Synthesis of 3-nitramino-4-(1 H-1,2,3-triazol-1-yl)-1,2,5-oxadiazoles and their salts

Article abstract of DOI:10.1007/s11172-011-0255-z

Nitration of 3-amino-4-(1 H-1,2,3-triazol-1-yl)-1,2,5-oxadiazoles (3-amino-4-triazolyl-furazans) with a mixture of NaNO₃ and conc. H₂SO₄ gave for the first time triazolylfurazans with a primary nitramino group attached to the furazan ring. If the starting amino(triazolyl)-furazan contains an aromatic substituent, the latter also undergoes nitration under the conditions studied. Some of these nitramines were converted into salts (K, Na, and NH₄).

Full text of DOI:10.1007/s11172-011-0255-z

Russian Chemical Bulletin, International Edition, Vol. 60, No. 8, pp. 1712—1718, August, 2011
1712
Synthesis of 3ꢀnitraminoꢀ4ꢀ(1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)ꢀ1,2,5ꢀoxadiazoles
and their salts
V. Yu. Rozhkov, L. V. Batog, and M. I. Struchkova
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5328. Eꢀmail: mnn@ioc.ac.ru
Nitration of 3ꢀaminoꢀ4ꢀ(1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)ꢀ1,2,5ꢀoxadiazoles (3ꢀaminoꢀ4ꢀtriazolylꢀ
furazans) with a mixture of NaNO3 and conc. H2SO4 gave for the first time triazolylfurazans
with a primary nitramino group attached to the furazan ring. If the starting amino(triazolyl)ꢀ
furazan contains an aromatic substituent, the latter also undergoes nitration under the condiꢀ
tions studied. Some of these nitramines were converted into salts (K, Na, and NH4).
Key words: amino(1,2,3ꢀtriazolꢀ1ꢀyl)furazans, nitramino(1,2,3ꢀtriazolꢀ1ꢀyl)furazans,
4ꢀaminoꢀ3ꢀazidofurazan, 1,3ꢀdicarbonyl compounds, 1,3ꢀcycloaddition, nitration, hydrolysis,
decarboxylation, nitramino(triazolyl)furazan salts, NMR spectroscopy.
Earlier,1—6 a number of Rꢀ(1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)ꢀ
1,2,5ꢀoxadiazoles (triazolylfurazans) have been obtained.
However, similar structures containing a nitramino group
in the oxadiazole ring have not been documented hitherto.
It is known that compounds containing nitramino
groups (NNO2) are of interest as highꢀenergy structures or
their precursors. Data on the synthesis, properties, and
few reactions of primary and secondary nitraminofurazans
are reviewed by Sheremetev.7 These compounds are
mainly obtained by nitration of furazans containing NH2 or
NHR groups. Furazans with an unsubstituted NH2 group
are usually nitrated with conc. HNO3 (d = 1.5 g cm–3) in
CCl4 or the system8 NaNO3—conc. H2SO4; nitrogen pentꢀ
oxide is also used. Recently,9 the nitration of aminoꢀ
furazans with aqueous HNO3 has been reported.
Scheme 1
i. NaNO3/H2SO4.
1
a
b
c
d
e
f
R
CO2Et
CO2Et
H
H
H
R´
Me
2
a
b
c
d
e
f
R
CO2Et
CO2Et
H
H
H
R´
Me
Ph
CH2Cl
Me
3ꢀNO2C6H4
CH2Cl
Me
3ꢀNO2C6H4
Ph
But
H
But
H
g
h
H
4ꢀClꢀ3ꢀNO2C6H3
4ꢀClꢀ3ꢀNO2C6H3
g
h
H
4ꢀClC6H4
4ꢀClC6H4
In the present work, we studied nitration of appropriꢀ
ate amines as a possible route to primary nitraminoꢀ
(triazolyl)furazans (1). Amino(triazolyl)furazans 2a—h
were employed as the starting reagents (Scheme 1). Comꢀ
pounds 2a—d have been described earlier;2,5,10 aminoꢀ
furazans 2e—h were prepared for the first time. First reꢀ
sults of our investigation have been briefly announced.11
Amino(triazolyl)furazans 2e—g with a 5ꢀmonosubstiꢀ
tuted triazole ring were prepared from 4,5ꢀdisubstituted
amines 2b,h,i containing the ester group in position 4 of
the triazole ring (Scheme 2).
