A general synthetic method for the formation of arylaminotetrazoles using natural natrolite zeolite as a new and reusable heterogeneous catalyst

Article abstract of DOI:10.1016/j.tet.2009.10.029

An efficient method for preparation of arylaminotetrazoles is reported using natrolite zeolite as a natural catalyst. Generally, isomer of 5-arylamino-1H-tetrazole can be obtained from arylcyanamides carrying electron-withdrawing substituent on aryl ring

Full text of DOI:10.1016/j.tet.2009.10.029

Tetrahedron 65 (2009) 10715–10719
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A general synthetic method for the formation of arylaminotetrazoles using natural
natrolite zeolite as a new and reusable heterogeneous catalyst
,
a
b
c
Mahmoud Nasrollahzadeh a , Davood Habibi , Zahra Shahkarami , Yadollah Bayat
*
a Department of Organic Chemistry, Faculty of Chemistry, Bu-Ali Sina University, Hamedan 6517838683, Iran
b Shahinshar Payam Noor University, Shahinshar, Isfahan, Iran
c Department of Chemistry, Malek-Ashtar University of Technology, Tehran, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
An efficient method for preparation of arylaminotetrazoles is reported using natrolite zeolite as a natural
catalyst. Generally, isomer of 5-arylamino-1H-tetrazole can be obtained from arylcyanamides carrying
electron-withdrawing substituent on aryl ring and as the electropositivity of substituent is increased, the
product is shifted toward the isomer of 1-aryl-5-amino-1H-tetrazole. This method has the advantages of
high yields, simple methodology, short reaction times and easy work-up. The catalyst can be recovered
by simple filtration and reused in good yields.
Received 9 May 2009
Received in revised form
23 September 2009
Accepted 8 October 2009
Available online 13 October 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Arylaminotetrazole
Cyanamide
Natrolite zeolite
Natural catalyst
Heterogeneous catalyst
1. Introduction
The addition of the azide anion to nitriles, cyanates and
cyanamides is the most common route for preparing 5-substituted
5-Substituted tetrazoles (RCN4H) may serve as a non-classical
isostere for the carboxylic acid moiety (RCO2H) in biologically ac-
tive molecules.1–7 Hansch has shown that anionic tetrazoles are
almost ten times more lipophilic than corresponding carboxylates,
which is an important factor to bear in mind when designing a drug
molecule to pass through cell membranes.8 There is considerable
interest in the medicinal and biological applications of tetra-
zoles,4,6,9 including 5-aminotetrazoles, due to their reported anti-
allergic and anti-asthmatic,10 antiviral, and anti-inflammatory,11
anti-neoplastic,12 and cognition disorder activities.13 Tetrazoles are
also applied as ligands in coordination chemistry,14–16 as explosives
and rocket propellants.17–19 Another important application of tet-
razoles is the preparation of imidoylazides.20 The earliest published
methods for the preparation of aminotetrazole derivatives were
reactions including the following: (1) addition of NaNO2 to
aminoguanidine21 (2) addition of NaN3 to carbodiimides21c or cy-
anamides22 (3) reactions of amines with a leaving group in the
tetrazoles 5-position23 (4) nucleophilic substitution by Nꢀ3 of (a)
tetrazoles, 5-aryl/alkyl oxytetrazoles and 5-aryl/alkyl amino-
tetrazoles, respectively.3,4,9,20,27–29 In most of them, the reaction
actually proceeds in solutions of hydrazoic acid in solvents such as
benzene, toluene, xylene, and chloroform. Herbst and Garbrecht
have shown that cyanamides may be converted to aminotetrazoles
using hydrazoic acid, which often result in a mixture of isomers
(Scheme 1).22b
NH
N
NH
N
A'
R
R
R
C
N
N
H
N
H
N3
A
HN3
HN
C
N
NH2
R
N
NH2
R
N
C
chlorine in a
-chloroformamidines24 and (b) sulfur from thioureas
B'
N
in the presence of mercury25,26 or lead salts.21a
N
N3
N
B
Scheme 1.
* Corresponding author. Tel.: þ98 811 8282807; fax: þ98 811 8257407.
E-mail address: mahmoudnasr81@gmail.com (M. Nasrollahzadeh).
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.10.029

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M. Nasrollahzadeh et al. / Tetrahedron 65 (2009) 10715–10719
More previously, the 5-monosubstitutedamino-1H-tetrazoles
natural catalyst (Table 1 and Scheme 2). This catalyst (from Sistan
and Baluchestan province, Iran) is safe, easy to handle, environ-
mentally benign with fewer disposals problems. However, to the
best of our knowledge, there has been no report on the use of the
zeolite as catalyst in synthesis of aminotetrazoles.
were synthesized by thermal isomerization of 1-substituted-5-
amino-1H-tetrazoles in boiling ethylene glycol or melt state (180–
200 ꢁC).21a,30 Miller and co-workers have reported synthesis of
some amino-1H-tetrazoles from the treatment of amino-
iminomethanesulfonic acid derivatives with sodium azide in acetic
acid at 50 ꢁC, but with 4–59% yields.31 Another possible method of
obtaining the 5-monoalkylaminotetrazoles was an adaption of the
von Braun degradation of tertiary amines with cyanogens bromide.
