Reactions of α-perfluorophenylpyrylium perchlorates with hydrazine hydrate

Article abstract of DOI:10.1007/s11172-010-0256-3

Reactions of α-perfluorophenylpyrylium salts with hydrazine hydrate in ethanol afforded derivatives of 1,2-diazepine, dihydro-1H-pyrazole, and/or 1-aminopyridinium salts, depending on the steric characteristics of the substituent in the second α-position. 1-Amino-2-methyl-6-perfluorophenyl- 4-phenylpyridinium perchlorate was used to obtain various pyridocyanines.

Full text of DOI:10.1007/s11172-010-0256-3

Russian Chemical Bulletin, International Edition, Vol. 59, No. 7, pp. 1414—1418, July, 2010
1414
Reactions of αꢀperfluorophenylpyrylium perchlorates with hydrazine hydrate
I. Yu. Kargapolova, K. S. Shmuilovich, I. V. Beregovaya, and N. A. Orlova
N. N. Vorozhtsov Institute of Organic Chemistry,
Siberian Branch of the Russian Academy of Sciences,
9 prosp. Akad. Lavrent´eva, 630090 Novosibirsk, Russian Federation.
Fax: +7 (383) 330 9752. Eꢀmail: ona@nioch.nsc.ru
Reactions of αꢀperfluorophenylpyrylium salts with hydrazine hydrate in ethanol afforded
derivatives of 1,2ꢀdiazepine, dihydroꢀ1Hꢀpyrazole, and/or 1ꢀaminopyridinium salts, dependꢀ
ing on the steric characteristics of the substituent in the second αꢀposition. 1ꢀAminoꢀ2ꢀmethylꢀ
6ꢀperfluorophenylꢀ4ꢀphenylpyridinium perchlorate was used to obtain various pyridocyanines.
Key words: αꢀperfluorophenylpyrylium salts, perfluorophenylꢀ1,2ꢀdiazepines, polyfluoriꢀ
nated dihydroꢀ1Hꢀpyrazoles, 1ꢀaminoꢀ2ꢀmethylꢀ6ꢀperfluorophenylpyridinium perchlorate, fluꢀ
orineꢀcontaining pyridocyanines.
Reactions of highly reactive pyrylium salts with variꢀ
ous nitrogenꢀcontaining nucleophiles and binucleophiles
are widely employed in the synthesis of not easily accessiꢀ
ble aromatic and heterocyclic compounds.1,2 The use of
polyfluorinated pyrylium salts3,4 in these reactions can
afford earlier unknown polyfluorinated nitrogenꢀcontainꢀ
ing heterocycles and novel fluorophores. In the last few
years, great interest has been shown in fluorescent labels
for biological structures, the labels being produced by reꢀ
actions of the pyrylium ring with aminoꢀcontaining fragꢀ
ments of biomolecules.5
1
R1
R2
a
Ph
H
b
C6F5
H
d
Me
H
c
R1 + R2
(CH2)4
salt 1a yields, like a nonfluorinated analog,6 3ꢀperfluoroꢀ
phenylꢀ5,7ꢀdiphenylꢀ4Hꢀ1,2ꢀdiazepine (2a) (Scheme 1).
It is known that the pathway of reactions of pyrylium
salts with hydrazines depends on the structure of the startꢀ
ing salt and the reaction conditions.6—9 For instance,
a reaction of 2,4,6ꢀtriphenylpyrylium perchlorate with hyꢀ
drazine hydrate in ethanol gives a sevenꢀmembered cyclic
product, viz., 3,5,7ꢀtriphenylꢀ6Hꢀ1,2ꢀdiazepine.6 Supꢀ
posedly, the reaction passes through intermediate acyclic
5ꢀhydrazonoꢀ1,3,5ꢀtriphenylpentꢀ2ꢀenꢀ1ꢀone. Depending
on the ratio of the reagents, alkylpyrylium salts form unꢀ
der these conditions pyrazole derivatives and/or Nꢀaminoꢀ
pyridinium salts.8
Scheme 1
Results and Discussion
Reagents and conditions: NH2NH2•H2O, EtOH, 20 °C.
Earlier, reactions of αꢀperfluorophenylpyrylium salts
with ammonia,10 ammonium salts,3 methylamine,10 and
hydroxylamine11 have been investigated. In the present
work, we studied roomꢀtemperature reactions of four pyryꢀ
lium perchlorates of the general formula 1, which contain
one or two αꢀperfluorophenyl groups, with a twofold exꢀ
cess of hydrazine hydrate in ethanol.