Two of these compounds (namely, 2h and 2i) have not
been documented hitherto. We obtained them by reacꢀ
tions of 4ꢀaminoꢀ3ꢀazidofurazan (4) with ethyl 4ꢀchloroꢀ
benzoylacetate (5a) and methyl 4,4ꢀdimethylꢀ3ꢀoxopenꢀ
tanoate (5b), respectively, in the presence of Et3N as deꢀ
scribed earlier2 for the synthesis of triazolylfurazans (see
CO2Et
CO2Et
Scheme 2). Hydrolysis of compounds 2b,h,i in boiling
solutions of NaOH in H2O—EtOH (1 : 1) followed by
acidification of the resulting sodium salts with 2 M HCl to
a neutral reaction gave previously unknown carboxylic
acids 3a—c. Their decarboxylation10 in boiling AcOH
yielded amino(triazolyl)furazans 2e—g (see Scheme 2).
Amines 2a—h were nitrated with NaNO3—conc. H2SO4
at 20 or 50 °C, depending on the starting compound. We
found that amino(triazolyl)furazans 2a—h under the conꢀ
ditions studied undergo transformations into nitramines
1a—h, respectively (see Scheme 1).
For compounds 2b,e,g,h containing an aromatic subꢀ
stituent in the triazole ring, the formation of primary nitrꢀ
amines is accompanied by nitration of the aromatic ring.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1687—1692, August, 2011.
1066ꢀ5285/11/6008ꢀ1712 © 2011 Springer Science+Business Media, Inc.

Synthesis of nitramino(triazolyl)furazans
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
1713
and spectroscopic characteristics (1H, 13C, and 14N NMR,
IR, and MS). These and other relevant data are given in
Tables 1—3.
Scheme 2
The 1H NMR spectra of compounds 1b, 7, and 8 conꢀ
taining the nitro group at the benzene ring show the folꢀ
lowing chemical shifts δ: a singlet (8.56 (1b), 8.42 (7),
8.41 (8)), two doublets (8.05, 8.50 (1b); 7.88, 8.36 (7);
7.94, 8.34 (8)), and a triplet (7.89 (1b), 7.76 (7), 8.34 (8)).
These signals can be assigned to the protons at the C(2),
(C(4), C(6)), and C(5) atoms of the benzene ring, respecꢀ
tively, which unambiguously indicates the formation of
metaꢀNO2 derivatives. For compounds 1g and 1h containꢀ
1
ing a chloronitrophenyl substituent, H NMR data are
insufficient for precise location of the NO2 group. However,
taking into account the electronꢀwithdrawing character of
the heterocycles and the directing effect of the Cl atom,
which is para to the triazole ring, one can assume that
the benzene ring in these compounds is nitrated at the
metaꢀposition as well.
14N NMR data for nitraminofurazans are very scarce
in the literature.16,17 In the 14N NMR spectrum of nitrꢀ
aminofurazan with the substituent N(O)NBut at the furazan
ring,16 the singlet at δ –40 corresponds to the nitro group
of the nitramine fragment. The 14N NMR spectra of nitrꢀ
amines 1a—h and salts 7 and 8 we obtained in this study
contain singlets at δ –14 to –17, which can be assigned to
the nitro N atom of the nitramine fragment. In the specꢀ
trum of ammonium salt 8, a very narrow singlet at δ –362
(observed together with the aforesaid singlet) is due to the
N atom of the ammonium group. These data agree with
the chemical shifts for the nitro N atoms in 4,4´ꢀbisꢀ
(nitramino)azofurazan and its salts.17
The 14N NMR spectra of compounds 1b,e,g,h conꢀ
taining the nitramino group at the furazan ring and the
nitro group at the benzene ring show two singlets: one
singlet mentioned above appears at δ –14 to –17 and the
other, at δ –37 to –41 (narrow or broadened, see Table 1).
The latter signal can be assigned to the N atom of the nitro
group at the benzene ring, as with Cꢀnitrated furazans7
and triazolylfurazans.6,18
2i: R = CO2Me, R´ = But; 3: R´ = Ph (a), But (b), 4ꢀClC6H4 (c);
5: R = CO2Et (a), CO2Me (b), R´ = 4ꢀClC6H4 (a), But (b)
These processes occur at room temperature (20 °C) for
compounds 2e,g,h but require heating to 50 °C for comꢀ
pound 2b.
