Reactions of polyfluorinated chalcones with hydrazine hydrate and phenylhydrazine

Article abstract of DOI:10.1007/s11172-010-0255-4

Polyfluorinated di- and triarylpyrazolines were synthesized by the reactions of polyfluorinated chalcones with hydrazine hydrate and phenylhydrazine, respectively. Reactions of benzyl-idenepolyfluoroacetophenones with phenylhydrazine resulted in the mixtures of isomeric 1,5-diphenyl-3- polyfluoroaryl-and 1,3-diphenyl-5-polyfluoroarylpyrazolines. Fluorescence properties of the synthesized triarylpyrazolines were studied.

Full text of DOI:10.1007/s11172-010-0255-4

Russian Chemical Bulletin, International Edition, Vol. 59, No. 7, pp. 1408—1413, July, 2010
1408
Reactions of polyfluorinated chalcones with hydrazine hydrate
and phenylhydrazine
K. S. Smuilovich, N. A. Orlova, E. V. Karpova, M. M. Shakirov, and V. V. Shelkovnikov
N. N. Vorozhtsov Novosibirsk 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
Polyfluorinated diꢀ and triarylpyrazolines were synthesized by the reactions of polyfluoriꢀ
nated chalcones with hydrazine hydrate and phenylhydrazine, respectively. Reactions of benzylꢀ
idenepolyfluoroacetophenones with phenylhydrazine resulted in the mixtures of isomeric
1,5ꢀdiphenylꢀ3ꢀpolyfluoroarylꢀ and 1,3ꢀdiphenylꢀ5ꢀpolyfluoroarylpyrazolines. Fluorescence
properties of the synthesized triarylpyrazolines were studied.
Key words: polyfluorinated chalcones, polyfluorinated 1ꢀacetylꢀ3,5ꢀdiarylꢀ4,5ꢀdihydroꢀ1Hꢀ
pyrazoles, polyfluorinated 1,3,5ꢀtriarylꢀ4,5ꢀdihydroꢀ1Hꢀpyrazoles, fluorescence spectra.
Chalcones (1,3ꢀdiphenylꢀ1ꢀpropenꢀ2ꢀones, benzylideꢀ
A number of hitherto unknown polyfluorinated triꢀ
arylpyrazolines were synthesized by the reactions of polyꢀ
fluorinated chalcones 1a and 2a with phenylhydrazine and
pentafluorophenylhydrazine (Scheme 1); their spectral
properties were studied.10 However, conditions of the
syntheses were described insufficiently. Besides, it was
important to extend the range of the polyfluorinated
triarylpyrazolines by introduction of different substiꢀ
tuents affecting the positions of the maxima of elecꢀ
tronic absorption and fluorescence in the perfluorinatꢀ
ed ring.
neacetophenones) possess high reactivity due to the presꢀ
ence of the carbonyl group conjugated with the double
bond.1 This instance suggests that the nucleophiles can
react with chalcones at both the carbonyl group and the
double bond. The reactions with binucleophiles leading to
the broad range of heterocyclic compounds are of particuꢀ
lar interest. Thus, the reactions of chalcones with phenylꢀ
hydrazine gave common fluorophores, triarylpyrazolines.2
Different pyrazoline derivatives, for example, monoꢀ and
dihalogenꢀsubstituted, possess a wide range of biological
activities.3—5
Polyfluorinated chalcones contain additional reactive
centers due to the presence of mobile nucleophilic fluoꢀ
rine atoms in the aromatic rings, which allow introducꢀ
tion of different substituents in the fluorinated ring. Penꢀ
taꢀ and decafluoroꢀsubstituted chalcones, pentafluorobenꢀ
zylideneacetophenone, benzylidenepentafluoroacetopheꢀ
none, and decafluorobenzylideneacetophenone were docꢀ
umented for the first time in Ref. 6. Later, we synthesized
a series of polyfluorinated chalcone derivatives by nucleoꢀ
philic substitution of the fluorine atoms at paraꢀ and/or
