), J = 8.1 Hz); 7.06—7.27 (m, 2 H, H(5), H(6)); 7.44
(dd, 2 H, H(3´), H(5´), J = 8.0 Hz, J = 1.8 Hz); 7.87 (d, 2 H,
H(2´), H(6´), J = 8.0 Hz). Found (%): C, 60.58; H, 4.44; Cl, 8.41;
N, 3.45. C21H18ClNO6. Calculated (%): C, 60.66; H, 4.36;
Cl, 8.53; N, 3.37.
N, 3.05. C20H16BrNO6. Calculated (%): C, 53.83; H, 3.61;
Br, 17.91; N, 3.14.
Methyl 3ꢀbenzoylꢀ1ꢀ(4ꢀchloroꢀ2ꢀmethylphenyl)ꢀ2,4ꢀdihydrꢀ
oxyꢀ5ꢀoxoꢀ2,5ꢀdihydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (5g). Yield
0.12 g (3%), m.p. 154—156 C (decomp.). IR, /cm–1: 3440,
3200, (OH); 1746 (COO); 1706, 1682 (C(5)=O); 1646 (PhCO);
1604 (C=C). 1H NMR (CDCl3), : 2.10, 2.28 (both s, 3 H, Me);
3.67, 3.84 (both s, 3 H, OMe); 4.68, 4.93 (both s, 1 H, OH); 7.35
(br.s, 2 H, H(3´), H(5´)); 7.46—7.50 (m, 3 H, H(3), H(5), H(6));
7.58—7.62 (m, 1 H, H(4´)); 7.89—7.91 (m, 2 H, H(2´), H(6´)).
1H NMR (DMSOꢀd6), : 2.06, 2.23 (both s, 3 H, Me); 3.60, 3.78
(both s, 3 H, OMe); 6.77, 7.37 (both br.s, 1 H, H(6)); 7.49 (m, 3 H,
H(3´), H(5´), H(4´)); 7.61—7.64 (m, 2 H, H(3), H(5)); 7.80
(d, 2 H, H(2´), H(6´), J = 7.5 Hz). 13C NMR (DMSOꢀd6), : 17.03,
17.74 (Me); 52.54, 52.90 (OMe); 87.81, 88.69 (C(2)); 119.26
(C(3)); 128.11, 128.95, 129.34, 129.70, 129.92, 131.25, 132.20,
132.77, 133.44, 137.53, 139.56, 141.31 (Ar); 151.47 (C(5));
163.91 (COO); 168.12, 168.88 (C(4)); 188.30, 188.33 (COPh).
Found (%): C, 59.89; H, 4.10; Cl, 8.98; N, 3.53. C20H16ClNO6.
Calculated (%): C, 59.78; H, 4.01; Cl, 8.82; N, 3.49.
Methyl 3ꢀbenzoylꢀ1ꢀ(2,4ꢀdichlorophenyl)ꢀ4,5ꢀdioxoꢀ4,5ꢀdiꢀ
hydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (1h) and methyl 3ꢀbenzoylꢀ1ꢀ
(2,4ꢀdichlorophenyl)ꢀ2,4ꢀdihydroxyꢀ5ꢀoxoꢀ2,5ꢀdihydroꢀ1Hꢀpyrꢀ
roleꢀ2ꢀcarboxylate (5h). Compound 1h was obtained in a similar
way from enamine 4h (2.00 g, 5.7 mmol) and oxalyl chloride
(0.76 g, 6 mmol). Yield 1.22 g (53%), m.p. 120—122 C. IR,
/cm–1: 1780 (C(5)=O); 1735 (COO, C(4)=O); 1665 (PhCO);
1605 (C=C). Found (%): C, 56.28; H, 2.79; Cl, 17.62; N, 3.50.
C19H11Cl2NO5. Calculated (%): C, 56.46; H, 2.74; Cl, 17.54;
N, 3.47.
Methyl 3ꢀbenzoylꢀ1ꢀ(2ꢀmethylphenyl)ꢀ4,5ꢀdioxoꢀ4,5ꢀdiꢀ
hydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (1e) and methyl 3ꢀbenzoylꢀ2,4ꢀ
dihydroxyꢀ1ꢀ(2ꢀmethylphenyl)ꢀ5ꢀoxoꢀ2,5ꢀdihydroꢀ1Hꢀpyrroleꢀ2ꢀ
carboxylate (5e). Compound 1e was obtained in a similar way
from enamine 4e (14.96 g, 50.7 mmol) and oxalyl chloride (6.41 g,
50.5 mmol). Yield 16.07 g (92%), m.p. 60—62 C (decomp.). IR,
/cm–1: 1784 (C(5)=O); 1744 (COO); 1728 (C(4)=O); 1640
(ArCO); 1548 (C=C). Found (%): C, 68.70; H, 4.34; N, 3.99.
C20H15NO5. Calculated (%): C, 68.96; H, 4.51; N, 4.01.
Compound 5e. Yield 0.86 g (5%), m.p. 145—146 C (deꢀ
comp.). IR, /cm–1: 3416, 2952 (OH); 1772, 1744 (COO); 1728
(C(5)=O); 1672 (ArCO); 1604 (C=C). 1H NMR (DMSOꢀd6),
: 2.07, 2.23 (both s, 3 H, Me); 3.56, 3.79 (both s, 3 H, OMe); 6.83
(d, 1 H, H(6), 3J = 6.0 Hz); 7.25—7.28 (m, 1 H, H(4)); 7.32—7.35
(m, 2 H, H(3), H(5)); 7.51—7.54 (m, 2 H, H(3´), H(5´)); 7.61—7.64
(m, 1 H, H(4´)); 8.81 (d, 2 H, H(2´), H(6´), J = 7.5 Hz).
13C NMR (DMSOꢀd6), : 17.33, 18.08 (Me); 52.46, 52.91 (OMe);
87.89, 88.77 (C(2)); 119.26 (C(3)); 126.26, 126.77, 127.82,
128.17, 128.57, 129.07, 129.47, 130.91, 132.84, 136.78, 137.59,
137.80, 138.45 (Ar); 151.63 (C(5)); 163.97 (COO); 168.29, 169.07
(C(4)); 188.51 (ArCO). Found (%): C, 65.47; H, 4.69; N, 3.75.
C20H17NO6. Calculated (%): C, 65.39; H, 4.66; N, 3.81.