The structure of compound 2a was determined from its
1H and 19F NMR spectra and elemental analysis data.
1
The H NMR spectrum of diazepine 2a shows multiplets
for two phenyl rings, the AB system of the methylene
protons in position 6 (broadened doublets at δ 2.90 and
3.93 with the geminal coupling constant J = 12 Hz), and
a singlet for the H(4) proton (δ 6.72), which is broadꢀ
ened because of its coupling with the C6F5 fragment.
The 19F NMR spectrum contains three signals with
We found that the reaction products largely depend on
the structure of the starting salt. For instance, pyrylium
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1383—1387, July, 2010.
1066ꢀ5285/10/5907ꢀ1414 © 2010 Springer Science+Business Media, Inc.

Reactions of fluorinated pyrylium salts
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 7, July, 2010
1415
Scheme 3
an intensity ratio of 2 : 1 : 2 for the perfluorophenyl
substituent.
Under the same conditions, compound 1b with two
αꢀC6F5 fragments mainly yields 1ꢀperfluorophenylꢀ2ꢀ(3ꢀ
perfluorophenylꢀ5ꢀphenylꢀ4,5ꢀdihydroꢀ1Hꢀpyrazolꢀ5ꢀyl)ꢀ
ethanone (3b) (Scheme 2).
Scheme 2
Reagents and conditions: NH2NH2•H2O, EtOH, 20 °C.
fragment favors the retention of the planar structure of the
intermediate hydrazone.11
Unlike compound 1c, methylpyrylium salt 1d yields
under these conditions a mixture of two isomeric diꢀ
azepines 2d´ and 2d″, which differ in the position of the
double bond, 1ꢀaminoꢀ2ꢀmethylꢀ6ꢀperfluorophenylꢀ4ꢀ
phenylpyridinium perchlorate (5d), and 6,7,8,9ꢀtetrafluoroꢀ
2ꢀmethylꢀ3aꢀphenylꢀ3a,4ꢀdihydropyrazolo[1,5ꢀa]quinꢀ
olinꢀ5(3H)ꢀone (6d) (1H and 19F NMR data). The formaꢀ
tion of the last compound can be attributed to intramolecꢀ
ular nucleophilic displacement of the oꢀF atom in the
perfluorophenyl ring of intermediate pyrazoline 3d by the
amino group of the pyrazoline ring (Scheme 4).
3b, 56%
Reagents and conditions: NH2NH2•H2O, EtOH, 20 °C.
The IR spectrum of pyrazoline 3b contains bands
at 3303 (N—H stretches), 1693 (C=O stretches), and
1488 cm–1 (C6F5 stretches). The 19F NMR spectrum exꢀ
hibits signals for the F atoms of two nonequivalent C6F5
1
fragments. The H NMR spectrum shows a multiplet for
the phenyl ring and two AB systems of the methylꢀ
ene protons in the pyrazoline ring (δ 3.50 and 3.71,
J = 16.5 Hz) and in the phenacyl fragment (δ 3.32 and
3.34, J = 16 Hz) (cf. Ref. 12). It should be noted that the
signal for the NH proton is absent from the 1H NMR
spectrum in CDCl3, probably, because of exchange proꢀ
cesses with water impurities.
The formation of pyrazolines in reactions of triarylpyryꢀ
lium salts with hydrazine hydrate has not previously been
observed. It is very likely that the unexpected formation of
pyrazoline 3b in the reaction of pyrylium perchlorate 1b
with hydrazine hydrate is due to the mutual steric influꢀ
ences of two pentafluorophenyl substituents. As a result,
the hydrazone fragment in the presumed intermediate
5ꢀhydrazonoꢀ1,5ꢀbis(perfluorophenyl)ꢀ3ꢀphenylpentꢀ2ꢀ
enꢀ1ꢀone (4b) becomes nonꢀcoplanar with the rest of the
molecule, which precludes closure of a sevenꢀmembered
ring. Earlier,11 we have observed a similar effect of two
C6F5 substituents in a reaction of salt 1b with hydrꢀ
oxylamine.
The formation of two isomers of diazepine (2d) was
confirmed by their calculated total energies (PBE/3z):
isomer 2d´ (–1300.20433 au) is more stable than isomer
2d″ (–1300.20341 au) only by 0.6 kcal mol–1
.