orthoꢀpositions of the perfluorophenyl ring with the amiꢀ
no, azido, arylalkoxy groups.7
Scheme 1
The reactions of chalcone and its monoꢀ and disubstiꢀ
tuted derivatives with hydrazines under acidic conditions
were extensively studied.4,5,8,9 It was shown that the iniꢀ
tial products of the reactions of these compounds with
phenylhydrazine are arylhydrazones, which, in acetic acid,
readily underwent ring closure to give 1,3,5ꢀtriarylꢀ2ꢀpyrꢀ
azolines. Under the similar conditions, the reactions
with hydrazine hydrate afforded 1ꢀacetylꢀ3,5ꢀdiarylꢀ2ꢀ
pyrazolines.5
1, 3: Ar = Ph, ArF = C6F5 (a), C6F4OPh (b), C6H4N(CH2)5 (c);
Ar = ArF = C6F5 (d), C6F4OPh (e), C6F4N(CH2)5 (f)
2, 4: ArF = C6F5 (a), C6F4OPh (b), C6F4N(CH2)5 (c)
Reagent and conditions: NH2NH2•H2O, AcOH, reflux, 6 h.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1378—1382, July, 2010.
1066ꢀ5285/10/5907ꢀ1408 © 2010 Springer Science+Business Media, Inc.

Reactions of polyfluorinated chalcones
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 7, July, 2010
1409
Scheme 3
The aim of this work was to study the reaction of polyꢀ
fluorinated chalcones 1a—f and 2a—c with hydrazine hyꢀ
drate and phenylhydrazine.
Results and Discussion
Boiling of chalcones 1a—f and 2a—c with hydrazine
hydrate in acetic acid resulted in polyfluorinated 1ꢀacetylꢀ
3,5ꢀdiarylpyrazolines 3a—f and 4a—c (see Scheme 1).
Under similar conditions, reactions of polyfluorinated
chalcones with phenylhydrazine proceed ambiguously:
chalcones 1a—f gave expected triarylpyrazolines 5a—f,
while chalcones 2a—c led to mixtures of two regioisomerꢀ
ic pyrazolines (in comparable amounts) differing in the
substituents at the positions 3 and 5 (Scheme 2).
Scheme 2
dineꢀsubstituted isomer 6c from its mixture with comꢀ
pound 5c failed.
Structures of pyrazolines 3—6 were established based
on 1H, 19F, and 13C NMR spectroscopy and confirmed by
elemental analysis. Yields and physicochemical data of
the compounds synthesized are given in Tables 1 and 2,
the 1H NMR spectroscopy data are listed in Table 3.
The choice between structures 5a and 6a was done
based on the following NMR data for isomer 5a: 1) in the
19F NMR spectrum, the broadening of the signals for the
fluorine atoms at the oꢀ and mꢀpositions of the perfluoroꢀ
phenyl ring was observed, which is due probably to the
steric hindrance impeding free rotation of the C6F5 group;
5: Ar = Ph, ArF = C6F5 (a), C6F4OPh (b), C6F4N(CH2)5 (c);
Ar = ArF = C6F5 (d), C6F4OPh (e), C6F4N(CH2)5 (f)
6: ArF = C6F5 (a), C6F4OPh (b), C6F4N(CH2)5 (c)
Reagent and conditions: PhNH—NH2, AcOH, reflux, 6 h.
1
We suggested that the formation of pyrazolines 5a—c
along with expected compounds 6a—c from chalcones
2a—c bearing the polyfluorobenzoyl groups can result from
the initial formation of both the corresponding phenylhydrꢀ
azones 7 and compounds 8, which are the products
of nucleophilic addition of phenylhydrazine at the
βꢀC atom (Scheme 3). The appearance of an electrophilic
center at the βꢀC atom in chalcones 2 competitive to the
carbonyl group can be explained by significant difference
in the inductive constants σ* of the substituents at vinylꢀ
ene fragment, which affect the polarization of the latter
(σ* = 2.58 for the C6F5CO group and σ* = 0.6 for the
Ph group).11 Thus, phenylhydrazine attacks both electroꢀ
philic centers and, as a result, two regioisomeric pyrꢀ
azolines formed.