In this way, it might be possible to eliminate an alkyl group from a 5-
dialkylaminotetrazoles.22b,32 These methods suffer from one or
more disadvantages, such as low yield, long reaction times, harsh
reaction conditions, difficult to obtain and/or prepare starting ma-
terials, use of expensive and toxic reagents, and the in situ generated
hydrazoic acid is highly toxic and explosive. If hydrazoic acid is used,
care must be taken by monitoring the concentration of hydrazoic
acid in the reaction mixture to avoid an explosion.3,4,9,17,29
NH2
R
NH
N
N
N
R
Zeolite (cat)
i or ii Route
N
HN
N
C
1a-l
N
or
NaN3
2
+
N
3a-e
N
H
N
3f-k
B
A
R
i: DMF, 110-115 °C
ii: H2O, reflux
Scheme 2.
Later Congreve has reported a two-step synthesis of 1-aryl-5-
amino-1H-tetrazoles from the corresponding 1-aryltetrazoles via
cyanamide intermediates.33 The reaction suffers from some draw-
backs such as harsh reaction conditions, low temperatures
(ꢀ70 ꢁC), use of large excess of sodium azide and organolithium
reagents that are potentially dangerous. Vorobiov and co-workers
published a three-step synthesis of 1-aryl-5-amino-1H-tetrazoles
in low yields from the corresponding aromatic amines via isolation
of intermediate cyanamides.34 Unfortunately, this approach is not
well developed due to insufficient stability of the intermediate
cyanamides. In most cases, N-arylureas and other by-products were
mostly formed and the intermediate cyanamides were not stable
enough to be isolated. Therefore, the 1-aryl-5-amino-1H-tetrazoles
were produced in low yields. To resolve this problem, more re-
cently, Vorobiov and co-workers have described a sufficiently
simple and convenient one-step synthesis of 1-aryl-5-amino-
1H-tetrazoles from the decomposition of 1-aryltetrazoles by
consecutive ring-opening, azidation and intramolecular cyclization,
without isolating intermediate cyanamides.35 The above men-
tioned syntheses require the use of highly toxic and explosive
hydrazoic acid. On the other hand, in most of these cases only the
1-aryl-5-amino-1H-tetrazoles or mixtures of isomers (5-aryl-
amino-1H-tetrazole and 1-aryl-5-amino-1H-tetrazoles) were
obtained. Due to safety considerations, we required a method that
did not use of hydrazoic acid or an azide source that produced
hydrazoic acid in situ because of the associated hazards. Therefore,
it is desirable to develop a more efficient and convenient method
for the regiospecific synthesis of arylaminotetrazoles.
Zeolites are crystalline hydrated aluminosilicates of the alkaline
earths. Natural zeolites are formed in several geological environ-
ments such as hydrothermal, burial melamorphic, closed system
(including alkaline earths), open system, and weathering profiles.
The application of inorganic solid acids, especially zeolites, as ef-
fective heterogeneous catalysts for organic synthesis has received
considerable attention in the recent decades due to their unique
physical and chemical properties such as shape, selectivity, acidic,
and basic nature and their thermal stability.36 The advantages of
these catalyst systems over homogeneous systems are well known,
such as stability, ease of handling, lack of corrosion and other en-
vironmental hazards, ease of recovery and regeneration. Natrolite,
Na2[Al2Si3O10]$2H2O, is one of the fibrous zeolites with the
framework constructed from the chains of corner-sharing Al and Si
oxygen tetrahedra.37
2. Result and discussion
The cyanamides 1a–k were prepared according to literature.40
In order to include a reasonable range of electrical and steric effects,
the aryl substituted cyanamides 1a–k studied included various
groups in ortho, meta, and para positions, Table 1. Several aromatic
cyanamides carrying either electron-donating or electron-with-
drawing substituents reacted and gave the products in good yields
(Table 1).
To show the advantages of natrolite zeolite as a catalyst in com-
parison with other materials, we compared the reaction of natrolite
zeolite with PPh3, LiCl, SiO2–HClO4, Al2O3–SO3H, glacial acetic acid
and FeCl3–SiO2 in the synthesis of 5-(2-chlorophenyl)amino-1H-
tetrazole (3b, Table 1, Entry 2). As shown in Table 2, natrolite zeolite
is a better catalyst in the synthesis of arylaminotetrazole, while PPh3,
LiCl, SiO2–HClO4, Al2O3–SO3H, glacial acetic acid, and FeCl3–SiO2
aren’t suitable for this reaction and result in a mixture of isomers. In
addition, in order to improve yield and due to the biological
importance of aminotetrazole derivatives, we started to study this
reaction by examining the different amounts of natrolite zeolite as
a catalyst for the reaction involving 2-chlorophenylcyanamide (1b,
Table 1, Entry 2) (2 mmol) and sodium azide (3 mmol) to afford the
product under thermal conditions, which best result was obtained
with a 0.1 g of natrolite zeolite and gave 5-(2-chlorophenyl)amino-
1H-tetrazole (3b, Table 1) in high yield. Not many organic solvents
are stable at the high temperatures necessary for cycloaddition
reactions (sometimes as high as 130 ꢁC), and for this reason DMF is
most commonly used for this purpose.9,17,29
Recently, Sharpless and co-workers reported a relatively simple,
convenient and safe procedure for the synthesis of tetrazoles by the
addition of sodium azide to nitriles using stoichiometric amounts
or 50 mol % of Zn(II) salts.29c–e However, zinc(II) chloride or bro-
mide being homogeneous Lewis acids and could not be recycled
from the reaction mixture, while in every experiment, the whole of
the natrolite zeolite was easily recovered from the reaction
mixture. The reusability of the catalysts is one of the most impor-
tant benefits and makes them useful for commercial applications.
