Vinyltetrazoles: III. Metal-catalyzed arylation, a new method of vinyltetrazoles functionalization

Article abstract of DOI:10.1134/S1070428012110097

New functionalization procedure was developed for C- and N-vinyltetrazoles based on Heck reaction. Applying this method diverse (E)-styryl- and (E)-distyryltetrazoles were obtained for the first time in 76-85% yields. C-Vinyltetrazoles are more reactive in Heck cross-coupling than N-vinyltetrazoles. The arylation of 1-vinyltetrazole along Heck reaction proceeds with a C-H-activation and leads to the formation of 5-phenyl-1-[2-(E)-phenylethenyl]tetrazole.

Full text of DOI:10.1134/S1070428012110097

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2012, Vol. 48, No. 11, pp. 1464−1472. © Pleiades Publishing, Ltd., 2012.
Original English Text © P.A. Aleshunin, K.A. Esikov, F.M. Dolgushin, V.A. Ostrovskii, 2012, published in Zhurnal Organicheskoi Khimii, 2012, Vol. 48, No. 11,
pp. 1480−1488.
Vinyltetrazoles: III.* Metal-Catalyzed Arylation, a New Method
of Vinyltetrazoles Functionalization
P. A. Aleshunina, K. A. Esikova, F. M. Dolgushinb, and V. A. Ostrovskiia
aSt. Petersburg State Technological Institute, St. Petersburg, 190013 Russia
e-mail: apa-ti@mail.ru
bNesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, Moscow, Russia
Received September 21, 2012
Abstract—New functionalization procedure was developed for C- and N-vinyltetrazoles based on Heck reaction.
Applying this method diverse (E)-styryl- and (E)-distyryltetrazoles were obtained for the first time in 76–85%
yields. C-Vinyltetrazoles are more reactive in Heck cross-coupling than N-vinyltetrazoles. The arylation of
1-vinyltetrazole along Heck reaction proceeds with a C–H-activation and leads to the formation of 5-phenyl-1-
[2-(E)-phenylethenyl]tetrazole.
DOI: 10.1134/S1070428012110097
Vinyl derivatives of tetrazole are first of all regarded
as monomers for the synthesis of macromolecular com-
pounds [1–5]. Polymers underlain by vinyltetrazoles are
included in the composition of promising energy-rich
materials, polymer gas-separation membranes, unwoven
filter materials for medicine, and the other composite ma-
terials [3–5]. Besides the vinyltetrazoles can be utilized
as intermediate reagents in the procedures of the total
synthesis of new compounds exhibiting the biological
action [4, 6–8].
Vinyltetrazoles possess simultaneously several reac-
tion sites: endocyclic nitrogen atoms and a carbon of
the heterocycle, and also contain in their structure an
exocyclic CH=CH2 group. The reactions involving the
nitrogen atoms of the ring are well known [4, 9]. These
are the alkylation, the acetylation, quaternization, Man-
nich condensation, complexing with metals through the
donor-acceptor interactions [3]. These processes do not
affect the double bond and can be used for the preparation
of new tetrazole-containing monomers and polymers.
Unlike that the vinyltetrazole reactions involving
the CH=CH2 group attracted less attention. Individual
instances are published of the addition of the electro-
philic and nucleophilic reagents to the double bond of
the vinyltetrazoles, namely, the hydration [10], the ad-
dition of trichloroacetonitrile in the presence of copper
catalysts [11], the reaction with hypobromous acid [12]
and with the elemental bromine [13]. In all these reac-
tions the products are formed as a result of the opening
of the double bond.
Lately an interest arose to styryltetrazoles. For in-
stance, some fluoroquinolones containing a styryltet-
razole fragment are regarded as bioisosteric analogs of
the drug Levofloxacin [7]. Similar bioisosteric tetrazole-
containing analogs were also described for chromones [8].
These compounds possess pronounced antibacterial and
antiallergic properties [7, 8]. However the methods of the
preparation of styryltetrazoles described in [7, 8] are of
particular character and cannot be applied to a targeted
functionalization of vinyltetrazoles.
In this connection the development and examination
of new method of vinyltetrazoles functionalization at the
exocyclic CH=CH2 group with the retention of the double
bond leading to styryltetrazoles is an urgent task.
To this end we developed a metal-catalyzed monoary-
lation of vinyltetrazoles underlain by Heck reaction that
provided a possibility to obtain previously unavailable
isomeric C- and N-styryltetrazoles. The Heck cross-
coupling is an efficient and stereoselective reaction that
is widely used for solving similar problems in the alkene
chemistry [14–17].
––––––––––––––––––––––––––––––
* For Communication II, see [1].
As initial compounds for Heck arylation we selected
1464

VINYLTETRAZOLES: III.
1465
5-vinyl-2-methyltetrazole (I), a typical example of C-
N-(E)-styryltetrazoles with yields exceeding 65%.
vinyltetrazoles, and also various N-vinyltetrazoles. The
following reagents were used in the arylation: catalyst
Pd(OAc)2, aryl iodides, aryl bromides, and aryl chlorides
with electron-donor and electron-acceptor substituents in
the aromatic ring, K2CO3 as the base, DMF as solvent.
The reactions were carried out under an inert atmosphere,
in argon.
We believe that the relatively low activity of the N-
vinyltetrazoles in Heck reaction may be due to the com-
bination of several factors. The data on the study of the
electronic structure of vinyltetrazoles show in general that
the electron-aceptor effect of the tetrazolyl substituent on
the double bond weakens in going from the C-vinyl- to
the N-vinyltetrazoles [3, 5] resulting in the deactivation of
the CH=CH2 group of N-vinyltetrazoles in Heck reaction.
