Synthesis of α,ω-bis(pyrazol-3-yl)alkanes: I. 1,4-bis(1-methyl- and 1-benzyl-5-chloro-1H-pyrazol-3-yl)-butanes from 1,1,10,10-Tetrachlorodeca- 1,9-diene-3,8-dione and 1,1-dimethyl- or benzylhydrazine

Article abstract of DOI:10.1134/S1070428011120141

First representatives of bis-2-chloro- and 2,2-dichlorovinyl ketones, 1,10-dichlorodeca-1,9-diene-3,8-dione and 1,1,10,10-tetrachlorodeca-1,9-diene-3, 8-dione, were synthesized by reaction of hexanedioyl dichloride with acetylene and 1,1-dichloroethene, respectively, in the presence of AlCl₃. 1,1,10,10-Tetrachlorodeca-1,9-diene-3,8-dione reacted with benzylhydrazine and 1,1-dimethylhydrazine to give 1,4-bis(1-benzyl-5-chloro-1H-pyrazol-3-yl)butane and 1,4-bis(5-chloro-1-methyl-1H-pyrazol-3-yl)butane, respectively.

Full text of DOI:10.1134/S1070428011120141

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 12, pp. 1870–1873. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © E.V. Rudyakova, D.O. Samul’tsev, G.V. Bozhenkov, G.G. Levkovskaya, 2011, published in Zhurnal Organicheskoi Khimii, 2011,
Vol. 47, No. 12, pp. 1834–1837.
Dedicated to Full Member of the Russian Academy of Sciences
M.G. Voronkov on his 90th anniversary
Synthesis of α,ω-Bis(pyrazol-3-yl)alkanes:
I. 1,4-Bis(1-methyl- and 1-benzyl-5-chloro-1H-pyrazol-3-yl)-
butanes from 1,1,10,10-Tetrachlorodeca-1,9-diene-3,8-dione
and 1,1-Dimethyl- or Benzylhydrazine
E. V. Rudyakova, D. O. Samul’tsev, G. V. Bozhenkov, and G. G. Levkovskaya
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: ggl@irioch.irk.ru
Received May 24, 2011
Abstract—First representatives of bis-2-chloro- and 2,2-dichlorovinyl ketones, 1,10-dichlorodeca-1,9-diene-
3,8-dione and 1,1,10,10-tetrachlorodeca-1,9-diene-3,8-dione, were synthesized by reaction of hexanedioyl
dichloride with acetylene and 1,1-dichloroethene, respectively, in the presence of AlCl3. 1,1,10,10-Tetrachloro-
deca-1,9-diene-3,8-dione reacted with benzylhydrazine and 1,1-dimethylhydrazine to give 1,4-bis(1-benzyl-5-
chloro-1H-pyrazol-3-yl)butane and 1,4-bis(5-chloro-1-methyl-1H-pyrazol-3-yl)butane, respectively.
DOI: 10.1134/S1070428011120141
Organic compounds containing two and more pyra-
zole fragments attract considerable interest from both
theoretical and practical viewpoints primarily due to
the possibility of using them as ligands for the pre-
paration of polynuclear complexes and coordination
polymers possessing valuable properties [1–17]. Multi-
topic pyrazole-containing ligands are also used as
sorbents and intermediate products for the synthesis of
compounds exhibiting biological and catalytic activity,
and they can be involved in self-assembly of supra-
molecular ensembles, etc. On the other hand, organic
polypyrazole ligands were studied insufficiently be-
cause of their low accessibility; therefore, search for
new synthetic approaches to such compounds remains
an important problem [1–17].
of the corresponding bis-β-diketones with hydrazine
hydrate [16, 17]. Thus chemoselective synthesis of
3,3′-bridged bis-pyrazoles attracts strong interest.
We develop a novel approach to linearly bridged
α,ω-bis(pyrazol-3-yl)alkanes via heterocyclization of
difunctional halovinyl ketones. In the present com-
munication we report on the synthesis of first repre-
sentatives of difunctional 2,2-dichloro- and 2-chloro-
vinyl ketones, 1,1,10,10-tetrachlorodeca-1,9-diene-3,8-
dione (II) and 1,10-dichlorodeca-1,9-diene-3,8-dione
(III) by reactions of adipoyl chloride with 1,1-di-
chloroethene and acetylene, respectively, in the pres-
ence of aluminum chloride according to the procedure
described in [18] (Scheme 1). The reactions were
carried out in methylene chloride at –5 to 20°C (reac-
tion time 8 h. Unlike known procedures for the syn-
thesis of alkyl 2,2-dichlorovinyl ketones [18], dehy-
drochlorination of 1,1,1,10,10,10-hexachlorodecane-
3,8-dione (I) was effected by treatment with triethyl-
amine. The yields (unoptimized) of ketones II and III
were 21 and 62%, respectively. Compounds II and III
were isolated as crystalline substances with a specific
odor; they were poorly soluble in hexane and readily
soluble in other organic solvents.
The most widely known are ensembles in which
pyrazole ring is linked through the pyrrole-type nitro-
gen atom [1–12]. 4,4′-Bis-pyrazole systems are fairly
accessible; they are synthesized by reactions of poly-
electrophiles with pyrazoles, aldehydes, and ketones
[13–15]. A number of 3(5)-methyl(ethyl)-substituted
bis-pyrazoles bridged at the 5,5′(3,3′)-positions by
alkanediyl, 1,4-methylenephenyl, and 1,4′-diphenyl-
eneoxy(disulfido) spacers were obtained by reaction
1870

