α-Nitro chalcones: Structure and reaction with pyrrole

Article abstract of DOI:10.1134/S1070363209100181

According to the ¹H NMR, IR, and electronic absorption spectra and X-ray diffraction data, 2-aryl-1-benzoyl-1-nitroethenes have E configuration with predominant s-cis conformation, where the nitro group lies in the plane of the double carbon-ca

Full text of DOI:10.1134/S1070363209100181

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 10, pp. 2191–2196. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © V.M. Berestovitskaya, R.I. Baichurin, N.I. Aboskalova, K.A. Lysenko, G.A. Berkova, A.V. Fel’gendler, 2009, published in Zhurnal
Obshchei Khimii, 2009, Vol. 79, No. 10, pp. 1697–1702.
α-Nitro Chalcones: Structure and Reaction with Pyrrole
V. M. Berestovitskayaa, R. I. Baichurina, N. I. Aboskalovaa, K. A. Lysenkob,
G. A. Berkovaa, and A. V. Fel’gendlera
a Hertzen Russian State Pedagogical University, nab. r. Moiki 48, St. Petersburg, 191186 Russia
e-mail: kohrgpu@yandex.ru
b Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences,
ul. Vavilova 28, Moscow, 119991 Russia
Received March 5, 2009
Abstract—According to the 1H NMR, IR, and electronic absorption spectra and X-ray diffraction data, 2-aryl-
1-benzoyl-1-nitroethenes have E configuration with predominant s-cis conformation, where the nitro group lies
in the plane of the double carbon–carbon bond, while the carbonyl group deviates from that plane. Reactions of
2-aryl-1-benzoyl-1-nitroethenes with pyrrole and N-methylpyrrole gave the corresponding alkylation products
at the C2 atom in the heteroring.
DOI: 10.1134/S1070363209100181
1
Chalcones (1,3-diarylprop-2-en-1-ones) are prepa-
ratively accessible conjugated enones. They are quite
reactive compounds and convenient synthons for the
preparation of various linear and cyclic substances
many of which possess important biological properties.
The presence in their molecules of two competing
reaction centers, activated double C=C bond and
carbonyl group, makes them interesting models for
studying regioselectivity problems in reactions with
nucleophiles [1]. Of particular importance are reac-
tions with difunctional nucleophiles (such as 1,2-
diamines, o-aminobenzenethiol, guanidine), which
give rise to heterocyclic structures [2–4]. In these reac-
tions chalcones act as bielectrophiles with strictly
discriminated electrophilic centers, i.e., carbon atoms
in positions 1 and 3 of the enone fragment [5].
The H NMR spectra of β-benzoyl-β-nitrostyrenes
I–III in CDCl3 indicated that they exist as a single
stereoisomer (Table 1). Their E configuration (i.e.,
trans orientation of the benzene ring and nitro group)
follows from downfield shift of the vinyl proton
signals (δA 8.27–8.34 ppm) upon introduction of elec-
tron-withdrawing benzoyl group into molecules of (E)-
β-nitrostyrenes (δA 7.87–7.94 ppm). The E configure-
tion of compounds I–III is also confirmed by the
electronic absorption spectra (Table 1). introduction of
a benzoyl group into the corresponding nitroethene
molecule induces a red shift of the longwave absorp-
tion maximum as compared to unsubstituted (E)-β-
nitrostyrene (IA) [11]. For example, (E)-p-dimethyl-
amino-β-nitrostyrene (IIIA) absorbs at λmax 437 nm
(ε = 28700), and its benzoyl-substituted analog III is
characterized by λmax 460 nm (ε = 17100).
Introduction of one more electron-withdrawing
group, namely nitro group, into the α-position with
respect to the carbonyl group in chalcone molecule
enhances electrophilicity of these compounds and
extends their synthetic potential. For example, Michael
adducts were obtained on the basis of nitro enones;
also, substituted derivatives of such heterocycles as
pyrimidine, 1,2,3-triazole, pyrazole, dihydrofuran, etc.,
were synthesized [6–10]. Structural specificity of 1-
benzoyl-1-nitroethenes, in particular their configure-
tion and conformation, attracts interest as a separate
subject for study. For this purpose, we used traditional
spectral methods in combination with X-ray analysis.
HA
NO2
HA
NO2
p-RC6H4
COC6H5
p-RC6H4
HB
I_III
IA_IIIA
I, R = H; II, R = MeO; III, R = Me2N.