Besides it is known that tetrazoles are capable of forming
complexes with various metals. In this event the metal
ion is coordinated to the nitrogen atom in the position 4
of the heterocycle [4]. Hence a possibility exists that in
the arylation of N-vinyltetrazoles a coordination occurs
of the tetrazole ring to Pd(OAc)2 catalyst thus removing
the catalyst from the zone of Heck reaction.
We showed that the arylation of tetrazole I with aryl
halides afforded (E)-styryltetrazoles IIa–IIe in 79–85%
yields (Table 1).
At the use of aryl iodides as the arylating agents the
reaction time was minimal, 2.5–3 h. The completion of
the tetrazole I reaction with aryl bromides containing
electron-acceptor substituents required 4–7 h. The aryl
bromides lacking the electron-acceptor substituents, and
also aryl chlorides did not react in the applied conditions.
The results obtained are in agreement with the published
data on the reactivity of aryl halides in the Heck reaction
[14–17].
The analysis of the published data on the metal-cat-
alyzed arylation of deactivated alkenes showed that the
above mentioned problem might be solved by introduc-
ing into the reaction mixture of triphenylphosphine and
copper(I) iodide [14, 16, 17]. These reagents stabilize the
formed in situ palladium complexes and as we presume
screen the nitrogen atom of the ring in the position 4
preventing the side processes of this atom coordination
to the catalyst.
In order to obtain the corresponding N-styryltetra-
zoles we extended the conditions of the arylation of the
C-vinyltetrazole to the N-vinyltetrazoles. However in this
case the reaction duration was 20–25 h. In this event the
arylation of N-vinyltetrazoles made it possible to obtain
On these assumptions we developed the reaction
conditions for the preparation of N-styryltetrazoles which
reduced the arylation time of the initial N-vinyltetrazoles
to 8 h and raised the yield of the target compounds to
85% (Tables 2 and 3).
Table 1. Arylation by Heck reaction of 5-vinyl-2-methyltet-
razole (I)
ArHlg,
Ar
N
N
,
Pd(OAc)2 K2CO3
N
N
N
N
N
N
The data obtained allow the estimation of the relative
reactivity of N-vinyl-5-R-tetrazoles IIIa–IIIg, Va–Vd in
Heck reaction. The arylation time of 2-vinyl-5-aryltetra-
zoles IIIa–IIId is shorter (on the average by 2 h) than
that of alkylanalogs IIIe, IIIf. A similar rule was found
for 1-vinyl-5-aryl- (Va) and -5-alkyltetrazoles Vb, Vc
(Table 3).
DMF, 120oС
IIа_IIIe
I
Ar = Ph (a), o-FC6H4 (b), p-O2NC6H4 (c), m-HO2CC6H4 (d),
m-NCC6H4 (e).
ArHlg
Time, h
Compound no. Yield, %
PhI
3
2.5
7
IIa
IIb
IIa
IIc
IId
IIe
–
80
81
85
79
83
85
0
At the arylation of 2-vinyl-5-aryltetrazoles IIIa–IIId
the duration of the reaction is notably affected by the
character of the substituent in the phenyl ring of the azole.
For instance, at the introduction of the electron-donor
substituent (reagent IIIb, R = p-CH3C6H4) the reaction
completion required more time, on the average, by
5 h (cf. R = Ph, IIIa). In contrast, the tetrazoles with
the electron-acceptor substituents (R = p-CF3C6H4,
o-NCC6H4) reacted faster with the haloarenes.
o-FC6H4I
PhBr
p-O2NC6H4Br
m-HO2CC6H4Br
m-NCC6H4Br
p-BrC6H4Br
p-MeOC6H4Br
p-O2NC6H4Cl
4
6
5.5
15
15
15
–
0
Besides the completion of the arylation of 1-vinyl-
tetrazoles requires less time (up to 3 h) than that of the
–
0
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 11 2012

ALESHUNIN et al.
1466
Table 2. Arylation by Heck reaction of 2-vinyl-5-R-tetrazoles
IIIa–IIIg
2-vinyl-5-aryl(alkyl)tetrazoles.
The attempt at performing Heck arylation of 5-amino-
N-vinyl-tetrazoles IIIg, Vd failed: no reaction products
were detected.
N
N
ArHlg
R +
N
N
IIIа_IIIg
Thus the highest activity in Heck reaction was
observed in C-vinyltetrazoles, the reaction of N-vinyl-
tetrazoles required more severe conditions.
Pd(OAc)2, PPh3,
CuI, Cs2CO3
DMF, 120оС
N
N
N
Ar
R
N
The structure and homogeneity of all compounds
obtained were confirmed by a complex of methods:
HPLC-MS, 1H, 13C NMR spectroscopy, XRD analysis.
IVа_IVj
III, R = Ph (a), p-MeC6H4 (b), p-F3CC6H4 (c), o-NCC6H4
(d), Me (e), Et (f), H2N (g); IV, R = Ph: Ar = o-FC6H4
(a), Ph (b), o-F3CC6H4 (c); R = p-MeC6H4:Ar = o-FC6H4
(d), Ph (e); R = p-F3CC6H4: Ar = o-FC6H4 (f), Ph (g);
R = o-NCC6H4, Ar = Ph (h); R = Me, Ar = o-FC6H4 (i);
R = Et, Ar = Ph (j).
The spin-spin coupling constants of the protons of
1
the CH=CH group in the H NMR spectra of obtained
styryltetrazoles IIa–IIe, IVa–IVi, VIa–VIc were in the
range 14.6–16.5 Hz characteristic of the disubstituted
alkenes of the E-configuration [18].
Compound
no.
Reaction
product
ArHlg
Time, h
7
Yield, %
78
The exhaustive information on the structure of the
synthesized compounds was obtained by the XRD anly-
sis of single crystals of compounds IIa, VIc (Figs. 1, 2).
The crystallographic data and the man parameters of
refinement for compounds IIa, VIc are listed in Table 4.
