Hydroarylation of (E)-2-methyl-5-(2-phenylethenyl)-2H-tetrazole under superelectrophilic activation

Full text of DOI:10.1134/S1070428015090274

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2015, Vol. 51, No. 9, pp. 1356–1358. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © A.D. Lisakova, D.S. Ryabukhin, R.E. Trifonov, V.A. Ostrovskii, A.V. Vasilyev, 2015, published in Zhurnal Organicheskoi Khimii,
2
015, Vol. 51, No. 9, pp. 1382–1384.
SHORT
COMMUNICATIONS
Dedicated to Full Member of the Russian Academy of Sciences
N.S. Zefirov on his 80th anniversary
Hydroarylation of (E)-2-Methyl-5-(2-phenylethenyl)-2H-tetrazole
under Superelectrophilic Activation
a
b, c
b
a
b, c
A. D. Lisakova , D. S. Ryabukhin , R. E. Trifonov , V. A. Ostrovskii , and A. V. Vasilyev
a
St. Petersburg State Institute of Technology, Moskovskii pr. 26, St. Petersburg, 190013 Russia
b
St. Petersburg State University, Universitetskaya nab., 7/9, St. Petersburg, 199034 Russia
e-mail: rost_trifonov@mail.ru
c
St. Petersburg State Forest Technical University, Institutskii per. 5, St. Petersburg, 194021 Russia
Received June 20, 2015
DOI: 10.1134/S1070428015090274
5
-(2-Phenylethenyl)tetrazoles (5-styryltetrazoles)
Obviously, tetrazole 1 in superacids can be pro-
tonated at both N of the tetrazole ring [11] and
4
are promising monomers for the preparation of tetra-
zole-containing polymers [1–4]. Functionalized styryl-
tetrazoles themselves exhibit antimicrobial [5], anti-
diabetic [6], and other kinds of biological activity.
double-bonded carbon atom to form reactive dication
A [8] which then reacts as electrophile with arenes,
yielding hydroarylation products at the C=C bond,
compounds 2a–2g. In the reactions with anisole and
veratrole, regioisomer mixtures 2d/2e and 2f/2g, re-
spectively, were obtained.
Thus, (E)-2-methyl-5-(2-phenylethenyl)-2H-tetra-
zole (1) effectively reacts with various arenes contain-
ing electron-donating substituents in the presence of
Brønsted or Lewis superacids to give 5-(2-aryl-2-
phenylethyl)-2-methyl-2H-tetrazoles 2a–2g.
5
-Styryltetrazoles contain an exocyclic double C=C
bond conjugated with the heterocyclic system and are
capable of entering classical chemical transformations
typical of that bond. Of particular interest are reactions
of 5-styryltetrazoles occurring in Brønsted or Lewis
acids. These reactions could give rise to various func-
tional derivatives of 5-alkyltetrazoles. Up to now such
chemical transformations remain almost unexplored.
We previously reported on the reaction of 2- and
5
-(2,2-Diphenylethyl)-2-methyl-2H-tetrazole
5
-(2-phenylethenyl)-2H-tetrazoles with benzene in
(
2a). Tetrazole 1, 0.27 mmol, was slowly added to
CF SO H (Brønsted superacid) [7].
3
3
a mixture of 4 mL of anhydrous benzene and
1.34 mmol of AlBr or AlCl under vigorous stirring at
Herein we describe the hydroarylation of
3
3
(
E)-2-methyl-5-(2-phenylethenyl)-2H-tetrazole (1) at
20°C. The mixture was stirred for 3 h, poured into
20 mL of water, treated with a saturated aqueous solu-
the exocyclic double bond with benzene, m- and
p-xylenes, anisole, and veratrole in trifluoromethane-
sulfonic acid or in the presence of strong Lewis acids
tion of NaHCO until pH 8–9, and extracted with
3
chloroform (3×30 mL). The combined extracts were
dried over Na SO , and the solvent was removed under
(
AlCl , AlBr ), i.e., under conditions of superelectro-
3 3
2
4
philic activation [8–10].