2) in the H NMR spectrum, the downꢀfield shift of the
signal for the proton at the C(5) atom by 0.45 ppm as
compared with that of the corresponding proton of isomer
6a was observed, this fact is attributed to the electronꢀ
withdrawing effect of the C6F5 group; 3) in the 13C NMR
spectra, the signal for the C(5) atom shifted upꢀfield
(δ 53.16 as compared with δ 63.93 for the isomer 6a).
Electronic absorption spectra and fluorescence spectra
of triarylpyrazolines 5a—f and 6a,b were studied (Table 4).
Fluorescence spectra of these compounds contained the
typical bands with maxima at 434—472 nm symmetrical
to the excitation spectra. The chromophoric system of
triarylpyrazolines included the nitrogen atom with a lone
electron pair, which interacted with the phenyl group at
the position 1, the azomethyne bond, and the aryl residue
at the position 3 of the heterocycle conjugated with the
aboveꢀmentioned bond. In this regard, the structure of the
Pyrazolines 6a,b were isolated from the isomeric mixꢀ
tures by preparative TLC on Al2O3. Isolation of piperiꢀ

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Russ.Chem.Bull., Int.Ed., Vol. 59, No. 7, July, 2010
Smuilovich et al.
Table 1. Yields and physicochemical characteristics of polyfluorinated 1ꢀacetylpyrazolines 3a—f and 4a—c
Comꢀ
pound
Ar
ArF
Yield
(%)
m.p./°C
(solvent)
Found
Calculated
Molecular
formula
(%)
F
C
H
N
3a
3b
3c
3d
3e
3f
Ph
Ph
C6F5
C6F4OPhꢀp
C6F4NC5H10ꢀp
C6F5
89
88
66
89
86
54
69
47
76
110—113
(hexane)
146—149
(ethanol)
163—165
57.70
57.63
64.58
64.49
62.91
2.98
3.13
4.09
3.76
5.05
5.05
1.34
1.36
2.75
2.72
4.55
4.56
3.19
3.13
3.71
3.76
5.30
5.05
26.76
26.81
17.73
17.74
17.98
7.78
7.91
6.45
6.54
9.99
C17H11N2OF5
C23H16N2O2F4
C22H21N3OF4
C17H6N2OF10
C29H16N2O3F8
C24H26N4OF8
C17H11N2OF5
C23H16N2O2F4
C22H21N3OF4
Ph
(hexane—benzene, 1 : 1) 62.99
18.12 10.01
C6F5
104—106
(hexane—ethanol)
179—181
(ethanol)
160—162
(ethanol)
90—92
46.02
45.96
58.67
58.79
56.69
56.45
58.01
57.63
64.99
64.49
62.92
62.99
43.14
42.77
25.35
25.66
26.5
6.46
6.31
4.64
4.73
9.87
9.75
7.97
7.91
6.74
6.54
C6F4OPhꢀp
C6F4OPhꢀp
C6F4NC5H10ꢀp C6F4NC5H10ꢀp
26.46
26.72
26.81
17.95
17.74
4а
4b
4c
Ph
Ph
Ph
C6F5
(ethanol)
73—76
C6F4OPhꢀp
C6F4NC5H10ꢀp
(hexane)
100—102
(ethanol)
17.98 10.07
18.12 10.01
aryl fragments in the positions 1 and 3 as well as the charꢀ
acter of the substituents at these rings strongly affected the
spectral fluorescent properties of triarylpyrazolines.2 Thus,
electronꢀwithdrawing groups in the aryl fragment at the
position 1 result in the bathochromic shifts of the bands in
the absorption and fluorescence spectra, while electronꢀ
withdrawing groups in the aryl fragment at the position 3
give rise to the opposite effect. It has been shown that
replacement of the phenyl ring by strong acceptor, the
C6F5 group, resulted in the bathochromic shift of the maxꢀ
imum of the fluorescence in chloroform by 31 nm. This is
in good agreement with the data given in Ref. 10, where it
was found that the bathochromic shift in toluene is 17 nm.