We isolated in the individual state only 3ꢀmethylꢀ7ꢀ
perfluorophenylꢀ5ꢀphenylꢀ4Hꢀ1,2ꢀdiazepine (2d´). Strucꢀ
ture 2d″ was identified from the 1H and 19F NMR spectra
of the reaction mixture. The 1H NMR spectra of both
isomers are similar; they exhibit singlets for the methyl
groups, multiplets for the aromatic protons, broadened
doublets of the AB systems for the methylene groups, and
singlets for the methine protons. The signal for the H(6)
atom of diazepine 2d´ is noticeably broader than the corꢀ
responding signal for diazepine 2d″ because of a coupling
with the perfluorophenyl substituent.
The IR spectrum of 6,7,8,9ꢀtetrafluoroꢀ2ꢀmethylꢀ3aꢀ
phenylꢀ3a,4ꢀdihydropyrazolo[1,5ꢀa]quinolinꢀ5(3H)ꢀone
(6d) contains intense bands at 1703 (C=O), 1642 (C=N),
and 1495 cm–1 (C—Farom). The 19F NMR spectrum shows
four signals of equal intensity for the F atoms of the annuꢀ
1
lated ring. The H NMR spectrum exhibits two AB sysꢀ
tems of the protons of two CH2 groups in the heterocycles,
a singlet for the methyl group, and signals for the aromatic
protons of the phenyl ring. The IR spectrum of pyridinium
salt 5d contains intense bands due to the vibrations of the
perchlorate anion, the amino group, and the C—F and
C=N bonds.
Pyrylium perchlorate 1c reacts with hydrazine hydrate
to give 3ꢀperfluorophenylꢀ5ꢀphenylꢀ6,7,8,9ꢀtetrahydroꢀ
4Hꢀbenzo[c][1,2]diazepine (2c) (Scheme 3).
Apparently, the predominant formation of diazepine
2c is also due to the steric factor: the rigidly fixed alicyclic
1ꢀAminopyridinium perchlorate 5d with an active
αꢀmethyl group was used in the synthesis of asymmetric
pyridocyanines from 4ꢀdimethylaminobenzaldehyde. The
reaction in a mixture of acetic acid and acetic anhydride
gives Schiff base 7; the αꢀmethyl group is inert under these

1416
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 7, July, 2010
Kargapolova et al.
Scheme 4
Reagents and conditions: NH2NH2•H2O, EtOH, 20 °C.
conditions. Pyridocyanine 8 was obtained in low yield by
heating salt 5d and 4ꢀdimethylaminobenzaldehyde in
AcOH—Ac2O in the presence of anhydrous sodium aceꢀ
tate (Scheme 5).
of the pyrylium ring. The pyrylium salt containing two
αꢀperfluorophenyl substituents yields a pyrazoline derivaꢀ
tive, in contrast to a nonfluorinated analog. 1ꢀAminoꢀ2ꢀ
methylꢀ6ꢀperfluorophenylꢀ4ꢀphenylpyridinium perꢀ
chlorate (5d) was employed in the synthesis of pyridoꢀ
cyanine dyes.
Scheme 5
Experimental
NMR spectra were recorded on Bruker ACꢀ200 instruments
(200.13 (1H) and 188.2 MHz (19F)) in CDCl3 and CD3CN. The
signals for the residual protons in CDCl3 (δ 7.24) and CD3CN
(δ 1.96) were used as the internal standards. IR spectra were
recorded on a Vector 22 instrument; electronic absorption specꢀ
tra were recorded on a HewlettꢀPackard 8453 spectrophotomeꢀ
ter. Highꢀresolution mass spectra were measured on a Finnigan
Mat 8200 instrument (ion source temperature 314 °C, ionizing
energy 70 eV, direct inlet probe).
Calculations with full optimization of the geometries of isoꢀ
meric diazepines 2d´ and 2d″ were performed at the PBE/3z
level with the Priroda program.13
Reactions of pyrylium perchlorates 1a—d with hydrazine
hydrate (general procedure). A conical flask was charged with
a solution of hydrazine hydrate (0.12 g, 2.0 mmol) in ethanol
(5 mL). Then pyrylium salt 1a—d (0.9 mmol) was added with
stirring. The reaction mixture was stirred with a magnetic stirꢀ
ring bar for 30 min and cooled in a freezer. The precipitate that
formed was filtered off and dried in air. The mother liquor was
poured onto crushed ice. The resulting precipitate was filtered
off or subjected to extraction with CH2Cl2, washed with water,
and dried over CaCl2. The solvent was removed on a rotary
evaporator in vacuo. The products were analyzed by 1H and
19F NMR spectroscopy and purified by recrystallization of the
precipitates. The yields, melting points, and elemental analysis
data of the reaction products are given in Table 1. Their IR and
NMR spectra are given in Table 2.
