Distinguishing features of reactions of 2-chloro- and 2,2-dichloro(bromo) vinyl ketones with alkyl- and arylhydrazines

Article abstract of DOI:10.1134/S1070428008070129

2-Chlorovinyl alkyl ketones react with alkylhydrazines to give mixtures of 1-R-3-R′- and 1-R-5-R′-pyrazoles: The 1-R-3-R′-pyrazoles form through the heterocyclization of 2-chlorovinyl ketone alkylhydrazones whereas in the heterocyclization into 1-R-5-R′-pyrazoles N¹-alkyl-N ²-(2-acylvinyl)hydrazines are involved. The regiospecific heterocyclization of 2-chloro-and 2,2-dichlorovinyl ketones with arylhydrazines and also of 2,2-dichloro(bromo)vinyl trifluoromethyl ketones with C alkylhydrazines into pyrazoles and 5-chloro(bromo)-pyrazoles proceeds through a stage of haloenones hydrazones formation. The study of the structure of the obtained 1-alkyl-3(5)-alkylpyrazoles by means of two-dimenaional ¹H and ¹³C NMR spectroscopy and GC-MS method made it possible to assign the proton and carbon signals of isomeric pyrazoles and to establish the diagnostic ions for the pair of 1,3-and 1,5-isomers.

Full text of DOI:10.1134/S1070428008070129

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2008, Vol. 44, No. 7, pp. 1014−1023. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © G.V. Bozhenkov, V.A. Savosik, L.I. Larina, L.V. Klyba, E.R. Zhanchipova, A.N. Mirskova, G.G. Levkovskaya, 2008, published in
Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 7, pp. 1024−1033.
Distinguishing Features of Reactions
of 2-Chloro- and 2,2-Dichloro(bromo)vinyl Ketones
with Alkyl- and Arylhydrazines
G. V. Bozhenkov, V. A. Savosik, L. I. Larina, L. V. Klyba, E. R. Zhanchipova,
A. N. Mirskova, and G. G. Levkovskaya
Faworsky Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk, 664033 Russia
e-mail: ggl@irioch.irk.ru
Received January 5, 2008
Abstract—2-Chlorovinyl alkyl ketones react with alkylhydrazines to give mixtures of 1-R-3-R'- and 1-R-5-R'-
pyrazoles: The 1-R-3-R'-pyrazoles form through the heterocyclization of 2-chlorovinyl ketone alkylhydrazones
whereas in the heterocyclization into 1-R-5-R'-pyrazoles N1-alkyl-N2-(2-acylvinyl)hydrazines are involved. The
regiospecific heterocyclization of 2-chloro- and 2,2-dichlorovinyl ketones with arylhydrazines and also of
2,2-dichloro(bromo)vinyl trifluoromethyl ketones with C alkylhydrazines into pyrazoles and 5-chloro(bromo)-
pyrazoles proceeds through a stage of haloenones hydrazones formation. The study of the structure of the obtained
1
1-alkyl-3(5)-alkylpyrazoles by means of two-dimenaional H and 13C NMR spectroscopy and GC-MS method
made it possible to assign the proton and carbon signals of isomeric pyrazoles and to establish the diagnostic ions
for the pair of 1,3- and 1,5-isomers.
DOI: 10.1134/S1070428008070129
Reactions of chorovinyl alkyl ketones with hydrazine,
alkyl- and arylhydrazines constitute a known method of
preparation of 1-unsubstituted 3-alkylpyrazoles and
1-aryl-(alkyl)-3-alkylpyrazoles, members of an important
class of compounds widely used as semiproducts in
synthesis of dyes, materials for optoelectronics, pesti-
cides, pharmaceuticals, etc. [1–3]. In these reaction the
formation of two isomers was not observed.
and benzylhydrazines in alcohols at heating in the
presence both of acids or bases (exess hydrazine could
operate as the latter) formed a mixture of two 1-R-5-
and 1-R-3-propylpyrazoles in a ratio 1:2 (by H NMR
data). These findings suggest different paths of the
isomers formation.
1
We believe that the formation of the mixture of
pyrazole isomers is due to two competitive pathways of
the reaction between 2-chlorovinyl ketones and alkyl-
hydrazines:Along the first route 1-R-3-propyl-pyrazoles
In this study we established for the first time that in
the reaction of 2-chlorovinyl propyl ketone with alkyl-
Scheme 1.
Pr
O
N H
HO
N
R
PrCCH=CHNHNHR
Pr
O
_HCl
_H2O
_H2O
N
PrCCH=CHCl
+
RNHNH2
Pr
N
Cl
N
Pr
N
R
_HCl
H
N
R
N
R
I_III
IV_VI
R = Et (I, IV), Bu (II, V), Bn (III, VI).
1014

DISTINGUISHING FEATURES OF REACTIONS OF 2-CHLORO(BROMO)VINYL KETONES
1015
1
The analysis of two-dimensional H and 13C NMR
spectra of the mixture of 1-alkyl-3-propylpyrazoles and
1-alkyl-5- propylpyrazoles I–VI [4–6] made it possible
to establish their structure and to assign the proton signals
in the positions 3, 4 and 4, 5 of the pyrazole ring.
I–III form via the heterocyclization of the initially arising
corresponding 2-chlorovinyl ketones alkylhydrazones;
the second route consists in the heterocyclization of N1-
alkyl-N2-(2-acylvinyl)-hydrazines into 1-R-5-propylpyr-
azoles IV–VI (Scheme 1).
The formation of N1-alkyl-N2-(2-acylvinyl)hydrazines
occurs probably by a nucleophilic addition of alkyl-
(benzyl)hydrazines to a butanoylacetylene, the dehydro-
chlorination product of propyl 2-chlorovinyl ketone.
Besides in the reaction of the nucleophilic substitution
of a halogen atom in the haloenone and in the addition
to the acetylene ketone may act the hydrochloride of the
hydrazine; as a result in the process would be involved
the more nucleophilic NH2 group and not N+H2RCl–.
On the other hand, N1-alkyl-N2-(2-acyl-vinyl)hydrazines
might arise by an intramolecular rearrangement of the
preliminary formed hydroxyalkylhydrazines (Scheme 2).
In the NOESY spectra of the mixture of 1-ethyl-3-
propylpyrazole (I) and 1-ethyl-5-propylpyrazole (IV)
a cross-peak was observed for the CH2 moiety of
ethyl and propyl groups in the positions 1 and 5 of the
pyrazole ring. The assignment of the carbon signals was
1
based on the 2D spectra HMBC H-13C and HSQC
13
1H− C.
In the 15N NMR spectra of 1-ethyl-3-propylpyrazole
(I) and 1-ethyl-5-propylpyrazole (IV) the signals of the
pyridine atom 15N appear in the region –76.5 ppm, and
the signals of the pyrrole nitrogen atom, in the regions
–164.5 and –166.5 ppm respectively.
The structure of compounds I–VI was investigated
by 1H and 13C NMR spectroscopy and GC-MS method,
their composition was confirmed by elemental analysis.