Primary nitraminofurazans are known to be strong acꢀ
ids forming stable salts with metals and amines.12—15 We
demonstrated that nitramino(triazolyl)furazans 1d,b,e in
solutions of K2CO3, NaHCO3, and ammonia form the
corresponding potassium, sodium, and ammonium salts
(6—8) (Scheme 3).
Scheme 3
To sum up, nitration of substituted amino(1,2,3ꢀtriꢀ
azolꢀ1ꢀyl)furazans with the system NaNO3—conc. H2SO4
gave for the first time 3ꢀnitraminoꢀ4ꢀ(1Hꢀ1,2,3ꢀtriazolꢀ
1ꢀyl)furazans. We found that an aromatic substituent
(if present in the starting compound) is also nitrated under
the reaction conditions. Some of the nitramines obtained
were transformed into salts. The synthesis of primary
3ꢀnitraminoꢀ4ꢀ(1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)furazans and their
salts offers great scope for the preparation of novel comꢀ
pounds of this series.
Comꢀ
R
R´
M
pound
6
7
8
H
CO2Et
H
Me
3ꢀNO2C6H4
3ꢀNO2C6H4
K
Na
NH4
Experimental
The structures of novel compounds 1a—h, 2e—i, 3a—c,
and 6—8 were determined from elemental analysis data
IR spectra were recorded on a Specord Mꢀ80 instrument in
1
KBr pellets. The 13C and H NMR spectra of the compounds

1714
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
Rozhkov et al.
Table 1. Selected physicochemical characteristics of the compounds obtained
Comꢀ
pound
Yield
(%)
M.p./°C
(solvent)
Rf
(eluent)
Found
Calculated
Molecular formula
(%)
С
H
N
Cl
М*
1a
1b
1с
84.9
53.8
32.7
65.8
88.9
66.7
63.0
79.4
88.2
129—130
(decomp.)
133
(decomp.)
115
0.54
(AcOEt)
0.68
(AcOEt)
0.62
(AcOEt)
0.63
(AcOEt)
0.24
(AсOEt)
0.60
(AcOEt)
0.15
(AcOEt)
0.77
(AcOEt)
0.53
33.50
33.93
40.14
40.01
24.37
24.44
28.61
28.44
37.50
37.75
38.21
37.95
34.21
34.06
36.39
36.76
52.57
52.63
3.35
3.21
2.56
2.58
1.60
1.63
2.58
2.39
1.75
1.90
4.20
4.38
1.48
1.43
2.00
2.14
3.47
3.53
34.27
34.62
28.30
28.71
39.73
39.92
46.07
46.44
34.80
35.21
38.94
38.72
31.69
31.77
26.24
26.38
36.74
36.83
—
—
—
—
14.29
14.46
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
C8H9N7O5
C13H10N8O7
С5Н4СlN7О3
C5H5N7O3
1d
1e**
1f
140
140—142
(decomp.)
143—144
C10H6N8O5
C8H11N7O3
C10H5ClN8O5
C13H9ClN8O7
C10H8N6O
—
1g
1h
2е
117—118
(decomp.)
160—161
(decomp.)
121
10.10
10.05
08.50
08.35
—
(PhH—AcOEt,
3 : 1)
—
2f
85
104—105
(EtOH—H2O)
175
0.49
(AcOEt)
0.65
46.03
46.15
45.65
45.73
5.78
5.81
2.61
2.69
40.15
40.36
32.15
32.00
—
—
13.43
13.50
—
—
—
—
C8H12N6O
2g
67.6
C10H7ClN6O
(PhH—AcOEt,
3 : 1)
2h
2i
85.2
81.2
155
181
0.68
(PhH—AcOEt,
3 : 1)
0.54
(PhH—AcOEt,
3 : 1)
46.57
46.65
3.34
3.31
25.27
25.11
10.49
10.59
—
—
C13H11ClN6O3
С10Н14N6O3
45.50
45.11
5.16
5.30
31.70
31.56
—
—
—
—
3a
3b
3с
6
93.4
87.2
89.5
84.7
94
184—185
(decomp.)
171
(decomp.)
193—194
(decomp.)