Reagents and conditions: i. Me2NC6H4CHO, Ac2O/AcOH,
100 °C; ii. Me2NC6H4CHO, Ac2O/AcOH, AcONa, 120 °C.
To sum up, αꢀperfluorophenylpyrylium salts easily reꢀ
act with hydrazine hydrate in ethanol to give a number of
earlier unknown polyfluorinated nitrogenꢀcontaining hetꢀ
erocyclic compounds: diazepines, pyrazolines, and pyriꢀ
dinium salts; the reaction pathway depends on the steric
characteristics of the substituent in the second αꢀposition
1ꢀ[4ꢀ(Dimethylamino)benzylideneamino]ꢀ2ꢀmethylꢀ6ꢀperꢀ
fluorophenylꢀ4ꢀphenylpyridinium perchlorate (7). 4ꢀDimethylꢀ

Reactions of fluorinated pyrylium salts
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 7, July, 2010
1417
Table 1. Reactions of pyrylium salts 1a—d with hydrazine hydrate. Yields, melting points, elemental analysis data, and mass
spectra of the products
Pyrylium Reaction
salt
Yield
(%)
M.p./°C
Found
Calculated
Molecular
formula
MSc
(%)
producta
(solvent)b
C
H
F
N
1а
1b
1c
1d
2а
3b
2c
70
56
68
21
11
6
180—182
(ethanol)
104—106
(heptane)
171—174
(heptane)
127—128
(hexane)
249—250
(ethanol)
119—122
(hexane)
67.02
66.99
53.06
53.09
64.50
64.61
61.20
61.71
47.47
47.96
0—
3.31
3.18
2.07
1.94
3.95
3.81
3.26
3.17
2.96
2.68
0—
22.48
6.72
6.79
5.25
5.38
7.17
7.18
8.08
8.00
3.92
3.99
0—
C23H13F5N2
412.10039
412.09988
521.04740
521.04730
390.11531
390.11553
350.08503
350.08423
—
23.04
36.39
36.51
24.48
24.34
27.16
27.12
27.40
27.04
0—
C23H10F10N2О
С21Н15F5N2
2d´
5d
6d
С18Н11F5N2
С18Н12ClF5N2O4
С18Н12F4N2O
348.08890
348.08800
a Salt 5d was isolated by washing the precipitate formed with ether. Compounds 2d´ and 6d were isolated by column chromaꢀ
tography of the ethereal fraction on Al2O3 with benzene as an eluent.
b The solvent for recrystallization.
c Found/calculated, m/z, [M]+/M.
Table 2. IR and 1H and 19F NMR spectra of compounds 2a,c,d´,d´´, 3b, 5d, and 6d
Comꢀ
pound
IR, ν/cm–1
(solvent)
1H NMR
δ (J/Hz)
19F NMR
Solvent
CDCl3
Solvent
CDCl3
δ*
2a
2c
1652 (C=N),
1523 (C6F5)
(CHCl3)
2.90, 3.93 (AB system, 2 Н, С(4)Н2,
J = 12.0); 6.72 (s, 1 Н, Н(6));
7.10—8.10 (m, 10 Н, 2 Ph)
0.92, 10.20, 21.64
(2 : 1 : 2)
1651 (C=N), 1496,
1522 (C6F5)
CDCl3
1.58 (1 Н), 1.82—1.90 (2 Н), 2.06 (1 Н),
2.24 (1 Н), 2.54—2.66 (2 Н) and 2.80
(1 Н) (all m, 4 (СН2)); 2.90, 3.33
(AB system, 2 Н, С(4)Н2,
CDCl3
0.54, 9.45, 21.07
(2 : 1 : 2)
J1 = 12.0, J2 = 3.0); 7.11—7.32 (5 Н, Ph)
2d´
2d″
3b
1654 (C=N), 1507,
1519 (C6F5)
(CHCl3)
CD3CN
CD3CN
CDCl3
2.07 (s, 3 Н, Mе); 2.31, 3.89 (AB system,
2 Н, С(4)H2, J = 14.0); 6.49 (s, 1 Н,
Н(6)); 7.45—7.65 (m, 5 H, Ph)
CD3CN
CD3CN
CDCl3
1.50, 12.97, 21.31
(2 : 1 : 2)
2.32 (s, 3 Н, Mе); 2.81 and 3.81 (AB system,
2 Н, С(4)H2, J = 13.0); 6.45 (s, 1 Н,
Н(6)); 7.34—7.47 (m, 5 H, Ph)
0.97, 9.35, 21.85
(2 : 1 : 2)
3303 (N—H),