A characteristic feature of the mass spectra of 1-alkyl-
3(5)-propylpyrazoles I–VI is the presence of an inten-
-
sive peak of the molecular ion whose fragmentation
occurs in accordance with the rules established for the
decomposition of pyrazoles [7]. The position of the
propyl substituent in 1-butylpyrazoles II and V virtually
does not affect the fragmentation route to one of the main
fragment ions with m/z 123 (Irel 100, 90%) resulting
Chemical shifts of protons in the position 4 are
virtually alike in the spectra of 3- and 5-alkylpyrazoles
I–VI, whereas the signal of the H5 proton of 3-alkyl-
pyrazoles is shifted upfield as compared with the
corresponding signals of H3 proton of 5-alkylpyrazoles.
Scheme 2.
O
RNHNH2
PrC
C CH
_HCl
R
O
Pr
O
_
+
C
.
NH2NH2R Cl
+
_
NH
.
Pr
Pr
CCH CHCl
CCH CHNHNH2R Cl
CH
HC NHNNR
N
R
HO
O
HO
_H2O
Pr
Pr
OH
RNHNH2
HN
H N
_HCl
Cl
N
N
NHR
Pr
N
R
R
Scheme 3.
.
+
Pr
Pr
N
R
N
N
.
+
_R
_C3
+
H6
N
N
N
H2C
CH2
CH2
.
II, V: M +
m/z 81 (45, 36, 12)
m/z 123 (100, 90, 15)
, 166 (27, 41)
.
VI: M + , 200 (26).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

BOZHENKOV et al.
1016
Scheme 7.
Scheme 4.
Pr
.
.
+
+
C2H5
Pr
.
N
_H
N
.
_R
+NH
Pr
N
+
N
N
C2H5
N
+
N
C
N
N
H
H
R
H
CH2
.
Ph
m/z 199 (8, 23)
V: M + , 166 (27)
VI: M + , 200 (26)
_N2
_HCN
m/z 109 (39, 25)
Ph
.
III, VI
.
M + , 200 (8, 26)
[C5H8N]+
[C6H9]+
m/z 81 (35, 12)
m/z 82 (54, 3)
from the elimination of the maximal alkyl radical [8]
(Scheme 3).
Scheme 8.
In the mass spectra of two 1-benzyl pyrazole
derivatives III and VI ion with m/z 123 (15%) [M –
C3H7]+ was observed only in the spectrum of 1,5-
substituted pyrazole VI. For these compounds as
expected the most abundant peak belonged to tropylium
ion [C7H7]+, m/z 91 (100%) [7]. Besides compounds III
and VI were characterized by the appearance of an ion
[M – H]+ (Scheme 4). Like in methylbenzylpyrazoles
[7] the hydrogen atom evidently was abstracted from the
bridging methylene group between pyrazole and benzene
rings.
Another general direction of M+· decomposition of
compounds II and V insensitive to the position of the
substituent is due to Mc Lafferty rearrangement [9]
(Scheme 5).
Despite the close resemblance of the mass spectra of
these isomeric pairs essential difference exists making
[C5H9]+
m/z 69 (10)
N
+
N
_HCN
_HCN
Pr
NH
+
Pr
CH2
V, m/z 123 (90)
m/z 96 (100)
possible an unambiguous identification of 1,3- and 1,5-
isomers.
For instance, the elimination of ethylene molecule
from the M+· of pyrazoles II and III by the mechanism
of Mc Lafferty rearrangement [9] proves the location of
propyl substituent in the position 3 of the pyrazole ring
(Scheme 6). This path of fragmentation is absent in the
mass spectra of pyrazoles V and VI.
On the other hand, exclusively in the mass spectra of
5-propyl-substituted pyrazoles V and VI the M+· suffered
fragmentation with the rupture of the C–N bond and the
formation of a diagnostic ion [M – R]+, m/z 109
(Scheme 7).
Besides 1-butyl-5-propylpyrazole (V) easily looses
HCN molecule from the ion [M – C3H7]+ of m/z 123
providing an ion of m/z 96, whose peak in the mass
spectrum is the most abundant (Scheme 8). This
fragmentation is impossible for 1-butyl-3-propylpyrazole
(II).
Thus the appearance of diagnostic ions for each
isomeric pair permits unambiguous identification of the
structure by means of mass spectra.
Scheme 5.
.
+
.
.
+
+
Pr
Pr
_C3H6
N
N
N
_ C3H6
N
H
N
N
CH3
CH3
CH3
166 (27, 41)
.
II, V:M + ,
m/z 82 (33, 54)
m/z 124 (32, 20)
Scheme 6.
CH2
In contrast to the observed formation of the mixture
of 1,3- and 1,5-substituted pyrazoles in the reaction of
2-chlorovinyl ketones with alkylhydrazines we formerly
[10–12] established that in the similar reaction of 1,2-
and 2,2-dichlorovinyl ketones with alkylhydrazines
occurred a chemoselective formation solely of 1,3-di-
organyl-substituted 4(5)-chloropyrazoles.
.
_Pr
.
NH
+
+
N
.
+
CH2
R = Pr
CH2
m/z 95 (28)
NH
N
N
H
_C2H4
N
R = Ph
H2C R
R
H2C
.
[C7H7]+
II: M + , 166 (27)
m/z 138 (27)
m/z 172 (37)
In this study the latter fact was once more proved by
m/z 91 (100) an example of reactions of trifluoromethyl 2,2-dichloro-
_C4H5N2
.
III: M + , 200 (8)
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

DISTINGUISHING FEATURES OF REACTIONS OF 2-CHLORO(BROMO)VINYL KETONES
1017
(bromo)vinyl ketones with ethyl- and benzylhydrazine.
Therewith under the conditions similar to the preparation
of mixtures of 1,3- and 1,5-substituted pyrazoles I–VI
from the 2-chlorovinyl alkyl ketones with alkyl-
hydrazines the trifluoromethyl-2,2-dihaloenones and
ethyl(benzyl)hydrazines chemoselectively provided
previously unknown 1-ethyl(benzyl)-3-trifluoromethyl-
substituted 5-chloro(bromo)pyrazoles VII–X.
Yet 2,2-difluoro-1-alkylvinyl phenyl(cyclohexyl)
ketones react with the monosubstituted alkyl(aryl)-
hydrazines giving 1-alkyl-(aryl)-3-phenyl(cyclohexyl)-
4-alkyl-5-fluoropyrazoles [14]. Ichikava et al. believe that
the reaction mechanism consisted in the initial replace-
ment of the fluorine atom followed by the intramolecular
heterocyclization of the arising 1-alkyl-(aryl)-1-(1-fluoro-
2-acyl-2-alkylvinyl)hydrazines into pyrazolines whose
dehydration led to the target pyrazoles.
O
CF3
In the present study we proved that the reactions of
2-chloro-, 1,2- and 2,2-dichlorovinyl ketones and of
dichloroacroleine with 1-phenyl- and 4-nitrophenyl-
hydrazine proceeded with primary formation of the
corresponding arylhydrazones XI–XX that were for the
first time isolated, characterized, or revealed by NMR
spectroscopy in the reaction mixture. These hydrazones
were converted in good yield into 1-aryl-3-R-pyrazoles
XXI–XXIX.
CF3CCH=CHlg2
NH2NHR
CF3CCH=CHlg2
NNHR
_HHlg
N
N
R
Hlg
VII_X
R =Et, Hlg = Cl (VII), Br (VIII); R = Bn, Hlg = Cl (IX),
Br (X).