According to the XRD data the styryltetrazoles exist in
the E-configuration.
IIIa
o-FC6H4I
IVa
PhI
o-F3CC6H4Br
o-FC6H4I
PhBr
7
9
IVb
IVc
IVd
IVe
IVf
IVg
IVh
82
81
79
82
84
81
85
84
78
80
–
IIIb
IIIc
IIId
12
17
5.5
10
6
At the next stage of the research we used as terminal
alkenes in Heck reaction C,N-divinyltetrazoles VII, VIII
containing in the structure two double bonds providing
a possibility of both selective and exhaustive arylation.
o-FC6H4I
PhBr
PhI
PhBr
14
8
IIIe
IIIf
IIIg
o-FC6H4I
PhI
IVi
IVj
–
9
PhI
20
Table 3. Arylation by Heck reaction of 1-vinyl-5-R-tetrazoles
Va–Vd
Fig. 1. Molecular structure of (E)-2-methyl-5-styryltetrazole
(IIa) according to XRD data.
Pd(OAc) , PPh
,
3
2
N N
N N
CuI, Cs2CO3
+ PhI
Ph
N
N
N
N
DMF, 120оС
R
R
Vа_Vd
VIа_VIc
R = Ph (a), Me (b), Et (c), H2N (d).
Reaction
product
Compound no.
Time, h
Yield, %
Va
Vb
Vc
Vd
4
6
7
VIa
VIb
VIc
–
82
80
81
0
Fig. 2. Molecular structure of (E)-1-styryl-5-ethyltetrazole
(VIc) according to XRD data.
20
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 11 2012

VINYLTETRAZOLES: III.
Table 4. Crystallographic data and refinement parameters for
1467
Ph
Scheme 1.
tetrazoles IIa, VIc
Ph
Compound no.
Data and refinement
i
N
N
parameters
IIa
VIc
C11H12N4
200.25
Rhombic
Pbca
PhI
+
N
N
N
N
N
Empirical formula
Molecular weight
Crystal system
Space group
Temperature, K
a, Å
C10H10N4
186.22
Monoclinic
P21/c
N
VII
IX
F
N
N
+
I
N
120(2)
100(2)
12.0020(6)
6.8047(4)
25.811(1)
90
N
VIII
6.0310(6)
8.5432(8)
18.453(2)
93.967(2)
948.5(2)
4
b, Å
i
c, Å
F
N
β, deg
V, Å3
N
F
N
N
2107.9(2)
8
X
Z
Dcalc, g cm–3
1.304
1.262
i: 4.0 mol% Pd(OAc)2, 12.0 mol% PPh3, CuI, Cs2CO3, DMF,
120°C.
2θmax, deg
μ, cm–1
Number of indepen-
dent reflections (Rint)
58
52
Scheme 2.
0.84
2524 (0.0340)
0.81
2069 (0.0403)
F
i
I
VIII
N
N
+
R1 [with respect to F
for reflections with
I >2σ(I)]
wR2 (with respect to F2
for all reflections)
0.0510 (1939)
0.1349
0.0355 (1665)
0.0932
N
F
N
XI
i: 4.0 mol% Pd(OAc)2, 12.0 mol% PPh3, CuI, Cs2CO3, DMF,
120°C.
Number of refined
parameters
GOF
128
136
1.064
1.002
the above described C- and N-styryltetrazoles.
Interesting results were obtained at Heck arylation of
1(2)-vinyltetrazoles XII, XIII. The arylation of 1-vinyl-
tetrazole (XII) at the double bond under the conditions
developed for the reaction with N-vinyltetrazoles was
accompanied by a C,H-arylation and afforded 1-(E)-
styryl-5-phenyltetrazole (VIa). The metal-catalyzed
C,H-arylation of 1-R-tetrazoles was described by an
example of the reaction of aryl and vinyl halides with
1-phenyltetrazole [19].
The arylation of tetrazoles VII, VIII under the condi-
tions of the reaction with N-vinyltetrazoles furnished the
products of the exhaustive arylation, tetrazoles IX, X, in
the yieldes up to 80% (Scheme 1).
The selective arylation of tetrazoles VII, VIII was
possible at the application of an excess of the terminal
alkene with respect to the arylating agent.
We detected the formation of the selective arylation
product by means of HPLC-MS and NMR spectroscopy;
only in the case of tetrazole XI we were able to isolate the
product from the reaction mixture (Scheme 2).
Ph
N
N
i
N
N
Ph
PhI
+
N
N
Styryltetrazole IX–XI according to the data of
N
N
1HNMR spectra1 exist in the E-configuration, same as
VIa
XII
________________________
1 Coupling constants of the protons of group CH=CH in styryltetrazoles
IX–XI were 14.8–16.1 Hz.
i: 3.0 mol% Pd(OAc)2, 9.0 mol% PPh3, CuI, Cs2CO3,
DMF, 100°C
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 11 2012

ALESHUNIN et al.
1468
Unlike that the arylation of 2-vinyltetrazole (XIII) oc-
curred exclusively at the double bond with the formation
of 2-(E)-styryltetrazole (XIV).
by the direct method and were refined by the full-matrix
root-mean-square method with respect to F2hkl with the
anisotropic thermal parameters for all nonhydrogen at-
oms. Hydrogen atoms were placed in the geometrically
calculated positions and were included in the refinement
in the rider model. All calculations were performed on
a PC applying SHELXTL software [22]. The complete
tables of atomic coordinates, bond lengths, bond angles,
and anisotropic thermal parameters are deposited in the
Cambridge Crystallographic Data Center, CCDC 906717
(IIa), 906718 (VIc).