Methyl 3ꢀ(4ꢀbromobenzoyl)ꢀ1ꢀ(2ꢀmethylphenyl)ꢀ4,5ꢀdioxoꢀ
4,5ꢀdihydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (1f) and methyl 3ꢀ(4ꢀ
bromobenzoyl)ꢀ2,4ꢀdihydroxyꢀ1ꢀ(2ꢀmethylphenyl)ꢀ5ꢀoxoꢀ2,5ꢀdiꢀ
hydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (5f). Compound 1f was obtained
in a similar way from enamine 4f (3.90 g, 10.4 mmol) and oxalyl
chloride (1.32 g, 10.4 mmol). Yield 3.94 g (88%), m.p. 156—158 C.
IR, /cm–1: 1782 (C(5)=O); 1734 (COO); 1724 (C(4)=O); 1636
Compound 5h. Yield 0.30 g (12%), m.p. 133—135 C (deꢀ
comp.). IR, /cm–1: 3500 (OH); 1740 (COO); 1712, 1678
1
(C(5)=O); 1632 (PhCO); 1598 (C=C). H NMR (DMSOꢀd6),
: 3.61, 3.80 (both s, 3 H, OMe); 7.05 (br.s, 1 H, H(6)); 7.50—7.58
(m, 4 H, H(5), H(3´), H(4´), H(5´)); 7.61—7.64 (m, 1 H, H(3));
7.80 (d, 2 H, H(2´), H(6´), J = 7.0 Hz). 13C NMR (DMSOꢀd6),
: 52.53, 53.04 (OMe); 87.56, 88.61 (C(2)); 119.23, 119.51 (C(3));
128.11, 128.87, 129.72, 130.27, 131.18, 132.74, 133.16, 134.08,
134.37, 135.40, 137.76 (Ar); 151.42 (C(5)); 163.88 (COO);
167.66, 168.80 (C(4)); 188.32 (COPh). Found (%): C, 54.21;
H, 3.19; Cl, 16.85; N, 3.38. C19H13Cl2NO6. Calculated (%):
C, 54.05; H, 3.10; Cl, 16.79; N, 3.32.
Methyl 1ꢀ(2,4ꢀdichlorophenyl)ꢀ3ꢀ(4ꢀethoxybenzoyl)ꢀ4,5ꢀdiꢀ
oxoꢀ4,5ꢀdihydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (1i) and methyl 1ꢀ(2,4ꢀ
dichlorophenyl)ꢀ3ꢀ(4ꢀethoxybenzoyl)ꢀ2,4ꢀdihydroxyꢀ5ꢀoxoꢀ2,5ꢀ
dihydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (5i). Compound 1i was obꢀ
tained in a similar way from enamine 4i (0.60 g, 1.5 mmol) and
oxalyl chloride (0.20 g, 1.64 mmol). Yield 0.54 g (79%), m.p.
138—140 C. IR, /cm–1: 1784 (C(5)=O); 1755, 1745, 1730
(COO, C(4)=O); 1632 (ArCO); 1606 (C=C). Found (%): C, 56.38;
H, 3.41; Cl, 15.71; N, 3.18. C21H15Cl2NO6. Calculated (%):
C, 56.27; H, 3.37; Cl, 15.82; N, 3.12.
1
(ArCO); 1588 (C=C). H NMR (CDCl3), : 2.28 (s, 3 H, Me);
3.70 (s, 3 H, OMe); 7.16—7.79 (m, 8 H, Ar). Found (%):
C, 56.01; H, 3.46; Br, 18.78; N, 3.34. C20H14BrNO5. Calculatꢀ
ed (%): C, 56.09; H, 3.30; Br, 18.66; N, 3.27.
Compound 5f. Yield 0.53 g (11%), m.p. 170—172 C (deꢀ
comp.). IR, /cm–1: 3408, 3320 (OH); 1736 (COO); 1708
(C(5)=O); 1684, 1640 (ArCO); 1592 (C=C). 1H NMR (DMSOꢀd6),
: 2.06, 2.22 (both s, 3 H, Me); 3.58, 3.78 (both s, 3 H, OMe);
6.82 (d, 1 H, H(6), 3J = 6.0 Hz); 7.25—7.36 (m, 3 H, H(3), H(4),
H(5)); 7.72—7.76 (m, 4 H, H(2´), H(3´), H(5´), H(6´)). 13C NMR
(DMSOꢀd6), : 17.25, 18.00 (Me); 52.42, 52.82 (OMe); 87.74,
88.60 (C(2)); 118.80 (C(3)); 126.22, 126.62, 127.75, 128.58,
128.85, 129.34, 130.84, 130.93, 131.23, 132.75, 136.67, 138.34
(Ar); 152.30 (C(5)); 163.76 (COO); 168.12, 168.92 (C(4));
187.379 (ArCO). Found (%): C, 53.51; H, 3.48; Br, 17.89;
Compound 5i. Pyrroledione 1i (0.09 g, 0.2 mmol) was disꢀ
solved in CH2Cl2 (4 mL). The resulting solution was heated with
water (0.1 mL) and concentrated. The precipitate that formed
was recrystallized from dichloromethane—hexane. Yield 0.06 g
(67%), m.p. 152—154 C (decomp.). IR, /cm–1: 3850, 3640
(OH); 1760 sh, 1740 sh, 1730 sh, 1714 (COO); 1672 (C(5)=O);
1
1632 (ArCO); 1600 (C=C). H NMR (CDCl3), : 1.42 (t, 3 H,
Me, J = 6.5 Hz); 3.66 (s, 3 H, OMe); 4.10 (q, 2 H, CH2, J = 6.9 Hz);
4.80 (br.s, 1 H, OH); 6.84 (d, 2 H, H(3´), H(5´), J = 8.4 Hz);

736
Russ.Chem.Bull., Int.Ed., Vol. 63, No. 3, March, 2014
Boteva et al.
7.16—7.21 (m, 2 H, H(5), H(6)); 7.43 (s, 1 H, H(3)); 7.83 (d, 2 H,
H(2´), H(6´), J = 8.4 Hz). Found (%): C, 54.25; H, 3.74;
Cl, 15.28; N, 3.03. C21H17Cl2NO7. Calculated (%): C, 54.09;
H, 3.67; Cl, 15.21; N, 3.00.
125.53, 128.48, 128.54, 132.90, 133.08, 135.83, 137.19, 139.35
(Ar); 161.92 (COO); 175.71 (C(4)); 193.90 (COPh).