Evidently here proceeded the heterocyclization of the
initially formed alkylhydrazones of the haloenones into
the corresponding 5-halo-1-alkylpyrazoles. However we
failed to isolate the corresponding individual hydrazones
under these conditions or at their variation.
A chemoselective synthesis gave in good yield pyr-
azoles XXII–XXIX by heating in acid medium pre-
liminary prepared arylhydrazones XI–XXI, among them
the previously described chloromethyl 2,2-dichlorovinyl
ketone 2,4-dinitrophenylhydrazone [15] (Scheme 9).
An alternative reaction mechanism involving primary
formation of 1-(1-halo-2-acylvinyl)-1-alkylhydrazine
halides followed by heterocyclization into pyrazoles we
regard as hardly probable since it is known that 1-[1-
bromo-2-benzoyl(2-thienoyl)vinyl]-1,1-dimethylhydra-
zine bromides obtained from the corresponding bromo-
ethynyl phenyl(thienyl-2) ketones and 1,1-di-methyl-
hydrazine whose structure has been established by XRD
study fail to undergo cyclization into pyrazoles [13].
1-Arylpyrazoles XXII–XXVIII were also obtained
in quantitative yields in one-pot procedure by heating a
mixture of arylhydrazines and halovinyl ketones in the
presence of acids. Here no isomeric 1-aryl-5-R-pyrazole
was obtained. This fact is evidently due to the lower
basicity of arylhydrazines that results in their inability
to nucleophilic addition-replacement of the halogen atom
in the haloenones.
Scheme 9.
NHR1
N
O
R2CCX=CYCl
s-cis-anti + s-trans-syn
XI_XXI
R1HNNH2 + R2CCX=CYCl
R2
X
R2
X
R2
X
C C
Y
_
C
N
.
_HCl
N
Cl
N
H
+
N
Y
N
R1
Cl
Y
N
R1
R1
H
XXII_XXIX
s-cis-anti
R1 = Ph: X = Y = H, R2 = Me (XI, XXII), Pr (XII); X = H, Y = Cl, R2 = CF3 (XIII, XXIII); X = Cl, Y = H, R2 = Me (XIV,
XXIV), C3H7 (XV, XXV); R1 = 4-O2NC6H4: X = Y = H, R2 = Me (XVI, XXVI); X = H, Y = Cl, R2 = H (XVII, XXVIII),
Pr (XVIII), Ph (XIX); X = Cl, Y = H, R2 = Et (XX), Pr (XXI); R1 = 2,4-(O2N)2C6H3, X = H, Y = Cl, R2 = CH2Cl (XXIX).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

BOZHENKOV et al.
1018
The addition of acid to the reaction mixture favors
phenylhydrazone (XIX) contains two pairs of singlets
belonging to these protons indicating that the substance
exists as a mixture of syn- and anti-isomers like the
phenyl 2,2-dichlorovinyl ketone 2,4-dinitrophenyl-
hydrazone [16].
In the 1H NMR spectra of the obtained pyrazoles the
signals of protons H4 appear in the region 5.9–6.5 ppm,
and the signals of protons H5, at 7.40–8.45 ppm.
the conversion of arylhydrazones into syn-isomers readily
undergoing cyclization into pyrazoles. In the course of
the heterocyclization of the 2,2-dichlorovinyl ketones
2,4-dinitrophenylhydrazones the syn-anti isomerism
plays the governing role: Dinitrophenylhydrazones of
aliphatic ketones exist mainly in the anti-form, dinitro-
phenylhydrazones of aromatic ketone, in the syn-form
facilitating the intramolecular heterocyclization [15–17].
The energy barrier of the transition between the forms is
relatively high [15], but as previously found [16] the syn-
anti conversion of the geometric isomers of hydrazones
is catalyzed by acids.
It is therefore established that alkyl 2-chlorovinyl
ketones react with alkyl(benzyl)hydrazines to provide
a mixture of 1,3- and 1,5-substituted pyrazoles, whereas
2,2-dihalovinyl ketones in the similar reaction chemo-
selectively form 1,3-disubstituted 5-halopyrazoles. A
chemo-selective formation of 1-arylpyrazoles also occurs
in reactions of 2-halo-, 2,2-dihaloenones and
arylhydrazines that undeniably makes these compounds
accessible and interesting objects of further research. The
employing in the pyrazole synthesis of alkyl(aryl) 2-
chloro- and 2,2-dichlorovinyl ketones and alkyl-,
arylhydrazines permits extensive variation both of the
structure and position of the substituents in the ring, and
also of the presence and position of chlorine in pyrazoles.
On the other hand the probable role of acid in the
heterocyclization of halovinyl ketones hydrazones
consists in the electrophilic activation of the nucleophilic
substitution. Thus the acid protonates the amidine
nitrogen, the effect is transferred along the system of the
conjugated bonds resulting in the increase in the
electrophilicity of the β-carbon of the double bond, and
it facilitates the nucleophilic attack of the amine nitrogen
on the carbon of the double bond.
Considering the experimental findings obtained it may
be concluded that 2-chlorovinyl ketones arylhydrazones
are already in the geometric form required for the
heterocyclization, or the energy barrier to the transition
between the configuration is far less that in 2,2-di-
chlorovinyl ketones 2,4-dinitrophenylhydrazones [15,
16]. For instance, already at the preparation of methyl-
2-chlorovinylketone arylhydrazones XI and XVI under
optimum conditions without heating the corresponding
pyrazoles XXII and XXVI form as impurity.
EXPERIMENTAL
IR spectra were recorded on a spectrophotometer
Specord 75IR from pellets with KBr or in thin film. 1H,
13C, and 15N NMR spectra of compounds obtained were
registered on spectrometers Bruker DPX-400 and Bruker
AV-400 (400.13, 100.62, and 40.56 MHz respectively).
1
Chemical shifts of H and 13C were measured from
tetramethylsilane with an accuracy of 0.01 and 0.02 ppm
respectively. Coupling constants JCH were measured with
an accuracy of 0.1 Hz. The carbon signals were assigned
using 2D heteronuclear NMR spectroscopy HSQC-GP
In the IR spectra of obtained hydrazones and pyrazoles
XI–XXIX characteristic absorption bands are observed
from the bonds C–HAlk, N–H, =C–H, C=N, C=C, and in
the spectra of hydrazones XVI–XXI and pyrazoles
XXVI–XXIX, also of NO2 groups. The IR spectra of
pyrazoles synthesized lack the strong absorption band
in the region 3300 cm–1 belonging to the vibrations of
NH in the initial hydrazones, and contain a new band in
the region 3145–3150 cm–1 characteristic of the stretch-
ing vibrations of =C4–H and =C5–H of the heterocycle.
13
1H− C [4], the quaternary carbon signals were assigned
with the help of 2D heteronuclear NMR spectroscopy
HMBC-GP 1H-13C [5]. HSQC-GP: matrix size 2Q × 1Q,
1H spectrum width 2000 Hz, 13C spectrum width
6000 Hz, relaxation delay 2 s. Before the Fourier trans-
form the signal of free induction decay was multiplied
by a bell function with a zero shift.