N
N
N
i
N
+
N
PhI
N
N
N
Ph
XIII
XIV
i: 3.0 mol% Pd(OAc)2, 9.0 mol% PPh3, CuI, Cs2CO3,
DMF, 100°C
The obtained styryl tetrazoles VIa, XIV according to
the H NMR data also exist in the E-configuration like
the above described C- and N-styryltetrazoles.
5-[2-(E)-Arylethenyl]-2-methyltetrazoles IIa–IIe.
To a solution of 9.0 mmol of ArHlg in 2 ml of DMF was
added 0.072 mmol of Pd(OAc)2, and the mixture was
stirred for 20 min at 50°C, then 1.8 mmol of tetrazole
I and 3.6 mmol of K2CO3 was added. The slurry was
stirred at 120°C till the completion of the reaction, it
was cooled, poured at a vigorous stirring into 20 ml of
water, and filtered through celite. The precipitate was
washed with water (2 × 5 ml). The filtrate was extracted
with ethyl acetate (3 × 10 ml), the combined extract was
dried with anhydrous Na2SO4 and evaporated to dryness
in a vacuum.
1
Therefore we have developed a new version of the
chemical modification of vinyltetrazoles based on the
metal-catalyzed arylation of monsubstituted alkenes
along Heck reaction providing a possibility to obtain in
high yields previously unavailable (E)-styryltetrazoles.
EXPERIMENTAL
1H and 13C NMR spectra were registered on a spec-
trometer Bruker DPX-300 at operating frequencies 300.1
(1H) and 75.5 MHz (13C). The signals of solvents served
as internal references: DMSO-d6 (δH 2.50, δC 39.52 ppm),
CDCl3 (δH 7.26, δC 77.16 ppm). Mass spectra were ob-
tained on a spectrometer Waters LCT Premier (ESI, TOF).
The melting points were measured on an instrument PTP
with the heating rate in the melting range of 1 deg/min.
The characteristics of tetrazoles I, IIIa–IIIg, Va–Vd,
VII, VIII, XII, XIII are consistent with the published
data [20].
2-Methyl-5-[2-(E)-phenylethenyl]tetrazole
(IIa). Yield 0.27 g (80%), colorless crystals, mp 87–
88°C. Rf 0.4 (hexane–dichloromethane–ethyl acetate,
1
7:2.5:0.5). H NMR spectrum (CDCl3), δ, ppm: 4.36 s
(3H, CH3), 7.14 d (1H, CH=CHPh, J 16.5 Hz), 7.34–
7.42 m (3H, Ph), 7.54–7.58 m (2H, Ph), 7.73 d (1H,
CH=CHPh, J 16.5 Hz). 13C NMR spectrum (DMSO-d6),
δ, ppm: 39.48 (CH3), 113.46 (CH=CHPh), 127.23,
128.93, 129.14, 135.75 (Ph), 136.37 (CH=CHPh),
164.46 (C5). Found: m/z 187.0921 [M + H]+. C10H10N4.
Calculated: M 186.2132.
Al reactions were carried out in an inert atmosphere
(argon). The consumption of vinyltetrazoles and the ac-
cumulation of the reaction products were monitored by
TLC on Merck Kieselgel 60F254 plates, visualization of
spots under UV irradiation (λ 254 nm). All compounds
obtained were isolated and purified by column chroma-
tography on a sorbent Merck Silica Gel 60 for Column
Chromatography (0.063–0.200). The eluent for the col-
umn chromatography always was the same as used in
TLC. After the chromatographic purification the product
was recrystallized from ethanol.
2-Methyl-5-[2-(E)-(2-fluorophenyl)ethenyl]-
tetrazole (IIb). Yield 0.3 g (81%), colorless crystals,
mp 74–75°C. Rf 0.3 (hexane–dichloromethane–ethyl
1
acetate, 9:0.5:0.5). H NMR spectrum (CDCl3), δ,
ppm: 4.36 C (3H, CH3), 7.07–7.32 m (4H, CH=CHAr,
Ar), 7.58–7.62 m (1H, Ar), 7.85 d (1H, CH=CHAr,
J 16.5 Hz). 13C NMR spectrum (DMSO-d6), δ, ppm:
39.45 (CH3), 115.92–116.35 m (CH=CHAr,Ar), 123.73 d
(Ar, J 0.23 Hz), 124.45 d (Ar, J 0.04 Hz), 128.26 (Ar),
129.09 (CH=CHAr), 130.39 d (Ar, J 0.17 Hz), 160.29 d
(Ar, J 3.3 Hz), 164.35 (C5). Found: m/z 205.0831 [M +
H]+. C10H9FN4. Calculated: M 204.2136.
XRD analysis of tetrazoles IIa, VIc. The experi-
mental arrays of data were obtained on a diffractometer
Bruker SmartApex II [graphite monochromator, λ(MoKα)
0.71073 E, ω-scanning] [21]. The structures were solved
2-Methyl-5-[2-(E)-(4-nitrophenyl)ethenyl]tetrazole
(IIc). Yield 0.33 g (79%), colorless crystals, mp 201–
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 11 2012

VINYLTETRAZOLES: III.
1469
1
202°C. Rf 0.2 (hexane–ethyl acetate, 7:3). H NMR
spectrum (CDCl3), δ, ppm: 4.36 s (3H, CH3), 7.25 d
(1H, CH=CHAr, J 16.4 Hz), 7.28 d (2H, Ar, J 8.6 Hz),
7.74 d (1H, CH=CHAr, J 16.4 Hz), 8.23 d (2H, Ar,
J 8.6 Hz). 13C NMR spectrum (DMSO-d6), δ, ppm:
39.58 (CH3), 117.85 (CH=CHAr), 124.27, 127.74 (Ar),
133.70 (CH=CHAr), 142.03, 147.80 (Ar), 163.54 (C5).
Found: m/z 232.0801 [M + H]+. C10H9N5O2. Calculated:
M 231.2107.