The IR spectrum of the simplest β-benzoyl-β-
nitrostyrene (I) contains absorption bands typical of
covalently bound conjugated nitro group (Table 1).
Taking into account that absorption bands of functional
groups are not split, as well as high intensity of the
2191

2192
BERESTOVITSKAYA et al.
Table 1. 1H NMR, electronic absorption, and IR spectra of β-benzoyl-β-nitrostyrenes I–III and model compounds IA–IIIA
Electronic absorption
1H NMR spectrum (CDCl3), δ, ppm (J, Hz)
IR spectrum (CHCl3), ν, cm–1
spectrum a (EtOH)
Comp.
no.
Configuration
CH3O or
(CH3)2N
λmax
nm
,
ε,
C=C,
NO2 (NOO–) C=O
C=N+
HA
HB
–
Ar
l mol–1 cm–1
Е
Е
Е
Е
Е
Е
8.34
–
7.35;
7.40–7.98
6.82;
314
360
460
309
355
437
15000
14000
17100
17200
21000
28700
1525, 1320
1680
1640
I
8.27
8.28
7.87
–
3.70
[2.99]
–
(1310, 1255) 1670
(1300, 1190) 1680
1595
II
7.45–7.95
6.60;
–
1590
III
7.30–7.98
7.38
7.60
7.51
7.42
1530, 1343
–
–
–
1640
IA
(3JAB 14)
7.94
(3JAB 14)
7.90
(3JAB 14)
Given are absorption maxima in the region λ > 280 nm.
3.91
[3.10]
6.95, 7.52
6.64, 7.40
(1320,
1300, 1258)
(1320,
1627, 1600
1600
IIA
IIIA
1298, 1267)
a
C=C stretching vibration band (νC=C 1640 cm−1; it is
comparable with the intensity of the carbonyl
absorption band νC=O at 1680 cm–1), we presumed that
compound I exists as a single conformer, namely s-cis.
In keeping with published data, the intensity ratio
ν(C=C)/ν(C=O) ≈ 1 is typical of cisoid conformers of
α,β-unsaturated carbonyl compounds [12, 13].
H
NO2
C6H5
O
(H3C)2N
H
NOO_
C6H5
H
NO2
C6H5
O
C6H5
+
O
(H3C)2N
s-cis
Thus comprehensive analysis of spectral parameters
of β-benzoyl-β-nitrostyrenes I–III allowed us to con-
clude that the nitro group and aromatic ring in their
molecules are oriented trans, i.e., nitroenones I–III
have E configuration of the double C=C bond.
The IR spectra of (E)-β-benzoyl-β-nitrostyrenes II
and III are similar to the spectra of model (E)-β-
nitrostyrenes IIA and IIIA having the corresponding
electron-donating groups in the benzene ring [11].
Their IR spectra lacked absorption bands typical of
covalently bound nitro group, but very strong
absorption bands appeared at 1590–1595 cm−1 (C=C,
C=N+) and in the regions 1300–1310 and 1190–
1255 cm−1 (NOO–); this is the result of participation of
p electrons on the nitrogen or oxygen atom in
conjugation with π electrons of the nitrovinyl fragment
(Table 1). The observed spectral pattern suggests an
appreciable contribution of dipolar structure (with
negatively charged nitro group) to the ground state of
the compounds under study.