We found that 1,3,5ꢀtriphenylꢀ4,5ꢀdihydroꢀ1Hꢀpyrazoline
is chemically unstable in chloroform in contrast to polyꢀ
fluorinated derivatives; this fact is consistent with the data
on increase in photostability of dyes due to introduction of
the fluorine atoms.2 No effect on the optical properties of
pyrazoline 6b was found, when the paraꢀfluorine atom of
the pentafluorophenyl ring at the position 3 was displaced
by the phenoxy group (Fig. 1). The C6F5 group at the
position 5 is not included in the conjugation and, thereꢀ
fore, does not significantly affect the positions of the maxꢀ
ima of absorption and fluorescence. Besides, the fluoresꢀ
cence intensity of 5ꢀC6F5ꢀsubstituted triarylpyrazolines is
one order of magnitude lower than that of 3ꢀsubstituted
derivatives. Triarylpyrazoline bearing two perfluoropheꢀ
nyl groups 5d and its substituted derivatives 5e and 5f
exhibited almost identical positions of the maxima of the
fluorescence shifted bathochromically by ~15—20 nm as
compared with the fluorescence maximum of tripheꢀ
nylpyrazoline.
In summary, novel polyfluorinated derivatives of diꢀ
and triarylpyrazolines were synthesized by the reaction of
polyfluorinated chalcones with hydrazine hydrate and pheꢀ
nylhydrazine. It was found that chalcone 2a bearing perꢀ
fluorobenzoyl group and its derivatives 2b and 2c containꢀ
ing substituents at the perfluorinated ring react with pheꢀ
nylhydrazine simultaneously on two directions: at the carꢀ
bonyl group and at the βꢀC atoms giving different regioꢀ
Ifl (rel. un.)
460
5e
800
472
600
400
200
6b
436
5b
500
400
600 λ/nm
Fig. 1. Fluorescence spectra of compounds 5b, 5e, and 6b.

Reactions of polyfluorinated chalcones
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 7, July, 2010
1411
Table 2. Yields and physicochemical characteristics of polyfluorinated triarylpyrazolines 5a—f and 6a—c
Starting Proꢀ
Ar
ArF
Yield
(%)
m.p./°C
(solvent)
Found
Calculated
Molecular
formula
(%)
F
chalꢀ
cone
duct
C
H
N
1a
1b
1c
1d
1e
1f
5a
5b
5c
5d
5e
Ph
Ph
C6F5
C6F4OPhꢀp
C6F4NC5H10ꢀp
C6F5
36a
64
171—174b
(hexane)
150—152c
0—
0—
0—
0—
70.02
70.12
69.34
68.86
52.81
52.73
63.39
63.26
61.25
61.18
0—
3.94
3.92
5.24
5.11
1.54
1.69
2.99
2.90
4.67
4.64
0—
16.44 3.94 C27H18N2OF4
16.43 6.06
Ph
64
182—184
(benzene)
163—166
16.64 9.29 C26H23N3F4
16.76 9.27
C6F5
51
39.91 5.87 C21H8N2F10
39.72 5.86
(hexane)
C6F4OPhꢀp
C6F4OPhꢀp
77a
40a
155—158
24.58 4.45 C33H18N2O2F8
24.26 4.47
(50% EtOH)
170—172c
5f C6F4NC5H10ꢀp C6F4NC5H10ꢀp
24.82 9.27 C31H28N4F8
24.97 9.21
2a
5a
6a
Ph
Ph
C6F5
C6F5
30a
21a
—
0—
0—
0—
0—
0—
0—
130—132b
(hexane)
—
0—
0—
2b
2c
5b
6b
Ph
Ph
C6F5
27a
28a
70.57d
70.12
4.01
3.92
16.8
6.13 C27H18N2OF4
16.43 6.06
C6F4OPhꢀp
110—112
(EtOH)
—
5c
6c
Ph
Ph
C6F4NC5H10ꢀp
C6F4NC5H10ꢀp
35a
35a
69.09d
68.86
5.03
5.11
16.79 9.31 C26H23N3F4
16.76 9.27
—
a Yields were calculated based on the data from the 19F NMR spectra of the reaction mixtures.