The following important results can be extracted from data in
Table 1:
1. As shown in Table 1, in the reaction between sodium azide with
secondary arylcyanamides using natrolite zeolite at 110–115 ꢁC
in DMF, the presence of electron-withdrawing groups and
electron-releasing groups on the aryl rings did exhibit signifi-
cant effects on reaction time. While, in the reaction between
sodium azide with secondary arylcyanamides using zeolite as
a catalyst in water, the nature of the substituent on the aryl
rings did not affect the time of reaction completion (Table 1,
In continuation of our recent work on the synthesis of hetero-
cycles38 and application of heterogeneous reagents for
development of the useful synthetic methodologies,39 we herein
report the synthesis of arylaminotetrazoles 3a–k from a wide va-
riety of arylcyanamides 1a–k with sodium azide 2 under thermal
conditions in DMF or H2O using natrolite zeolite as a reusable and

M. Nasrollahzadeh et al. / Tetrahedron 65 (2009) 10715–10719
10717
Table 1
Table 2
Synthesis of arylaminotetrazoles 3 in the presence of natrolite zeolite by reaction
between sodium azide and cyanamides 1a–k at 110–115 ꢁC
Comparison of different amounts of natrolite zeolite catalyst with PPh3, FeCl3–SiO2,
SiO2–HClO4, Al2O3–SO3H, glacial acetic acid and LiCl in the synthesis of 5-(2-
chlorophenyl)amino-1H-tetrazole (3b) at 110–115 ꢁC
Entry
Substrate
Routea 3 (A or B) Yieldb
%
Time
Entry Reagent or catalyst Solvent
Time (min) Product (A or B) Yielda (%)
CN
NH
1
2
3
4
5
6
7
8
PPh3
FeCl3–SiO2
DMF
DMF
db
120
120
30
30
100
AþB
AþB
AþB
AþB
AþB
AþB
A
A
A
A
A
64
75
87
88
65
86
72
77
48
80
80
81
81
1
i
ii
3a (A)
3a (A)
80
46
115 min
9 h
O2N
SiO2–HClO4
Al2O3–SO3H
LiCl
1a
db
DMF
CH3COOHc
CH3COOH 24 hd
2
3
Cl
Zeolite (0.05 g)
Zeolite (0.07 g)
Zeolite (0.1 g)
Zeolite (0.1 g)
Zeolite (0.1 g)
Zeolite (0.13 g)
Zeolite (0.16 g)
DMF
DMF
H2O
DMSO
DMF
DMF
DMF
95
95
95
95
95
95
95
CN
NH
1b
i
ii
3b (A)
3b (A)
80
48
95 min
9 h
9
10
11
12
13
A
A
Cl
a
Isolated yield.
Solvent-free.
b
c
CN
NH
1c
Glacial acetic acid as both solvent and proton donor source.
Room temperature.
i
ii
3c (A)
3c (A)
81
49
95 min
9 h
d
Cl
Entries 1–11). In general, when the substitution was electron-
donating, the reaction was completed in less time (starting
material (cyanamide) is consumed faster) than when the sub-
stitution was electron-withdrawing (compare Entries 6–11
with 1–4 in Table 1).
