Fluorine-containing heterocycles: XII. Fluorine-containing quinazolin-4-ones and azolo[a]quinazolinone derivatives

Article abstract of DOI:10.1007/s11178-005-0295-7

Methods for the synthesis of fluorine-containing derivatives of 2-imino-1,3-diphenylquinazolin-4-one, imidazo[1,2-a]quinazolin-5-one, pyrazolo[1,5-a]quinazolin-5-one, and [1,2,4]triazolo[1,5-a]quinazolin-5-one were developed on the basis of the reaction o

Full text of DOI:10.1007/s11178-005-0295-7

Russian Journal of Organic Chemistry, Vol. 41, No. 7, 2005, pp. 1071–1080. Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 7, 2005,
pp. 1092–1100.
Original Russian Text Copyright © 2005 by Lipunova, Nosova, Laeva, Kodess, Charushin.
Fluorine-Containing Heterocycles: XII.* Fluorine-Containing
Quinazolin-4-ones and Azolo[a]quinazolinone Derivatives
G. N. Lipunova1, E. V. Nosova1, A. A. Laeva1, M. I. Kodess2, and V. N. Charushin2
1 Ural State Technical University, Yekaterinburg, Russia
2 Institute of Organic Synthesis, Ural Division, Russian Academy of Sciences,
ul. S. Kovalevskoi 20, Yekaterinburg, 620219 Russia
Received June 14, 2004
Abstract—Methods for the synthesis of fluorine-containing derivatives of 2-imino-1,3-diphenylquinazolin-4-
one, imidazo[1,2-a]quinazolin-5-one, pyrazolo[1,5-a]quinazolin-5-one, and [1,2,4]triazolo[1,5-a]quinazolin-5-
one were developed on the basis of the reaction of tetrafluorobenzoyl chloride with N,N'-diphenylguanidine and
aminoazoles.
Fused quinazolin-4-one derivatives attract strong
interest from the viewpoint of their potential biological
activity. Antibacterial, antitoxoplasmatic, antihyper-
tensive, and antihistaminic agents, phosphodiesterase
inhibitors, and compounds possessing other kinds of
biological activity have been revealed among quinazo-
lin-4-one derivatives [2–8]. A known procedure for
building up such heterocyclic systems is based on cy-
clization of 2-halo-substituted benzoyl chlorides with
difunctional nitrogen-centered nucleophiles [4, 9–11].
This approach was not applied previously to the syn-
thesis of fused imidazo-, pyrazolo[a]- and triazolo[a]-
quinazolinones. There are published data only on the
preparation of triazolo[a]quinazolinone derivatives via
transformations of quinazolinones having a sulfanyl,
hydrazino, thiosemicarbazido, or S-methylisothiosemi-
carbazido group in the 2-position [2, 5, 12–15].
In continuation of our studies on the synthesis of
fused fluorine-containing nitrogen heterocycles, we
have developed a general procedure for the preparation
of fluorinated triazolo-, pyrazolo-, and imidazo[a]-
quinazolinones by reaction of tetrafluorobenzoyl
chloride with difunctional N,N'-dinucleophiles. By
acylation of N,N'-diphenylguanidine (II) with tetra-
fluorobenzoyl chloride (I) in boiling toluene we ob-
tained N,N'-diphenyl-N-(2,3,4,5-tetrafluorobenzoyl)-
1
guanidine (III) (Scheme 1). The H NMR spectrum of
III confirmed the presence in its molecule of two
Scheme 1.
O
F
O
F
NH
F
F
F
F
Ph
NH
Cl
N
N
+
H
Ph
Ph
Ph
N
N
H
H
F
F
I
II
III
O
N
O
F
F
Ph
F
Ph
N
N
R
NH
N
N
NH
F
Ph
R'
F
Ph
IV
Va–Vd
V, RR'N = 1-pyrrolidinyl (a), morpholino (b), 2,6-dimethylmorpholino (c), 4-methylpiperidino (d).
* For communication XI, see [1].
1070-4280/05/4107-1071 © 2005 Pleiades Publishing, Inc.

LIPUNOVA et al.
1072
Table 1. 1H NMR and mass spectra of compounds IV and Va–Vd
1H NMR spectrum (DMSO-d6), δ, ppm (J, Hz)
Comp.
no.
Mass spectrum, m/z (Irel, %)
5-H
NRR'
–
NH, br.s
Ph
7.76 d.d.d
(3J = 10.0,
4J = 8.0,
14.0–15.0 7.12 m (1H), 7.28 m (4H), 367 (84) [M]+, 366 (100), 250
IV
7.62 m (5H)
(34), 240 (47), 221 (13), 220
(10), 77 (11)
5J = 2.2)
7.40 d.d 1.81 m [4H, (CH2)2],
(3J = 12.4, 3.41 m [4H, N(CH2)2]
5J = 2.0)
14.0–15.0 7.08 m (1H), 7.25 m (2H), 418 (100) [M]+, 417 (99), 301
Va
7.32 m (2H), 7.58 m (5H)
(13), 299 (21), 279 (15), 278
(25), 244 (11), 212 (18)
Vba
7.52 d.d 3.07 m [4H, N(CH2)2],
(3J = 12.2, 3.61 m [4H, O(CH2)2]
5J = 1.8)
14.0–15.0 7.09 m (1H), 7.23 m (4H), 434 (100) [M]+, 433 (73), 392
7.59 m (5H)
(25), 391 (28), 376 (13), 375
(30), 259 (13), 258 (29)
7.48 d.d 1.03 m (3H, CH3),
(3J = 11.5, 1.06 m (3H, CH3),
5J = 1.6) 2.72 m (2H, CH2),
2.81 m (2H, CH2),
14.0–15.0 7.09 m (1H), 7.28 m (4H), 462 (83) [M]+, 461 (35). 392 (89),
Vc
Vd
7.59 m (5H)
391 (100), 376 (46), 375 (67),
273 (19), 259 (23), 258 (33)
3.60 m (2H, CH)
7.47 d.d 0.92 d (3H, CH3, 3J = 6.3), 14.0–15.0 7.08 m (1H), 7.31 m (4H), 446 (100) [M]+, 445 (87), 375 (6),
(3J = 11.3, 1.2–1.4 (2H, CH2),
5J = 1.5) 1.6 m (2H, CH),
1.7 m (2H, CH2),
7.59 m (5H)
329 (7), 327 (8), 259 (6), 258 (7)
3.19 m (2H, NCH2),
3.55 m (2H, NCH2)
a
19F NMR spectrum (DMSO-d6), δF, ppm: 34.23 m (1F), 38.25 m (1F).