The structure of one β-benzoyl-β-nitrostyrene
derivative, 3-(4-methoxyphenyl)-2-nitro-1-phenylprop-
2-en-1-one (II), was determined by X-ray analysis. It
was found that this compound in crystal exists as E
isomer (see figure). Principal geometric parameters of
molecule II (bond lengths and bond angles) are
collected in Table 2. The substituted benzene ring in
molecule II is slightly turned with respect to the
relatively planar nitrovinyl fragment (the correspond-
ing dihedral angle is 17°), while the carbonyl group is
turned through an angle of 71.8° with respect to the
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

2193
α-NITRO CHALCONES: STRUCTURE AND REACTION WITH PYRROLE
Table 2. Principal bond lengths d and bond angles ω in the molecule of 3-(4-methoxyphenyl)-2-nitro-1-phenylprop-2-en-1-
one (II)
Bond
d, Å
Bond angle
ω, deg
Bond angle
ω, deg
O1–C4
N1–O4
N1–O3
N1–C8
C1–C6
C1–C2
C1–C7
O2–C9
C2–C3
C3–C4
C4–C5
C5–C6
C7–C8
C9–C10
1.356(1)
1.226(1)
1.238(1)
1.457(1)
1.402(1)
1.404(1)
1.454(1)
1.215(1)
1.379(1)
1.396(1)
1.397(1)
1.387(1)
1.339(2)
1.477(1)
C4O1C16
O4N1O3
O4N1C8
O3N1C8
C6C1C2
C6C1C7
C2C1C7
C3C2C1
C2C3C4
117.17(9)
123.38(9)
120.65(10)
115.97(9)
117.98(10)
123.81(10)
118.17(9)
121.21(10)
119.96(10)
O1C4C3
O1C4C5
C3C4C5
C6C5C4
C5C6C1
C8C7C1
C7C8N1
C7C8C9
N1C8C9
116.04(10)
124.04(10)
119.91(10)
119.53(10)
121.32(10)
128.54(10)
118.25(9)
129.06(10)
112.45(9)
same plane. The nitro group lies in the C=C bond
plane: the torsion angles C7C8N1O3 and C7C8N1O4 are
179.50 and –0.34°, respectively. Conjugation with the
nitroethene system and effect of the methoxy group
lead to alternation of bonds in the substituted benzene
ring, so that the C2–C3 and C5–C6 bonds are slightly
shortened (Table 2). The C8–N1 bond in molecule II
[1.457(1) Å] has almost the same length as the
corresponding bond in (E)-N-benzyl-2-nitro-3-(4-
methoxyphenyl)prop-2-enamide (1.459 Å) [14], but it
is appreciably shorter than the C–N bond in (Z)-4-(4-
methoxyphenyl)-3-nitrobut-3-en-2-one (1.476 Å) [15],
methyl (Z)-α-nitrocinnamate (1.475 Å), and p-
methoxy-substituted analog of the latter (1.485 Å) [14,
16], where the nitro group is forced out from the
double bond plane.
С13
С14
С16
С15
С12
С5
С4
O1
С11
С10
С6
O2
С9
С3
С1
С8
С2
С7
N1
O3
O4
Structure of the molecule of 3-(4-methoxyphenyl)-2-nitro-1-phenylprop-2-en-1-one (II) according to the X-ray diffraction data; non-
hydrogen atoms are shown as thermal vibration ellipsoids with a probability of 50%.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

2194
BERESTOVITSKAYA et al.
Table 3. Yields, melting points, and spectral parameters of pyrrolylnitropropanones IV–VIIa
IR spectrum (CHCl3), ν, cm –1
1H NMR spectrum (CDCl3), δ, ppm; J, Hz
Comp.
no.
Yield, %
88
mp, °C
NCH3
(OCH3)
NO2
C=O
NH
HA
HB
NH
pyrrole (Ar)
6.78 d
5.33 d
3JAB = 11.30
8.10 s
–
5.83, 5.94, 6.57
(7.1–7.8 m, 8.04 m)
6.14, 6.69
IVa
IVb
116–117
1560, 1360
1695
3465
6.79 d
6.76 d
5.31 d
8.10 s
–
3JAB = 10.90
(7.1–7.8 m, 8.04 m)
5.82, 5.90, 6.44
(7.00–8.10 m)
6.12, 6.32, 6.55
(7.00–8.10 m)
5.84, 5.88, 6.45
(7.20–8.15 m)
5. 30 d
3JAB = 11.77
–
–
–
3.50 s
3.44 s
3.50 s
Va
Vb
Va
68b
47
110–113
140–142
1560, 1360
1700
–
6.76 d
5.27 d
3JAB = 11.50
6.76 d
5.30 d
3JAB = 11.77
6.71 d
5.28 d
8.08 s
(3.78 s)
(3.74 s)
5.81, 5.94, 6.57
VIa
3JAB = 11.20
(7.12–7.64 m, 8.04 m)
6.17, 6.34, 6.68
(7.09–8.06 m)
30
51
120–122
114–115
1560, 1360
1560, 1360
1695
1700
3465
–
6.74 d
5.27 d
8.08 s
–
VIb
3JAB = 10.50
6.69 d
5.22 d
3.47 s
5.79, 5.85, 6.44
VIIa
3JAB = 11.77
(3.76 s)
(6.82–8.05 m)
a
Compounds IV–VI were isolated as mixtures of diastereoisomers with intensity ratios a:b of 3:1, ~1:1, and ~6:1, respectively; the
index “a” refers to diastereoisomer with closer chemical shifts of the HA and HB protons. b The maximal yield of adduct V is given.