b Compounds were previously documented;10 m.p. and elemental analysis data are coincided with published data.
c Pure compound was isolated by column chromatography on Al2O3 using benzene as eluent.
d Elemental analysis is given for the mixture of isomers.
Table 3. 1H and 19F NMR spectra of pyrazolines 3a—f, 4a—c, 5a—f, and 6a—c in CDCl3
Comꢀ
pound
1H NMR, δ (J/Hz)
19F NMR, δ
(intensity ratio)
3a
3b
3c
2.35 (s, 3 H, MeСО); 3.25 (dd, 1 Н, Нa(4), J1 = 18.0, J2 = 6.0); 3.77 (dd, 1 Н, Нb(4),
J1 = 18.0, J2 = 12.5); 5.81 (dd, 1 Н, Н(5), J1 = 12.5, J2 = 6.0); 7.38—7.76 (m, 5 Н, Ph)
0.07, 7.10, 18.49
(2 : 1 : 2)
2.42 (s, 3 H, MeСО); 3.34 (dd, 1 Н, Нa(4), J1 = 18.0, J2 = 6.5); 3.82 (dd, 1 Н, Нb(4),
J1 = 18.0, J2 = 12.5); 5.90 (dd, 1 Н, Н(5), J1 = 12.5, J2 = 6.5); 6.90—7.82 (m, 10 Н, 2 Ph)
10.53, 20.82
(1 : 1)
1.59 (m, 6 Н); 3.13 (m, 4 Н, C6F4N(CH2)5); 2.33 (s, 3 H, MeСО); 3.24 (dd, 1 Н, Нa(4),
J1 = 18.0, J2 = 6.0); 3.70 (dd, 1 Н, Нb(4), J1 = 18.0, J2 = 12.0); 6.25 (dd, 1 Н, Н(5),
J1 = 12.0, J2 = 6.0); 7.24—7.73 (m, 5 H, Ph)
10.20, 15.43
(1 : 1)
3d
2.31 (s, 3 H, MeСО); 3.29 (dd, 1 Н, Нa(4), J1 = 19.0, J2 = 6.0); 3.82 (dd, 1 Н, Нb(4),
J1 = 19.0, J2 = 13.0); 5.81 (dd, 1 Н, Н(5), J1 = 13.0, J2 = 6.0)
0.42, 1.03, 7.77,
11.22, 18.45, 23.85
(2 : 2 : 1 : 1 : 2 : 2)
3e
3f
2.36 (s, 3 H, MeСО); 3.38 (dd, 1 Н, Нa(4), J1 = 18.0, J2 = 6.5); 3.86 (dd, 1 Н, Нb(4),
J1 = 18.0, J2 = 13.0); 5.87 (dd, 1 Н, Н(5), J1 = 13.0, J2 = 6.5); 6.98—7.37 (m, 10 Н, 2 Ph)
7.87, 8.42, 17.95,
23.23 (1 : 1 : 1 : 1)
1.58 (m, 12 Н); 3.15 (m, 8 Н, 2 C6F4N(CH2)5); 2.31 (s, 3 H, MeСО); 3.30 (dd, 1 Н, Нa(4),
J1 = 18.5, J2 = 6.0); 3.74 (dd, 1 Н, Нb(4), J1 = 18.5, J2 = 12.6); 5.73 (dd, 1 Н, Н(5),
J1 = 12.7, J2 = 6.0)
10.11, 10.31,
15.48, 21.15
(1 : 1 : 1 : 1)
4a
2.37 (s, 3 H, MeСО); 3.18 (dd, 1 Н, Нa(4), J1 = 8.0, J2 = 5.0); 3.82 (dd, 1 Н, Нb(4),
J1 = 18.0, J2 = 12.0); 5.55 (dd, 1 Н, Н(5), J1 = 12.0, J2 = 5.0); 7.16—7.35 (m, 5 Н, Ph)
0.71, 10.51, 23.80
(2 : 1 : 2)
(to be continued)

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Russ.Chem.Bull., Int.Ed., Vol. 59, No. 7, July, 2010
Smuilovich et al.