Methyl 3ꢀbenzoylꢀ7,8ꢀdimethylꢀ4ꢀoxoꢀ1,4ꢀdihydroquinolineꢀ
2ꢀcarboxylate (3b). A solution of compound 1b (7.88 g, 22 mmol) in
Dowtherm A (10 mL) was kept at 190 C for 50 min. The precipꢀ
itate that formed was cooled, filtered off, and recrystallized. The
yield of compound 3b was 3.78 g (52%), m.p. 222—224 C
(decomp.) (from dioxane). Found (%): C, 71.60; H, 5.13; N, 4.22.
C20H17NO4. Calculated (%): C, 71.53; H, 5.11; N, 4.18. IR,
/cm–1: 3355 (NH); 1745 (COO); 1690 (Bz); 1625 (C(4)=O);
Methyl 3ꢀ(4ꢀchlorobenzoyl)ꢀ1ꢀ(2,4ꢀdichlorophenyl)ꢀ4,5ꢀdiꢀ
oxoꢀ4,5ꢀdihydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (1j) and methyl 3ꢀ(4ꢀ
chlorobenzoyl)ꢀ1ꢀ(2,4ꢀdichlorophenyl)ꢀ2,4ꢀdihydroxyꢀ5ꢀoxoꢀ2,5ꢀ
dihydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (5j). Compound 1j was obꢀ
tained in a similar way from enamine 4j (2.28 g, 5.9 mmol) and
oxalyl chloride (0.79 g, 6.2 mmol). Yield 1.63 g (63%), m.p.
162—164 C. IR, /cm–1: 1780 (C(5)=O); 1750 sh, 1732 (COO,
C(4)=O); 1658 (ArCO); 1590 (C=C). Found (%): C, 52.24;
H, 2.27; Cl, 24.26; N, 3.17. C19H10Cl3NO5. Calculated (%):
C, 52.02; H, 2.30; Cl, 24.25; N, 3.19.
1
1600 (C=C). H NMR (DMSOꢀd6), : 2.45 (s, 3 H, Me); 2.49
(s, 3 H, Me); 3.74 (s, 3 H, OMe); 7.31 (br.d, 1 H, H(6), J = 7.5 Hz);
7.48—7.51 (m, 2 H, H(3´), H(5´)); 7.61—7.64 (m, 1 H, H(4´));
7.78 (d, 2 H, H(2´), H(6´), J = 7.0 Hz); 7.87 (br.d, 1 H, H(5),
J = 7.5 Hz); 10.70 (s, 1 H, NH). 13C NMR (DMSOꢀd6), : 12.73
(Me(8)); 20.37 (Me(7)); 53.34 (OMe); 120.79, 122.14, 124.23,
127.83, 127.18, 128.46, 128.66, 132.98, 137.28, 137.41, 138.73,
141.81 (Ar); 162.35 (COO); 175.49 (C(4)); 193.97 (COPh).
Methyl 3ꢀ(4ꢀethoxybenzoyl)ꢀ7,8ꢀdimethylꢀ4ꢀoxoꢀ1,4ꢀdihydroꢀ
quinolineꢀ2ꢀcarboxylate (3c) was obtained in a similar way from
compound 1c (2.27 g, 5.6 mmol). Yield 1.08 g (51%), m.p.
185—187 C (decomp.) (from dioxane). Found (%): C, 69.74;
H, 5.77; N, 3.72. C22H21NO5. Calculated (%): C, 69.64; H, 5.58;
N, 3.69. IR, /cm–1: 3310 (NH); 1745 (COO); 1655 (ArCO);
1620 (C(4)=O); 1610 (C=C). 1H NMR (DMSOꢀd6), : 1.34
(t, 1 H, Me, J = 7.0 Hz); 2.43 (s, 3 H, Me); 2.48 (s, 3 H, Me); 3.74
(s, 3 H, OMe); 4.10 (q, 2 H, CH2, J = 7.0 Hz); 6.99 (d, 2 H,
H(3´), H(5´), J = 9.0 Hz); 7.29 (br.d, 1 H, H(6), J = 5.5 Hz);
7.73 (d, 2 H, H(2´), H(6´), J = 9.0 Hz); 7.88 (br.d, 1 H, H(5),
J = 5.5 Hz); 10.65 (s, 1 H, NH). 13C NMR (DMSOꢀd6), : 12.78
(Me(8)); 14.47 (MeCH2); 20.43 (Me(7)); 53.33 (OMe); 63.51
(CH2); 118.56, 121.19, 122.21, 124.18, 124.78, 127.13, 130.21,
131.19, 137.44, 138.56, 141.72 (Ar); 162.43 (COO); 175.50
(C(4)); 192.30 (COPh).
Methyl 3ꢀ(4ꢀchlorobenzoyl)ꢀ7,8ꢀdimethylꢀ4ꢀoxoꢀ1,4ꢀdiꢀ
hydroquinolineꢀ2ꢀcarboxylate (3d) was obtained in a similar way
from compound 1d (5.83 g, 15 mmol). Yield 3.66 g (68%), m.p.
230—232 C (decomp.) (from MeCN). Found (%): C, 64.75;
H, 4.43; Cl, 10.03; N, 3.66. C20H16ClNO4. Calculated (%):
C, 64.96; H, 4.36; Cl, 9.59; N, 3.79. IR, /cm–1: 3400, 3370 (NH);
1755 (COO); 1680 (ArCO); 1620 (C(4)=O); 1595 (C=C).
1H NMR (DMSOꢀd6), : 2.44 (s, 3 H, Me); 2.49 (s, 3 H, Me,
masked by the signal of DMSO); 3.77 (s, 3 H, OMe); 7.32 (d, 1 H,
H(6), J = 7.5 Hz); 7.56 (dd, 2 H, H(3´), H(5´), J = 6.8 Hz,
J = 2.0 Hz); 7.79 (dd, 2 H, H(2´), H(6´), J = 6.8 Hz, J = 2.0 Hz);
7.89 (d, 1 H, H(5), J = 7.5 Hz); 10.78 (s, 1 H, NH). 13C NMR
(DMSOꢀd6), : 12.77 (Me(8)); 20.37 (Me(7)); 53.35 (OMe);
119.96, 121.96, 124.15, 125.06, 127.39, 128.63, 130.53, 136.06,
137.45, 137.86, 139.28, 141.76 (Ar); 162.46 (COO); 175.47
(C(4)); 193.03 (ArCO).