4
5
CN
NH
1d
3d (A)
82
95 min
i
Br
2. In this work, we have observed that the regiospecificity of cy-
cloaddition of azide ion to the cyanamides is strongly affected
by the type of catalysts. In other words, in both cases the
process was completely regiospecific, Tables 1 and 2. This is in
contrast with the reports that were presented for the synthesis
of aminotetrazoles using hydrazoic acid, which often results in
mixture of isomers A and B.22b
3. Perhaps the most remarkable feature of the reaction of the
monosubstituted cyanamides with hydrazoic acid is the
unidirectional character of the cyclization.3,4,9,21a,22b,27,30,41
The nature of the substituent appears to play at best a minor
role in directing the course of the reaction. Substituents as
different in their electrical effects as the methyl group and
the p-nitrophenyl group permit the formation of the same
type of compound, presumably through the intermediate
formation of a guanyl azide. Surprisingly, ring closure of the
substituted guanyl azide in all of these methods yields the
1-alkyl- or 1-aryl-5-aminotetrazole as the major product (as
much as 95% in certain cases). No serious consideration ap-
pears to have been given by previous workers to the isolation
or detection of the other isomer, although Stolle and Heintz
reported the isolation of 5-anilinotetrazole in very small
yield from the reaction of phenylthiourea with lead oxide
and sodium azide.42
i
ii
3e (A)
3e (A)
81
49
95 min
9 h
CN
NH
1e
6
7
CN
i
ii
3f (B)
3f (B)
80
48
65 min
9 h
H3C
H3C
NH
1f
CH3
CN
i
ii
3g (B)
3g (B)
81
50
65 min
9 h
NH
1g
8
CH3
CN
NH
1h
i
ii
3h (B)
3h (B)
79
47
65 min
9 h
9
CN
HN
i
ii
3i (B)
3i (B)
82
47
65 min
9 h
In contrast with the reports that have previously been published,
in our methods, the nice distinction is that tetrazoles 3 are strongly
under the effect of the type of substituents in arylcyanamides 1a–k
and isomer A or B is just obtained, Table 1. In other words, there is an
excellent correlation between the effect of substitution on the
benzene ring and the major product. Generally, when the
substitution on the aryl ring is electron-donating in arylcyanamides
1a–k, the formation of 1-aryl-5-amino-1H-tetrazoles (B) is favored
via guanidine azide intermediate B0 (Table 1 and Entries 6–11) and
as the electronegativity of substituent is increased, the product is
shifted toward the 5-arylamino-1H-tetrazole (A) (Table 1 and
Entries 1–4). In other words, if cyclization were to involve the ni-
trogen carrying the aryl substituent in guanidine azide intermediate
B0, 1-aryl-5-amino-1H-tetrazoles (B) would result. On the other
hand, involvement of the terminal unsubstituted nitrogen in the
1i
10
CN
NH
1j
i
ii
3j (B)
3j (B)
83
46
65 min
9 h
H3CO
H3CO
OCH3
CN
NH
1k
11
i
ii
3k (B)
3k (B)
81
48
65 min
9 h
a
Route (i) DMF, 110–115 ꢁC; (ii) H2O, reflux.
Yields refer to the pure isolated products.
b

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M. Nasrollahzadeh et al. / Tetrahedron 65 (2009) 10715–10719
cyclization would result in 5-arylamino-1H-tetrazoles (A) via gua-
nidine azide intermediate A0. This is similar to the substituent effect
on the aryl ring of mechanism that was presented by Henry and co-
workers for thermal isomerization.30
In a typical experiment, after the reaction was completed, na-
trolite zeolite as a catalyst was isolated from the reaction mixture
by simple filtration in the work-up stage. We found that natrolite
zeolite can be reused several times without the loss of activity, by
simply filtering the catalyst, washing with water and ethanol,
drying and immediately reusing. In fact, the reaction 4-methyl-
phenylcyanamide (Table 1, Entry 6) with NaN3 in DMF has been
repeated five times using the same catalyst with respectably high
yields: 76–80%.
4.3. General procedure for the synthesis of
arylaminotetrazoles 3 using natrolite zeolite
Natrolite zeolite (0.1 g) was added to a mixture of appropriate
cyanamide 1 (2 mmol), NaN3 2 (3 mmol) in 8 mL of distilled dime-
thylformamide (DMF) and stirred at 110–115 ꢁC for the appropriate
time (Table 1). After completion (as monitored by TLC), the reaction
mixture was cooled to room temperature, the catalyst was centri-
fuged and the centrifugate was treated with ethyl acetate (35 mL)
and 4 N HCl (20 mL), and then the mixture stirred vigorously. The
resultant organic layer was separated and the aqueous layer was
again extracted with ethyl acetate (25 mL). The combined organic
layers were washed with water and concentrated to give the crude
solid arylaminotetrazole. After concentration, a crystallization step
was performed using aqueous ethanol. Similarly, to a 50 mL round-
bottomed flask, the cyanamide 1 (2 mmol), sodium azide 2
(2.5 mmol), zeolite (0.1 g) and 16 mL of water were added. The re-
action mixture was stirred at reflux for 9 h. After consumption of
cyanamide 1, the mixture was cooled to room temperature, the solid
residue was filtered from the reaction mixture and thenwas washed
with water. In continuation of work-up, the solid residuewas treated
with 10 mL 3 N HCl to obtain pure arylaminotetrazole derivatives.
The products were characterized by 1H NMR, 13C NMR, IR, FTIR,
elemental analysis (CHN) and melting points. Elimination of one
strong and sharp absorption bands (CN stretching band), and ap-
pearance of two absorption bands in the range of 3139–3550 cmꢀ1
(NH stretching bands) in IR spectrum, confirmed the formation of
arylaminotetrazoles. 13C NMR spectra displayed signals about
d
¼154–157.5 ppm for C5 of tetrazole ring.43
3. Conclusions
4.3.1. 1-Naphthylcyanamide (1i, Table 1). Mp 143–145 ꢁC; FTIR
(KBr): v 3382, 3165, 3079, 2961, 2897, 2226, 1613, 1515, 1436, 1409,
In conclusion, we have developed two efficient procedures
for preparation of substituted arylaminotetrazoles using natro-
lite zeolite as a natural and reusable heterogeneous catalyst.