1
In the H NMR spectra of hydrazones XI–XX the
HMBC-GP: matrix size 2Q×1Q, 1H spectrum width
2000 Hz, 13C spectrum width 6000 Hz, relaxation delay
2 s. Parameter of pulse sequence were selected for
averaged coupling constants values 1JCH and nJCH. Before
the Fourier transform the signal of free induction decay
was multiplied by a bell function with a zero shift.
protons of NH group and of CH of the halovinyl group
give rise to singlets indicating that the compounds exist
as single geometric isomers and analogously to the struc-
ture of alkyl 2,2-dichlorovinyl ketones dinitrophenyl-
hydrazones presumably in the anti-form. The 1H NMR
spectrum of phenyl 2,2-dichlorovinyl ketone 4-nitro-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

DISTINGUISHING FEATURES OF REACTIONS OF 2-CHLORO(BROMO)VINYL KETONES
1019
Chemical shifts in 15N NMR spectrum were measured
with an accuracy of 0.1 ppm (relative to the external
reference CH135NO2) applying 2D heteronuclear NMR
Found, %: C 69.50; H 10.02; N 20.21. C8H14N2.
Calculated, %: C 69.52; H 10.21; N 20.27.
1-Butyl-3-propylpyrazole (II) and 1-butyl-5-
propylpyrazole (V) were obtained by procedure b from
0.88 g (0.01 mol) of butylhydrazine and 1.33 g
(0.01 mol) of 2-chlorovinyl propyl ketone. Yield 1.16 g,
ratio II:V = 5:2, bp 83–85°C (12 mm Hg). IR spectrum,
ν, cm–1: 3080 (=CH); 2960, 2930, 2875 (Alk); 1680, 1580
15
spectroscopy HMBC-GP 1H− N.
1
1
2D H− H-NMR spectra were obtained by NOESY
procedure using a standard program NOESYTP in the
phase-sensitive version [6], matrix size 2Q×1Q, spectrum
width 3000 Hz. The mixing period was adjusted for each
sample and amounted from 0.2 to 2 s.
1
(C=N, C=C). H NMR spectrum (CDCl3), δ, ppm:
7.45 d (H3, J 1.6 Hz), 7.27 d (H5, J 2.0 Hz), 6.04 d (H4,
J 2.0 Hz), 5.96 d (H4, J 1.6 Hz), 4.09 m (2H, CH2N,
J 7.2 Hz), 2.63, 2.56, 1.77, 1.65, 1.29 m (8H, 4CH2,
J 7.2 Hz), 0.93 m (6H, 2CH3, J 7.2 Hz). Found, %:
C 72.28; H 10.35; N 16.62. C10H18N2. Calculated, %:
C 72.24; H 10.91; N 16.85.
Mass spectra of electronic ionization (70 eV) of
compounds I–VI were measured on a Shimadzu GCMS-
QP5050A instrument (quadrupole mass analyzer, the
range of detected masses 34–650 D). The chromato-
graphic separation of compounds under study was per-
formed on a capillary column SPB-5 (60 m×0.25 mm×
0.25 μm), carrier gas helium, flow rate 0.7 ml/min. For
1-butyl-3(5)-propylpyrazoles (II, V) the temperature of
vaporizer and ion source 220°C, pressure 100 kPa; ramp
from 60 to 220°C at a rate 8 deg/min. For 1-benzyl-3(5)-
propylpyrazoles (III, VI) temperature of vaporizer and
ion source 250°C, pressure 280 kPa; ramp from 70 to
250°C at a rate 10 deg/min. The samples of 1μl were
chaged in the mode of flow division 1:2.
1-Benzyl-3-propylpyrazole (III) and 1-benzyl-5-
propylpyrazole (VI) were obtained by procedure a from
1.22 g (0.01 mol) of benzylhydrazine, 1.33 g (0.01 mol)
of 2-chlorovinyl propyl ketone, and 0.5 ml of acetic acid.
Yield 1.30 g, ratio III:VI = 2:1, undistillable oily liquid.
IR spectrum, ν, cm–1: 3080 (=CH); 2960, 2930, 2875
1
(Alk); 1680, 1580 (C=N, C=C). H NMR spectrum
(CDCl3), δ, ppm: 7.25 d (H3, J 16.7 Hz), 7.23, 7.03 m
(6H, H5, Ph), 6.04 d, 6.09 d (1H, H4, J 1.6, J 2.2 Hz),
5.27 s (2H, CH2N), 2.61 m (2H, CH2, J 7.2 Hz), 1.53 m
(2H, CH2, J 7.2 Hz), 0.92 m (3H, CH3, J 7.2 Hz). Found,
%: C 77.90; H 8.00; N 14.01. C13H16N2. Calculated, %:
C 77.96; H 8.05; N 13.99.
3-Propyl-1-ethylpyrazole (I) and 5-propyl-1-ethyl-
pyrazole (IV). a. To a solution of 0.60 g (0.01 mol) of
ethylhydrazine in 15 ml of ethanol was slowly added
dropwise 1.33 g (0.01 mol) of 2-chlorovinyl propyl
ketone and 1 ml of acetic acid. The reaction mixture
was boiled for 3 h, then cooled and poured into water.
The product was extracted into ethyl ether, the ether
extract was dried with CaCl2 and distilled. Yield of
pyrazoles I and IV mixture in the ratio 2:1 1 g (60%),
bp 78–84°C (8 mm Hg).
3-Trifluoromethyl-5-chloro-1-ethylpyrazole (VII).
To a solution of 1.93 g (0.01 mol) of 2,2-dichlorovinyl
trifluoromethyl ketone in 30 ml of ethanol was added
dropwise 0.60 g (0.01 mol) ethylhydrazine and 1.01 g
(0.01 mol) of triethylamine. The reaction mixture was
boiled for 3 h, cooled, and poured into water. The product
was extracted into ethyl ether, the ether extract was dried
with CaCl2 and distilled. Yield 1.48 g (74%), bp 158–
160°C, nD20 1.4235. IR spectrum, ν, cm–1: 3150 (=CH);
2985, 2950, 2900, 2875 (Alk); 1550 (C=N, C=C).
1H NMR spectrum (CDCl3), δ, ppm: 6.44 (1H, H4),
4.21 q (2H, CH2, J 7.3 Hz), 1.43 t (3H, CH3, J 7.3 Hz).
13C NMR spectrum (CDCl3), δ, ppm: 142.86 q (C3,
JC−F 39.1 Hz), 127.73 (C5), 120.69 q (CF3, JC−F 286.3 Hz),
103.25 q (C4, JC−F 2.3 Hz), 45.09 (CH2), 14.60 (CH3).
Found, %: C 36.15; H 3.02; Cl 17.83; F 28.72; N 14.05.