1693 (C=O),
1488 (C6F5)
(CHCl3)
3.32, 3.34 (AB system, 2 Н,
0.00, 2.15, 7.98,
13.93, 21.32, 22.10
(2 : 2 : 1 : 1 : 2 : 2)
C6F5COCH2, J = 16.0); 3.50, 3.71
(AB system, 2 Н, С(4)Н2, J = 16.5);
7.26—7.42 (m, 5 Н, Ph)
5d
6d
3347 (NH2),
1629 (C=N),
1507, 1526 (C6F5),
1104 (ClO4–) (KBr)
CD3CN
CD3CN
2.89 (s, 3 Н, С(2)Mе); 6.18 (s, 2 Н, NH2);
7.64—7.91 (m, 5 H, Ph); 8.22 (d, 1 Н,
H(3), J = 2.0); 8.33 (d, 1 Н, Н(5), J = 2.0)
CD3CN
CD3CN
0.00, 9.42, 24.32
(2 : 1 : 2)
1703 (C=O),
1642 (C=N),
1495 (C6F5) (CHCl3)
2.06 (s, 3 Н, Mе); 3.06, 3.24 (AB system,
2 Н, СH2, J = 18.0); 3.15, 3.39
(AB system, 2 Н, СН2, J = 15.0);
7.28—7.42 (m, 5 Н, Ph)
–5.77, 14.05,
15.15, 19.74
(1 : 1 : 1 : 1)
* The intensity ratios are given in parentheses.

1418
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 7, July, 2010
Kargapolova et al.
aminobenzaldehyde (0.09 g, 0.6 mmol) was added to a suspenꢀ
sion of 1ꢀaminopyridinium perchlorate 5d (0.09 g, 0.2 mmol) in
AcOH—Ac2O (1 : 1 v/v, 0.5 mL). The reaction mixture was heatꢀ
ed at 110—120 °C (bath temperature) for 3 h, cooled to room
temperature, and triturated with ether (10 mL). The resulting
precipitate of a bright yellow dye was filtered off and purified by
column chromatography on Al2O3 with CHCl3—MeCN (10 : 1)
as an eluent. Yield 0.05 g (43%), m.p. 117—120 °C. UVꢀVIS
(CH2Cl2), λmax/nm (logε): 387 (5.15), 415tr (4.87). 1H NMR
(CDCl3), δ: 2.85 (s, 3 H, C(2)Me); 3.09 (s, 6 H, NMe2); 6.65
and 7.67 (2 H each, AB system, 4 Harom, J = 9 Hz); 7.47—7.86
(m, 5 H, Ph); 7.98 (d, 1 H, H(3), J = 1 Hz); 8.22 (d, 1 H, H(5),
J = 1 Hz); 8.65 (s, CH=N). 19F NMR (CD3CN), δ: 2.78, 14.70,
26.75; intensity ratio 2 : 1 : 2. Found (%): C, 55.50; H, 3.91;
Cl, 6.06; F, 16.31; N, 7.01. C27H21ClF5N3O4. Calculated (%):
C, 55.73; H, 3.64; Cl, 6.09; F, 16.32; N, 7.22.
1ꢀ[4ꢀ(Dimethylamino)benzylideneamino]ꢀ2ꢀ[4ꢀ(dimethylꢀ
amino)styryl]ꢀ6ꢀperfluorophenylꢀ4ꢀphenylpyridinium perchlorate
(8). A mixture of 1ꢀaminopyridinium perchlorate 5d (0.10 g,
0.23 mmol), 4ꢀdimethylaminobenzaldehyde (0.10 g, 0.69 mmol),
and freshly calcined MeCOONa (0.10 g, 1.28 mmol) in
AcOH—Ac2O (1 : 1 v/v, 1 mL) was heated at 110—120 °C (bath
temperature) for 1.5 h. The reaction mixture was cooled, washed
with water to remove the excess of MeCOONa and then with
ether, and dissolved in acetonitrile. The product was precipitatꢀ
ed with ether. The yield of dye 8 was 0.028 g (17%), dark green
crystals (m.p. 208—210 °C) producing a dark pink solution in
CHCl3. UVꢀVIS (CH2Cl2), λmax/nm (logε): 548 (4.37). 1H NMR
(CD3CN), δ: 2.92 (s, 6 H, NMe2); 3.03 (s, 6 H, NMe2);
lium Salts: Syntheses, Reactions, and Physical Properties, in
Adv. Heterocycl. Chem., Ed. A. R. Katrizky, Suppl. 2, Acaꢀ
demic Press, New York, 1982, 434 pp.