reduced pressure. Yield 90–95%, colorless crystals,
CF SO H
(1) ArH, 20°C, 3 h
(2) H O, NaHCO
Ph
3
3
Ph
Ph
N
or AlCl (AlBr )
N
N
N
N
3
3
2
3
N
Me
N
Me
N
Me
Ar
N
N
HN
N
1
A
2a–2g
Ar = Ph (a), 2,4-Me
2
C
6
H
3
(b), 2,5-Me
2
C
6
H
3
(c), 4-MeOC
6
H
4
6 4 2 6 3 2 6 3
(d), 2-MeOC H (e), 3,4-(MeO) C H (f), 2,3-(MeO) C H (g).
1
356

HYDROARYLATION OF (E)-2-METHYL-5-(2-PHENYLETHENYL)-2H-TETRAZOLE
1357
1
+
mp 115–116°C [7]. H NMR spectrum, δ, ppm: 3.64 d
2H, CH , J = 8.2 Hz), 4.20 s (3H, CH ), 4.70 t (1H,
m/z 295.1558 [M + H] . C H N O. Calculated:
1
7
18
4
(
M + H 295.1553.
-[2-(3,4-Dimethoxyphenyl)-2-phenylethyl]-
-methyl-2H-tetrazole (2f). Yield 66%, oily material.
2
3
CH, J = 8.2 Hz), 6.78–6.80 m (3H, Harom), 7.15–7.29 m
7H, Harom). C NMR spectrum, δ , ppm: 31.6, 39.1,
5
13
(
C
2
4
9.5, 126.5, 127.8, 128.5, 143.3, 165.2.
-[2-(2,4-Dimethylphenyl)-2-phenylethyl]-
-methyl-2H-tetrazole (2b). Tetrazole 1, 0.27 mmol,
was slowly added to a solution of 0.32 mmol of the
corresponding arene in 1 mL of CF SO H under vigor-
ous stirring at 20°C. The mixture was stirred for 3 h,
poured into 20 mL of water, and then treated as
described above. Yield 73%, oily substance. H NMR
1
H NMR spectrum, δ, ppm: 3.59 d.d (2H, CH , J =
2
5
8.3 Hz), 3.81 s (3H, OCH
(3H, CH ), 4.64 t (1H, CH, J = 9 Hz), 6.72–7.27 m
(8H, Harom). C NMR spectrum, δ , ppm: 31.9, 39.2,
C
3 3
), 3.82 s (3H, OCH ), 4.20 s
2
3
13
49.1, 55.8, 55.8, 111.2, 111.5, 119.6, 126.5, 127.7,
3
3
128.5, 135.9, 143.6, 147.6, 148.8, 165.3. Found:
+
m/z 325.1654 [M + H] . C18
M + H 325.1659.
H N O . Calculated:
20 4 2
1
spectrum, δ, ppm: 2.25 s (6H, CH ), 3.60 d (2H, CH ,
3
2
5-[2-(2,3-Dimethoxyphenyl)-2-phenylethyl]-
2-methyl-2H-tetrazole (2g). Yield 10%, oily material.
J = 8.2 Hz), 4.21 s (3H, CH ), 4.61 t (1H, CH, J =
3
1
3
1
8
.2 Hz), 7.00–7.27 m (8H, Harom). C NMR spectrum,
H NMR spectrum, δ, ppm: 3.59 d (2H, CH , J =
2
δC, ppm: 21.3, 31.6, 39.2, 49.4, 125.6, 126.4, 126.5,
8.3 Hz), 3.81 s (3H, OCH ), 3.82 s (3H, OCH ), 4.20 s
3
3
1
27.8, 128.2, 128.4, 128.5, 137.9, 143.3, 143.5, 165.3.