C6H6ClF3N2. Calculated, %: C 36.29; H 3.05; Cl 17.85;
F 28.70; N 14.11.
b. To a solution of 1.33 g (0.01 mol) of 2-chlorovinyl
propyl ketone in 15 ml of ethanol was slowly added
0.60 g (0.01 mol) of ethylhydrazine and 1.01 g (0.01 mol)
of triethylamine. The reaction mixture was stirred for
5 h and left overnight. Further workup was the same
as in procedure a. Yield 0.85 g. IR spectrum, ν, cm–1:
3080 (=CH); 2960, 2930, 2875 (Alk); 1680, 1580 (C=N,
C=C). 1H NMR spectrum (CDCl3), δ, ppm: 7.41 d (H3,
J 1.6 Hz), 7.27 d (H5, J 2.0 Hz), 6.01 d.d (1H, H4,
J 1.6, J 2.0 Hz), 4.09 m (2H, CH2N, J 7.2 Hz), 2.58 m
(2H, CH2, J 7.2 Hz), 1.68 m (2H, CH2, J 7.2 Hz) 1.43 m
(3H, CH3, J 7.2 Hz), 0.98 (3H, CH3, J 7.2 Hz). 13C NMR
spectrum (CDCl3), δ, ppm: 152.57, 141.62, 137.78,
128.40, 103.66, 103.42, 46.25, 43.31, 30.18, 27.15, 22.93,
22.70, 21.79 (CH2), 15.41, 15.30 (CH3), 13.69, 13.59.
5-Bromo-3-trifluoromethyl-1-ethylpyrazole (VIII)
was similarly obtained from 2.82 g (0.01 mol) of 2,2-di-
bromovinyl trifluoromethyl ketone, 0.60 g (0.01 mol) of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

BOZHENKOV et al.
1020
1
ethylhydrazine, and 1.01 g (0.01 mol) of triethylamine.
Yield 1.18 g (49%), bp 58–60°C, nD20 1.4425. IR spectrum,
ν, cm–1: 3150 (=CH); 2995, 2950, 2900, 2880 (Alk); 1575
3050 (=CH); 2950 (CH3); 1590 (C=C). H NMR
spectrum (CDCl3), δ, ppm: 7.68 d (1H, Hβ, J 13.7 Hz),
7.55 d, 7.29 m (5H, C6H5), 6.13 d (1H, Hα, J 13.7 Hz),
2.30 (3H, CH3). Found, %: C 61.75; H 5.68; Cl 18.24;
N 14.40. C10H11ClN2. Calculated, %: C 61.70; H 5.70
Cl 18.21; N 14.39;.
1
(C=N, C=C). H NMR spectrum (CDCl3), δ, ppm: 6.52
(1H, H4), 4.22 q (2H, CH2, J 7.3 Hz), 1.44 t (3H, CH3,
J 7.3 Hz). 13C NMR spectrum (CDCl3), δ, ppm: 142.63 q
(C3, JC−F 39.1 Hz), 127.73 (C5), 120.69 q (CF3,
JC−F 286.3 Hz), 107.03 q (C4, JC−F 2.3 Hz), 46.33 (CH2),
14.85 (CH3). Found, %: C 29.45; H 2.33; Br 31.07;
F 22.13; N 16.30. C6H6BrF3N2. Calculated, %: C 29.65;
H 2.49; Br 31.09; F 22.17; N 16.35.
Propyl 2-chlorovinyl ketone phenylhydrazone
(XII) was obtained from 1.33 g (0.01 mol) of propyl
2-chlorovinyl ketone and 1.08 g (0.01 mol) of phenyl-
hydrazine in 25 ml of ethanol. Yield 1.26 g (57%). IR
spectrum, ν, cm–1: 3250 (NH), 3100, 3050 (=CH); 2950,
1
1-Benzyl-3-trifluoromethyl-5-chloropyrazole (IX)
was similarly obtained from 1.93 g (0.01 mol) of 2,2-di-
chlorovinyl trifluoromethyl ketone, 1.22 g (0.01 mol) of
benzylhydrazine, and 1.01 g (0.01 mol) of triethylamine.
Yield 1.58 g (61%), bp 130–132°C (12 mm Hg). IR
spectrum, ν, cm–1: 3145, 3090, 3070, 3030 (=CH); 2975,
2930, 2870 (C3H7); 1590 (C=C). H NMR spectrum
(CDCl3), δ, ppm: 7.69 d (1H, Hβ, J 13.3 Hz), 7.55 d,
7.29 m (5H, C6H5), 6.18 d (1H, Hα, J 13.3 Hz), 2.70 t
(2H, CH2, J 7.2 Hz), 1.76 m (2H, CH2), 1.01 t (3H, CH3,
J 7.2 Hz). Found, %: C 65.20; H 6.29; Cl 15.97; N 12.62.
C12H14ClN2. Calculated, %: C 65.01; H 6.36; Cl 15.99;
N 12.64.
1
2950 (CH2); 1600, 1575, 1545 (C=N, C=C). H NMR
spectrum (CDCl3), δ, ppm: 7.35 m, 7.28 d (5H, C6H5),
6.53 (1H, H4), 5.40 (2H, CH2). Found, %: C 50.30;
H 3.08; Cl 13.58; F 21.89; N 10.73. C11H8ClF3N2.
Calculated, %: C 50.59; H 3.09; Cl 13.54; F 21.87; N 10.75.
2,2-Dichlorovinyl trifluoromethyl ketone phenyl-
hydrazone (XIII) was obtained from 1.93 g (0.01 mol)
of trifluoromethyl 2,2-dichlorovinyl ketone and 1.08 g
(0.01 mol) of phenylhydrazine in 25 ml of ethanol in 4 h.
Yield 1.23 g (54%). IR spectrum, ν, cm–1: 3300 (NH);
1-Benzyl-5-bromo-3-trifluoromethylpyrazole (X)
was similarly obtained from 2.82 g (0.01 mol) of 2,2-di-
bromovinyl trifluoromethyl ketone, 1.22 g (0.01 mol) of
benzylhydrazine, and 1.01 g (0.01 mol) of triethylamine.
Yield 2.19 g (72%), bp 130–132°C (12 mm Hg). IR
spectrum, ν, cm–1: 3145, 3090, 3070, 3030 (=CH); 2975,
1
3140, 3060 (=CH); 1590 (C=C). H (CDCl3), δ, ppm:
7.50 m, 7.44 m (5H, C6H5), 6.63 (1H, Hα). Found, %:
C 40.89; H 2.60; Cl 25.00; F 19.97; N 9.84.
C10H7Cl2F3N2. Calculated, %: C 42.43; H 2.49; Cl 25.05;
F 20.13; N 9.90.
1
2950 (CH2); 1600, 1575, 1545 (C=N, C=C). H NMR
1,2-Dichlorovinyl methyl ketone phenylhydrazone
(XIV) was obtained from 1.39 g (0.01 mol) of methyl
1,2-dichlorovinyl ketone and 1.08 g (0.01 mol) of phenyl-
hydrazine in 20 ml of ethanol. Yield 1.6 g (70%). IR
spectrum, ν, cm–1: 3340 (NH); 3130, 3055 (=CH); 2960,
spectrum (CDCl3), δ, ppm: 7.35 m, 7.26 d (5H, C6H5),
6.61 (1H, H4), 5.43 (2H, CH2). Found, %: C 43.15; H 2.66;
Br 26.20; F 18.69; N 9.19. C11H8BrF3N2. Calculated, %:
C 43.30; H 2.64; Br 26.19; F 18.68; N 9.18.
1
Phenylhydrazones of halovinyl ketones. To
a solution of halovinyl ketone in ethanol was slowly at
stirring added dropwise at room temperature equimolar
quantity of phenylhydrazine. The reaction mixture was
stirred at room temperature for 2–4 h and then diluted
with cold water. The separated oily dark-red substance
was extracted into ether, the extract was dried with
MgSO4, filtered from the drying agent, and the solvent
was removed in a vacuum. The residue consisted of the
hydrazone as oily undistillable fluid.