Compound 5j was obtained as described for pyrrolone 5b.
Yield 0.28 g (14%), m.p. 152—153 C (decomp.). IR, /cm–1
:
3750, 3640 (OH); 1740 sh, 1706 (COO, C(5)=O); 1678 (C(5)=O);
1642 (ArCO); 1586 (C=C). 1H NMR (DMSOꢀd6), : 3.62, 3.81
(both s, 3 H, OMe); 7.04 (br.s, 1 H, H(6)); 7.54 (br.s, 1 H,
H(5)); 7.60 (d, 2 H, H(3´), H(5´), J = 8.5 Hz); 7.80 (d, 2 H,
H(2´), H(6´), J = 8.5 Hz); 7.85 (br.s, 1 H, H(3)). 13C NMR
(DMSOꢀd6), : 52.52, 52.98 (OMe); 87.41, 88.55 (C(2)); 118.88,
119.19 (C(3)); 128.30, 129.68, 130.23, 130.71, 131.16, 133.11,
134.03, 134.38, 135.36, 136.21, 136.49, 137.53 (Ar); 152.06
(C(5)); 163.74 (COO); 167.55, 168.70 (C(4)); 187.08 (ArCO).
Found (%): C, 49.75; H, 2.57; Cl, 23.50; N, 3.21. C19H12Cl3NO6.
Calculated (%): C, 49.97; H, 2.65; Cl, 23.29; N, 3.07.
Methyl 1ꢀ(2,4ꢀdichlorophenyl)ꢀ4,5ꢀdioxoꢀ3ꢀthenoylꢀ4,5ꢀdiꢀ
hydroꢀ1Hꢀpyrroleꢀ2ꢀcarboxylate (1k) and methyl 1ꢀ(2,4ꢀdichloroꢀ
phenyl)ꢀ2,4ꢀdihydroxyꢀ5ꢀoxoꢀ3ꢀthenoylꢀ2,5ꢀdihydroꢀ1Hꢀpyrꢀ
roleꢀ2ꢀcarboxylate (5k). Compound 1k was obtained in a similar
way from enamine 4k (2.38 g, 6.7 mmol) and oxalyl chloride
(0.89 g, 7 mmol). Yield 2.14 g (78%), m.p. 83—84 C. IR, /cm–1
:
1784 (C(5)=O); 1740 (COO, C(4)=O); 1616 (PhCO, C=C).
1H NMR (CDCl3), : 3.71 (s, 3 H, OMe); 7.16—7.27 (m, 3 H,
H(4´), H(5), H(6)); 7.47 (s, 1 H, H(3)); 7.66 (m, 1 H, H(3´));
7.89 (m, 1 H, H(5´)). Found (%): C, 49.61; H, 2.23; Cl, 17.23;
N, 3.44. C17H9Cl2NO5S. Calculated (%): C, 49.77; H, 2.21;
Cl, 17.28; N, 3.41.
Compound 5k was obtained as described for pyrrolone 5i.
Yield 0.13 g (70%), m.p. 162—164 C (decomp.). IR, /cm–1
:
3180 (OH); 1750 (COO); 1724, 1708 (C(5)=O); 1638 (HetCO);
1
1600 (C=C). H NMR (DMSOꢀd6), : 3.59, 3.78 (both s, 3 H,
OMe); 7.03 (br.s, 1 H, H(6)); 7.24 (m, 1 H, H(4´)); 7.50—7.57
(m, 1 H, H(5)); 7.82 (s, 1 H, H(3)); 8.04 (d, 1 H, H(3´), J = 4.5 Hz);
8.14 (s, 1 H, H(5´)). 13C NMR (DMSOꢀd6), : 52.49, 53.00
(OMe); 87.53, 88.56 (C(2)); 119.12 (C(3)); 128.43, 129.70,
130.20, 131.21, 133.15, 134.15, 134.36, 135.14, 143.72 (Ar);
150.63 (C(5)); 163.85 (COO); 167.63, 168.82 (C(4)); 179.05
(COHet). Found (%): C, 47.74; H, 2.68; Cl, 16.87; N, 3.23.
C17H11Cl2NO6S. Calculated (%): C, 47.68; H, 2.59; Cl, 16.56;
N, 3.27.
Methyl 3ꢀbenzoylꢀ4ꢀoxoꢀ1,4ꢀdihydroquinolineꢀ2ꢀcarboxylate
(3a) was obtained as described earlier.2 Found (%): C, 70.34;
H, 4.28; N, 4.52. C18H13NO4. Calculated (%): C, 70.35; H, 4.26;
N, 4.56. 1H NMR (DMSOꢀd6), : 3.75 (s, 3 H, OMe); 7.43—7.46
(m, 1 H, H(6)); 7.47—7.50 (m, 2 H, H(3´), H(5´)); 7.60—7.63
(m, 1 H, H(4´)); 7.78—7.80 (m, 1 H, H(8)); 7.81—7.83 (m, 2 H,
H(2´), H(6´)); 8.00 (br.d, 1 H, H(7), J = 8.0 Hz); 8.07 (dd, 1 H,
H(5), J = 6.5 Hz, J = 1.0 Hz); 12.40 (s, 1 H, NH). 13C NMR
(DMSOꢀd6), : 53.40 (OMe); 119.57, 122.69, 124.62, 124.67,
Methyl 3ꢀbenzoylꢀ8ꢀmethylꢀ4ꢀoxoꢀ1,4ꢀdihydroquinolineꢀ2ꢀ
carboxylate (3e) was obtained in a similar way from comꢀ
pound 1e (1.47 g, 4.2 mmol). Yield 0.65 g (52%), m.p. 206—208 C
(decomp.) (from dioxane). Found (%): C, 71.16; H, 4.78;
N, 4.31. C19H15NO4. Calculated (%): C, 71.02; H, 4.71; N, 4.36.
IR, /cm–1: 3360 (NH); 1740 (COO); 1680 (PhCO); 1588
(C(4)=O, C=C). 1H NMR (DMSOꢀd6), : 2.63 (s, 3 H, Me);
3.75 (s, 3 H, OMe); 7.36—7.39 (m, 1 H, H(6)); 7.49—7.52 (m, 2 H,
H(3´), H(5´)); 7.62—7.65 (m, 1 H, H(4´)); 7.67 (d, 1 H, H(7),
J = 7.0 Hz); 7.80 (d, 2 H, H(2´), H(6´)); 7.98 (d, 1 H, H(5),
J = 6.0 Hz); 10.87 (s, 1 H, NH). 13C NMR (DMSOꢀd6), : 16.94

4ꢀQuinolones: synthesis and crystal structure
Russ.Chem.Bull., Int.Ed., Vol. 63, No. 3, March, 2014
737
(Me); 53.33 (OMe); 121.17, 122.85, 124.60, 125.85, 127.45,
128.48, 128.70, 133.03, 134.07, 137.25, 137.48, 138.95 (Ar);
162.35 (COO); 175.56 (C(4)); 193.93 (COPh).