phenyl groups (multiplet signals in the region δ 7.3–
8.0 ppm) and two NH groups (broadened signals at
δ 10.8 and 12.1 ppm); also, the spectrum character-
istically contained a signal at δ 6.82 ppm (m) belong-
ing to proton in the tetrafluorobenzoyl fragment.
placement of one fluorine atom with formation of
compounds Va–Vd. Compound Va was also obtained
by reaction of quinazolinone IV with pyrrolidine. The
site of fluorine replacement (7-F) was determined on
the basis of multiplicity of the 5-H signal in the
1H NMR spectra of Va–Vd: it appeared as a doublet of
doublets at δ 7.40–7.52 ppm, 3J = 11.5–12.5, 5J = 1.5–
Heating of compound III for 5 h in boiling di-
methylformamide resulted in cyclization with forma-
tion of 81% of 2-imino-1,3-diphenyl-2,3-dihydro-1H-
quinazolin-4-one (IV). In the 1H NMR spectrum of IV
we observed a broadened singlet from the NH proton,
signals from protons in two phenyl rings, and a signal
at δ 7.76 ppm from proton in the trifluorobenzoyl
fragment; change of the multiplicity of the latter
indicated that cyclization occurred (Table 1). The mass
spectrum of quinazolinone IV contained a strong peak
(84%) from the molecular ion peak, while the most
abundant was [M – 1]+ ion (100%). No other strong
peaks were present in the spectrum, presumably due to
high stability of the 2-imino-1,3-diphenyl-2,3-dihydro-
1H-quinazolin-4-one system.
1
2.0 Hz). In addition, the H NMR spectra of 7-substi-
tuted quinazolin-4-ones Va–Vd contained signals from
the NH proton, protons in the R and R' substituents at
the amino group, and protons in the N-phenyl substit-
uents. Compounds Va–Vd showed strong molecular
ion peaks in the mass spectra. The 19F NMR spectrum
of Vb displayed signals from two fluorine atoms as
an additional support to structure V.
Another difunctional N,N'-nucleophile was 2-amino-
imidazole-4,5-dicarbonitrile (VI). Acylation of amine
VI with tetrafluorobenzoyl chloride (I) in methylene
chloride in the presence of triethylamine at room tem-
perature afforded N-(4,5-dicyano-1H-imidazol-2-yl)-
2,3,4,5-tetrafluorobenzamide (VII) (Scheme 2). The
1H NMR spectrum of VII contained broadened sing-
lets from the two NH protons at δ 10.3 and 12.6 ppm
and a multiplet signal from the tetrafluorobenzoyl
When compound III was heated in dimethylform-
amide in the presence of pyrrolidine, morpholine, cis-
2,6-dimethylmorpholine, or 4-methylpiperidine, the
intramolecular cyclization was accompanied by re-
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FLUORINE-CONTAINING HETEROCYCLES: XII.
1073
Scheme 2.
OH
N
F
N
N
·
CN
F
N
N
O
F
N
CN
F
CN
F
F
NC
N
N
N
H
CN
VIII
H
I
+
H2N
CN
N
O
H
F
F
NH
VI
VII
R
N
N
N
R'
F
NC
CN
XIa–XIc
OH
N
O
F
F
F
N
NH
N
·
VIII
N
N
N
N
N
F
F
NC
NC
CN
CN
X
IX
XI, RR'N = 1-pyrrolidinyl (a), morpholino (b); R = R' = Me (c).
5
proton. By heating amide VII in acetonitrile in the
presence of 1,8-diazabicycloundec-7-ene (DBU) we
obtained 7,8,9-trifluoro-5-oxo-4,5-dihydroimidazo-
[1,2-a]quinazoline-1,2-dicarbonitrile salt VIII with
protonated DBU molecule as cation. Salt VIII did not
change on treatment with a solution of acetic acid at
room temperature. The multiplicity of the 6-H signal
(Table 2) is indicative of the fused polycyclic structure
of VIII; eight methylene groups of DBU give signals
in a strong field.
By heating salt VIII for a short time in boiling
acetic acid we succeeded in isolating imidazo[a]-
quinazolinone IX. The 1H NMR spectrum of IX lacked
signals from methylene protons typical of DBU, the
6-H signal was a double doublet of doublets, which
was displaced downfield by 0.3 ppm, and the NH
signal was displaced downfield by 4.2 ppm. The 19F
NMR spectrum of IX contained signals (d.d.d) from
three fluorine atoms (Table 2).
doublets (3J = 12.1, J = 1.5 Hz) from the 6-H proton,
a broadened singlet from the NH proton, and multiplet
signals from methylene groups in the pyrrolidine and
DBU fragments. Reactions of amide VII with pyrro-
lidine and morpholine in boiling dimethylformamide
resulted in intramolecular ring closure with simulta-
neous replacement of the 8-F atom with formation of
compounds XIa and XIb, respectively. Our attempt to
isolate imidazoquinazolinone IX by heating amide VII
in dimethylformamide was unsuccessful: the process
was accompanied by substitution of the 8-F atom by
dimethylamine residue to afford compound XIc. The
1
structure of XIa–XIc was confirmed by the H NMR
and mass spectra (Table 2).
3-Aminopyrazoles XIIa and XIIb are also acces-
sible N,N'-nucleophiles. Compound (I) reacted with
3-aminopyrazole (XIIa) in toluene under reflux (reac-
tion time 3 h) to give bis-aroyl derivative XVI
1
(Scheme 3). Compound XVI showed in the H NMR
When compounds VIII was heated with pyrrolidine
in boiling dimethylformamide, the 8-F atom was re-
placed by the cyclic amine residue, and the product
(like the initial compound) was a salt with DBU. In
spectrum multiplet signals from two protons in the
tetrafluorobenzoyl fragments, a broadened singlet from
one NH proton, and signals from two protons in the
pyrazole ring. The mass spectrum of XVI was consist-
ent with the assumed structure (see Experimental).
1
the H NMR spectrum of X we observed a doublet of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 7 2005

LIPUNOVA et al.