We previously showed that β-benzoyl-β-nitro-
1360 cm−1) and carbonyl groups (1695–1700 cm−1),
while compounds IV and VI displayed absorption
bands typical of stretching vibrations of the pyrrole
NH group (~3465 cm–1). Molecules IV–VII possess
two chiral centers; therefore, they may be formed as
styrene molecules can readily be modified by intro-
duction of such pharmacophoric fragments as indole
and substituted indoles [17]. In continuation of our
studies on the chemical properties of nitro enones, β-
benzoyl-β-nitrostyrenes I and II were brought into
reactions with pyrrole and N-methylpyrrole. The
reactions did not require the presence of any catalyst,
and they occurred under solvent-free conditions or in
carbon tetrachloride to afford the corresponding
alkylation (so-called substitutive addition) products
IV–VII.
1
mixtures of stereoisomers. In fact, in the H NMR
spectra of IV–VI in chloroform-d we observed double
sets of signals with intensity ratios of 3:1, ~1:1, and
~6:1, respectively (Table 3). Compound VII turned
1
out to be stereochemically homogeneous. Its H NMR
spectrum in CDCl3 contained doublets from the CH
protons at δ 5.22 (HB) and 6.69 ppm (HA) with a
3
coupling constant JAB of 11.77 Hz; protons in the
methoxy and methyl groups resonated as singlets at δ
3.76 and 3.47 ppm, respectively; and protons in the
phenyl and pyrrole rings gave rise to multiplets in the
regions δ 6.82–8.05 and 5.79–6.44 ppm.
N
NO2
HA
*
R
*
I, II
C(O)C6H5
N
R
HB
Ar
By varying the reaction conditions we succeeded in
IV_VII
isolating individual diastereoisomer Va with mp 140–
1
142°C; its H NMR spectral parameters are also given
IV, Ar = Ph, R = H; V, Ar = Ph, R = Me; VI, Ar = 4-MeOC6H4,
R = H; VII, Ar = 4-MeOC6H4, R = Me.
in Table 3. However, the configuration of diastereo-
isomers isolated as individual substances was not
determined specially.
The structure of pyrrolylnitropropanones IV–VII
was confirmed by spectral data (Table 3). Their IR
spectra contained strong absorption band due to
stretching vibrations of unconjugated nitro- (1560,
Thus the reaction of β-benzoyl-β-nitrostyrenes with
pyrrole and N-methylpyrrole has demonstrated that 1-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

2195
α-NITRO CHALCONES: STRUCTURE AND REACTION WITH PYRROLE
benzoyl-1-nitroethenes can be used as nitroketo-
alkylating agents toward compounds of the pyrrole
series. Search for preparatively convenient methods of
pyrrole ring functionalization constitutes one of the
most vigorously developing fields of the pyrrole chem-
istry. The newly synthesized nitro ketones containing a
pharmacophoric pyrrole fragment are potential bio-
logically active compounds.
in 8 ml of anhydrous carbon tetrachloride, and the
mixture was kept for 2 days at room temperature in the
dark. The mixture was then poured into a Petri dish
and evaporated, and the residue was treated with
ethanol to isolate 0.56 g (88%) of compound IV as off-
white crystals (mixture of diastereoisomers at a ratio of
3:1), mp 116–117°C (from ethanol). Found N, %:
8.95. C19H16N2O3. Calculated N, %: 8.75.
1,3-Diphenyl-3-(1-methyl-1H-pyrrol-2-yl)-2-nitro-
propan-1-one (V). a. N-Methylpyrrole, 1.8 ml, was
added to 0.506 g of 1,3-diphenyl-2-nitroprop-2-en-1-
one (I), and the mixture was kept for 3 days at room
temperature in the dark. The precipitate, 0.31 g (47%),
of compound Va (individual diastereoisomer) were
filtered off; white crystals, mp 140–142°C (from
ethanol). The filtrate was treated with ethyl acetate and
water at a ratio of 4:1, and the mixture was separated
in a separatory funnel. The organic phase was washed
with two portions of a saturated solution of sodium
chloride and dried over calcined magnesium sulfate for
24 h. The solvent was evaporated on a Petri dish, and
the residue was treated with ethanol to isolate 0.125 g
(21%) of compound V (a mixture of stereoisomers at a
ratio of 1:1); beige crystals, mp 110–113°C (from
ethanol). Overall yield of V 0.435 g (68%). Found N,
%: 8.63. C20H18N2O3. Calculated N, %: 8.38.