Table 3 (continued)
Comꢀ
pound
1H NMR, δ (J/Hz)
19F NMR, δ
(intensity ratio)
4b
4c
2.42 (s, 3 H, MeСО); 3.25 (dd, 1 Н, Нa(4), J1 = 18.5, J2 = 5.0); 3.88 (dd, 1Н, Нb(4),
J1 = 18.5, J2 = 12.0); 5.60 (dd, 1 Н, Н(5), J1 = 12.0, J2 = 5.0); 6.85—7.45 (m, 10 Н, 2 Ph)
8.22, 23.09
(1 : 1)
1.62 (m, 6 Н); 3.19 (m, 4 Н, C6F4N(CH2)5); 2.39 (s, 3 H, MeСО); 3.27 (dd, 1 Н, Нa(4),
J1 = 17.5, J2 = 6.0); 3.75 (dd, 1 Н, Нb(4), J1 = 17.0, J2 = 12.5); 5.82 (dd, 1 Н, Н(5),
J1 = 12.5, J2 = 6.0); 7.44—7.77 (m, 5 H, Ph)
10.17, 15.42
(1 : 1)
5a
3.33 (dd, 1 Н, Нa(4), J1 = 18.0, J2 = 6.5); 3.89 (dd, 1 Н, Нb(4), J1 = 18.0, J2 = 13.0);
5.75 (dd, 1 Н, Н(5), J1 = 13.0, J2 = 6.5); 6.80—7.79 (m, 10 Н, 2 Ph)
0.87, 7.96 (br),
19.58 (br)
(2 : 1 : 2)
5b
5c
3.36 (dd, 1 Н, Нa(4), J1 = 17.5, J2 = 6.0); 3.88 (dd, 1 Н, Нb(4), J1 = 17.5, J2 = 12.5);
5.76 (dd, 1 Н, Н(5), J1 =12.5, J2 = 6.0); 6.79—7.77 (m, 15 Н, 3 Ph)
8.37, 18.96
(1 : 1)
1.62 (m, 6 Н); 3.17 (m, 4 Н, C6F4N(CH2)5); 3.31 (dd, 1 Н, Нa(4), J1 = 17.0, J2 = 6.0);
3.83 (dd, 1 Н, Нb(4), J1 = 17.0, J2 = 13.0); 5.68 (dd, 1 Н, Н(5), J1 = 13.0, J2 = 6.0);
6.78—7.80 (m, 10 H, 2 Ph)
10.82, 16.38
(1 : 1)
5d
3.36 (dd, 1 Н, Нa(4), J1 = 18.0, J2 = 6.0); 3.93 (dd, 1 Н, Нb(4), J1 = 18.0, J2 = 13.0);
5.80 (dd, 1 Н, Н(5), J1 = 13.0, J2 = 6.0); 6.85—7.31 (m, 10 Н, 2 Ph)
–0.22, 1.35, 7.80,
22.59, 8.87, 19.56,
(2 : 2 : 1 : 1 : 2 : 2)
5e
5f
3.47 (dd, 1 Н, Нa(4), J1 = 18.0, J2 = 6.0); 3.99 (dd, 1 Н, Нb(4), J1 = 18.0, J2 = 13.5);
5.84 (dd, 1 Н, Н(5), J1 = 13.5, J2 = 6.0); 6.86—7.40 (m, 15 Н, 3 Ph)
7.39, 8.72, 19.01,
22.05 (1 : 1 : 1 : 1)
1.62 (m, 12 Н); 3.19 (m, 8 Н, 2 C6F4N(CH2)5); 3.35 (dd, 1 Н, Нa(4), J1 = 17.0, J2 = 7.0);
3.76 (dd, 1 Н, Нb(4), J1 = 17.0, J2 = 13.0); 5.65 (dd, 1 Н, Н(5), J1 = 13.0, J2 = 7.0);
6.76—7.26 (m, 5 Н, Ph)
9.71, 10.90,
16.50, 20.05
(1 : 1 : 1 : 1)
6a
6b
6c
3.21 (dd, 1 Н, Нa(4), J1 = 18.0, J2 = 8.0); 3.90 (dd, 1 Н, Нb(4), J1 = 18.0, J2 = 13.0);
5.30 (dd, 1 Н, Н(5), J1 = 13.0, J2 = 8.0); 6.78—7.40 (m, 10 Н, 2 Ph)