Table 2. 1H NMR and mass spectra of compounds VIII–XI
1074
NMR spectrum 1H (DMSO-d6), δ, ppm (J, Hz)
Comp.
no.
Mass spectrum, m/z (Irel, %)
6-H
NH
NRR'
–
other signals
7.90 d.d.d
(3J = 10.1, 4J = 8.2,
5J = 2.0)
09.9 br.s
1.70 m (6H, 3CH2), 289 (100) [M – DBU]+, 183 (12),
VIII
2.00 m (2H, CH2),
2.75 m (2H, CH2),
3.35 m (2H, CH2),
3.54 m (2H, CH2),
3.60 m (2H, CH2)
158 (12), 152 (37), 151 (35),
137 (13), 130 (16), 123 (19), 98
(16), 96 (24), 55 (12)
IXa
X
8.20 d.d.d
(3J = 9.9, 4J = 7.9,
5J = 2.2)
14.1 br.s
–
–
7.54 d.d
10.3 br.s 1.95 m [4H, (CH2)2],
1.72 m (6H, 3CH2),
(3J = 12.1, 5J = 1.5)
3.66 m [4H, N(CH2)2] 1.93 m (2H, CH2),
2.78 m (2H, CH2),
3.37 m (2H, CH2),
3.52 m (2H, CH2),
3.56 m (2H, CH2)
7.63 d.d
13.2 br.s 1.92 m [4H, (CH2)2],
–
340 (88) [M]+, 339 (100), 297
XIa
XIb
(3J = 12.1, 5J = 1.5)
3.70 m [4H, N(CH2)2]
13.5 br.s 3.35 m [4H, N(CH2)2],
3.75 m [4H, O(CH2)2]
(20), 285 (13), 284 (26)
7.78 d.d
–
356 (81) [M]+, 314 (56), 313 (65),
299 (25), 298 (100), 297 (20),
271 (21), 149 (12), 133 (12)
313 (100) [M]+, 289 (44), 156
(3J = 11.7, 5J = 1.5)
7.76 d.d
11.6 br.s 3.07 s (6H, 3CH3)
–
XIc
(3J = 12.3, 5J = 1.8)
(11)
a
3
3
4
3
19F NMR spectrum (DMSO-d6), δ, ppm: 14.27 d.d.d (1F, 8-F, JFF = 22.4, JFF = 21.2, JFH = 7.5 Hz), 29.96 d.d.d (1F, 7-F, JFF = 22.4,
3JFH = 9.5, 4JFF = 6.7 Hz), 31.38 d.d.d (1F, 9-F, 3JFF = 21.2, 4JFF = 6.7, 5JFH = 1.7 Hz).
Table 3. 1H and 19F NMR and mass spectra of compounds XIVa, XIVb, and XVa–XVc
19F NMR spec-
trum (DMSO-d6),
δ, ppm
1H NMR spectrum (DMSO-d6), δ, ppm (J, Hz)
Comp.
no.
Mass spectrum,
m/z (Irel, %)
6-H
3-H
NH
R1
NR2R3
–
7.93 d.d.d
6.09 d 12.3 br.s 7.90 d
11.00 m (1F), 239 (100) [M]+, 183 (16),
XIVa
(3J = 10.0, (3J = 2.0)
4J = 8.0,
(3J = 2.0)
1.84 m (1F),
19.26 m (1F)
182 (11), 157 (10), 156
(21), 130 (12)
5J = 2.1)
7.47 d.d.d
(3J = 9.9,
4J = 7.7,
5J = 1.5)
7.58 d.d
(3J = 12.6,
5J = 1.7)
7.70 d.d
(3J = 12.4,
5J = 1.7)
6.59 s 12.8 br.s 7.51 m (2H),
8.04 m (3H)
–
11.01 m (1F), 315 (100) [M]+, 287 (9),
2.07 m (1F),
19.41 m (1F)
XIVb
258 (31), 102 (12)
6.45 s 12.1 br.s 7.45 m (1H), 1.90 m [4H, (CH2)2],
7.51 m (2H), 3.70 m [4H, N(CH2)2]
7.98 m (2H)
6.51 s 12.3 br.s 7.67 m (3H), 3.36 m [4H, N(CH2)2],
7.99 m (2H) 3.74 m [4H, O(CH2)2]
366 (100) [M]+, 365 (42),
182 (13)
XVa
XVb
382 (100) [M]+, 341 (15),
340 (73), 324 (43), 297
(20), 296 (14), 267 (11),
162 (16), 148 (16)
7.71 d.d
(3J = 12.1,
5J = 1.5)
6.52 s 11.9 br.s 7.44 m (1H), 1.22 t (3H, CH3),
7.51 m (2H), 3.34 m [4H, N(CH2)2],
8.01 m (2H) 3.54 m [4H, N(CH2)2],
4.09 q (2H, OCH2)
453 (100) [M]+, 433 (18),
351 (30), 340 (48), 339
(50), 338 (23), 325 (12),
324 (11), 237 (15), 102
(11), 56 (58)
XVc
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FLUORINE-CONTAINING HETEROCYCLES: XII.
1075
Scheme 3.
R1
O
O
N
N
F
F
F
N
N
NH
H
H
F
F
R1
N
F
F
R1
I
+
XIIIa, XIIIb
XIVa, XIVb
N
H2N
XIIa, XIIb
N
H
O
N
F
F
N
N
H
F
F
O
F
F
F
F
XVI
O
N
F
NH
R2
XIVb
N
R3
F
N
Ph
XVa–XVc
XII–XIV, R1 = H (a), Ph (b); XV, R2R3N = 1-pyrrolidinyl (a), morpholino (b), 4-ethoxycarbonylpiperazin-1-yl (c).
The reaction of tetrafluorobenzoyl chloride (I) with
3-aminopyrazole (XIIa) in the presence of triethyl-
amine in methylene chloride at room temperature
(reaction time 24 h) afforded monoaroyl derivative
boiling dimethylformamide (reaction time 5 h) to
obtain derivatives XVa–XVc. In the mass spectra of
XVa–XVc, the molecular ion was the most abundant.