Methyl 6,8ꢀdichloroꢀ3ꢀ(4ꢀchlorobenzoyl)ꢀ4ꢀoxoꢀ1,4ꢀdihydroꢀ
quinolineꢀ2ꢀcarboxylate (3j) was obtained in a similar way from
compound 1j (1.11 g, 2.5 mmol). Yield 0.29 g (28%), m.p.
220—222 C (decomp.) (from MeCN). Found (%): C, 52.59;
H, 2.50; Cl, 25.81; N, 3.40. C18H10Cl3NO4. Calculated (%):
C, 52.65; H, 2.45; Cl, 25.90; N, 3.41. IR, /cm–1: 3352 (NH); 1734
(COO); 1684 (ArCO); 1626 (C(4)=O); 1600, 1590 (C=C). 1H NMR
(DMSOꢀd6), : 3.77 (s, 3 H, OMe); 7.57 (dd, 2 H, H(3´), H(5´),
J = 7.0 Hz, J = 2.0 Hz); 7.85 (dd, 2 H, H(2´), H(6´), J = 7.0 Hz,
J = 2.0 Hz); 8.07 (br.s, 1 H, H(7)); 8.22 (d, 1 H, H(5), J = 2.5
Hz); 11.29 (s, 1 H, NH). 13C NMR (DMSOꢀd6), : 53.46 (OMe);
121.14, 123.05, 126.76, 128.73, 129.70, 130.67, 132.67, 135.60,
138.25 (Ar); 162.30 (COO); 172.59 (C(4)); 192.08 (ArCO).
Methyl 6,8ꢀdichloroꢀ4ꢀoxoꢀ3ꢀthenoylꢀ1,4ꢀdihydroquinolineꢀ
2ꢀcarboxylate (3k) was obtained in a similar way from comꢀ
pound 1k (2.42 g, 5.9 mmol). Yield 0.59 g (26%), m.p. 206—208 C
(decomp.) (from dioxane). Found (%): C, 50.36; H, 2.41;
Cl, 19.00; N, 3.63. C16H9Cl2NO4S. Calculated (%): C, 50.28;
H, 2.37; Cl, 18.55; N, 3.66. IR, /cm–1: 3344 (NH); 1730 (COO);
1662 (C4H3SCO); 1622, 1608 (C(4)=O). 1H NMR (DMSOꢀd6),
: 3.77 (s, 3 H, OMe); 7.19 (dd, 1 H, H(4´), J = 4.9 Hz, J = 3.8 Hz);
7.65 (d, 1 H, H(3´), J = 3.4 Hz); 8.07 (dd, 1 H, H(5´), J = 4.9 Hz,
J = 1.1 Hz); 8.10 (br.s, 1 H, H(7)); 8.21 (d, 1 H, H(5), J = 2.4 Hz);
11.15 (br.s, 1 H, NH). 13C NMR (DMSOꢀd6), : 53.51 (OMe);
121.40, 123.20, 126.84, 128.63, 129.68, 132.71, 135.27, 135.53,
143.87 (Ar); 162.26 (COO); 173.26 (C(4)); 184.69 (COHet).
Methyl (Z)ꢀ2ꢀ(2,3ꢀdimethylphenylamino)ꢀ4ꢀoxoꢀ4ꢀphenylꢀ
butꢀ2ꢀenoate (4b). Methyl benzoylpyruvate (6 g, 29 mmol) and
2,3ꢀxylidine (3.52 g, 29 mmol) were dissolved in benzene (50 mL).
The reaction mixture was refluxed with a Dean—Stark trap for
6 h and concentrated by half. The precipitate that formed was
filtered off and recrystallized from EtOH. Yield 7.60 g (84%),
m.p. 74—76 C. IR, /cm–1: 1740 (COO); 1600 (PhCO, C=C).
1H NMR (CDCl3), : 2.22 (s, 6 H, 2 Me); 3.56 (s, 3 H, OMe);
6.26 (s, 1 H, CH); 6.59—8.23 (m, 8 H, Ar); 11.85 (s, 1 H, NH).
Found (%): C, 73.70; H, 6.15; N, 4.55. C19H19NO3. Calculatꢀ
ed (%): C, 73.77; H, 6.19; N, 4.53.
Methyl 3ꢀ(4ꢀbromobenzoyl)ꢀ8ꢀmethylꢀ4ꢀoxoꢀ1,4ꢀdihydroꢀ
quinolineꢀ2ꢀcarboxylate (3f) was obtained in a similar way from
compound 1f (3.59 g, 8.4 mmol). Yield 2.84 g (85%), m.p.
204—206 C (decomp.) (from MeCN). Found (%): C, 57.30;
H, 3.50; Br, 19.87; N, 3.48. C19H14BrNO4. Calculated (%):
C, 57.02; H, 3.53; Br, 19.96; N, 3.50. IR, /cm–1: 3368 (NH);
1744 (COO); 1680 (ArCO); 1624 (C(4)=O); 1584 (C=C). 1H NMR
(DMSOꢀd6), : 2.62 (s, 3 H, Me); 3.77 (s, 3 H, OMe); 7.37—7.40
(m, 1 H, H(6)); 7.67 (d, 1 H, H(7), J = 7.0 Hz); 7.70—7.74 (m, 4 H,
H(2´), H(3´), H(5´), H(6´)); 7.97 (d, 1 H, H(5), J = 6.0 Hz);
10.95 (s, 1 H, NH). 13C NMR (DMSOꢀd6), : 16.98 (Me); 53.43
(OMe); 120.50, 122.86, 124.74, 125.99, 127.09, 127.52, 130.68,
131.63, 134.23, 136.34, 137.53, 139.51, 162.31 (COO); 175.51
(C(4)); 193.21 (ArCO).