These methods have the advantages of high yields, simple
methodology, easy work-up and no chromatographic separation
is necessary to get the spectra-pure compounds. Natrolite Zeolite
as a catalyst is important from an environmental point of view
and from the view point of economic considerations, because it
produces little waste. It also has excellent activity on an in-
dustrial scale and in most cases can be recovered from reaction
mixtures and reused.
1302, 1256, 1181, 1108, 1016, 859, 835, 811, 771 cmꢀ1 1H NMR
;
(300 MHz, DMSO-d6):
7.54–7.59 (m, 3H), 7.89–7.93 (m, 1H), 8.09–8.12 (m, 1H); 13C NMR
(75 MHz, DMSO-d6):
d
¼7.21 (d, J¼7.4 Hz,1H), 7.47 (t, J¼7.8 Hz,1H),
d
¼136.4, 134.4, 128.7, 127.0, 126.6, 126.3, 124.1,
122.8, 121.7, 114.3, 111.5; Anal. Calcd for C11H8N2: C, 78.55; H, 4.79;
N, 16.65. Found: C, 78.66; H, 4.90; N, 16.53.
4.3.2. 5-(4-Nitrophenyl)amino-1H-tetrazole (3a, Table 1). Mp 218–
220 ꢁC; IR (KBr): v 3550, 3235, 3100,1635,1572,1488,1337,1290,1257,
1111, 1052, 839, 745 cmꢀ1; 1H NMR (500 MHz, DMSO-d6):
d
¼7.76 (d,
J¼7.3 Hz, 2H), 8.21 (d, J¼9.3 Hz, 2H), 10.96 (br s, 1H); 13C NMR
(125 MHz, DMSO-d6):
d¼155.2,147.1,140.3,124.9,116.8; Anal. Calcd for
4. Experimental
4.1. General
C7H6N6O2: C, 40.78; H, 2.93; N, 40.77. Found: C, 40.90; H, 3.03; N, 40.64.
4.3.3. 5-(2-Chlorophenyl)amino-1H-tetrazole (3b, Table 1). Mp
228–230 ꢁC; IR (KBr): v 3260, 3210, 3140, 3100, 1626, 1573, 1551,
1470,1440,1286,1233,1134,1052, 796, 742, 674, 633 cmꢀ1; 1H NMR
All reagents were purchased from Merck and Aldrich and used
without further purification. Products were characterized by
spectroscopy data (IR, FTIR, 1H NMR and 13C NMR spectra), ele-
mental analysis (CHN) and melting points. The NMR spectra were
recorded in DMSO and acetone. 1H NMR spectra were recorded on
a Bruker Avance DRX 300 and 500 MHz instruments. The chemical
(500 MHz, DMSO-d6):
7.46 (d, J¼7.9 Hz, 1H), 8.00 (d, J¼8.2 Hz 1H), 9.12 (s, 1H), 14.86 (br s,
1H); 13C NMR (125 MHz, DMSO-d6):
d
¼7.04 (t, J¼7.7 Hz,1H), 7.33 (t, J¼8.4 Hz,1H),
d
¼154.8, 136.6, 129.6, 127.9,
123.5, 122.6, 120.2; Anal. Calcd for C7H6N5Cl: C, 42.98; H, 3.09; N,
35.80. Found: C, 43.10; H, 3.19; N, 35.68.
shifts (d) are reported in ppm relative to the TMS as internal stan-
dard. J values are given in Hertz. 13C NMR spectra were recorded at
125 and 75 Hz. IR (KBr) and FTIR (KBr) spectra were recorded on
a Shimadzu 470 and Perkin–Elmer 781 spectrophotometer, re-
spectively. Melting points were taken in open capillary tubes with
a BUCHI 510 melting point apparatus and were uncorrected. The
elemental analysis was performed using Heraeus CHN–O-Rapid
analyzer. TLC was performed on silica gel polygram SIL G/UV 254
plates. Natural Iranian natrolite zeolite from the Hormak area
(Zahedan city, Sistan & Baluchestan province, Iran) was used in this
work.44
4.3.4. 5-(2,5-Dicholorophenyl)amino-1H-tetrazole (3c, Table 1). Mp
272–274 ꢁC; IR (KBr): v 3245, 3184, 3156, 3115, 1620, 1592, 1569,
1544, 1467, 1411, 1090, 1054, 1038, 836, 799, 772, 664, 563,
538 cmꢀ1; 1H NMR (500 MHz, DMSO-d6):
d
¼7.06 (d, J¼8.5 Hz, 1H),
7.48 (d, J¼8.6 Hz,1H), 8.19 (s,1H), 9.38 (br s,1H),14.72 (br s,1H); 13C
NMR (125 MHz, DMSO-d6):
d
¼154.4, 137.8, 132.3, 130.8, 122.5,
120.3, 118.7; Anal. Calcd for C7H5N6Cl2: C, 36.52; H, 2.17; N, 30.43.