2920 (CH3); 1597 (C=C). H NMR spectrum (CDCl3),
δ, ppm: 7.78 (1H, Hβ), 7.45 m (5H, C6H5), 2.35 (3H,
CH3). Found, %: C 52.40; H 4.45; Cl 30.80; N 12.32.
C10H10Cl2N2. Calculated, %: C 52.42; H 4.40; Cl 30.95;
N 12.23.
1,2-Dichlorovinyl propyl ketone phenylhydrazone
(XV) was obtained from 1.67 g (0.01 mol) of propyl 1,2-
dichlorovinyl ketone and 1.08 g 0.01 mol) of
phenylhydrazine in 20 ml of ethanol. Yield 1.8 g (70%).
IR spectrum, ν, cm–1: 3300 (NH); 3130, 3050 (=CH);
1
Methyl 2-chlorovinyl ketone phenylhydrazone
(XI) was obtained from 1.05 g (0.01 mol) of 2-chloro-
vinyl methyl ketone in 20 ml of ethanol and 1.08 g
(0.01 mol) of phenylhydrazine in 2 h. The reaction
product contained up to 20% of 1-phenyl-3-methylpyr-
azole (XXII). IR spectrum, ν, cm–1: 3205 (NH), 3100,
2955, 2930, 2875 (C3H7); 1595 (C=C). H NMR
spectrum (CDCl3), δ, ppm: 7.80 s (1H, Hβ), 7.41 m (5H,
C6H5), 2.70 t (2H, CH2, J 7.2 Hz), 1.76 m (2H, CH2),
1.01 t (3H, CH3, J 7.2 Hz). Found, %: C 56.00; H 5.46;
Cl 27.53; N 10.86. C12H14Cl2N2. Calculated, %: C 56.05;
H 5.49; Cl 27.57; N 10.89.
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DISTINGUISHING FEATURES OF REACTIONS OF 2-CHLORO(BROMO)VINYL KETONES
1021
139°C. IR spectrum, ν, cm–1: 3300 (NH); 3115, 3070
(=CH); 1585 (C=C); 1550, 1305 (NO2). 1H NMR spec-
trum (DMSO-d6), δ, ppm: 10.64, 10.11 (NH), 8.17 d (2H,
H3',5', J 9.2 Hz), 7.44 d (2H, H2',6', J 9.2 Hz), 7.13, 6.91 s
(1H, H4). Found, %: C 53.59; H 3.30; Cl 21.09; N 12.50.
C15H11Cl2N3O2. Calculated, %: C 53.58; H 3.28; Cl 21.08;
N 12.48.
4-Nitrophenylhydrazones of halovinyl ketones. To
a solution of 1.53 g (0.01 mol) of 4-nitrophenyl-
hydrazine and 0.5 ml of H2SO4 in 40 ml of ethanol was
slowly at stirring added dropwise at room temperature
an equimolar quantity of halovinyl ketone. The reaction
mixture was stirred for 4 h at room temperature, then it
was diluted with cold water, the separated precipitate
was filtered off, washed with water, and dried.
Ethyl 1,2-dichlorovinyl ketone 4-nitrophenyl-
hydrazone (XX) was obtained from 1.53 g (0.01 mol)
of 1,2-dichlorovinyl ethyl ketone and 1.53 g (0.01 mol)
of 4-nitrophenylhydrazine. Yield 2.66 g (97%), mp 122–
123°C. IR spectrum, ν, cm–1: 3295 (NH); 3180, 3075
(=CH); 2975 (C2H5); 1600 (C=N); 1590 (C=C); 1520,
1310 (NO2). 1H NMR spectrum (DMSO-d6), δ, ppm:
10.34 (1H, NH), 8.12 d (2H, H3',5', J 7.4 Hz), 7.37 s (1H,
H5), 7.34 d (2H, H2',6', J 7.4 Hz), 2.69 q (2H, CH2,
J 7.7 Hz), 1.06 t (3H, CH3, J 7.7 Hz). Found, %: C 45.85;
H 3.85; Cl 24.61; N 14.58. C11H11Cl2N3O2. Calculated,
%: C 45.83; H 3.81; Cl 24.60; N 14.56.
Methyl 2-chlorovinyl ketone 4-nitrophenyl-
hydrazone (XVI) was obtained from 1.05 g (0.01 mol)
of methyl 2-chlorovinyl ketone and 1.53 g (0.01 mol) of
4-nitrophenylhydrazine. The precipitate consisted of
hydrazone XVI and 1-(4-nitrophenyl)-3-methylpyrazole
(XXVI) in the ratio 1:1, mp 165–166ºC. IR spectrum, ν,
cm–1: 3300 (NH); 3050 (=CH); 2960 (CH3); 1600 (C=N);
1
1585 (C=C); 1540, 1330 (NO2). H NMR spectrum
(DMSO-d6), δ, ppm: 10.18 (NH), 8.33 d (2H, H3',5'
,
J 9.0 Hz), 8.11 d (2H, H2',6', J 9.0 Hz), 6.98 d (1H, Hβ,
J 13.7 Hz), 6.62 d (1H, Hα, J 13.7 Hz), 2.30 c (3H, CH3).
Propyl 1,2-dichlorovinyl ketone 4-nitrophenyl-
hydrazone (XXI) was obtained from 1.67 g (0.01 mol)
of 1,2-dichlorovinyl propyl ketone and 1.53 g (0.01 mol)
of 4-nitrophenylhydrazine. Yield 2.82 g (98%), mp 114–
116°C. IR spectrum, ν, cm–1: 3295 (NH); 3180, 3075
(=CH); 2950, 2910 (C3H7); 1600 (C=N); 1590 (C=C);
β,β-Dichloroacrolein 4-nitrophenylhydrazone
(XVII) was obtained from 1.25 g (0.01 mol) of β,β-di-
chloroacrolein and 1.53 g (0.01 mol) of 4-nitro-
phenylhydrazine. Yield 2.52 g (97%), mp 207–208°C.
IR spectrum, ν, cm–1: 3250 (NH); 3150, 3100, 3070
(=CH); 1600 (C=N); 1580 (C=C); 1550, 1305 (NO2).
1H NMR spectrum (DMSO-d6), δ, ppm: 11.43 (1H, NH),
8.10 d(2H, H3',5', J 9.3 Hz), 7.79 d (1H, Haλüd., J 8.9 Hz),
7.05 d (2H, H2',6', J 9.3 Hz), 6.84 d (1H, Hα, J 8.9 Hz).
Found, %: C 47.56; H 2.71; Cl 30.26; N 18.16.
C9H7Cl2N3O2. Calculated, %: C 47.58; H 3.11; Cl 30.81;
N 18.51.
1
1520, 1310 (NO2). H NMR spectrum (DMSO-d6), δ,
ppm: 10.34 (1H, NH), 8.12 d (2H, H3',5', J 7.4 Hz),
7.37 s (1H, H5), 7.34 d (2H, H2',6', J 7.4 Hz), 2.60 t (2H,
CH2, J 7.7 Hz), 1.59 m (2H, CH2, J 7.7 Hz), 1.01 t (3H,
CH3, J 7.7 Hz). Found, %: C 47.70; H 4.34; Cl 23.47;
N 13.91. C12H13Cl2N3O2. Calculated, %: C 47.68; H 4.35;
Cl 23.45; N 13.90.