EXPERIMENTAL
The IR spectra were recorded on an Infralyum FT-
02 instrument from solutions in chloroform with a
concentration c of 0.1 to 0.001 M. The H NMR
spectra were measured on Bruker AC-200 (200 MHz)
and Bruker WM-400 (400 MHz) spectrometers using
chloroform-d as solvent and tetramethylsilane as
reference. Compounds I–III were synthesized accord-
ing to the procedures described in [6].
1
X-Ray diffraction data for compound II.
Monocllinic crystals, C16H13NO4 (M 283.27) with the
following unit cell parameters (100 K): a = 24.234(1) Å,
b = 8.0518(4), c = 17.783(1) Å; β = 127.645(1)°; V =
2747.5(3) Å3; space group C2/c; Z = 8; dcalc
=
1.370 g cm–3; F(000) = 1184. Experimental set
including 17466 reflections was acquired on a Bruker
APEX II CCD diffractometer at 100 K (λMoKα irradia-
tion, ω scanning, 2θmax = 60°). Averaging of equivalent
reflections gave 4009 independent reflections with
Rint = 0.0295, which were used in the structure solution
and refinement. No correction for absorption was
introduced (μ = 0.99 mm–1). The structure was solved
by the direct method. All non-hydrogen atoms were
localized by difference syntheses of electron density
and were refined in anisotropic approximation with
respect to F2hkl. The positions of all hydrogen atoms
were set on the basis of geometry considerations and
were refined according to the riding model with
U(H) = 1.2U(C), where U(C) is the equivalent tem-
perature factor of carbon atom bearing the
corresponding hydrogen atom. The final divergence
factors were R1 = 0.0399 [calculated by Fhkl for 3332 re-
b. N-Methylpyrrole, 0.089 ml, was added to 0.127 g
of 1,3-diphenyl-2-nitroprop-2-en-1-one (I), and the
mixture was heated under continuous stirring until a
melt was obtained. The mixture was kept for 3 days at
room temperature in the dark and treated with ethanol,
and the precipitate was filtered off. Yield 0.103 g
(62%) of compound V as a mixture of diastereo-
isomers at a ratio of 1:1; beige crystals, mp 110–113°C
(from ethanol). The product showed no depression of
the melting point on mixing with a sample prepared as
described above in a.
3-(4-Methoxyphenyl)-2-nitro-1-phenyl-3-(1H-pyrrol-
2-yl)propan-1-one (VI). Pyrrole, 0.7 ml, was added to
0.283 g of 3-(4-methoxyphenyl)-2-nitro-1-phenylprop-
2-en-1-one (II), and the mixture was kept for 2 days at
room temperature in the dark and treated with ethyl
acetate and water as described above for compound V
(method a). Yield 0.105 g (30%), mixture of
diastereoisomers at a ratio of 6:1; gray crystals, mp
120–122°C (from ethanol).
flections with I > 2σ(I)], wR2 = 0.1106 (calculated by F
2
for all 4009 independent reflections); goodness of
hkl
fit 1.014; 191 refined parameter. All calculations were
performed using SHELXTL PLUS 5 software package
[18].
1,3-Diphenyl-2-nitro-3-(1H-pyrrol-2-yl)propan-1-
one (IV). Pyrrole, 0.28 ml, was added to a suspension
of 0.506 g of 1,3-diphenyl-2-nitroprop-2-en-1-one (I)
3-(4-Methoxyphenyl)-3-(1-methyl-1H-pyrrol-2-yl)-
2-nitro-1-phenylpropan-1-one (VIIa). N-Methyl-
pyrrole, 0.9 ml, was added to 0.283 g of 3-(4-meth-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

2196
BERESTOVITSKAYA et al.