(2H, Ar), 7.33 m (1H, Ar), 7.49–7.52 m (4H, Ph,
Ar), 7.72 d (1H, CH=CHHt, J 14.7 Hz), 8.14 d (1H,
CH=CHHt, J 14.7 Hz), 8.21 d (2H, Ph). 13C NMR
spectrum (DMSO-d6), δ, ppm: 116.30 d (Ar, J 0.3 Hz),
118.46 (CH=CHHt), 121.20 d (Ar, J 0.2 Hz), 124.75
(CH=CHHt), 124.80 (Ar), 127.01, 127.22, 129.08
(Ph), 129.30 d (Ar, J 0.3 Hz), 130.72 (Ar), 130.81 (Ph),
161.03d(Ar, J3.3Hz), 165.11(C5). Found:m/z267.1121
[M + H]+. C15H11FN4. Calculated: M 266.2730.
Methyl
3-[2(E)-(2-methyltetrazol-5-yl)ethenyl]
5-Phenyl-2-[2-(E)-phenylethenyl]tetrazole (IVb).
benzoate(IId).Yield0.35g(83%),colorlesscrystals,mp
148–149°C. Rf 0.2 (hexane–ethyl acetate, 8:2). 1H NMR
spectrum (CDCl3), δ, ppm: 3.93 s (3H, CO2CH3), 4.35 s
(3H, CH3), 7.20 d (1H, CH=CHAr, J 16.4 Hz), 7.44–
7.48 m (1H, Ar), 7.71–7.75 m (2H, CH=CHAr, Ar),
7.99 m (1H, Ar), 8.23 C (1H, Ar). 13C NMR spectrum
(DMSO-d6), δ, ppm: 39.50 (2-CH3), 52.36 (CO2CH3),
114.81 (CH=CHAr), 128.17, 129.03, 129.96, 130.93,
131.43 (Ar), 135.21 (CH=CHAr), 136.15 (Ar), 164.13
(C5), 166.77 (Ar). Found: m/z 245.1123 [M + H]+.
C12H12N4O2. Calculated: M 244.2492.
Yield 0.36 g (82%), colorless crystals, mp 113–114°C.
Rf 0.2 (hexane–ethyl acetate, 8:2). H NMR spectrum
1
(CDCl3), δ, ppm: 7.26–7.56 m (8Harom), 7.69 d (1H,
CH=CHHt, J 14.5 Hz), 7.99 d (1H, CH=CHHt,
J 14.5 Hz), 8.21–8.23 m (2Harom). 13C NMR spectrum
(DMSO-d6), δ, ppm: 122.53 (CH=CHHt), 124.95
(CH=CHHt); 127.13, 127.23, 127.33, 129.10, 129.24,
129.31, 130.77, 133.20 (Ph); 164.96 (C5). Found: m/z
249.2121 [M + H]+. C15H12N4. Calculated: M 248.2825.
2-{2-(E)-[3-(Trifluoromethyl)phenyl]ethenyl}-5-
phenyltetrazole (IVc). Yield 0.45 g (81%), colorless
crystals, mp 160–161°C. Rf 0.2 (hexane–ethyl acetate,
9:1). 1H NMR spectrum (CDCl3), δ, ppm: 7.52–7.64 m
(5H, Ph, Ar), 7.71–7.75 m (1H, CH=CHHt, 1H, Ar,
J 13.9 Hz), 7.80 s (1H, Ar), 8.05 d (1H, CH=CHHt,
3-[2-(E)-(2-Methyltetrazol-5-yl)ethenyl]
benzonitrile (IIe).Yield 0.32 g (85%), colorless crystals,
mp 135–136°C. Rf 0.2 (hexane–dichloromethane, 7:3).
1H NMR spectrum (CDCl3), δ, ppm: 4.36 s (3H, CH3),
7.18 d (1H, CH=CHAr, J 16.5 Hz), 7.48–7.61 m (2H,
Ar), 7.67 d (1H, CH=CHAr, J 16.5 Hz), 7.75–7.80 m
(2H, Ar). 13C NMR spectrum (DMSO-d6), δ, ppm: 39.54
(CH3), 113.28 (Ar), 116.17 (CH=CHAr), 118.47, 129.80,
130.55, 131.11, 132.13 (Ar), 133.73 (CH=CHAr),
137.05 (CN), 163.35 (C5). Found: m/z 212.0919 [M +
H]+. C11H9N5. Calculated: M 211.2226.
13
J 13.9 Hz), 8.22–8.24 m (2H, Ph). C NMR spectrum
(DMSO-d6), δ, ppm: 123.28 (CH=CHHt), 123.89 (Ar),
124.10 d (Ar, J 0.05 Hz), 125.96 m (Ar), 126.93, 127.28,
129.17 (Ph), 129.81 (CH=CHHt), 130.24 (Ar), 130.96
(Ph), 134.12 (CF3), 165.19 (C5). Found: m/z 317.1108
[M + H]+. C16H11F3N4. Calculated: M 316.0912.
5-(4-Methylphenyl)-2-[2-(E)-(2-fluorophenyl)
ethenyl]tetrazole (IVd). Yield 0.39 g (79%), colorless
crystals, mp 120–121°C. Rf 0.2 (hexane–ethyl acetate,
1(2)-[2-(E)-Arylethenyl]-5-R-tetrazoles IVa–IVj,
VIa–VIc. To a slurry of 1.8 mmol of CuI and 1.8 mmol
of tetrazole IIIa–IIIg, Va–Vd in 2 ml of DMF was added
0.072 mmol of Pd(OAc)2, 0.21 mmol of PPh3, 9.0 mmol
of ArHlg, and 2.7 mmol of Cs2CO3, the mixture was
stirred at 120°C till the completion of the reaction. On
cooling the mixture was poured at vigorous stirring into
20 ml of water, and the slurry was filtered through celite.