SYNTHESIS OF α,ω-BIS(PYRAZOL-3-YL)ALKANES: I.
1871
Scheme 1.
O
Cl
O
CH2
Cl
Cl
Cl
AlCl3, CH2Cl2, 8 h
Cl
+
Cl
Cl
Cl
Cl
O
O
Cl
I
Cl
O
Et3N, Et2O, 30 min
Cl
Cl
O
Cl
II
O
H
O
AlCl3, CH2Cl2, 8 h
Cl
Cl
+
HC CH
Cl
Cl
O
O
H
III
We previously showed [19] that 2,2-dichlorovinyl
alkyl (or aryl) ketones chemoselectively react with
alkyl-, aryl-, and dialkylhydrazines to give the corre-
sponding 1-substituted 5-chloropyrazoles. Reactions of
2-chlorovinyl alkyl ketones with dialkylhydrazines
lead to 1,3-substituted pyrazoles, whereas alkylhydra-
zines give rise to mixtures of 1,3- and 1,5-dialkylpyra-
zoles [20]. We have found that bis(dichlorovinyl
ketone) II reacts with benzylhydrazine and 1,1-dimeth-
ylhydrazine in a chemoselective fashion, yielding pre-
viously unknown bridged bis-pyrazoles, 1,4-bis(1-ben-
zyl-5-chloro-1H-pyrazol-3-yl)butane (IV) and 1,4-bis-
(5-chloro-1-methyl-1H-pyrazol-3-yl)butane (V), re-
spectively, in up to 83% yield (Scheme 2). Pyrazoles
IV and V are oily substances with a specific odor; they
are poorly soluble in hexane and readily soluble in
other organic solvents. The structure of diketones I–III
and bis-pyrazoles IV and V was confirmed by their
1H and 13C NMR spectra and elemental analyses.
100.61 MHz, respectively, from solutions in CDCl3
using hexamethyldisiloxane as internal reference.
Adipoyl chloride was prepared by heating a mixture of
adipic acid and 4 equiv of thionyl chloride under reflux
over a period of 40 h; bp 95–97°C (4 mm).
1,1,1,10,10,10-Hexachlorodecane-3,8-dione (I)
and 1,1,10,10-tetrachlorodeca-1,9-diene-3,8-dione
(II). Adipoyl chloride, 9.15 g (0.05 mol), was dis-
solved in 100 ml of thionyl chloride, 13.33 g (0.1 mol)
of aluminum chloride was added under vigorous
stirring at room temperature, and the mixture was
stirred for 15–20 min. The mixture was then cooled to
–5 to 0°C, 5.82 g (0.06 mol) of 1,1-dichloroethene was
added dropwise over a period of 10 min, and the
mixture was stirred for 8 h, allowing it to gradually
warm up to 20°C, and poured onto ice. The organic
phase was separated, the aqueous phase was extracted
with methylene chloride, and the extract was combined
with the organic phase and dried over MgSO4. The
drying agent was filtered off, and the filtrate was
evaporated. The residue was a mixture containing 78%
of diketone I and 22% of diketone II. Recrystallization
from hexane gave 4.12 g of mixture I/II with mp 36–
50°C. 1H NMR spectrum, δ, ppm: I: 1.63 m (4H, CH2,
J = 6.8 Hz), 2.26 m (4H, CH2, J = 6.8 Hz), 3.79 s (4H,
CH2CCl3); II: 1.62 m (4H, CH2, J = 6.9 Hz), 2.30 m
(4H, CH2, J = 6.9 Hz), 6.67 s (2H, CH=). 13C NMR
Thus we were the first to synthesize bis(chloro- and
dichlorovinyl ketones) and demonstrate their potential
for the synthesis of bis-pyrazole ensembles.
EXPERIMENTAL
1
The H and 13C NMR spectra were recorded on
a Bruker DPX-400 spectrometer at 400.13 and
Scheme 2.
Cl
O
N
Cl
R
N
Et2O, 5 h
Cl
+
H2NNRR'
Cl
N
Cl
R
N
O
Cl
II
IV, V
R = H, R′ = PhCH2; R = R′ = Me; IV, R = PhCH2; V, R = Me.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 12 2011