7. Bakhareva, S.V., Aboskalova, N.I., and Berestovits-
kaya, V.M., Russ. J. Gen. Chem., 2001, vol. 71, no. 9,
p. 1493.
oxyphenyl)-2-nitro-1-phenylprop-2-en-1-one (II), and
the mixture was kept for 3 days at room temperature in
the dark and treated with ethyl acetate and water as
described above for compound V (method a). Yield
0.185 g (51%), individual diastereoisomer, beige
crystals, mp 114–115°C (from ethanol).
8. Aboskalova, N.I., Berestovitskaya, V.M., Bakhareva, S.V.,
and Fel’gendler, A.V., Khim. Geterotsikl. Soedin., 2002,
no. 10, p. 1462.
9. Berestovitskaya, V.M., Aboskalova, N.I., Ishmaeva, E.A.,
Bakhareva, S.V., Berkova, G.A., Vereshchagina, Ya.A.,
Fel’gendler, A.V., and Fattakhova, G.R., Russ. J. Gen.
Chem., 2001, vol. 71, no. 12, p. 1942.
REFERENCES
1. Yanovskaya, L.A., Kryshtal’, G.V., and Kul’ganek, V.V.,
Usp. Khim., 1984, vol. 53, no. 8, p. 1280.
10. Remennikov, G.A., Khim. Geterotsikl. Soedin., 1997,
2. Orlov, V.D., Kolosov, M.A., Kotlyar, V.N., Marrugo
Gonzalez, A.Kh., Sidorenko, D.Yu., Pushkarev, A.P.,
and Baraban, A.Yu., Sbornik nauchnykh trudov
no. 12, p. 1587.
11. Paperno, T.Ya., Perekalin, V.V., and Sopova, A.S., Zh.
Prikl. Spektrosk., 1973, vol. 19, no. 4, p. 649.
Vserossiiskoi
nauchno-prakticheskoi
konferentsii
12. Savin, V.I. and Kitaev, Yu.P., Zh. Org. Khim., 1973,
“Korshunovskie chteniya” (Collection of Scientific
Papers Presented at the All-Russian Scientific and
Practical Conf. “Korshunov’s Readings”), Tol’yatti,
2008, p. 11.
vol. 9, no. 6, p. 1101.
13. Bellamy, L.J., Advances in Infra-red Group
Frequencies, London: Methuen, 1966. Translated under
the title Novye dannye po IK spektram slozhnykh
molekul, Moscow: Mir, 1971, p. 172.
3. Shikhaliev, Kh.E., Falaleev, A.V., and Kryl’skii, D.V.,
Izbrannye metody sinteza i modifikatsii geterotsiklov
(Selected Methods of Synthesis and Modification of
Heterocycles), Kartsev, V.G., Ed., Moscow: IBS, 2003,
vol. 1, p. 450.
4. Desenko, S.M., Chebanov, V.A., Kolos, N.N., and
Orlov, V.D., Izbrannye metody sinteza i modifikatsii
geterotsiklov (Selected Methods of Synthesis and
Modification of Heterocycles), Kartsev, V.G., Ed.,
Moscow: IBS, 2003, vol. 1, p. 140.
14. He, L., Srikanth, G.S.C., and Castle, S.L., J. Org.
Chem., 2005, vol. 70, no. 20, p. 8140.
15. Aboskalova, N.I., Smirnova, N.N., Kataeva, O.N.,
Baichurin, R.I., Fel’gendler, A.V., Berkova, G.A., and
Berestovitskaya, V.M., Russ. J. Gen. Chem., 2008,
vol. 78, no. 9, p. 1711.
16. Andrianov, V.G., Struchkov, Yu.T., and Babievsky, K.K.,
Cryst. Struct. Commun., 1982, vol. 11, p. 31.
5. Desenko, S.M. and Orlov, V.D., Azageterotsikly na
osnove aromaticheskikh nepredel’nykh ketonov (Aza
Heterocycles Based on Aromatic Unsaturated Ketones),
Khar’kov: Folio, 1998.
17. Aboskalova, N.I., Berestovitskaya, V.M., Berkova, G.A.,
and Fel’gendler, A.V., Russ. J. Org. Chem., 1999, vol. 35,
no. 1, p. 151.
6. Fel’gendler, A.V., Aboskalova, N.I., and Beresto-
vitskaya, V.M., Russ. J. Gen. Chem., 2000, vol. 70,
no. 7, p. 1087.
18. Sheldrick, G.M., SHELXTL Ver.5.0. Software Reference
Manual, Siemens Industrial Automation: Madison WI,
1995.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009