Phosphorylation of C-alkenylsubstituted pyrazoles with phosphorus pentachloride

Full text of DOI:10.1134/S1070363209060358

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 6, pp. 1221–1222. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © L.I. Larina, E.V. Rudyakova, V.А. Savosik, G.G. Levkovskaya, V.G. Rozinov, M.Yu. Dmitrichemko, 2009, published in Zhurnal
Obshchei Khimii, 2009, Vol. 79, No. 6, pp. 1046–1047.
LETTERS
TO THE EDITOR
Phosphorylation of С-Alkenylsubstituted Pyrazoles
with Phosphorus Pentachloride
L. I. Larinaa, E. V. Rudyakovaa, V. А. Savosika, G. G. Levkovskayaa,
V. G. Rozinovb, and M. Yu. Dmitrichenkob
a Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: larina@irioch.irk.ru
b Irkutsk State University, Irkutsk, Russia
Received February 19, 2009
DOI: 10.1134/S1070363209060358
The reaction of phosphorus pentachloride with
styrenes affords unsaturated organophosphorus com-
pounds in which the phosphorus chloride substituent is
attached to the carbon atom of the double bond [1]. N-
Vinylsubstituted azoles are also phosphorylated at the
double bond [2–3]. Phosphorylation of С-alken-
ylazoles with phosphorus pentachloride was not
studied until now.
The presence in the azole cycles the “pyridine”
nitrogen atoms with enhanced nucleophilicity could
direct the attack of phosphorus pentachloride to the
heterocycle rather than to the double bond of С-
vinylazoles to give donor–acceptor complexes. Indeed,
the reaction of phosphorus pentachloride with 1-allyl-
3,5-dimethylpyrazole led to formation of the donor–
acceptor complex I.
Me
Me
_
+
N
PCl5
N
+ PCl5
N
N
Me
Me
CH2CH=CH2
CH2CH=CH2
I
In the 31Р NMR spectrum of compound I a singlet
signal at –264.3 ppm characteristic of hexacoordinate
phosphorus atom [3] is observed.
propenyl-1H-pyrazole in 2 ml of benzene was added
dropwise upon stirring to the solution of 1.5 g of
phosphorus pentachloride in 5 ml of benzene. Com-
pound III is isolated as a heavy oil crystallized
overnight to give yellow crystals hydrolyzed in the air.
Yield of III 1.2 g (91%). 31Р NMR spectrum (MeNO2),
δP, ppm: 77.0 d (PCl3+, 2JРН1 60.3 Hz); –294.4 s (PCl6–).
It was established that 1-benzyl-5-chloro-3-vinyl-
1H-pyrazole and 1-benzyl-5-chloro-3-isopropenyl-1H-
pyrazole are phosphorylated with phosphorus penta-
chloride at the vinyl and isopropenyl groups to afford
organyltrichlorophosphonium hexachlorophosphates II
and III. Hexachlorophosphates II, III readily undergo
conversion into phosphonic acids dichlorides IV, V
upon the action of acetone in di-ethyl ether.
2-(1-Benzyl-5-chloro-1Н-pyrazol-3-yl)-1-propenyl-
phosphonic acid dichlorides (V). 1.2 g of compound
III was treated with the solution of 1 ml of acetone in
3 ml of diethyl ether and after the solution was formed
the volatile products were removed in vacuum.
Compound V is formed as an orange oil. Yield 0.63 g
2-(1-Benzyl-5-chloro-1Н-pyrazol-3-yl)-1-propenyl-
trichlorophosphonium hexachlorophosphate (III).
The solution of 0.5 g of 1-benzyl-5-chloro-3-iso-
1
(92%). Н NMR spectrum, δ, ppm: 2.34 d (3H, СН31,
2
4JРН 1.2 Hz); 5.36 s (2H, СН2); 6.18 d (1H, Н1, JРН
1221

1222
LARINA et al.
Cl
H3
H
Cl
2 PCl5
_HCl
_
PCl3+ PCl6
CH2
C
R
CH1
C
R
N
N
N
N
N
PhCH2
PhCH2
II, III
H3
Cl
2 Me2CO, Et2O
CH1
C
POCl2
_POCl3, _2 Me2CCl2
N
PhCH2
R
IV, V
R = H2 (II, IV), Me (III, V).
34.3 Hz); 6.79 s (1H, Н3); 7.28–7.35 m (5H, Ph). 13С
NMR spectrum, δC, ppm: 24.81 d (СН3, 3JСР 26.8 Hz),
measured relative to TMS, 31Р chemical shifts relative
to H3PO4.
1
53.56 s (СН2), 106.68 s (С4), 121.42 d (СН1, JСР
REFERENCES
150.4 Hz), 127.51, 127.88, 128.24, 128.82 (Ph),
2
135.12 s (С3), 146.99 d (СМе, JСР 9.9 Hz), 152.01 s
1. Fridland, S.V. and Malkov, Yu.K., Reaktsii i metody
issledovaniya organicheskikh soedinenii (Reations and
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Мoscow: Khimiya, 1986, p. 106.
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Kalabina, A.V., Domnina, E.S., and Skvortsova, G.G.,
Zh. Obshch. Khim., 1983, vol. 53, no. 3, p. 697.
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Es’kova, L.A., Magn. Reson. Chem., 2009, vol. 49, no. 2,
p. 149.
1
(С5). 31Р NMR spectrum, δP, ppm: 28.9 d (POCI2, 2JРН
34.3 Hz). Found, %: С 44.25; Н 3.51; Cl 29.17; N
9.02; P 8.43. C13H12Cl3N2OP. Calculated, %: С 44.67;
Н 3.46; CI 30.42; N 8.01; P 8.86.
1Н, 13С and 31Р NMR spectra were registered on a
Bruker DPX 400 spectrometer in СDСl3 at working
frequencies of 400.13, 100.62 and 161.98 MHz,
respectively. 1Н and 13С chemical shifts were
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 6 2009