Methyl 3ꢀbenzoylꢀ6ꢀchloroꢀ8ꢀmethylꢀ4ꢀoxoꢀ1,4ꢀdihydroquinꢀ
olineꢀ2ꢀcarboxylate (3g). Oxalyl chloride (1.62 g, 12.8 mmol)
was added to a solution of enamine 4g (4.00 g, 12.1 mmol) in
anhydrous dichloroethane (30 mL). The reaction mixture was
refluxed for 50 min (monitoring by TLC) and concentrated
in vacuo. After addition of diphenyl ether (10 mL), the resulting
mixture was kept at 205—210 C for 7 min and cooled. The
precipitate that formed was washed with hot light petroleum and
recrystallized from dioxane. The yield of compound 3g was 2.78 g
(72%), m.p. 222—224 C (decomp.). Found (%): C, 64.28; H, 3.90;
Cl, 9.69; N, 3.86. C19H14ClNO4. Calculated (%): C, 64.14;
H, 3.97; Cl, 9.97; N, 3.94. IR, /cm–1: 3372 (NH); 1732 (COO);
1672 (PhCO); 1618 (C(4)=O); 1594 (C=C). 1H NMR (DMSOꢀd6),
: 2.63 (s, 3 H, Me); 3.75 (s, 3 H, OMe); 7.48—7.52 (m, 2 H,
H(3´), H(5´)); 7.62—7.65 (m, 1 H, H(4´)); 7.80 (d, 2 H, H(2´),
H(6´), J = 8.0 Hz); 7.88 (br.s, 1 H, H(7)); 8.06 (br.s, 1 H, H(5));
11.08 (s, 1 H, NH). 13C NMR (DMSOꢀd6), : 16.75 (Me); 53.36
(OMe); 117.52, 121.27, 124.69, 127.08, 128.51, 128.75, 130.91,
133.17, 136.16, 137.06, 139.71 (Ar); 162.20 (COO); 174.15
(C(4)); 193.55 (COPh).
Methyl 3ꢀbenzoylꢀ6,8ꢀdichloroꢀ4ꢀoxoꢀ1,4ꢀdihydroquinolineꢀ
2ꢀcarboxylate (3h) was obtained in a similar way from comꢀ
pound 1h (1.00 g, 2.5 mmol). Yield 0.17 g (18%), m.p. 224—226 C
(decomp.) (from toluene). Found (%): C, 57.21; H, 2.88; Cl, 18.91;
N, 3.73. C18H11Cl2NO4. Calculated (%): C, 57.47; H, 2.95;
Cl, 18.85; N, 3.72. IR, /cm–1: 3365 (NH); 1730 (COO); 1680
(PhCO); 1625 (C(4)=O). 1H NMR (DMSOꢀd6), : 3.74 (s, 3 H,
OMe); 7.49—7.52 (m, 2 H, H(3´), H(5´)); 7.62—7.66 (m, 1 H,
H(4´)); 7.83 (d, 2 H, H(2´), H(6´), J = 7.5 Hz); 8.08 (br.s, 1 H,
H(7)); 8.22 (d, 1 H, H(5), J = 2.5 Hz); 11.23 (s, 1 H, NH). 13C NMR
(DMSOꢀd6), : 53.39 (OMe); 121.66, 123.03, 125.20, 126.62,
128.09, 128.54, 128.80, 129.63, 132.61, 133.33, 136.83 (Ar);
162.36 (COO); 171.38 (C(4)); 193.01 (COPh).
Methyl (Z)ꢀ2ꢀ(2,3ꢀdimethylphenylamino)ꢀ4ꢀ(4ꢀethoxyphenꢀ
yl)ꢀ4ꢀoxobutꢀ2ꢀenoate (4c) was obtained in a similar way from
methyl (4ꢀethoxybenzoyl)pyruvate (5 g, 20 mmol) and 2,3ꢀxylidꢀ
ine (2.42 g, 20 mmol). Yield 3.79 g (54%), m.p. 100—102 C
(from EtOH). IR, /cm–1: 1725 (COO); 1605 (ArCO); 1585
(C=C). 1H NMR (CDCl3), : 1.35 (t, 3 H, Me, J = 7.2 Hz); 2.22
(s, 6 H, 2 Me); 3.56 (s, 3 H, OMe); 4.01 (q, 2 H, CH2, J = 7.2 Hz);
6.24 (s, 1 H, CH); 6.52—7.83 (m, 7 H, Ar); 11.73 (s, 1 H, NH).
Found (%): C, 71.26; H, 6.50; N, 3.84. C21H23NO4. Calculatꢀ
ed (%): C, 71.37; H, 6.56; N, 3.96.
Methyl (Z)ꢀ4ꢀ(4ꢀchlorophenyl)ꢀ2ꢀ(2,3ꢀdimethylphenylamino)ꢀ
4ꢀoxobutꢀ2ꢀenoate (4d) was obtained in a similar way from meꢀ
thyl (4ꢀchlorobenzoyl)pyruvate (6 g, 24.9 mmol) and 2,3ꢀxylidꢀ
ine (3.02, 24.9 mmol). Yield 5.95 g (69%), m.p. 105—106 C
(from EtOH). IR, /cm–1: 1745 (COO); 1605 (ArCO); 1575
Methyl 6,8ꢀdichloroꢀ3ꢀ(4ꢀethoxybenzoyl)ꢀ4ꢀoxoꢀ1,4ꢀdihydroꢀ
quinolineꢀ2ꢀcarboxylate (3i) was obtained in a similar way from
compound 1i (0.30 g, 0.7 mmol). Yield 0.12 g (43%), m.p.
189—190 C (decomp.) (from dioxane). Found (%): C, 57.26;
H, 3.63; Cl, 16.91; N, 3.37. C20H15Cl2NO5. Calculated (%):
C, 57.16; H, 3.60; Cl, 16.87; N, 3.33. IR, /cm–1: 3348 (NH); 1730
1
(C=C). H NMR (CDCl3), : 2.30 (s, 3 H, Me); 2.31 (s, 3 H,
Me); 3.65 (s, 3 H, OMe); 6.30 (s, 1 H, CH); 6.72—6.77 (m, 1 H,
H(5)); 6.98—7.04 (m, 2 H, H(4), H(6)); 7.41 (dd, 2 H, H(3´),
H(5´), J = 6.8 Hz, J = 1.9 Hz); 7.88 (dd, 2 H, H(2´), H(6´),
J = 6.8 Hz, J = 1.9 Hz); 12.02 (s, 1 H, NH). Found (%): C, 66.21;
H, 5.35; Cl, 10.09; N, 4.09. C19H18ClNO3. Calculated (%):
C, 66.38; H, 5.28; Cl, 10.31; N, 4.07.