–0.50, 6.99, 22.45
(2 : 1 : 2)
3.25 (dd, 1 Н, Нa(4), J1 = 17.0, J2 = 7.0); 3.94 (dd, 1 Н, Нb(4), J1 = 17.0, J2 = 13.0);
5.32 (dd, 1 Н, Н(5), J1 = 13.0, J2 = 7.0); 6.78—7.38 (m, 15 Н, 3 Ph)
7.09, 21.91
(1 : 1)
1.66 (m, 6 Н); 3.22 (m, 4 Н, 2 C6F4N(CH2)5); 3.20 (dd, 1 Н, Нa(4), J2 = 9.0); 3.88 (dd, 1 Н,
Нb(4), J2 = 13.0); 5.23 (dd, 1 Н, Н(5), J1 = 13.0, J2 = 9.0); 6.75—7.74 (m, 10 H, 2 Ph)
9.69, 19.90
(1 : 1)
isomers of triarylpyrazolines. Spectral and fluorescent
properties of the synthesized polyfluorinated triarylpyraꢀ
zolines were studied.
Experimental
The NMR spectra were recorded on Bruker ACꢀ200
(200.13 MHz for 1H and 188.2 MHz for 19F) and Bruker AVꢀ600
(600.30 MHz for 1H, 150.94 MHz for 13C, and 564.76 MHz for
19F) in CDCl3. Chemical shifts are given in the δ scale relative to
Table 4. Absorption (A) and fluorescence* (fl) spectra of comꢀ
pounds 5a—f and 6a—b
C6F6 (
19F NMR) and residual signal of the protons of CDCl3
(1H and 13C NMR). Electron absorption spectra were recorded
on a Hewlett Packard 8453 spectrophotometer; excitation and
fluorescence spectra were obtained on a Varian Cary Eclipse
spectrofluorimeter in chloroform.
Compound
λ
max(A)/nm (lgε)
λ
fl/nm (Ifl)
max
5a
6a
5d
5b
6b
5e
5c
5f
354 (4.28)
356 (4.07)
357 (4.46)
355 (4.25)
362 (4.22)
363 (4.19)
357 (4.59)
367 (4.37)
—
433 (36)0
471 (666)
458 (724)
436 (46)0
472 (744)
460 (908)
436 (423)
452 (107)
43900000
Starting chalcones 1a, 1d, and 2a were synthesized by the
known procedures,6 paraꢀsubstituted chalcones were prepared
according to the known method7.
Reactions of chalcones 1a—f, 2a—c with hydrazine hydrate
and phenylhydrazine (general procedure). Acetic acid (10 mL)
was added to a mixture of chalcone (1 mmol) and hydrazine
hydrate or phenylhydrazine (5 mmol), and the reaction mixture
was refluxed for 6 h. After cooling to room temperature, the
reaction mixture was poured onto ice, the precipitate that formed
was filtered off, washed with water until neutral, and airꢀdried.