Replacement of the 8-F atom in pyrazoloquinazolinone
XIVb follows from the presence in the 1H NMR spec-
tra of XVa–XVc of a characteristic doublet of doublets
1
XIIIa. Unlike compound XVI, the H NMR spectrum
of XIIIa displayed only one tetrafluorobenzoyl proton
signal, and two NH protons gave a broadened singlet at
about δ 5.6 ppm. By acylation of 3-amino-5-phenyl-
pyrazole (XIIb) with tetrafluorobenzoyl chloride (I) in
boiling toluene (3 h) we obtained amide XIIIb. In the
1H NMR spectrum of XIIIb, broadened signals from
the NH protons appeared in a much weaker field
(δ 11.0–13.0 ppm), as compared to the corresponding
signals of XIIIa.
5
from the 6-H proton (3J = 12.1–12.6, J = 1.5–1.7 Hz)
and signals from protons in the corresponding amine
fragment (Table 3).
Acylation of 3-amino-1,2,4-triazoles XVIIa and
XVIIb with tetrafluorobenzoyl chloride (I) in boiling
toluene (2 h) gave amides XVIIIa and XVIIIb
(Scheme 4) whose structure was confirmed by the
1H NMR spectra. Intramolecular cyclization of aroyl
derivatives XVIIIa and XVIIIb to 7,8,9-trifluoro-4H-
[1,2,4]triazolo[1,5-a]quinazolin-5-ones XIXa and
XIXb was effected by heating for 5 h in boiling aceto-
nitrile in the presence of DBU. The yield of the cyclic
product from trifluoromethyl-substituted derivative
XVIIIb was considerably greater (76%) than from
compound XVIIIa (32%). Triazoloquinazolinones
Heating of amides XIIIa and XIIIb in acetonitrile
in the presence of DBU (3 h, 80°C) led to formation of
pyrazoloquinazolinones XIVa and XIVb, respectively.
1
The H NMR spectra of compounds XIVa and XIVb
contained a double doublet of doublets from the 6-H
proton, and signals from three fluorine atoms were
present in their 19F NMR spectra (Table 3). Compound
XIVb was brought into reactions with pyrrolidine,
morpholine, and ethyl piperazine-1-carboxylate in
1
XIXa and XIXb showed in the H NMR spectra
a signal from the 6-H proton (d.d.d) and a broadened
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LIPUNOVA et al.
1076
Scheme 4.
R1
N
R1
O
N
O
N
F
F
F
F
I
+
5
N
6
9
N
4NH
3a
N
7
8
5a
9a
H2N
H
H
N
H
F
N
3 N
1
N
2
F
F
R1
XVIIa, XVIIb
XVIIIa, XVIIIb
XIXa, XIXb
O
N
F
NH
R2
N
N
R3
F
N
R1
XXa, XXb
XVII–XIX, R1 = H (a), CF3 (b); XX, R2R3N = 1-pyrrolidinyl (a), morpholino (b).
one-proton singlet from the NH group; the molecular
ion peak in the mass spectra of XIXa and XIXb had
the maximal intensity (Table 4). Signals from three
fluorine atoms were present in the 19F NMR spectra of
XIXa and XIXb (d.d.d); in the 19F NMR spectrum of
XIXb, a singlet from the trifluoromethyl group was
also observed at δF 97.8 ppm.
XXI. To distinguish between these alternative struc-
tures, we analyzed the 13C NMR spectra of XIXa and
XIXb (see Experimental). The chemical shifts of C3a
and C5–C9a in these compounds have similar values,
and the corresponding signals have similar multiplic-
ities. A difference was observed in the multiplicities
of the C2 signal: it was a quartet of doublets in the
spectrum of XIXb (J = 40.5, 3.5 Hz) and a doublet (J =
4.0 Hz) in the spectrum of XIXa. The coupling con-
stant equal to 3.5–4.0 Hz may be assigned to inter-
It should be noted that the above spectral data are
equally consitent with structure XIX and alternative
4H-[1,2,4]triazolo[4,3-a]quinazolin-5-one structure
Table 4. 1H and 19F NMR and mass spectra of compounds XIXa, XIXb, XXa, and XXb
1H NMR spectrum (DMSO-d6), δ, ppm (J, Hz)
Comp.
no.
19F NMR spectrum (DMSO-d6),
δ, ppm (J, Hz)
Mass spectrum, m/z
(Irel, %)
6-H
NH
R1
NR2R3
8.06 d.d.d 13.4 br.s 8.22 s
(3J = 10.0,
–
13.28 d.d.d (1F, 3-F, 3JFF = 22.5, 20.1, 240 (100) [M]+, 212
XIXa
XIXb
4J
= 7.7), 19.90 d.d.d (1F, 9-F, (9), 188 (9), 157
FH
4
5
4J = 7.7,
3JFF = 20.1, JFF = 4.6, JFH = 2.3), (17), 130 (14)
5J = 2.3)
26.22 d.d.d (1F, 7-F, JFF = 22.5,
3
3J FH = 10.0, 4JFF = 4.6)
8.15 d.d.d 13.8 br.s
(3J = 9.9,
–
–
14.06 d.d.d (1F, 8-F, 3JFF = 22.8, 20.2, 308 (100) [M]+, 280
4JFH = 7.7), 19.96 d.d.d (1F, 9-F, (11), 183 (10), 158
4J = 7.7,
3JFF = 20.2, JFF = 5.4, JFH = 2.2), (14), 144 (13), 130
4
5
5J = 2.2)
28.23 d.d.d (1F, 7-F, 3JFF = 22.8, 3JFH
9.9, 4JFF = 5.4), 97.79 s (3F, CF3)
=
(16), 69 (12), 53
(18)
7.61 d.d 13.3 br.s
(3J = 13.9,
–
–
1.91 m [4H, (CH2)2],
3.72 m [4H, N(CH2)2]
359 (89) [M]+, 358
(100), 317 (11), 316
(27), 303 (51), 179
(10)
XXa
XXb
5J = 1.5)
7.74 d.d 13.5 br.s
(3J = 12.4,
3.37 m [4H, N(CH2)2],
3.74 m [4H, O(CH2)2]
5J = 1.6)
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FLUORINE-CONTAINING HETEROCYCLES: XII.
1077
action between the C2 and 9-F nuclei. Such carbon–
fluorine couplings between atoms located in different
rings have been reported [16].
(1.2 mmol) of compound III in 5 ml of dimethyl-
formamide was heated for 5 h under reflux. The mix-
ture was cooled and diluted with 15 ml of water, and
the colorless precipitate was filtered off and recrystal-
lized from acetonitrile. Yield 0.35 g (81%), mp 242–
244°C. Found, %: C 65.47; H 3.18; N 11.35.