Found: C, 36.66; H, 2.22; N, 30.56.
4.3.5. 5-(4-Bromophenyl)amino-1H-tetrazole (3d, Table 1). Mp249–
250 ꢁC; IR (KBr): v 3285, 3205,1617,1574,1534,1485,1240,1054,1023,
4.2. Catalyst characterization
828, 772, 720 cmꢀ1
;
1H NMR (300 MHz, DMSO-d6):
d
¼7.45–7.53
(m, 4H), 9.98 (br s,1H),15.57 (br s,1H); 13C NMR (75 MHz, DMSO-d6):
This catalyst has recently been found in the Hormak area
(Zahedan city, Sistan and Baluchestan province, Iran) and was used
as catalyst in this work. Noroozifar and co-workers studied the
characterization of the natural zeolite (Natrolite) using powder
XRD, XRF, TG-DTA, and FTIR spectroscopy.44
d
¼112.8,119.2,132.2, 140.3, 156.1; Anal. Calcd for C7H6N5Br: C, 35.02;
H, 2.52; N, 29.17. Found: C, 35.11; H, 2.64; N, 29.24.
4.3.6. 5-Phenylamino-1H-tetrazole (3e, Table 1). Mp 215–217 ꢁC,
lit.,10 211–212 ꢁC; IR (KBr): v 3325, 3220, 1620, 1580, 1533, 1498,

M. Nasrollahzadeh et al. / Tetrahedron 65 (2009) 10715–10719
10719
1243, 1053, 785, 742, 735, 688, 660 cmꢀ1 1H NMR (500 MHz,
;
4. Wittenberger, S. J. Org. Prep. Proceed. Int. 1994, 26, 499.
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and Biology; American Chemical Society: Washington, DC, 1995; Chapter 13.
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274867, 1988; Chem. Abstr. 1989, 110, 23890.
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9811093, 1998; Chem. Abstr. 1998, 128, 230253.
13. Mitch, C.H.; Quimby, S.J. Int. Patent WO 9851312, 1998; Chem. Abstr. 1998, 130,
13997.
14. Ek, F.; Wistrand, L.-G.; Frejd, T. Tetrahedron 2003, 59, 6759.
15. Flippin, L. A. Tetrahedron Lett. 1991, 32, 6857.
16. Rhonnstad, P.; Wensbo, D. Tetrahedron Lett. 2002, 43, 3137.
17. Jursic, B. S.; LeBlanc, B. W. J. Heterocycl. Chem. 1998, 35, 405.
18. John, E. O.; Kirchmeier, R. L.; Shreeve, J. M. Inorg. Chem. 1989, 28, 4629.
19. Zhao-Xu, C.; Heming, X. Int. J. Quantum Chem. 2000, 79, 350.
20. Modarresi-Alam, A. R.; Khamooshi, F.; Rostamizadeh, M.; Kieykha, H.;
Nasrollahzadeh, M.; Bijanzadeh, H. R.; Kleinpeter, E. J. Mol. Struct. 2007,
841, 67.
21. (a) Finnegan, W. G.; Henry, R. A.; Lieber, E. J. Org. Chem. 1953, 18, 779; (b) Jensen,
K. A.; Holm, A.; Rachlin, S. Acta Chem. Scand. 1966, 20, 2795; (c) Percival, D. F.;
Herbst, R. M. J. Org. Chem. 1957, 22, 925.
22. (a) Moderhack, D.; Goos, K.-H.; Preu, L. Chem. Ber. 1990, 123, 1575; (b) Gar-
brecht, W. L.; Herbst, R. M. J. Org. Chem. 1953, 18, 1014; (c) Herbst, R. M.;
Roberts, C. W.; Harvill, E. J. Org. Chem. 1951, 16, 139; (d) Marchalin, M.; Martvon,
A. Collect. Czech. Chem. Commun. 1980, 45, 2329.
23. (a) Klich, M.; Teutsch, G. Tetrahedron 1986, 42, 2677; (b) Barlin, G. B. J. Chem.
Soc. B 1967, 641.
DMSO-d6):
d
¼6.93 (t, J¼7.3 Hz, 1H), 7.29 (t, J¼7.9 Hz, 2H), 7.49 (d,
J¼8.2 Hz, 2H), 9.74 (s, 1H), 15.33 (br s, 1H); 13C NMR (DMSO-d6,
125 MHz):
d
¼155.8, 140.3, 128.9, 121.0, 116.7.
4.3.7. 1-(4-Methylphenyl)-5-amino-1H-tetrazole (3f, Table 1). Mp
178–179 ꢁC, lit.,30a 175.5–177 ꢁC, lit.,35 174–175 ꢁC; FTIR (KBr): v
3306, 3141,1655,1594,1572,1519,1467,1320,1306,1142,1090,1017,
839, 818, 618, 545, 483 cmꢀ1; 1H NMR (500 MHz, DMSO-d6):
d¼2.40
(s, 3H), 6.80 (s, 2H), 7.41 (d, J¼8.4 Hz, 2H), 7.45 (d, J¼8.4 Hz, 2H); 13C
NMR (125 MHz, DMSO-d6):
d
¼155.8, 139.8, 131.8, 131.1, 124.8, 21.6.