The precipitate on the filter was washed with water (2 ×
5 ml). The filtrate was extracted with ethyl acetate (3 ×
15 ml), the combined extract was dried with anhydrous
Na2SO4 and evaporated to dryness in a vacuum.
1
9:1). H NMR spectrum (CDCl3), δ, ppm: 2.43 C (3H,
CH3), 7.13–7.22 m (2H, Ar), 7.31–7.35 m (3H, Ar, Tol),
7.53 m (1H, Ar), 7.72 d (1H, CH=CHHt, J 14.7 Hz),
8.10–8.16 m (3H, Tol, CH=CHHt, J 14.7 Hz). 13C NMR
spectrum (DMSO-d6), δ, ppm: 21.69 (CH3), 116.41 d
(Ar, J 0.3 Hz), 118.28 (CH=CHHt), 121.30 d (Ar,
J 0.2 Hz), 124.24 (Tol), 124.82 (CH=CHHt), 125.10
(Ar), 127.18, 129.39, 129.82 (Tol), 130.75 d (Ar,
J 0.3 Hz), 141.09 (Ar), 161.23 (Ar, J 3.4 Hz), 165.13
(C5). Found: m/z 281.2151 [M + H]+. C16H13FN4.
Calculated: M 280.2996.
5-Phenyl-2-[2-(E)-(2-fluorophenyl)ethenyl]
tetrazole (IVa). Yield 0.37 g (78%), colorless crystals,
mp 139–140°C. Rf 0.1 (hexane–ethyl acetate, 95 : 5).
1H NMR spectrum (CDCl3), δ, ppm: 7.12–7.21 m
5-(4-Methylphenyl)-2-[2-(E)-phenylethenyl]
tetrazole (IVe). Yield 0.38 g (82%), colorless crystals,
mp 118–119°C. Rf 0.2 (hexane–ethyl acetate, 8 : 2).
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ALESHUNIN et al.
1470
1H NMR spectrum (CDCl3), δ, ppm: 2.42 s (3H, CH3),
7.30–7.43 m (5H, Ph, Tol), 7.54 m (2H, Ph), 7.67 d
(1H, CH=CHHt, J 14.7 Hz), 7.97 d (1H, CH=CHHt,
J 14.7 Hz), 8.10 d (2H, Tol). 13C NMR spectrum
(DMSO-d6), δ, ppm: 21.68 (CH3), 122.58, 124.35 (Tol),
124.74 (CH=CHHt), 127.16 (Tol), 127.31, 129.24 (Ph),
129.46 (CH=CHHt), 129.82, 133.29 (Ph), 141.03 (Tol),
165.06 (C5). Found: m/z 263.1301 [M + H]+. C16H14N4.
Calculated: M 262.3091.
Calculated: M 274.1120.
5-Methyl-2-[2-(E)-(2-fluorophenyl)ethenyl]
tetrazole (IVi). Yield 0.29 g (78%), light-yellow
crystals, mp 88–89°C. Rf 0.2 (hexane–ethyl acetate,
1
9:1). H NMR spectrum (CDCl3), δ, ppm: 2.60 s (3H,
CH3), 7.11–7.20 m (2H, Ar), 7.32 m (1H, Ar), 7.48 m
(1H, Ar), 7.61 d (1H, CH=CHHt, J 14.7 Hz), 8.05 d (1H,
CH=CHHt, J 14.7 Hz). 13C NMR spectrum (DMSO-d6),
δ, ppm: 11.09 (CH3), 116.35 d (Ar, J 0.3 Hz), 118.08 d
(CH=CHHt, J 0.2 Hz), 121.23 d (Ar, J 0.2 Hz), 124.74,
124.93 (Ar), 129.37 (CH=CHHt), 130.69 d (Ar,
J 0.1 Hz), 161.14 (Ar, J 3.3 Hz), 163.17 (C5). Found: m/z
205.1103 [M + H]+. C10H9FN4. Calculated: M 204.0736.
5-[4-(Trifluoromethyl)phenyl]-2-[2-(E)-(2-
fluorophenyl)ethenyl]tetrazole (IVf). Yield 0.48
g (84%), colorless crystals, mp 129–130°C. Rf 0.1
(hexane–ethyl acetate, 9:1). 1H NMR spectrum
(CDCl3), δ, ppm: 7.16–7.22 m (2H, Ar), 7.36 m (1H,
Ar), 7.54 m (1H, Ar), 7.74–7.79 m (3H, Ar, CH=CHHt,
J 14.7 Hz), 8.16 d (1H, CH=CHHt, J 14.7 Hz), 8.35 d
(2H, Ar). 13C NMR spectrum (DMSO-d6), δ, ppm:
116.42 d (Ar, J 0.3 Hz), 119.15 (CH=CHHt), 121.10 d
(Ar, J 0.2 Hz), 122.18 q (Ar, J 7.1 Hz), 124.71, 124.85
(Ar), 124.90 (CH=CHHt), 126.11 m (Ar), 127.55 (Ar),
129.53 (Ar, J 0.3 Hz), 130.45, 131.05 (Ar), 161.12 (Ar,
J 3.3 Hz), 163.84 (C5). Found: m/z 335.1101 [M + H]+.
C16H10F4N4. Calculated: M 334.0711.
2-[2-(E)-Phenylethenyl]-5-ethyltetrazole
Yield 0.28 g (80%), colorless crystals, mp 160–161°C.
Rf 0.2 (hexane–ethyl acetate, 8:2). H NMR spectrum
(IVj).