Methyl (Z)ꢀ2ꢀ(2ꢀmethylphenylamino)ꢀ4ꢀoxoꢀ4ꢀphenylbutꢀ2ꢀ
enoate (4e) was obtained in a similar way from methyl benzoꢀ
ylpyruvate (10 g, 48.5 mmol) and oꢀtoluidine (5.20 g, 48.5 mmol).
1
(COO); 1680 (ArCO); 1628 (C(4)=O); 1604 (C=C). H NMR
(DMSOꢀd6), : 1.34 (t, 3 H, Me, J = 6.9 Hz); 3.72 (s, 3 H,
OMe); 4.12 (q, 2 H, CH2, J = 6.9 Hz); 6.98 (dd, 2 H, H(3´),
H(5´), J = 6.9 Hz, J = 2.1 Hz); 7.73 (dd, 2 H, H(2´), H(6´),
J = 6.9 Hz, J = 2.1 Hz); 8.07 (br.s, 1 H, H(7)); 8.16 (d, 1 H,
H(5), J = 2.7 Hz); 11.00 (br.s, 1 H, NH).

738
Russ.Chem.Bull., Int.Ed., Vol. 63, No. 3, March, 2014
Boteva et al.
Yield 11.66 g (80%), m.p. 47—49 C (from PriOH). IR, /cm–1
:
(from PriOH). IR, /cm–1: 1740 (COO); 1610 (ArCO); 1590
(C=C). 1H NMR (CDCl3), : 3.69 (s, 3 H, OMe); 6.28 (s, 1 H,
CH); 7.31 (m, 8 H, Ar); 11.81 (s, 1 H, NH). Found (%): C, 53.15;
H, 3.19; Cl, 27.62; N, 3.48. C17H12Cl3NO3. Calculated (%):
C, 53.08; H, 3.14; Cl, 27.65; N, 3.64.
1730 (COO); 1618 (PhCO); 1586 (C=C). 1H NMR (CDCl3),
: 2.40 (s, 3 H, Me); 3.67 (s, 3 H, OMe); 6.41 (s, 1 H, CH); 6.86
(dd, 1 H, H(3), J = 8.0 Hz, J = 1.5 Hz); 7.05—7.14 (m, 2 H,
H(4), H(5)); 7.21—7.24 (m, 1 H, H(6)); 7.41—7.53 (m, 3 H,
H(3´), H(4´), H(5´)); 7.95 (d, 2 H, H(2´), H(6´), J = 7.7 Hz);
11.98 (s, 1 H, NH). Found (%): C, 73.29; H, 5.83; N, 4.79.
C18H17NO3. Calculated (%): C, 73.20; H, 5.80; N, 4.74.
Methyl (Z)ꢀ4ꢀ(4ꢀbromophenyl)ꢀ2ꢀ(2ꢀmethylphenylamino)ꢀ4ꢀ
oxobutꢀ2ꢀenoate (4f) was obtained in a similar way from methyl
(4ꢀbromobenzoyl)pyruvate (10 g, 35.1 mmol) and oꢀtoluidine
(3.76 g, 35.1 mmol). Yield 7.04 g (54%), m.p. 99—100 C (from
PriOH). IR, /cm–1: 1740 (COO); 1605 sh, 1580 (ArCO, C=C).
1H NMR (CDCl3), : 2.39 (s, 3 H, Me); 3.67 (s, 3 H, OMe);
6.32 (s, 1 H, CH); 6.86 (d, 1 H, H(3), J = 8.3 Hz); 7.07—7.12
(m, 2 H, H(4), H(6)); 7.21—7.24 (m, 1 H, H(5)); 7.57 (dd, 2 H,
H(3´), H(5´), J = 6.8 Hz, J = 2.0 Hz); 7.81 (dd, 2 H, H(2´),
H(6´), J = 6.8 Hz, J = 2.0 Hz); 12.00 (s, 1 H, NH). Found (%):
C, 57.62; H, 4.39; Br, 21.42; N, 3.68. C18H16BrNO3. Calculatꢀ
ed (%): C, 57.77; H, 4.31; Br, 21.35; N, 3.74.
Methyl (Z)ꢀ2ꢀ(2,4ꢀdichlorophenylamino)ꢀ4ꢀoxoꢀ4ꢀ(2ꢀthiꢀ
enyl)butꢀ2ꢀenoate (4k) was obtained in a similar way from methyl
thenoylpyruvate (6 g, 28.3 mmol) and 2,4ꢀdichloroaniline (4.58 g,
28.3 mmol). Yield 3.73 g (37%), m.p. 132—133 C (from benzꢀ
ene). IR, /cm–1: 1730 (COO); 1625, 1615, 1605 (C4H3SCO,
1
C=C). H NMR (CDCl3), : 3.78 (s, 3 H, OMe); 6.47 (s, 1 H,
CH); 6.82 (d, 1 H, H(6), J = 8.4 Hz); 7.14—7.18 (m, 2 H, H(4´),
H(5)); 7.43 (d, 1 H, H(3), J = 2.4 Hz); 7.64 (dd, 1 H, H(3´),
J = 5.3 Hz, J = 1.2 Hz); 7.75 (dd, 1 H, H(5´), J = 3.6 Hz,
J = 1.2 Hz); 11.63 (s, 1 H, NH). Found (%): C, 50.56; H, 3.12;
Cl, 19.92; N, 3.95. C15H11Cl2NO3S. Calculated (%): C, 50.58;
H, 3.18; Cl, 19.90; N, 3.88.
Some portion of this work was fulfilled as Part of the
Program "Cooperation of the Perm National Research
Polytechnic University and the Federal Polytechnic School
of Lausanne on metabolism and diabetes" (including its
initial stage at the Perm State Pharmaceutical Academy)
and financially supported by the Neva Foundation.
Methyl (Z)ꢀ2ꢀ(4ꢀchloroꢀ2ꢀmethylphenylamino)ꢀ4ꢀoxoꢀ4ꢀ
phenylbutꢀ2ꢀenoate (4g) was obtained in a similar way from meꢀ
thyl benzoylpyruvate (6 g, 29.1 mmol) and 4ꢀchloroꢀ2ꢀmethylꢀ
aniline (4.12 g, 29.1 mmol). Yield 6.34 g (66%), m.p. 114—116 C
(from CCl4). IR, /cm–1: 1732 (COO); 1616 (PhCO, C=C).