C20H12F3N3O. Calculated, %: C 65.39; H 3.29; N 11.44.
O
F
NH
F
N
N
6,8-Difluoro-2-imino-1,3-diphenyl-7-(1-pyrroli-
dinyl)-2,3-dihydro-1H-quinazolin-4-one (Va). a. Pyr-
rolidine, 0.13 g (1.8 mmol), was added to a solution
of 0.17 g (0.44 mmol) of compound III in 3 ml of
dimethylformamide. The mixture was heated for 5 h
under reflux, cooled, and diluted with 10 ml of water.
The colorless precipitate was filtered off and recrys-
tallized from acetonitrile. Yield 0.15 g (83%), mp 213–
215°C. Found, %: C 69.02; H 4.91; N 13.27.
C24H20F2N4O. Calculated, %: C 68.89; H 4.82; N 13.39.
F
N
R
XXIa, XXIb
An additional support to structure XIX was obtain-
ed by studying intramolecular cyclization of 3-azolyl-
amino-2-polyfluorobenzoylacrylates [17]. Further-
more, the 19F NMR spectrum of cyclic compound
XXIb should reveal coupling between 9-F and the
trifluoromethyl group (an analogous interaction was
discussed in [18]). According to the data of [19–22],
the N2 rather than N4 atom of the 1,2,4-triazole ring is
preferentially involved in intramolecular cyclizations.
b. Pyrrolidine, 0.23 g (3.2 mmol), was added to
a solution of 0.3 g (0.8 mmol) of compound IV in 4 ml
of dimethylformamide. The mixture was heated for 5 h
under reflux, cooled, and diluted with 12 ml of water.
The colorless precipitate was filtered off and recrystal-
lized from acetonitrile. Yield 0.25 g (76%).
EXPERIMENTAL
1
The H NMR spectra were recorded on Bruker
Compounds Vb–Vd were synthesized in a similar
way (method a).
WM-250 and Bruker DRX-400 spectrometers at
250.14 and 400.13 MHz, respectively. The 19F NMR
spectra were obtained on a Bruker DRX-400 spectrom-
eter at 376.45 MHz. The chemical shifts were measur-
ed relative to tetramethylsilane (1H) and hexafluoro-
benzene (19F). The 13C NMR spectra were recorded on
a Bruker DRX-400 spectrometer at 100.61 MHz. The
mass spectra (electron impact, 70 eV) were run on
a Varian MAT 311A instrument (accelerating voltage
3 kV, cathode emission current 300 μA, direct sample
admission into the ion source).
6,8-Difluoro-2-imino-7-morpholino-1,3-diphen-
yl-2,3-dihydro-1H-quinazolin-4-one (Vb). Yield
78%, mp 259–261°C. Found, %: C 66.43; H 4.71;
N 12.79. C24H20F2N4O2. Calculated, %: C 66.35;
H 4.64; N 12.90.
7-(2,6-Dimethylmorpholino)-6,8-difluoro-2-
imino-1,3-diphenyl-2,3-dihydro-1H-quinazolin-4-
one (Vc). Yield 88%, mp 264–266°C. Found, %:
C 67.40; H 5.31; N 12.18. C26H24F2N4O2. Calculated,
%: C 67.52; H 5.23; N 12.11.
N,N'-Diphenyl-N-(2,3,4,5-tetrafluorobenzoyl)-
guanidine (III). Tetrafluorobenzoyl chloride (I), 0.74 g
(3.5 mmol), was added to a suspension of 0.5 g
(2.4 mmol) of N,N'-diphenylguanidine (II) in 10 ml of
anhydrous toluene. The mixture was heated for 3 h
under reflux and cooled, and the colorless precipitate
was filtered off and recrystallized from DMSO. Yield
6,8-Difluoro-2-imino-7-(4-methylpiperidino)-1,3-
diphenyl-2,3-dihydro-1H-quinazolin-4-one (Vd).
Yield 90%, mp 190–192°C. Found, %: C 70.05; H 5.30;
N 12.46. C26H24F2N4O. Calculated, %: C 69.94; H 5.42;
N 12.55.
N-(4,5-Dicyano-1H-imidazol-2-yl)-2,3,4,5-tetra-
fluorobenzamide (VII). Triethylamine, 0.6 g
(6 mmol), and tetrafluorobenzoyl chloride (I), 0.63 g
(3 mmol), were added to a suspension of 0.4 g
(3 mmol) of 2-aminoimidazole-4,5-dicarbonitrile (VI)
in 5 ml of dry methylene chloride. The mixture was
kept for 24 h at room temperature and evaporated, the
residue was washed with water, and the light brown
precipitate was recrystallized from ethanol. Yield 0.8 g
1
0.76 g (82%), mp 182–184°C. H NMR spectrum
(DMSO-d6), δ, ppm: 6.82 m (1H, C6HF4), 7.31 m
(4H), 7.41 m (3H), 7.55 m (2H), 7.93 m (1H), 10.8 br.s
(1H, NH), 12.1 br.s (1H, NH). Found, %: C 61.86;
H 3.49; N 10.98. C20H13F4N3O. Calculated, %:
C 62.02; H 3.38; N 10.85.
6,7,8-Trifluoro-2-imino-1,3-diphenyl-2,3-dihy-
dro-1H-quinazolin-4-one (IV). A solution of 0.45 g
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 7 2005

LIPUNOVA et al.
1078
(86%), mp 162–164°C. 1H NMR spectrum (DMSO-d6),
δ, ppm: 7.52 m (1H, C6HF4), 10.3 br.s and 12.6 br.s
(1H each, NH). Found, %: C 46.53; H 1.01; N 22.77.
C12H3F4N5O. Calculated, %: C 46.62; H 0.98; N 22.65.
8-Dimethylamino-7,9-difluoro-5-oxo-4,5-dihy-
droimidazo[1,2-a]quinazoline-1,2-dicarbonitrile
(XIc). A solution of 0.7 g (2.3 mmol) of amide VII in
6 ml of moist dimethylformamide was heated for 5 h
under reflux. The mixture was cooled and diluted with
15 ml of water, and the precipitate was filtered off and
recrystallized from acetonitrile. Yield 0.62 g (86%),
mp 244–246°C. Found, %: C 53.39; H 2.47; N 26.82.