246
0.56
(AcOEt)
0.83
(AcOEt)
0.52
(AcOEt)
—
48.90
48.53
42.43
42.86
42.73
43.08
24.45
24.10
35.94
35.53
33.66
33.15
1.89
2.96
4.78
4.80
2.45
2.30
1.82
1.61
2.56
2.73
3.25
3.31
30.56
30.87
33.45
33.32
27.21
27.40
39.05
39.36
25.25
25.51
34.58
34.80
—
—
—
—
—
—
—
—
C11H8N6O3
C9H12N6O3
—
11.30
11.56
—
—
—
—
—
—
C11H7ClN6O3
C5H4КN7O3
C13H9NaN8O7
C10H9N9O5
—
15.40
15.66
05.29
05.24
—
7**
8**
166—167
—
—
82
167—168
(decomp.)
—
* M = K (6) and Na (7).
** Calculated for C10H6N8O5•1/3 H2O (1e), C13H9NaN8O7•1.5 H2O (7), and C10H9N9O5•1.5 H2O (8).
obtained were recorded on Bruker AC 200, Bruker AM 300, and
Bruker DRx500 spectrometers using the PFG FTꢀNMR techꢀ
nique. 14N NMR spectra were recorded on a Bruker AM 300
CDCl3 (1f, 14N), CD3OD (1e, 1g, 14N), CD3CN (7, 13C), and
THF (1h, 14N). Mass spectra were measured on a Varian MAT
CHꢀ6 instrument. The course of the reactions was monitored by
TLC on Silufol UVꢀ254 plates.
Synthesis of nitramines 1a—h (general procedure). Amines
2a—h were stirred with a fourꢀ to fivefold excess of NaNO3 in
conc. H2SO4 (5—10 mL) at 20 or 50 °C for 1—4 h. The reaction
mixture was poured into ice water. The precipitate that formed
1
spectrometer (21.5 MHz). The H and 13C chemical shifts are
referenced to Me4Si as the internal standard; the 14N chemical
shifts are referenced to MeNO2 as the external standard. In NMR
experiments, samples were mostly dissolved in DMSOꢀd6. The
1
exceptions included acetoneꢀd6 (1a, 14N; 1b, 8, H, 13C, 14N),

Synthesis of nitramino(triazolyl)furazans
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
1715
Table 2. 1H and 13C NMR spectra of the compounds obtained
Comꢀ
pound
1H NMR
(δ, J/Hz)
13C NMR
14N NMR
(δ, Δν1/2/Hz)
(δ)
1a
1.35 (t, 3 H, CH2Me, J = 7.0);
2.58 (s, 3 H, Me); 4.38 (q, 2 H,
CH2, J = 7.0)
9.1 (Me); 14.1 (CH2Me); 60.9 (CH2);
135.9 (C(4´)); 141.4 (C(4)); 145.7
(C(5´)); 153.5 (CNHNO2); 160.5 (CO)
–16.40 (NHNO2)
1b
1.21 (t, 3 H, Me, J = 7.0); 4.32
(q, 2 H, CH2, J = 7.0); 7.89 (t,
1H, C(5″)H, J = 7.8); 8.05 (d,
1 H, CH, J = 7.1); 8.50 (d, 1 H,
C(2″)H, J = 8.3); 8.56 (s, 1 H,
CH); 10.55 (br.s, 1 H, NH)
13.8 (Me); 61.2 (CH2); 125.3 (Ar); 125.4
(Ar); 126.2; 130.1 (Ar); 136.4 (Ar); 136.6;
140.5; 145.9; 147.7; 155.1 (CNHNO2);
160.0 (CO)
–14.00 (NHNO2,
Δν1/2 = 27); –39.58
(NO2, ,Δν1/2 = 9)
1c
1d
1e
5.07 (s, 2 H, CH2); 8.10 (s, 1 H,
CH)
32.3 (CH2); 134.3 (C(4´)); 136.4 (C(5´));
145.8 (C(4)); 153.1 (CNHNO2)
–16.40 (NHNO2)
2.40 (s, 3 H, Me); 7.80 (s, 1 H,
CH)
8.6 (Me); 133.3 (C(4´)); 136.5 (C(5´));
146.8 (C(4)); 150.4 (CNHNO2)
—