Propyl 2,2-dichlorovinyl ketone 4-nitrophenyl-
hydrazone (XVIII) was obtained from 1.67 g (0.01 mol)
of 2,2-dichlorovinyl propyl ketone and 1.53 g (0.01 mol)
of 4-nitrophenylhydrazine. Yield 2.87 g (95%), mp 115–
117°C. IR spectrum, ν, cm–1: 3300 (NH); 3030 (=CH);
2950, 2920, 2870 (C3H7); 1600 (C=N); 1585 (C=C);
1550, 1310 (NO2). 1H NMR spectrum (DMSO-d6), δ,
ppm: 10.32 s (1H, NH), 8.09 d (2H, H3',5', J 7.3 Hz),
7.28 d (2H, H2',6', J 7.3 Hz), 6.71 s (1H, H4), 2.46 t (2H,
CH2, J 7.2 Hz), 1.46 m (2H, CH2, J 7.2 Hz), 0.91 t (3H,
CH3, J 7.2 Hz). Found, %: C 43.83; H 4.35; Cl 23.23;
N 13.95. C12H13Cl2N3O2. Calculated, %: C 47.80; H 4.32;
Cl 23.22; N 13.94.
1-Phenyl-3-alkylpyrazoles, 1-phenyl-3-alkyl-4(5)-
chloropyrazoles, and 1-(4-nitrophenyl)-3-alkyl-
pyrazoles. a. To a solution of 0.01–0.02 mol of aryl-
hydrazine in 30–40 ml of ethanol and 0.5 ml of H2SO4
was added dropwise at stirring an equimolar quantity of
chlorovinyl ketone. The reaction mixture was boiled for
2 h and then poured into 100 ml of water. The target
pyrazole was extracted into chloroform, dichloro-
methane, or ether, the extract was dried with CaCl2 and
distilled in a vacuum; or the precipitate formed on
removing the solvents was filtered off, washed with
water, and dried.
b. A solution of 0.01 mol of chlorovinyl ketone
arylhydrazone in 30 ml of ethanol and 0.5 ml of H2SO4
was boiled for 2 h and poured into water. Further workup
was carried out as described above.
Phenyl 2,2-dichlorovinyl ketone 4-nitrophenyl-
hydrazone (XIX) was obtained from 2.01 g (0.01 mol)
of 2,2-dichlorovinyl phenyl ketone and 1.53 g (0.01 mol)
of 4-nitrophenylhydrazine. Yield 3.23 g (96%), mp 94–
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

BOZHENKOV et al.
1022
CH2, J 7.4 Hz), 0.98 t (3H, CH3, J 7.4 Hz). 13C NMR
spectrum (CDCl3), δ, ppm: 151.46 (C3), 139.83 (C1'),
129.41 (C3',4'), 126.36 (C5), 124.84 (C4'), 118.59 (C2',6'),
27.89 (CH2), 21.89 (CH2), 13.87 (CH3). Found, %:
C 65.35; H 6.00; Cl 16.08; N 12.66. C12H13ClN2.
Calculated, %: C 65.31; H 5.99; Cl 16.06; N 12.69.
3-Methyl-1-phenylpyrazole (XXII). a. It was
obtained from 1.05 g (0.01 mol) of methyl 2-chlorovinyl
ketone and 1.08 g (0.01 mol) of phenylhydrazine. Yield
1.19 g (75%), bp 103°C (4 mm Hg), nD20 1.5870. IR
spectrum, ν, cm–1: 3105, 3045 (=CH); 2920 (CH3); 1580
1
(C=C). H NMR spectrum (CDCl3), δ, ppm: 7.66 d (1H,
H5, J 2.3 Hz), 7.54 d, 7.28 t, 7.12 t (5H, C6H5), 6.11 d
(1H, H4, J 2.3 Hz). 13C NMR spectrum, δ, ppm: 150.48
(C3), 140.31 (C1'), 129.40 (C3',5'), 127.35 (C5), 125.90
(C4'), 118.76 (C2',6'), 13.82 (CH3). Found, %: C 75.90;
H 6.40; N 17.70. C10H10N2. Calculated, %: C 75.92;
H 6.37; N 17.71.
3-Methyl-1-(4-nitrophenyl)pyrazole (XXVI). a. It
was obtained from 1.05 g (0.01 mol) of methyl 2-chloro-
vinyl ketone and 1.53 g (0.01 mol) of 4-nitrophenyl-
hydrazine. Yield 1.83 g (90%), mp 165–166°C.
b. To the cyclization was subjected 1 g of a mixture
of methyl 2-chlorovinyl ketone 4-nitrophenylhydrazone
and 1-(4-nitrophenyl)-3-methylpyrazole in a ratio 1:1.
Yield 0.83 g (90%). IR spectrum, ν, cm–1: 3145, 3120,
3085, 3055 (=CH); 1600 (C=N); 1595 (C=C); 1535, 1320
(NO2). 1H NMR spectrum (DMSO-d6), δ, ppm: 8.62 d
(1H, H5, J 2.3 Hz), 8.36 d (2H, H3',5', J 7.9 Hz), 8.08 d
(2H, H2',6', J 7.9 Hz), 6.50 (1H, H4, J 2.3 Hz), 2.34 (3H,
CH3). Found, %: C 59.15; H 4.43; N 20.70. C10H9N3O2.
Calculated, %: C 59.11; H 4.46; N 20.68.
3-Trifluoromethyl-1-phenyl-5-chloropyrazole
(XXIII). a. It was obtained from 1.93 g (0.01 mol) trifluoro-
methyl 2,2-dichlorovinyl ketone and 1.08 g (0.01 mol)
of phenylhydrazine. Yield 1.75 g (71%), bp 97°C (4 mm
Hg), nD20 1.5075.
b. It was obtained from 1 g (3.5 mmol) of trifluoro-
methyl 2,2-dichlorovinyl ketone phenylhydrazone. Yield
0.7 g (80%). IR spectrum, ν, cm–1: 3150, 3070 (=CH);
1595 (C=C). 1H NMR spectrum (CDCl3), δ, ppm: 7.48 d,
7.42 m (5H, C6H5), 6.60 (1H, H4). 13C NMR spectrum,
δ, ppm: 143.34 q (C3, JC−F 39.2 Hz), 137.47 (C1'), 129.37
(C5), 129.24 (C3',5'), 128.93 (C4'), 125.34 (C2',6'), 120.79 q
(CF3, JC−F 269.4 Hz), 104.80 q (C4, JC−F 2.2 Hz). Found,
%: C 48.72; H 2.47; Cl 14.41; N 11.39. C10H6ClF3N2.
Calculated, %: C 48.70; H 2.45; Cl 14.38; N 11.36.
1-(4-Nitrophenyl)-3-propylpyrazole (XXVII). a. It
was obtained from 1.33 g (0.01 mol) of propyl 2-chloro-
vinyl ketone and 1.53 g (0.01 mol) of 4-nitrophenyl-
hydrazine. Yield 2.10 g (90%), mp 104–105°C. IR spec-
trum, ν, cm–1: 3130, 3120, 3080 (=CH); 2950, 2915, 2870
(C3H7); 1600 (C=N); 1595 (C=C); 1525, 1320 (NO2).