1
(CDCl3), δ, ppm: 1.41 t (3H, CH3), 2.96 q (2H, CH2),
7.33–7.40 m (3H, Ph), 7.48 m (2H, Ph), 7.55 d (1H,
CH=CHHt, J 14.7 Hz), 7.88 d (1H, CH=CHHt,
J 14.7 Hz). 13C NMR spectrum (DMSO-d6), δ, ppm:
12.41 (CH3), 19.24 (CH2), 122.56 (Ph), 124.44
(CH=CHHt), 127.22, 129.19 (Ph), 129.37 (CH=CHHt),
133.26 (Ph), 167.98 (C5). Found: m/z 201.2199 [M +
H]+. C11H12N4. Calculated: M 200.2397.
5-[4-(Trifluoromethyl)phenyl]-2-[2-(E)-phenyl-
ethenyl]tetrazole (IVg). Yield 0.46 g (81%), light-
yellow crystals, mp 140–141°C. Rf 0.1 (hexane–ethyl
5-Phenyl-1-[2-(E)-phenylethenyl]tetrazole (VIa).
Yield 0.36 g (82%), colorless crystals, mp 160–161°C.
Rf 0.2 (hexane–ethyl acetate, 8:2). H NMR spectrum
1
1
acetate, 95:5). H NMR spectrum (CDCl3), δ, ppm:
7.41–7.46 m (3H, Ph), 7.56 d (2H, Ar), 7.72 d (1H,
CH=CHHt, J 14.7 Hz), 7.78 d (2H, Ph), 8.01 d (1H,
CH=CHHt, J 14.7 Hz), 8.35 d (1H, Ar). 13C NMR
spectrum (DMSO-d6), δ, ppm: 122.17 q (Ar, J 7.1 Hz),
122.34 (Ar), 125.54 (CH=CHHt), 126.11 m (Ar), 127.39
(Ar), 127.49, 129.28 (Ph), 129.72 (CH=CHHt), 130.47
(Ph), 132.55 (Ar), 132.94 (Ph), 163.72 (C5). Found:
m/z 317.1221 [M + H]+. C16H11F3N4. Calculated:
M 316.0905.
(CDCl3), δ, ppm: 7.38–7.45 m (6H, Ph, CH=CHHt,
J 14.5 Hz), 7.58–7.60 m (4H, Ph), 7.77 m (2H,
CH=CHHt, Ph). 13C NMR spectrum (DMSO-d6), δ,
ppm: 119.81 (CH=CHHt), 123.25, 127.40 (Ph), 127.98
(CH=CHHt), 128.86, 129.19, 129.30, 131.47, 133.13
(Ph), 152.87 (C5). Found: m/z 249.1911 [M + H]+.
C15H12N4. Calculated: M 248.2825.
5-Methyl-1-[2-(E)-phenylethenyl]tetrazole (VIb).
Yield 0.27 g (80%), colorless crystals, mp 168–169°C.
1
Rf 0.3 (hexane–ethyl acetate, 8:2). H NMR spectrum
2-{2-[(E)-2-Phenylethenyl]tetrazol-5-yl}benzo-
nitrile (IVh). Yield 0.42 g (85%), light-yellow crystals,
mp 124–125°C. Rf 0.2 (hexane– ethyl acetate, 9:1).
1H NMR spectrum (CDCl3), δ, ppm: 7.38–7.44 m (3H,
Ph), 7.55–7.63 m (3H, Ar, Ph), 7.74–7.78 t (2H, Ar,
CH=CHHt, J 14.7 Hz), 7.87 m (1H, Ar), 8.04 d (1H,
CH=CHHt, J 14.7 Hz), 8.36 m (1H, Ar). 13C NMR
spectrum (DMSO-d6), δ, ppm: 110.51 (Ar), 117.60
(CN), 122.46 (CH=CHHt), 125.90 (Ar), 127.49 (Ph),
129.02 (Ar), 129.11 (Ph), 129.50, 129.61 (Ar), 130.88
(CH=CHHt), 132.72, 133.30 (Ph), 134.86 (Ar), 161.98
(C5). Found: m/z 275.0912 [M + H]+. C16H11N5.
(CDCl3), δ, ppm: 7.34 d (1H, CH=CHHt, J 14.4 Hz),
7.41–7.52 m (7H, Ph, CH=CHHt). 13C NMR spectrum
(DMSO-d6), δ, ppm: 9.38 (CH3), 117.64 (CH=CHHt),
127.00 (CH=CHHt), 127.11, 129.22, 129.57, 133.12
(C6H4), 150.52 (C5). Found: m/z 187.1391 [M + H]+.
C10H10N4. Calculated: M 186.0932.
1-[2-(E)-Phenylethenyl]-5-ethyltetrazole (VIc).
Yield 0.27 g (81%), colorless crystals, mp 112–113°C.
1
Rf 0.3 (hexane–ethyl acetate, 8:2). H NMR spectrum
(CDCl3), δ, ppm: 1.47 t (3H, CH3), 2.99 m (2H, CH2),
7.30 d (1H, CH=CHHt, J 14.5 Hz), 7.39–7.52 m (7H,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 11 2012

VINYLTETRAZOLES: III.
1471
Ph, CH=CHHt). 13C NMR spectrum (DMSO-d6), δ,
ppm: 11.48 (CH3), 17.33 (CH2), 117.51 (CH=CHHt),
127.02 (CH=CHHt), 127.13, 129.23, 129.56, 133.22
(C6H4), 154.86 (C5). Found: m/z 201.1198 [M + H]+.
C11H12N4. Calculated: M 200.0497.