6.95 (m, 1 H, CH); 7.10 (d, 1 H,
C(6″)H, J = 7.7); 7.40 (s, 1 H,
C(4´)H); 7.60 (m, 2 H, 2 CH)
126.0 (C(4´)); 127.1 (Ar); 127.8 (C(5´));
132.6 (Ar); 136.4 (Ar); 137.1 (Ar); 139.4
(ipsoꢀCAr); 147.9 (C(4)); 148.0 (CNO2);
149.7 (CNHNO2)
–14.40 (NHNO2,
Δν1/2 = 15); –37.26
(NO2, Δν1/2 = 3)
1f
1.23 (s, 3 H, Me); 7.80 (s, 1 H,
C(4´)H)
29.4; 30.6; 131.3 (C(4´)); 147.7 (C(4));
148.9 (C(5´)); 154.3 (CNHNO2)
–16.87 (NHNO2)
1g
7.75 (dd, 1 H, С(6″)Н, J = 8.4,
J = 1.8); 7.82 (d, 1 H, C(5″)H,
J = 8.4); 8.16 (d, 1 H, C(2″)H,
J = 1.8); 8.22 (s, 1 H, C(4´)H)
127.0 (Ar); 127.6 (Ar); 130.0 (CCl); 134.2
(Ar); 135.2 (Ar); 136.1 (Ar); 139.0 (C(4));
148.0 (ipsoꢀCAr); 148.5 (CNO2); 150.17
(CNHNO2)
–14.76 (NHNO2,
Δν1/2 = 26); –37.73
(NO2, Δν1/2 = 10)
1h
2е
1.17 (t, 3 H, Me, J = 7.0); 4.25
(q, 2 H, CH2, J = 7.0); 7.55 (m,
2 H, NH, CH(Ar)); 7.91 (d,
1 H, CH, J = 8.4); 8.32 (d, 1 H,
C(2″)H, J = 1.6)
14.8 (Me); 61.6 (CH2); 125.2 (ipsoꢀCAr);
127.8 (CCl); (128.0, 132.4, 135.4) (Ar);
137.3 (C(4´)); 139.6 (C(5´)); 145.9
(C(4)); 147.6 (CNHNO2); 155.1 (CNO2);
159.8 (CO)
–17.28 (NHNO2,
Δν1/2 = 15); –40.95
(NO2, Δν1/2 = 6)
6.65 (s, 2 H, NH2); 7.43 (br.s,
5 H, Ph); 8.28 (s, 1 H, C(4´)H)
(124.8, 128.2, 129.1, 130.1) (Ph); 133.2
(C(4´)); 140.0 (C(5´)); 143.0 (C(4));
153.2 (CNH2)
—
2f
1.24 (s, 9 H, 3 Me); 6.67 (s,
2 H, NH2); 7.84 (s, 1 H, C(4´)H)
29.2; 30.5; 131.5 (C(4´)); 144.5 (C(4));
149.4 (C(5´)); 153.9 (CNH2)
—
—
2g
6.65 (s, 2 H, NH2); 7.45 (d, 2 H,
2 CH, J = 7.8); 7.57 (d, 2 H, 2 CH,
J = 7.7); 8.30 (s, 1 H, C(4´)H)
123.8 (Ar); 129.3 (Ar, 2 CH); 130.3 (Ar,
2 CH); 133.6 (C(4´)H); 135.2 (Ar); 138.9
(C(5´)H); 142.9 (C(4)H); 153.0 (CNH2)
2h
1.16 (t, 3 H, Me, J = 7.1); 4.25 (q,
2 H, CH2, J = 7.1); 6.66 (s, 2 H,
NH2); 7.46 (d, 2 H, 2 CH, J = 8.4);
7.56 (d, 2 H, 2 CH, J = 8.4)
13.7 (Me); 61.0 (ОCH2); 122.7 (Ar); 128.5
(Ar, 2 CH); 131.8 (Ar, 2 CH); 135.6
(ipsoꢀCAr); 136.6 (C(4´)); 142.0 (C(5´));
142.1 (C(4)); 153.0 (CNH2); 159.5 (CO)
—
2i
1.31 (s, 9 H, 3 Me); 3.92 (s, 3 H,
OMe); 6.85 (s, 2 H, NH2)
28.9; 32.2; 52.7 (OMe); 136.5 (C(4´));
144.6 (C(4)); 150.7 (C(5´)); 154.0 (CNH2);
162.3 (CO)
—
—
3а
6.55 (s, 2 H, NH2); 7.45 (m, 5 H,
Ph); 13.15 (br.s, 1 H, OH)
124.2 (ipsoꢀCAr); 128.3 (CAr(3)); 129.9
(CAr(2)); 130.4 (CAr(4)); 137.1 (C(4´));
142.3 (C(4)); 143.1 (C(5´)); 153.3 (CNH2);
161.1 (CO)
3с
6
6.61 (s, 2 H, NH2); 7.48 (m, 4 H,
Ar)
—
—
—
2.32 (s, 3 H, Me); 7.75 (s, 1 H,
8.0 (Me); 132.8 (C(4´)); 136.2 (C(5´));
C(4´)H)
146.3 (C(4)); 154.9 (CNKNO2)
(to be continued)

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Rozhkov et al.