C14H8F2N6O. Calculated, %: C 53.51; H 2.56; N 26.74.
1-Aza-8-azoniabicyclo[5.4]undec-7-ene 1,2-di-
cyano-7,8,9-trifluoro-4,5-dihydroimidazo[1,2-a]-
quinazolin-5-olate (VIII). 1,8-Diazabicyclo[5.4]un-
dec-7-ene, 0.26 g (2 mmol), was added to a solution of
0.5 g (1.6 mmol) of amide VII in 10 ml of anhydrous
acetonitrile. The mixture was heated for 3 h and evap-
orated, and the residue was treated with 15 ml of water
and 0.5 ml of acetic acid. The precipitate was filtered
off and recrystallized from ethanol. Yield 0.55 g
(77%), mp 236–238°C. Found, %: C 57.21; H 4.04;
N 22.15. C21H18F3N7O. Calculated, %: C 57.14;
H 4.11; N 22.22.
N-(1H-Pyrazol-5-yl)-2,3,4,5-tetrafluorobenz-
amide (XIIIa). Tetrafluorobenzoyl chloride (I), 1.3 g
(6 mmol), was added to a solution of 0.5 g (6 mmol)
of 3-aminopyrazole (XIIa) in 5 ml of dry methylene
chloride, and the mixture was kept for 24 h at room
temperature. The precipitate was filtered off, washed
with water, and recrystallized from ethanol. Yield 1.1 g
(71%), mp 145–147°C. 1H NMR spectrum (DMSO-d6),
3
7,8,9-Trifluoro-5-oxo-4,5-dihydroimidazo[1,2-a]-
quinazoline-1,2-dicarbonitrile (IX). Acetic acid,
3 ml, was added to 0.57 g (1.3 mmol) of salt VIII, the
solution was heated to the boiling point, 12 ml of water
was added, and the precipitate was filtered off and re-
crystallized from ethanol. Yield 0.33 g (87%), mp 248–
250°C. Found, %: C 49.92; H 0.74; N 24.16.
C12H2F3N5O. Calculated, %: C 49.84; H 0.70; N 24.22.
δ, ppm: 5.62 br.s (2H, NH), 6.08 d (1H, 4-H, J =
3
3.0 Hz), 7.65 m (1H, 6'-H), 8.09 d (1H, 5-H, J =
3.0 Hz). Found, %: C 46.42; H 2.01; N 16.16.
C10H5F4N3O. Calculated, %: C 46.33; H 1.93; N 16.22.
N-(5-Phenyl-2H-pyrazol-3-yl)-2,3,4,5-tetra-
fluorobenzamide (XIIIb). Tetrafluorobenzoyl chlo-
ride (I), 1.0 g (4.5 mmol), was added to a suspension
of 0.5 g (3.1 mmol) of 3-amino-5-phenylpyrazole
(XIIb) in 12 ml of anhydrous toluene. The mixture
was heated for 3 h under reflux and cooled, and the
precipitate was filtered off and recrystallized from
DMSO. Yield 0.84 g (84%), mp 223–225°C. 1H NMR
spectrum (DMSO-d6), δ, ppm: 6.59 s (1H, 4-H),
7.51 m (3H, Ph), 7.94 m (1H, 6'-H), 8.04 m (2H, Ph),
11.3 br.s (1H, NH), 12.8 br.s (1H, NH). Found, %:
C 55.85; H 2.90; N 12.89. C15H9F4N3O. Calculated, %:
C 55.74; H 2.81; N 13.00.
7,8,9-Trifluoro-4H-pyrazolo[1,5-a]quinazolin-5-
one (XIVa). 1,8-Diazabicyclo[5.4]undec-7-ene, 0.3 g
(2.5 mmol), was added to a solution of 0.55 g
(2.1 mmol) of amide XIIIa in 10 ml of anhydrous
acetonitrile, and the mixture was heated for 3 h at
80°C. The mixture was evaporated, the residue was
treated with 10 ml of water and 1 ml of acetic acid, and
the precipitate was filtered off and recrystallized from
ethanol. Yield 0.4 g (80%), mp 302–304°C. Found, %:
C 50.18; H 1.94; N 17.33. C10H4F3N3O. Calculated, %:
C 50.09; H 1.83; N 17.42.
1-Aza-8-azoniabicyclo[5.4]undec-7-ene 1,2-di-
cyano-7,9-trifluoro-8-(1-pyrrolidinyl)-4,5-dihydro-
imidazo[1,2-a]quinazolin-5-olate (X). Pyrrolidine,
0.17 g (2.4 mmol), was added to a solution of 0.25 g
(0.6 mmol) of compound VIII in 4 ml of dimethyl-
formamide. The mixture was heated for 5 h under
reflux and cooled, and the precipitate was filtered off
and recrystallized from DMSO. Yield 0.22 g (73%),
mp 272–274°C. Found, %: C 61.07; H 5.25; N 22.68.
C25H26F2N8O. Calculated, %: C 60.96; H 5.32; N 22.76.
7,9-Difluoro-5-oxo-8-(1-pyrrolidinyl)-4,5-dihy-
droimidazo[1,2-a]quinazoline-1,2-dicarbonitrile
(XIa). Pyrrolidine, 0.65 g (9.2 mmol), was added to
a solution of 0.7 g (2.3 mmol) of amide VII in 6 ml of
dimethylformamide. The mixture was heated for 5 h
under reflux, cooled, and diluted with 15 ml of water,
and the precipitate was filtered off and recrystallized
from acetonitrile. Yield 0.68 g (87%), mp 263–265°C.
Found, %: C 56.59; H 3.04; N 24.61. C16H10F2N6O.
Calculated, %: C 56.47; H 2.96; N 24.70.
7,8,9-Trifluoro-2-phenyl-4H-pyrazolo[1,5-a]-
quinazolin-5-one (XIVb) was synthesized in a similar
way. The product was recrystallized from DMSO.
Yield 82%, mp 284–286°C. Found, %: C 61.04;
H 2.68; N 13.21. C16H18F3N3O. Calculated, %: C 60.96;
H 2.56; N 13.33.