(3H, CH ), 4.59 t (1H, CH, J = 8.3 Hz), 6.72–7.27 m
3
+
13
Mass spectrum, m/z (I , %): 292 (16) [M] , 195 (100),
1
(8H, Harom). C NMR spectrum, δ , ppm: 31.7, 39.2,
rel
C
+
80 (18), 165 (25). Found: m/z 293.1760 [M + H] .
49.0, 55.8, 111.2, 114.2, 119.1, 127.8, 126.4, 128.5,
C H N . Calculated: M + H 293.1761.
135.9, 143.6, 147.6, 165.3. Found: m/z 325.1654
1
8
20
4
+
[
M + H] . C H N O . Calculated: M + H 325.1659.
1
8
20
4
2
Compounds 2c–2g were synthesized in a similar
way.
(E)-2-Methyl-5-(2-phenylethenyl)-2H-tetrazole (1)
was reported previously [12].
5
-[2-(2,5-Dimethylphenyl)-2-phenylethyl]-
1
13
2
-methyl-2H-tetrazole (2c). Yield 80%, oily material.
The H and C NMR spectra were recorded at
25°C on Bruker AM-500 (500 and 125 MHz, respec-
tively) and Bruker AM-400 spectrometers (400 and
1
H NMR spectrum, δ, ppm: 2.24–2.33 m (6H, CH3),
.60–3.64 m (2H, CH ), 4.21 s (3H, CH ), 4.60–4.71 m
3
2
3
3
1
(
1H, CH), 7.08–7.27 m (8H, Harom). C NMR spec-
100 MHz) from solutions in CDCl
were measured relative to the residual proton and
carbon signals of the solvent (CHCl , δ 7.26 ppm;
CDCl , δ 77.0 ppm). GC/MS analyses were obtained
on an Agilent Technologies G2570A/6850s instrument
HP-5MS capillary column, 3 m×0.25 mm, film thick-
3
; the chemical shifts
trum, δ , ppm: 20.9, 31.5, 39.1, 49.5, 124.6, 126.4,
C
1
27.7, 128.4, 129.1, 129.8, 132.4, 134.0, 143.3, 165.1.
3
+
Found: m/z 293.1764 [M + H] . C H N . Calculated:
M + H 293.1761.
3
C
1
8
20
4
(
5
-[2-(4-Methoxyphenyl)-2-phenylethyl]-2-meth-
ness 0.25 μm). The high-resolution mass spectra were
recorded on a Bruker MicroTOF spectrometer (electro-
spray ionization) at the Resource Center for Chemical
Analysis and Materials Research (St. Petersburg State
University).
yl-2H-tetrazole (2d). Yield 62%, oily material.
1
H NMR spectrum, δ, ppm: 3.59 d (2H, CH , J =
2
8
.2 Hz), 3.75 s (3H, OCH ), 4.21 s (3H, CH ), 4.64 t
3 3
(
1H, CH, J = 8.2 Hz), 6.79 d (2H, Harom, J = 8.7 Hz),
1
3
7
.14–7.18 m (4H, Harom), 7.25 s (3H, Harom). C NMR
This study was performed under financial support
by the St. Petersburg State University (project
no. 12.38.195.2014) and by the Russian Foundation for
Basic Research (project no. 15-03-02936).
spectrum, δ , ppm: 31.8, 39.2, 48.8, 55.2, 113.9, 126.4,
C
1
27.7, 128.5, 128.8, 135.5, 143.8, 158.1, 165.3. Mass
+
spectrum, m/z (I , %): 294 (5) [M] , 197 (100), 182
rel
+
(
4), 165 (10), 153 (11). Found: m/z 295.1558 [M + H] .
C H N O. Calculated: M + H 295.1553.
1
7
18
4
REFERENCES
5
-[2-(2-Methoxyphenyl)-2-phenylethyl]-2-meth-
yl-2H-tetrazole (2e). Yield 24%, oily material.
H NMR spectrum, δ, ppm: 3.49–3.55 m (2H, CH2),
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1
3
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3 3
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1
3
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1
27.8, 128.7, 129.4, 135.4, 143.2, 158.1, 165.1. Found:
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