4.3.8. 1-(2,4-Dimethylphenyl)-5-amino-1H-tetrazole (3g, Table 1). Mp
199–201 ꢁC, lit.,11 199–201 ꢁC; IR (KBr): v 3310, 3150, 1651, 1573, 1506,
1458, 1377, 1312, 1134, 1088, 1027, 868, 823, 614, 562 cmꢀ1; 1H NMR
(500 MHz, DMSO-d6):
d
¼1.99 (s, 3H), 2.36 (s, 3H), 6.63 (s, 2H), 7.22 (d,
J¼8.1 Hz, 1H), 7.19 (d, J¼8.3 Hz, 1H), 7.28 (s, 1H); 13C NMR (125 MHz,
DMSO-d6):
d¼155.6, 140.0, 134.9, 131.7, 129.4, 127.6, 127.1, 20.6, 16.7.
4.3.9. 1-(2-Methylphenyl)-5-amino-1H-tetrazole (3h, Table 1). Mp
191–192 ꢁC, lit.,11,10 191–192 ꢁC, lit.,14 189–190 ꢁC; FTIR (KBr): v
3323, 3158, 1655, 1593, 1575, 1503, 1473, 1313, 1126, 1091, 1026, 772,
757, 715, 673, 564 cmꢀ1; 1H NMR (300 MHz, DMSO-d6):
d
¼2.06 (s,
3H), 6.74 (s, 2H), 7.36–7.51 (m, 4H); 13C NMR (75 MHz, DMSO-d6):
¼17.4, 127.7, 127.9, 130.9, 131.8, 132.5, 135.8, 156.1.
d
4.3.10. 1-(1-Naphthyl)-5-amino-1H-tetrazole (3i, Table 1). Mp 220–
221 ꢁC; FTIR (KBr): v 3322, 3139, 1655, 1598, 1577, 1509, 1483, 1397,
1085, 806, 772, 662 cmꢀ1
;
1H NMR (500 MHz, DMSO-d6):
d¼6.78
24. Ried, W.; Erle, H.-E. Liebigs Ann. Chem. 1982, 201.
25. Batey, R. A.; Powell, D. A. Org. Lett. 2000, 2, 3237.
(br s, 2H), 7.28 (d, J¼8.3 Hz, 1H), 7.74–7.62 (m, 4H), 8.14 (d, J¼8.2 Hz,
1H), 8.22 (d, J¼7.5 Hz, 1H); 13C NMR (125 MHz, DMSO-d6):
¼157.3,
d
26. Yu, Y.; Ostresh, J. M.; Houghten, R. A. Tetrahedron Lett. 2004, 45, 7787.
27. (a) Benson, F. R. Chem. Rev. 1947, 47, 1; (b) Koldobskii, G. I.; Ostrovskii, V. A.;
Popavskii, V. S. Chem. Heterocycl. Comp. 1982, 965; (c) Kadaba, P. K. Synthesis
1973, 71.
28. Katritzky, A. R.; Rogovoy, B. V.; Kovalenko, K. V. J. Org. Chem. 2003, 68, 4941.
29. (a) Kantam, M. L.; Shiva Kumar, K. B.; Sridhar, C. Adv. Synth. Catal. 2005, 347,
1212; (b) Jin, T.; Kitahara, F.; Kamijo, S.; Yamamoto, Y. Tetrahedron Lett. 2008, 49,
2824; (c) Demko, P. Z.; Sharpless, K. B. J. Org. Chem. 2001, 66, 7945; (d) Himo, F.;
Demko, P. Z.; Noodleman, L.; Sharpless, K. B. J. Am. Chem. Soc. 2002, 124, 12210;
(e) Himo, F.; Demko, P. Z.; Noodleman, L.; Sharpless, K. B. J. Am. Chem. Soc. 2003,
125, 9983.
30. (a) Henry, R. A.; Finnegan, W. G.; Lieber, E. J. Am. Chem. Soc. 1954, 76, 88; (b)
Henry, R. A.; Finnegan, W. G.; Lieber, E. J. Am. Chem. Soc. 1955, 77, 2264.
31. Miller, A. E.; Feeney, D. J.; Ma, Y.; Zarcone, L.; Aziz, M. A.; Magnuson, E. Synth.
Commun. 1990, 20, 217.
32. Braun, V. J. Chem. Ber. 1900, 33, 1438.
33. Congreve, M. S. Synlett 1996, 359.
134.8,131.6,129.9,129.3,128.8,127.9,126.7,126.6,122.7; Anal. Calcd
for C11H9N5: C, 62.56; H, 4.26; N, 33.17. Found: C, 62.64; H, 4.38; N,
33.29.