1.9 mmol of Cs2CO3. Yield 0.31 g (80%), colorless
crystals, mp 69–70°C. Rf 0.2 (hexane–ethyl acetate,
1
9 : 1). H NMR spectrum (DMSO-d6), δ, ppm: 5.50 d
(1H, CH2=CHHt, J 7.8 Hz), 6.16 d (1H, CH2=CHHt,
J 14.7 Hz), 7.21–7.27 m (2H, Ar, CH=CHHt, J 15.7 Hz),
7.38–7.42 m (2H, Ar, CH2=CHHt), 7.77–7.90 m (3H,
Ar, CH=CHHt). 13C NMR spectrum (DMSO-d6),
δ, ppm: 109.30 (CH2=CHHt), 115.69 (CH=CHHt),
116.51 (Ar), 122.63 d (Ar, J 0.2 Hz), 124.91 (Ar),
128.36 (CH=CHHt), 128.52 (Ar), 130.11 (CH2=CHHt),
131.25 d (Ar, J 0.2 Hz), 160.38 d (Ar, J 3.3 Hz), 162.59
(C5). Found: m/z 217.1139 [M + H]+. C11H9FN4.
Calculated: M 216.0743.
1,2(5)-Bis[2-(E)-arylethenyl]tetrazoles IX, X. To a
slurry of 1.8 mmol of CuI and 1.8 mmol of tetrazole
VII, VIII in 3 ml of DMF was added 0.072 mmol of
Pd(OAc)2, 0.21 mmol of PPh3, 18.0 mmol of ArHlg,
and 5.4 mmol of Cs2CO3, the mixture was stirred at
120°C till the completion of the reaction. On cooling
the mixture was poured at vigorous stirring into 25 ml
of water, and the slurry was filtered through celite. .
The precipitate on the filter was washed with water (2 ×
7 ml). The filtrate was extracted with ethyl acetate (2 ×
20 ml), the combined extract was dried with anhydrous
Na2SO4 and evaporated to dryness in a vacuum.
N-[2-(E)-Arylethenyl]tetrazoles VIa, XIV. To
a slurry of 1.8 mmol of CuI and 1.8 mmol of tetrazole
XII, XIII in 1 ml of DMF was added 0.054 mmol of
Pd(OAc)2, 0.16 mmol of PPh3, 18.0 mmol of ArHlg,
and 5.1 mmol of Cs2CO3, the mixture was stirred at
100°C till the completion of the reaction. On cooling
the mixture was poured at vigorous stirring into 15 ml
of water, and the slurry was filtered through celite. .
The precipitate on the filter was washed with water (2 ×
5 ml). The filtrate was extracted with ethyl acetate (2 ×
15 ml), the combined extract was dried with anhydrous
Na2SO4 and evaporated to dryness in a vacuum.
1,5-Bis[2-(E)-phenylethenyl]tetrazole
(IX).
Yield 0.4 g (80%), colorless crystals, mp 118–
1
119°C. Rf 0.2 (hexane–ethyl acetate, 8:2). H NMR
spectrum (DMSO-d6), δ, ppm: 7.38–7.49 m (6H,
Ph), 7.55 d (1H, CH=CHHt, J 14.4 Hz), 7.67 d (1H,
CH=CHHt, J 16.0 Hz), 7.76–7.86 m (4H, Ph), 7.90 d
(1H, CH=CHHt, J 16.1 Hz), 8.27 d (1H, CH=CHHt,
J 14.1 Hz). 13C NMR spectrum (DMSO-d6), δ, ppm:
108.34 (CH=CHHt), 119.21 (CH=CHHt), 124.99
(CH=CHHt), 127.45, 128.11, 128.82, 128.89, 129.01,
130.05 (Ph), 133.61 (CH=CHHt), 134.94, 139.83 (Ph),
151.47 (C5). Found: m/z 275.3181 [M + H]+. C17H14N4.
Calculated: M 274.3198.
2-[2-(E)-Phenylethenyl]tetrazole (XIV). Yield
0.25 g (80%), light-yellow crystals, mp 40–41°C.
1
Rf 0.3 (hexane–ethyl acetate, 8:2). H NMR spectrum
(CDCl3), δ, ppm: 7.38–7.43 m (3H, Ph), 7.52–7.55 m
(2H, Ph), 7.68 d (4H, CH=CHN, J 14.7 Hz), 7.99 d
(1H, CH=CHCN, J 14.7 Hz), 8.58 s (1H, H5). 13C NMR
spectrum, δ, ppm: 122.43 (CH=CHHt); 125.67, 127.39,
129.26, 129.68 (Ph); 132.94 (CH=CHHt), 152.75 (C5).
Found: m/z 173.1211 [M + H]+. C9H8N4. Calculated:
M 172.0766.
1,2-Bis[2-(E)-(2-fluorophenyl)ethenyl]tetrazole
(X). Yield 0.42 g (76%), colorless crystals, mp 134–
1
135°C. Rf 0.1 (hexane–ethyl acetate, 9:1). H NMR
spectrum (DMSO-d6), δ, ppm: 7.22–7.29 m (4H, Ar,
CH=CHHt, J 15.8 Hz), 7.43 m (3H, Ar), 7.68 d (1H,
CH=CHHt, J 14.8 Hz), 7.85–7.95 m (3H,Ar, CH=CHHt,
J 15.8 Hz), 8.49 d (1H, CH=CHHt, J 14.8 Hz). 13C NMR
spectrum (CDCl3), δ, ppm: 116.40 d (CH=CHHt,
J 0.1 Hz), 116.53, 116.92 (Ar), 117.73 d (CH=CHHt,
J 0.05 Hz), 125.59–125.81 m (Ar, CH=CHHt), 129.30 d
(Ar, J 0.05 Hz), 129.69 d (CH=CHHt, J 0.05 Hz), 129.73
(Ar), 132.01 d (Ar, J 0.1 Hz), 161.03 d (Ar, J 3.3 Hz),
163.26 (C5). Found: m/z 311.3881 [M + H]+. C17H12F2N4.
Calculated: M 310.3007.
ACKNOWLEDGMENTS
The study was carried out under the financial support of
the Russian Foundation for Basic Research (grant no. 11-08-
00483-a).
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 11 2012

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