2. G. N. Dorofeenko, E. I. Sadekova, E. V. Kuznetsov, Preparꢀ
ativnaya khimiya pirilievykh solei [The Preparative Chemistry
of Pyrylium Salts], Izd. Rostov. Univ., RostovꢀonꢀDon, 1972,
234 pp. (in Russian).
3. V. M. Vlasov, Izv. Sib. Otd. Akad. Nauk SSSR, Ser. Khim.
Nauk [Bulletin of the Siberian Branch of the Academy of Sciꢀ
ences of the USSR, Division of Chemical Sciences], 1971, 96
(in Russian).
4. N. A. Orlova, T. N. Gerasimova, M. A. Kudinova, A. I.
Tolmachev, Zh. Org. Khim., 1990, 26, 1313 [J. Org. Chem.
USSR (Engl. Transl.), 1990, 26].
5. B. K. Hofelschweiger, The Pyrylium Dyes: A New Class of
Biolabels. Synthesis, Spectroscopy, and Application as Labels
and in General Protein Assay, PhD Diss., Regensburg, Gerꢀ
many, 2005.
6. A. T. Balaban, Tetrahedron, 1968, 24, 5059.
7. E. A. Zvezdina, M. P. Zhdanova, O. S. Anisimova, G. N.
Dorofeenko, Khim. Geterotsikl. Soedin., 1983, 695 [Chem.
Heterocycl. Compd. (Engl. Transl.), 1983, 19, 564].
8. G. N. Dorofeenko, A. N. Narkevich, Yu. A. Zhdanov, O. E.
Shelepin, T. G. Soroka, Khim. Geterotsikl. Soedin., Sb. 2:
Kislorodsoderzhashchie Geterotsikl., 1970, 223 [Chem. Hetꢀ
erocycl. Compd., Proc. 2: OxygenꢀContaining Heterocycles
(Engl. Transl.), 1970].
9. S. V. Tolkunov, S. Yu. Suikov, M. Yu. Zubritskii, V. I. Duꢀ
lenko, Khim. Geterotsikl. Soedin., 1998, 1137 [Chem. Heteroꢀ
cycl. Compd. (Engl. Transl.), 1998, 34, 983].
6.64—6.72 (m, 5 H, 4 Harom + —CH=); 7.33 (d, 2 Harom
,
J = 8 Hz); 7.47 (d, 2 Harom, J = 8 Hz); 7.66—7.68 (m, 3 H(Ph));
7.92—8.04 (m, 5 H, 2 H(Ph) + H(3) + —CH= + N=CH); 8.61
(d, 1 H, H(5), J = 1 Hz). 19F NMR (CD3CN), δ: 2.19, 14.09,
24.64, 25.72; intensity ratio 2 : 1 : 1 : 1. Found (%): C, 60.21;
H, 4.20; F, 13.07; N, 7.63. C36H30ClF5N4O4. Calculated (%):
C, 60.63; H, 4.24; F, 13.32; N, 7.86.
10. I. Yu. Kargapolova, N. A. Orlova, T. N. Gerasimova, Khim.
Geterotsikl. Soedin., 1991, 1100 [Chem. Heterocycl. Compd.
(Engl. Transl.), 1991, 27, 883].
11. I. Yu. Kargapolova, K. S. Shmuilovich, N. A. Orlova, M. M.
Shakirov, T. V. Rybalova, V. V. Shelkovnikov, Izv. Akad.
Nauk, Ser. Khim., 2008, 402 [Russ. Chem. Bull., Int. Ed.,
2008, 57, 412].
This work was financially supported by the Federal
Agency for Science and Innovations (State Contract
No. 02.513.11.3167) and the Siberian Branch of the Rusꢀ
sian Academy of Sciences (Integrating Project No. 65).
12. A. T. Balaban, W. Silhan, Tetrahedron, 1970, 26, 743.
13. D. N. Laikov, Chem. Phys. Lett., 1997, 281, 151.
References
1. A. T. Balaban, A. Dinculescu, G. N. Dorofeenko, G. W.
Received June 11, 2009;
Fischer, A. V. Koblik, V. V. Mezheritskii, W. Schroth, Pyryꢀ
in revised form March 10, 2010