7,9-Difluoro-8-morpholino-5-oxo-4,5-dihydro-
imidazo[1,2-a]quinazoline-1,2-dicarbonitrile (XIb)
was synthesized in a similar way. Yield 85%, mp 218–
220°C. Found, %: C 54.02; H 2.89; N 23.48.
C16H10F2N6O2. Calculated, %: C 53.94; H 2.83; N 23.59.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 7 2005

FLUORINE-CONTAINING HETEROCYCLES: XII.
1079
thesized in a similar way. Yield 74%, mp 288–290°C.
1H NMR spectrum (DMSO-d6), δ, ppm: 7.90 m (1H,
C6HF4), 12.6 br.s (1H, NH), 13.8 br.s (1H, NH).
Found, %: C 36.47; H 1.00; N 16.99. C10H3F7N4O.
Calculated, %: C 36.59; H 0.91; N 17.08.
7,9-Difluoro-2-phenyl-8-(1-pyrrolidinyl)-4H-
pyrazolo[1,5-a]quinazolin-5-one (XVa). Pyrrolidine,
0.45 g (6.4 mmol), was added to a solution of 0.5 g
(1.6 mmol) of compound XIVb in 5 ml of dimethyl-
formamide. The mixture was heated for 5 h under
reflux and cooled, and the precipitate was filtered off
and recrystallized from DMSO. Yield 0.48 g (81%),
mp 310–312°C. Found, %: C 65.48; H 4.29; N 15.32.
C20H16F2N4O. Calculated, %: C 65.57; H 4.40; N 15.29.
7,8,9-Trifluoro-4H-[1,2,4]triazolo[1,5-a]quina-
zolin-5-one (XIXa). 1,8-Diazabicyclo[5.4]undec-7-
ene, 0.32 g (2.1 mmol), was added to a suspension of
0.6 g (2.1 mmol) of amide XVIIIa in 15 ml of an-
hydrous acetonitrile. The mixture was heated for 5 h
under reflux and evaporated, the residue was treated
with 15 ml of water and 1 ml of acetic acid, and the
colorless precipitate was filtered off. The product was
washed with hot ethanol, and the residue was recrystal-
lized from DMSO. Yield 0.16 g (32%), mp 280–
282°C. 13C NMR spectrum (CD3COOD), δ, ppm (JC,F,
Hz): 113.16 d.d (C6, J = 20.8, 3.9), 114.85 d.d (C5a, J =
7.5, 3.2), 124.46 d.d (C9a, J = 7.5, 3.0), 142.03 d.d.d
(C9, J = 262.5, 14.1, 2.6), 146.42 d.d (C8, J = 259.8,
13.6), 149.56 s (C3a), 150.31 d.d.d (C7, J = 251.9, 11.4,
1.0), 152.40 d (C2, J = 4.0), 159.62 m (C5). Found, %:
C 44.92; H 1.21; N 23.38. C9H3F3N4O. Calculated, %:
C 45.01; H 1.26; N 23.34. Evaporation of the ethanol
solution afforded unreacted amide XVIIIa.
Compounds XVb and XVc were synthesized in
a similar way.
7,9-Difluoro-8-morpholino-2-phenyl-4H-pyra-
zolo[1,5-a]quinazolin-5-one (XVb). Yield 77%,
mp 294–296°C. Found, %: C 62.87; H 4.28; N 14.60.
C20H16F2N4O2. Calculated, %: C 62.82; H 4.22;
N 14.65.
Ethyl 4-(7,9-difluoro-5-oxo-2-phenyl-4H-pyra-
zolo[1,5-a]quinazolin-8-yl)piperazine-1-carboxylate
(XVc). Yield 79%, mp 286–288°C. Found, %: C 61.00;
H 4.72; N 15.38. C23H21F2N5O3. Calculated, %:
C 60.92; H 4.67; N 15.44.
N-[1-(2,3,4,5-Tetrafluorobenzoyl)pyrazol-5-yl]-
2,3,4,5-tetrafluorobenzamide (XVI). Tetrafluoroben-
zoyl chloride (I), 6.3 g (30 mmol), was added to a so-
lution of 1.25 g (15 mmol) of 3-aminopyrazole (XIIa)
in 12 ml of anhydrous toluene. The mixture was heated
for 3 h under reflux and cooled, and the precipitate was
filtered off and recrystallized from ethanol. Yield 4.6 g
(71%), mp 103–105°C. 1H NMR spectrum (DMSO-d6),
7,8,9-Trifluoro-2-trifluoromethyl-4H-[1,2,4]tri-
azolo[1,5-a]quinazolin-5-one (XIXb) was synthe-
sized in a similar way. After treatment with an aqueous
solution of acetic acid, the whole precipitate was re-
crystallized from ethanol. Yield 76%, mp 215–217°C.
13C NMR spectrum (CD3COOD), δ, ppm (JC,F, Hz):
113.29 d.d (C6, J = 20.9, 4.1), 115.44 d.d (C5a, J = 7.6,
3.4), 119.96 q (CF3, J = 269.9), 124.09 d.d.d (C9a, J =
7.8, 3.0, 2.4), 142.26 d.d.d (C9, J = 264.0, 14.1, 2.9),
146.39 d.d.d (C8, J = 260.7, 16.7, 13.1), 150.61 s (C3a),
150.85 d.d.d (C7, J = 252.9, 10.8, 1.5), 154.51 q.d (C2,
J = 40.5, 3.5), 159.40 m (C5). Found, %: C 44.92;
H 0.79; N 23.38. C10H2F6N4O. Calculated, %: C 38.96;
H 0.65; N 18.18.
3
δ, ppm: 7.18 d (1H, 4-H, J = 3.0 Hz), 7.57 m (1H,
3
C6HF4), 7.78 m (1H, C6HF4), 8.48 d (1H, 3-H, J =
3.0 Hz), 11.52 br.s (1H, NH). Mass spectrum, m/z
(Irel, %): 435 [M]+ (13), 239 (12), 177 (100), 149 (25).
Found, %: C 46.92; H 1.18; N 9.59. C17H5F8N3O2.
Calculated, %: C 46.87; H 1.15; N 9.65.
N-(1H-1,2,4-Triazol-5-yl)-2,3,4,5-tetrafluoro-
benzamide (XVIIIa). Tetrafluorobenzoyl chloride (I),
5.2 g (24 mmol), was added to a suspension of 1.6 g
(19 mmol) of 5-amino-1,2,4-triazole XVIIa in 20 ml
of anhydrous toluene. The mixture was heated for 2 h
under reflux and cooled, and the colorless precipitate
was filtered off and recrystallized from chloroform.