The products were analyzed by 1H and 19F NMR spectroscopy.
The products were purified by recrystallization or column chroꢀ
**
* The fluorescence spectra were recorded using excitation at
362 nm.
** 1,3,5ꢀTriphenylꢀ4,5ꢀdihydroꢀ1Hꢀpyrazoline.

Reactions of polyfluorinated chalcones
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 7, July, 2010
1413
matography (see Tables 1 and 2). The mixtures of isomers 5a and
6a, 5b and 6b were separated by TLC on Al2O3, elution with
a hexane—benzene mixture (3 : 1)—(5 : 1).
4. J. SafaeiꢀGhomi, A. H. Bamoniri, M. SoltanianꢀTelkabadi,
Khim. Geterotsikl. Soedin., 2006, 42, 1032 [Chem. Heterocycl.
Comp., 2006, 42, 892].
5ꢀPerfluorophenylꢀ1,3ꢀdiphenylꢀ4,5ꢀdihydroꢀ1Hꢀpyrazole
(5a). 13C NMR, δ: 40.70 C(4), 53.18 C(5), 113.07, 119.86,
125.70, 128.54, 128.84, 129.12, 132.01, 143.77, 146.61 C(3).
3ꢀPerfluorophenylꢀ1,5ꢀdiphenylꢀ4,5ꢀdihydroꢀ1Hꢀpyrazole
(6a). 13C NMR, δ: 45.93 C(4), 63.91 C(5), 113.77, 120.23,
125.73, 127.79, 128.91, 129.19, 141.49, 143.68 C(3).
5. A. Levai, ARKIVOC, 2005, 9, 344.
6. R. Filler, V. D. Beaucaire, H. H. Kang, J. Org. Chem., 1975,
40, 935.
7. N. A. Orlova, E. F. Maior, T. N. Gerasimova, Izv. Sib. Otd.
Akad. Nauk SSSR, Ser. Khim. Nauk, 1989, No. 3, 117 [Bull.
Sib. Branch Acad. Sci. USSR, Div. Chem. Sci. (in Russian),
1989, No. 3].
This work was financially supported by Ministry of
Education and Science of the Russian Federation (State
Contract No 02.513.11.3167) and the Russian Academy
of Sciences (Integration Project of the Siberian Branch,
the Russian Academy of Sciences No. 55).
8. K. C. Joshi, V. N. Pathak, S. Sharda, J. Indian Chem. Soc.,
1984, 61, 1014.
9. K. C. Joshi, A. K. Jauhar, J. Indian Chem. Soc., 1965, 42, 733.
10. D. G. Pereyaslova, V. T. Skripkina, B. M. Krasovitskii, G. G.
Yakobson, Izv. Sib. Otd. Akad. Nauk SSSR, Ser. Khim. Nauk,
1974, No. 1, 81 [Bull. Sib. Branch Acad. Sci. USSR, Div.
Chem. Sci. (in Russian), 1974, No. 1].
11. V. M. Vlasov, O. Kh. Poleshchuk, O. V. Zakharova, Yu. K.
Maksyutin, G. G. Yakobson, Izv. Sib. Otd. Akad. Nauk SSSR,
Ser. Khim. Nauk, 1976, No. 9, 116 [Bull. Sib. Branch Acad.
Sci. USSR, Div. Chem. Sci. (in Russian), 1976, No. 9].
References
1. D. N. Dhar, The Chemistry of Chalcones and Related Comꢀ
pounds, WileyꢀInterscience Publication, New York—Chichꢀ
ester—Brisbane—Toronto, 1981, 285 p.
2. B. M. Krasovitskii, L. M. Afanasiadi, Monoꢀ i bifluorofory
[Monoꢀ and Bifluorophores], Institute for Single Crystals,
Kharkov, 2002, 448 pp. (in Russian).
Received November 13, 2009;
in revised form March 19, 2010
3. D. Azarifar, B. Maleki, J. Heterocyclic Chem., 2005, 42, 157.