RUDYAKOVA et al.
1872
spectrum, δC, ppm: I: 22.7 (CH2), 43.8 (CH2),
63.8 (CH2), 92.8 (CCl3), 200.7 (CO); II: 19.6 (CH2),
22.7 (CH2), 43.6 (CH2), 126.3 (=CH), 134.5 (CCl2),
195.0 (CO).
(CH2), 28.8 (CH2), 52.3 (NCH2), 103.5 (C4), 126.9
(Co), 127.6 (C5), 128.4 (Cp), 128.7 (Cm), 136.2 (Ci),
153.1 (C3). Found, %: C 66.22; H 5.78; Cl 5.64;
N 12.36. C24H24Cl2N4. Calculated, %: C 65.61; H 5.51;
Cl 16.14; N 12.75.
1,1,10,10-Tetrachlorodeca-1,9-diene-3,8-dione
(II). A solution of 4.12 g of diketone mixture I/II in
50 ml of diethyl ether was cooled to –5 to 0°C,
an equimolar amount of triethylamine was added, and
the mixture was stirred for 10 min and treated with
water. The organic phase was separated, dried over
MgSO4, filtered, and evaporated, and the residue was
recrystallized from hexane. Yield 3.16 g (21%, calcu-
lated on the initial adipoyl chloride), mp 76–78°C.
Found, %: C 39.71; H 3.52; Cl 46.05. C10H10Cl4O2.
Calculated, %: C 39.51; H 3.32; Cl 46.65.
3,3′-(Butane-1,4-diyl)bis(5-chloro-1-methyl-1H-
pyrazole) (V) was synthesized in a similar way from
1.52 g (0.005 mol) of diketone II and 1.2 g (0.02 mol)
of 1,1-dimethylhydrazine. Yield 1.27 g (80%), oily
1
substance. H NMR spectrum, δ, ppm: 1.65 m (4H,
CH2, J = 6.8 Hz), 2.55 m (4H, CH2, J = 6.8 Hz), 3.73 s
(6H, NCH3), 5.95 s (2H, 3-H). 13C NMR spectrum, δC,
ppm: 28.3 (CH2), 28.9 (CH2), 35.7 (NCH3), 103.0 (C4),
126.9 (C5), 152.6 (C3). Found, %: C 50.29; H 5.68;
Cl 24.99; N 19.01. C12H16Cl2N4. Calculated, %:
C 50.19; H 5.62; Cl 24.69; N 19.51.
1,10-Dichlorodeca-1,9-diene-3,8-dione (III).
Acetylene was bubbled over a period of 2 h through
a solution of 9.15 g (0.05 mol) of adipoyl chloride in
100 ml of methylene chloride under vigorous stirring
at room temperature. The mixture was cooled to 0°C,
13.33 g (0.1 mol) of aluminum chloride was added,
and the mixture was stirred for 8 h, allowing it to
slowly warm up to 20°C, and poured onto ice. The
organic phase was separated, the aqueous phase was
extracted with methylene chloride, the extract was
combined with the organic phase, dried over MgSO4,
filtered, and evaporated, and the residue was recrystal-
lized from petroleum ether. Yield 7.29 g (62%),
This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 11-03-00461).
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