7,9-Difluoro-8-(1-pyrrolidinyl)-2-trifluoro-
methyl-4H-[1,2,4]triazolo[1,5-a]quinazolin-5-one
(XXa). Pyrrolidine, 0.45 g (0.4 mmol), was added to
a solution of 0.5 g (1.6 mmol) of compound XIXb in
5 ml of dimethylformamide. The mixture was heated
for 5 h under reflux, cooled, and diluted with 15 ml of
water. The precipitate was filtered off and recrystalliz-
ed from DMSO. Yield 0.46 g (81%), mp 276–278°C.
Found, %: C 17.57; H 2.90; N 15.77. C14H10F5N4O.
Calculated, %: C 17.46; H 2.82; N 15.82.
1
Yield 3.8 g (78%), mp 245–247°C. H NMR spectrum
(DMSO-d6), δ, ppm: 7.78 s (1H, 5-H), 8.07 m (1H,
C6HF4), 11.7 br.s (1H, NH), 13.6 br.s (1H, NH).
Found, %: C 41.61; H 1.60; N 21.47. C9H4F4N4O.
Calculated, %: C 41.55; H 1.55; N 21.54.
N-(3-Trifluoromethyl-1H-1,2,4-triazol-5-yl)-
2,3,4,5-tetrafluorobenzamide (XVIIIb) was syn-
7,9-Difluoro-8-morpholino-2-trifluoromethyl-
4H-[1,2,4]triazolo[1,5-a]quinazolin-5-one (XXb)
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 7 2005

LIPUNOVA et al.
1080
10. Nosova, E.V., Lipunova, G.N., Kodess, M.I., Vasil’e-
va, P.V., and Charushin, V.N., Izv. Ross. Akad. Nauk,
Ser. Khim., 2004, p. 2216.
11. Popov, I.I., Boroshko, S.L., Tertov, B.A., and Tyukavi-
na, E.V., Khim. Geterotsikl. Soedin., 1989, p. 272.
12. Abdelhadi, H.A., Abdallah, T.A., and Hassaneen, H.M.,
Heterocycles, 1995, vol. 41, p. 1999.
13. Shaaban, M.A.R. and Al-Ashamawi, M.I., Egypt J.
Pharm. Sci., 1991, vol. 32, p. 295.
14. Ram, V.J. and Verma, M., Indian J. Chem., Sect. B,
1992, vol. 31, p. 195.
was synthesized in a similar way. Yield 79%, mp 292–
294°C. Found, %: C 44.74; H 2.75; N 18.68.
C14H10F5N5O2. Calculated, %: C 44.80; H 2.67;
N 18.75.
This study was performed under financial support
by the Russian Foundation for Basic Research (project
nos. 03-03-32254 and 04-03-96107-Ural), by the
Ministry of Education of the Russian Federation,
CRDF, Annex BF4M05, EK-005-X2[REC-005], and
“BRHE 2004 Post-Doctoral Fellowship Award” (grant
no. Y2-C-05-01).
15. Badawy, M.A., Abdel-Hady, S.A., Mahmoud, A.H., and
Ibrahim, Y.A., Justus Liebigs Ann. Chem., 1990, p. 815.
16. Charushin, V.N., Mokrushina, G.A., and Tkachev, A.V.,
REFERENCES
J. Fluorine Chem., 2000, vol. 107, p. 71.
1. Kotovskaya, S.K., Romanova, S.A., Charushin, V.N., and
17. Lipunova, G.N., Nosova, E.V., Kodess, M.I., Charu-
shin, V.N., Rozin, Yu.A., and Chasovskikh, O.M., Russ.
J. Org. Chem., 2001, vol. 37, p. 570.
18. Aizikovich, A.Ya., Nikonov, M.N., Kodess, M.I., Koro-
taev, V.Yu., and Charushin, V.N., Tetrahedron, 2000,
vol. 56, p. 1923.
19. Filyakova, V.I., Kuznetzova, O.A., Pashkevich, K.I.,
Rusinov, G.L., and Plechanov, P.V., Abstracts of Papers,
Int. Memorial I. Postovsky Conf. on Organic Chemistry,
1998, p. 60.
20. Desenko, S.M., Orlov, V.D., Shishkin, O.V., Bary-
kin, K.E., Lindeman, S.V., and Struchkov, Yu.T., Khim.
Geterotsikl. Soedin., 1993, p. 1357.
Kodess, M.I., Russ. J. Org. Chem., 2004, vol. 40, p. 1167.
2. Ram, V.J., Goel, A., and Verma, M., Bioorg. Med. Chem.
Lett., 1994, vol. 4, p. 2087.
3. Omar, A.M., El-Din, S.A., and Labouta, I.M., Alexandria
J. Pharm. Sci., 1991, vol. 5, p. 94.
4. Deetz, M.J., Malerich, J.P., Beatty, A.M., and Smith, B.D.,
Tetrahedron Lett., 2001, vol. 42, p. 1851.
5. El-Tombary, A.A., Ismail, K.A., Aboulwafa, O.M.,
Omar, A.M., El-Azzouni, M.Z., and El-Nansoury, S.T.,
Farmaco, 1999, vol. 54, p. 486.
6. Liu, K.C. and Hsu, W.C., Zhonghua Yooxue Zazhi, 1993,
vol. 45, p. 53.
7. Ram, V.J., Srimal, R.C., Kushwaha, D.S., and Mishra, L.,
J. Prakt. Chem., 1990, vol. 332, p. 629.
8. Int. Patent Appl. no. 0066584, 2000; Chem. Abstr., 2000,
vol. 133, no. 356240u.
9. Nosova, E.V., Lipunova, G.N., and Charushin, V.N., Izv.
Ross. Akad. Nauk, Ser. Khim., 2004, p. 1091.
21. Kofman, T.P., Uvarova, T.A., Kartseva, G.Yu., and
Uspenskaya, T.L., Russ. J. Org. Chem., 1997, vol. 33,
p. 1784.
22. Vartayan, M.M., Solov’eva, T.Yu., Eliseev, O.L., and
Panina, M.E., Izv. Ross. Akad. Nauk, Ser. Khim., 1993,
p. 1322.
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