1H NMR (CDCl3), : 1.56 (s, 3 H, Me); 3.73 (s, 3 H, OMe);
6.48 (s, 1 H, CH); 6.71 (d, 1 H, H(6), J = 8.4 Hz); 7.24—7.26
(m, 1 H, H(5)); 7.37 (d, 1 H, H(3), J = 2.0 Hz); 7.45—7.49 (m, 2 H,
H(3´), H(5´)); 7.52—7.54 (m, 1 H, H(4´)); 7.95—7.97 (m, 2 H,
H(2´), H(6´)); 11.91 (s, 1 H, NH). Found (%): C, 65.50; H, 4.76;
Cl, 10.72; N, 4.20. C18H16ClNO3. Calculated (%): C, 65.56;
H, 4.89; Cl, 10.75; N, 4.21.
References
1. L. VasrarꢀDebreczy, J. Hermecz, Z. Meszaros, P. Dvortsok,
G. Toth, J. Chem. Soc., Perkin Trans. 1, 1980, 227.
2. A. N. Maslivets, O. P. Krasnykh, L. I. Smirnova, Yu. S.
Andreichikov, Zh. Org. Khim., 1989, 25, 1045 [J. Org. Chem.
USSR (Engl. Transl.), 1989, 25, 941].
3. C. Wentrup, V. V. Ramana Rao, W. Frank, B. E. Fulloon,
D. W. J. Moloney, T. Mosandl, J. Org. Chem., 1999, 64, 3608.
4. Quinolone Antimicrobial Agents, Eds D. C. Hooper, E. Ruꢀ
binstein, Washington, ASM Press, 2003.
Methyl (Z)ꢀ2ꢀ(2,4ꢀdichlorophenylamino)ꢀ4ꢀoxoꢀ4ꢀphenylbutꢀ
2ꢀenoate (4h) was obtained in a similar way from methyl benꢀ
zoylpyruvate (3 g, 14.7 mmol) and 2,4ꢀdichloroaniline (2.38 g,
14.7 mmol). Yield 2.65 g (50%), m.p. 139—141 C (from CCl4).
1
IR, /cm–1: 1730 (COO); 1630, 1600 (PhCO, C=C). H NMR
(CDCl3), : 3.77 (s, 3 H, OMe); 6.62 (s, 1 H, CH); 6.85 (d, 1 H,
H(6), J = 8.6 Hz); 7.17 (dd, 1 H, H(5), J = 8.6 Hz, J = 2.4 Hz);
7.44 (m, 1 H, H(4´)); 7.48 (m, 2 H, H(3´), H(5´)); 7.53 (m, 1 H,
H(3)); 7.98 (m, 2 H, H(2´), H(6´)); 11.94 (s, 1 H, NH).
Found (%): C, 58.21; H, 3.68; Cl, 20.21; N, 4.05. C17H13Cl2NO3.
Calculated (%): C, 58.31; H, 3.74; Cl, 20.25; N, 4.00.
5. Yu. S. Andreichikov, A. N. Maslivets, L. I. Smirnova, O. P.
Krasnykh, A. P. Kozlov, L. A. Perevozchikov, Zh. Org. Khim.,
1987, 23, 1534 [J. Org. Chem. USSR (Engl. Transl.), 1987,
23].
6. Comprehensive Organic Chemistry, Ed. P. G. Sammes, Pergaꢀ
mon, Oxford, 1979, Vol. 4.
Methyl (Z)ꢀ2ꢀ(2,4ꢀdichlorophenylamino)ꢀ4ꢀ(4ꢀethoxyphenꢀ
yl)ꢀ4ꢀoxobutꢀ2ꢀenoate (4i) was obtained in a similar way from
methyl (4ꢀethoxybenzoyl)pyruvate (5 g, 21.3 mmol) and 2,4ꢀdiꢀ
chloroaniline (3.46 g, 21.3 mmol). Yield 1.37 g (17%), m.p.
144—146 C (from EtOH). IR, /cm–1: 1728 (COO); 1630, 1608
(ArCO, C=C). 1H NMR (CDCl3), : 1.40—1.46 (m, 3 H, Me);
3.75 (s, 3 H, OMe); 4.06—4.13 (m, 2 H, CH2); 6.58 (s, 1 H,
CH); 6.80 (d, 1 H, H(6), J = 8.6 Hz); 6.92 (dd, 2 H, H(3´),
H(5´), J = 6.7 Hz, J = 2.2 Hz); 7.13 (dd, 1 H, H(5), J = 8.6 Hz,
J = 2.5 Hz); 7.40 (d, 1 H, H(3), J = 2.5 Hz); 7.95 (dd, 2 H,
H(2´), H(6´), J = 6.7 Hz, J = 2.2 Hz); 11.83 (s, 1 H, NH).
Found (%): C, 57.71; H, 4.27; Cl, 18.03; N, 3.58. C19H17Cl2NO4.
Calculated (%): C, 57.88; H, 4.35; Cl, 17.99; N, 3.55.
7. M. J. Mphahlele, A. M. ElꢀNahas, J. Mol. Struct., 2004,
688, 129.
8. F. H. Alen, O. Kennard, D. G. Watson, L. Brammer, A. G.
Orpin, R. Taylor, J. Chem. Soc., Perkin Trans. 2, 1987, 1.
9. CrysAlis RED, Version 1.171.28cycle4 beta (Release 11ꢀ11ꢀ2005
CrysAlis171.NET), Oxford Diffraction Ltd., 2005.
10. G. M. Sheldrick, SHELXS97. Program for the Solution of
Crystal Structure, University of Göttingen, Göttingen (Gerꢀ
many), 1997.
11. G. M. Sheldrick, SHELXL97. Program for the Refinement of
Crystal Structure, University of Göttingen, Göttingen (Gerꢀ
many), 1997.
Methyl (Z)ꢀ4ꢀ(4ꢀchlorophenyl)ꢀ2ꢀ(2,4ꢀdichlorophenylamino)ꢀ
4ꢀoxobutꢀ2ꢀenoate (4j) was obtained in a similar way from methꢀ
yl (4ꢀchlorobenzoyl)pyruvate (6 g, 24.9 mmol) and 2,4ꢀdichloroꢀ
aniline (4.04 g, 24.9 mmol). Yield 6.33 g (66%), m.p. 140—141 C
Received August 20, 2012;
in revised form March 6, 2014