4.3.11. 1-(4-Methoxyphenyl)-5-amino-1H-tetrazole (3j, Table 1). Mp
211–213 ꢁC; IR (KBr): v 3300, 3125, 2975, 2925, 1657, 1608, 1588,
1573,1518, 1458,1441, 1382, 1293, 1248, 1180, 1169,1139, 1104,1084,
1042, 1020, 840, 635, 620, 580, 550 cmꢀ1 1H NMR (500 MHz, ac-
;
etone-d6):
d
¼3.89 (s, 3H), 6.14 (s, 2H), 7.14 (d, J¼8.9 Hz, 2H), 7.49 (d,
J¼8.9 Hz, 2H); 13C NMR (125 MHz, acetone-d6):
d
¼56.19, 115.9,
127.1, 127.7, 156.2, 161.5; Anal. Calcd for C8H9N5O: C, 50.25; H, 4.74;
N, 36.63. Found: C, 50.21; H, 4.81; N, 36.75.
34. Vorobiev, A. N.; Gaponik, P. N.; Petrov, P. T. Vestsi Nats. Akad. Navuk Belarusi, Ser.
Khim. Navuk 2003, 50; Chem. Abstr. 2004, 140, 16784g.
35. Vorobiev, A. N.; Gaponik, P. N.; Petrov, P. T.; Ivashkevich, O. A. Synthesis 2006,1307.
36. Hoelderich, W. F.; Haft, B. A. Structure–Activity and Selectivity Relationships in
Heterogeneous Catalysis; Elsevier: Amsterdam, 1991.
4.3.12. 1-(2,4-Dimethoxyphenyl)-5-amino-1H-tetrazole (3k, Table 1). Mp
183–185 ꢁC; FTIR (KBr): v 3378, 3276, 3222, 3139, 3058, 1689, 1612,
1593, 1524, 1456, 1435, 1297, 1263, 1211, 1161, 1118, 1047, 1023, 986,
37. Line, C.; MB; Kearley, G. J. Chem. Phys. 1998, 234, 207.
933, 837 cmꢀ1; 1H NMR (300 MHz, DMSO-d6):
d
¼3.78 (s, 3H), 3.85
38. (a) Nasrollahzadeh, M.; Bayat, Y.; Habibi, D.; Moshaee, S. Tetrahedron Lett. 2009,
50, 4435; (b) Kamali, T. A.; Bakherad, M.; Nasrollahzadeh, M.; Farhangi, S.;
Habibi, D. Tetrahedron Lett. 2009, 50, 5459.
39. (a) Modarresi-Alam, A. R.; Nasrollahzadeh, M.; Khamooshi, F. ARKIVOC 2007,
xvi, 234; (b) Modarresi-Alam, A. R.; Khamooshi, F.; Nasrollahzadeh, M.; Amir-
azizi, H. A. Tetrahedron 2007, 63, 8723; (c) Modarresi-Alam, A. R.; Nasrollah-
zadeh, M.; Khamooshi, F. Scientia Iranica 2008, 15, 452.
(s, 3H), 6.67 (d, J¼8.5 Hz,1H), 6.78 (d, 3H), 7.30 (d, J¼8.6 Hz,1H); 13C
NMR (75 MHz, DMSO-d6):
d
¼56.2, 56.4, 100.0, 105.9, 114.7, 129.7,
155.9, 156.4, 162.5; Anal. Calcd for C9H11N4: C, 48.87; H, 5.01; N,
31.66. Found: C, 48.95; H, 5.12; N, 31.55.
40. Crutchley, R. J.; Nakicki, M. L. Inorg. Chem. 1989, 28, 1955.
41. (a) Garbrecht, W. L.; Herbst, R. M. J. Org. Chem. 1953, 18, 1003; (b) Garbrecht, W.
L.; Herbst, R. M. J. Org. Chem. 1953, 18, 1022.
Acknowledgements
We are thankful to the University of Bu-Ali Sina Council for the
partial support of this work.
42. Stolle, R.; Heintz, J. Prakt. Chem. 1937, 147, 286.
43. (a) Goljer, I.; Svetlik, J.; Hrusovsky, I. Monatshefte fur Chemie 1983, 114, 65; (b)
Svetlik, J.; Hrusovsky, I.; Martvon, A. Collect. Czech. Chem. Commun. 1979, 44,
2982; (c) Butler, R. N.; Garvin, N. L. J. Chem. Soc., Perkin Trans. 1 1981, 390; (d)
Butler, R. N.; McEvoy, T. M.; Scott, F. L.; Tobin, J. C. Can. J. Chem. 1977, 55, 1564;
(e) Butler, R. N. Can. J. Chem. 1972, 51, 2315; (f) Batterhan, T. J. NMR Spectra of
Simple Heterocycles; Wiley: New York, NY, 1973; p 226.
44. (a) Noroozifar, M.; Khorasani-Motlagh, M.; Gorgij, M. N.; Naderpour, H. R.
J. Hazard. Mater. 2008, 155, 566; (b) Noroozifar, M.; Khorasani-Motlagh, M.;
Ahmadzadeh Fard, P. J. Hazard. Mater. 2009, 166, 1060.
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