1H NMR spectrum (DMSO-d6), δ, ppm: 8.52 d (1H,
H5, J 2.3 Hz), 8.26 d (2H, H3',5', J 8.9 Hz), 8.00 d
(2H, H2',6', J 8.9 Hz), 6.42 (1H, H4, J 2.3 Hz), 2.56 t (2H,
CH2, J 7.7 Hz), 1.61 m (2H, CH2, J 7.7 Hz), 0.89 t (3H,
CH3, J 7.7 Hz). 13C NMR spectrum (DMSO-d6), δ, ppm:
156.58 (C3), 144.63 (C4'), 144.54 (C1'), 129.71 (C5),
125.79 (C3',5'), 118.24 (C2',6'), 109.01 (C4), 30.15 (CH2);
23.30 (CH2); 14.13 (CH3). Found, %: C 62.35; H 5.70;
N 18.15. C12H13N3O2. Calculated, %: C 62.33; H 5.67;
N 18.17.
3-Methyl-1-phenyl-4-chloropyrazole (XXIV). a. It
was prepared from 1.39 g (0.01 mol) of methyl 1,2-di-
chlorovinyl ketone and 1.08 g (0.01 mol) of phenyl-
hydrazine. Yield 1.48 g (77%), bp 125°C (4 mm Hg). IR
spectrum, ν, cm–1: 3130, 3050 (=CH); 2950, 2920 (CH3);
1595 (C=C). 1H NMR spectrum (CDCl3), δ, ppm: 7.76
(1H, H5), 7.55 d, 7.37 t, 7.20 t (5H, C6H5), 2.28 (3H,
CH3). Found, %: C 62.30; H 4.75; Cl 18.38; N 14.52.
C10H9ClN2. Calculated, %: C 62.35; H 4.71; Cl 18.40;
N 14.54.
1-(4-Nitrophenyl)-5-chloropyrazole (XXVIII).
A solution of 2.6 g (0.01 mol) of β,β-dichloroacrolein
4-nitrophenylhydrazone in 30 g of polyphosphoric acid
was heated at 130°C with stirring for 30 min. The reaction
mixture was cooled, diluted with cold water, the
separated precipitate was filtered off, washed, and dried.
Yield 1.90 g (85%), mp 102–104°C. IR spectrum, ν,
cm–1: 3145, 3075 (=CH); 1600 (C=N); 1595 (C=C);
3-Propyl-1-phenyl-4-chloropyrazole (XXV). a. It
was prepared from 1.67 g (0.01 mol) of propyl 1,2-di-
chlorovinyl ketone and 1.08 g (0.01 mol) of
phenylhydrazine. Yield 1.55 g (70%), bp 155°C (8 mm
Hg), nD20 1.5766.
b. It was obtained from 1.5 g (5.8 mmol) of propyl
1,2-dichlorovinyl ketone phenylhydrazone. Yield 1.54 g
(70%). IR spectrum, ν, cm–1: 3140, 3050 (=CH); 2950,
1
1510, 1340 (NO2). H NMR spectrum (DMSO-d6), δ,
1
ppm: 8.40 d (2H, H3',5', J 7.2 Hz), 7.93 d (2H, H2',6'
,
2925, 2870 (C3H7); 1595 (C=C). H NMR spectrum
(CDCl3), δ, ppm: 7.76 (1H, H5), 7.57 d, 7.37 t, 7.21 t
(5H, C6H5), 2.65 t (2H, CH2, J 7.4 Hz), 1.73 m (2H,
J 7.2 Hz), 7.92 (1H, H3, J 1 Hz), 6.77 (1H, H4, J 1 Hz).
13C NMR spectrum (DMSO-d6), δ, ppm: 146.38 (C4'),
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

DISTINGUISHING FEATURES OF REACTIONS OF 2-CHLORO(BROMO)VINYL KETONES
1023
142.44 (C1'), 142.17 (C3), 126.61 (C5), 125.07 (C3',5'),
124.70 (C2',6'), 108.27 (C4). Found, %: C 48.35; H 2.75;
Cl 15.83; N 18.80. C9H6ClN3O2. Calculated, %: C 48.34;
H 2.70; Cl 15.85; N 18.79.
7. Polyakova, A.A. and Khmel’nitskii, R.A., Mass-
spektrometriya organicheskoi khimii (Mass
v
Spectrometry in Organic Chemistry), Leningrad: Khimiya,
1972, p. 367; Zaikin, V.G., Varlamov, A.V., Mikaya, A.I.,
and Prostakov, N.S., Osnovy mass-spektrometrii
organicheskikh soedinenii (Bases of Mass Spectrometry
of Organic Compounds), Moscow: MAIK “Nauka/
Interperiodika”, 2001, p. 285.
1-(2,4-Dinitrophenyl)-5-chloro-3-chloromethyl-
pyrazole (XXIX) was similarly obtained from 3.53 g
(0.01 mol) of 2,2-dichlorovinyl chloromethyl ketone 2,4-
dinitrophenylhydrazone [16] in 40 g of polyphosphoric
acid. Yield 3.01 g (95%), mp 70–72°C. IR spectrum, ν,
cm–1: 3145, 3075 (=CH); 2880 (CH2Cl); 1600 (C=C);
8. Lebedev, A.T., Mass-spektrometriya v organicheskoi
khimii (Mass Spectrometry in Organic Chemistry),
Moscow: BINOM, 2003, p. 493.
9. Kingston, D.G.I., Bursey, J.T., and Bursey, M.M., Chem.
Rev., 1974, vol. 74, p. 215.
10. Levkovskaya, G.G., Bozhenkov, G.V., and Mirskova,A.N.,
Izbrannye metody sinteza i modifikatsii geterotsiklov
(Selected Methods of Synthesis and Heterocycle Modifica-
tion), Kartsev, V.G., Ed., Moscow: IBS PRESS, 2003,
vol. 2, p. 284.
11. Levkovskaya, G.G., Mirskova, A.N., Dolgushin, G.V.,
Larina, L.N., Ushakov, P.E., and Bozhenkov, G.V., Zh. Org.
Khim., 2003, vol. 39, p. 1140.
1
1525, 1330 (NO2). H NMR spectrum (CDCl3), δ, ppm:
8.90 (1H, H3'), 8.62 d (1H, H5', J 8.7 Hz), 7.91 d (1H, H6',
J 8.7 Hz), 6.61 (1H, H4), 4.57 (2H, CH2Cl). Found, %: C
37.86; H 2.00; Cl 22.38; N 17.69. C10H6Cl2N4O4.
Calculated, %: C 37.88; H 1.91; Cl 22.36; N 17.67.
The study was carried out under a financial support
of the Russian Foundation for Basic Research (grant no.
05-03-97202) and of Siberian Division of the Russian
Academy of Sciences (interdisciplinary integration
project no. 54 “Scientific fundamentals of development
of new pharmaceuticals. Prospects of application of
recycled raw materials”).
12. Bozhenkov, G.V., Levkovskaya, G.G., Larina, L.I.,
Ushakov, P.E., Dolgushin, G.V., and Mirskova, A.N., Zh.
Org. Khim., 2004, vol. 40, p. 1632.
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