First example of a reaction of C- and N-styryltetrazoles with benzene in superacid CF3SO3H

Full text of DOI:10.1134/S1070428013050333

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2013, Vol. 49, No. 5, pp. 784−785. © Pleiades Publishing, Ltd., 2013.
Original English Text © P.A. Aleshunin, A.V. Vasil’ev, V.A. Ostrovskii, 2013, published in Zhurnal Organicheskoi Khimii, 2013, Vol. 49, No. 5, pp. 799−800.
SHORT
COMMUNICATIONS
Dedicated to the memory of Professor G.I. Koldobskii
First Example of a Reaction of С- and N-Styryltetrazoles
with Benzene in Superacid CF3SO3H
P. A. Aleshunina, A. V. Vasil’evb,c, and V. A. Ostrovskiia
aSt. Petersburg State Technological Institute (Technical University), St. Petersburg, Russia
bSt. Petersburg State Forestry Engineering University, St. Petersburg,194021 Russia
e-mail: aleksvasil@mail.ru
c St. Petersburg, State University, St. Petersburg, Russia
Received March 2, 2013
DOI: 10.1134/S1070428013050333
Tetrazole derivatives are utilized in versatile spheres of
human action [1].Among the most promising compounds
for the organic synthesis are С- and N-styryltetrazoles
[2], yet they are the least studied. These compounds
possessing a heteroaromatic system conjugated with a
double carbon-carbon bond can be involved into chemical
reactions at both these structural moieties. The reactions
of С- and N-styryltetrazoles in superacids are especially
interesting. These reactions are able to result in new,
previously unavailable tetrazole derivatives of unusual
structure and practically useful properties. However no
information was published on the action of superacids
on the styryltetrazoles.
applied to the superelectrophilic activation of organic
compounds [3].
The protonation in CF3SO3H of compounds Iа, Ib at
the atom N4 of the tetrazole ring [4] and at the carbon atom
of the С=С bond of the phenylvinyl substituent provides
reactive dications А and B. These species are involved
in the reaction of the electrophilic aromatic substitution
with benzene at 20°С for 1–2 h and then are subjected to
the treatment with aqueous alkali to destroy the superacid
which leads to the formation of tetrazoles IIa, IIb in 70
and 67% yields respectively.
We have demonstrated for the first time that the con-
version of both С- and N-styryltetrazoles in superacid
proceeds chemoselectively exclusively at the С=С bond
and does not affect the tetrazole ring.
We report here on the investigation of the reac-
tions between 2-methyl-5-[(E)-2-phenylethenyl]- and
5-phenyl-2-[(E)-2-phenylethenyl]-2H-tetrazoles (Iа, Ib)
and benzene in the superacid of Brønsted type CF3SO3H
Ethenyltetrazoles Ia, Ib were prepared and character-
Me
Me
Me
(1) C6H6 , 20oC, 2 h
(2) H2O_Na2CO3
N
N
N
N
CF3SO3H
N
N
N
N
N
N
N
N
H
Ph
Ph
Ph
Ph
Ph
Ia
A
IIa
Ph
Ph
H
Ph
N
N
N
N
CF3SO3H
(1) C6H6 , 20oC, 1 h
(2) H2O_Na2CO3
N
N
N
N
N
N
Ph
N
Ph
N
Ph
Ib
IIb
B
784

FIRST EXAMPLE OF A REACTION OF С- AND N-STYRYLTETRAZOLES
785
ized before [5].
ACKNOWLEDGMENTS
Reaction of tetrazoles Iа, Ib with benzene in
CF3SO3H. To a mixture of 0.5 ml of anhydrous benzne
and 1 ml of CF3SO3H at 20°С while vigorously stir-
ring was gradually added within 5 min 0.27 mmol of
styryltetrazole Ia, Ib. The reaction mixture was stirred
additionally for 1–2 h, then it was poured into 15 ml of
Н2О, the saturated water solution of Na2CO3 was added
to pH 8–9, and the product was extracted into chloroform
(3 × 30 ml). The combined extract was dried with Na2SO4,
evaporated in a vacuum, the residue was recrystallized
from 2-propanol.
The study was carried out under the financial support
of the Ministry of Education and Science of the Russian
Federation (Federal targeted program “Scientific and
scientific-pedagogical staff of innovational Russia” for
2009–2013, contract no. 14.В37.21.0794 of 03.09.2012)
and the Russian Foundation for Basic Research (grant
no. 11-08-00757-a).
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5-(2,2-Diphenylethyl)-2-methyl-2Н-tetrazole (IIa).
Yield 70%, mp 113–114°С. 1Н NMR spectrum, δ, ppm:
3.58 d (2Н, СН2, J 8.1 Hz), 4.21 s (3Н, Mе), 4.59 t (1Н,
СН, J 8.1 Hz), 7.14 t (2Нarom, J 7.2 Hz), 7.24 t (4Нarom
,
J 7.2 Hz), 7.30 d (4Нarom, J 7.2 Hz). 13C NMR spectrum,
δ, ppm: 30.36, 39.25, 49.10, 126.27, 127.55, 128.36,
143.57, 164.56. Mass spectrum, m/z: 264.9852 [M]+,
302.9377 [M + K]+. C16H16N4. Calculated: M 264.1375,
[M + K] 303.1012.
2-(2,2-Diphenylethyl)-5-phenyl-2Н-tetrazole
1
(IIb). Yield 67%, mp 104–105°С. Н NMR spectrum,
δ, ppm: 4.91 t (1Н, СН, J 8.4 Hz), 5.51 d (2Н, СН2,
J 8.4 Hz), 7.17–7.20 m (2Нarom), 7.26–7.30 m (4Нarom),
7.45–7.54 m (7Нarom), 7.97–7.99 m (2Нarom). 13C NMR
spectrum, δ, ppm: 50.12, 56.43, 126.22, 126.91, 127.75,
128.52, 129.20, 130.62, 141.17, 164.01. Mss-spectrum,
m/z: 326.9507 [M]+, 364.9091 [M + K]+. C21H18N4.
Calculated: M 326.1531, [M + K] 365.1169.
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1H and 13C NMR spectra were registered on a spec-
trometer Bruker Avance 400 (operating frequencies
400.13 and 100.62 МHz respectively) in DMSO-d6 at
20°C. As internal references served the solvent signal,
that of residual protons at δ 2.50 ppm (1Н) and of carbon
atom at δ 39.5 ppm (13C). Mass spectrum of high resolu-
tion was obtained on an instrument Waters LCT Premier,
(ESI, TOF).
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 5 2013