Table 2 (continued)
Comꢀ
pound
1H NMR
(δ, J/Hz)
13C NMR
14N NMR
(δ, Δν1/2/Hz)
(δ)
7
1.15 (t, 3 Н, Ме, J = 7.1);
4.24 (q, 2 Н, СН2, J = 7.1);
7.76 (t,1 Н, С(5″)Н, J = 7.9);
7.88 (d,1 Н, С(6″)Н, J = 7.8);
8.36 (d,1 Н, C(4″)Н, J = 8.2);
8.42 (s,1 H, C(2″)Н)
13.73 (Me); 61.13 (CH2); 125.22 (Ar);
125.28 (Ar); 125.96 (Ar); 130.02 (Ar);
136.33 (Ar); 140.13 (C(5´)); 145.53 (C(4));
147,27 (CNNaNO2); 155.46 (CNO2);
159.46 (CO)
–13.23 (NHNO2,
Δν1/2 = 22)
8
7.79 (t, 1 Н, С(5″)Н, J = 8.0);
7.95 (d, 1 Н, С(6″)Н, J = 8.0);
8.25 (s, 1 Н, C(4´)Н); 8.34 (dd,
1 H, C(4″)H, J = 8.2; J = 1.7);
8.41 (br.s, 1 Н, С(2″)Н)
123.83 (C(4´)); 124.90 (CAr(6)); 128.10
(ipsoꢀCAr); 130.20 (CAr(5)); 131,00 (C(5´));
133.86 (CAr(4)); 135.20 (CAr(2)); 138.20
(C(4)); 147.30 (CNO2); 149.00 (CNNO2)
–13.94 (NNO2);
–362 (NH4)
Table 3. IR and mass spectra of the compounds obtained
Comꢀ
pound
IR, ν/cm–1
MS, m/z (Irel (%))
1a
1b
3096 (NH); 2948, 2792 (СH); 1728 (CO); 1316, 1140,
283 [M]+ (15), 238 [MH – NO2]+ (40), 67 (100)
262 [MH – NHNO2]+ (18), 256 [M – CC6H4NO2]+
3112, 3040, 2968 (NH, CH); 1712 (CO); 1616, 1524,
1360, 1312
(2), 44 (100)
1с
1d
1e
1f
3156 (С(4´)H); 3104, 3036, 2920, 2852 (NH, CH);
1624, 1600, 1308
—
3152 (C(4´)H); 3068, 2980, 2848, 2740 (NH, CH);
1616, 1600, 1304
211 [M]+ (10), 165 [M – NNO2]+ (40), 108 (100)
3156 (C(4´)H); 3088, 3020, 2864 (CH, NH); 1624,
1596, 1528, 1308
273 [M – NO2]+ (10), 245 [M – NO2 – N2]+ (5),
46 (100)
207 [M – NO2]+ (40), 57 (100)
3156 (С(4´)H); 3064, 2972, 2700 (NH, CH); 1620,
1596, 1316, 1256
1g
3160, 3080, 2992, 2864 (CH, NH); 1608, 1592,
1524, 1304, 840
—
1h
2е
3108, 2972 (NH, CH); 1720 (CO); 1620, 1540, 1312,
—
—
3432, 3308 (NH2); 3132 (C(4´)H); 1632, 1568, 1484,
980
2f
3448, 3328, 3184 (NH2); 3136, 2976 (CH), 1640,
1560, 1252, 984
—
2g
2h
3136 (C(4´)H); 1596, 1476, 1092, 984, 732
—
—
3460, 3348 (NH2); 2984 (CH); 1736 (CO); 1636,
1488, 1220, 984
2i
3408, 3312, 3200 (NH2); 2952 (CH); 1732 (CO);
1644, 1564, 1364, 1232, 992
266 [M]+ (21), 235 [M – OMe]+ (62), 182 (85),
166 (100), 151 (95), 136 (90)
3a
3b
3с
3424, 3304 (NH2); 2920, 2556 (CH, OH); 1720
(CO); 1640, 1220, 984
272 [M]+ (32), 228 [M – CO2]+ (30), 145 (100)
3408, 2960, 2584 (NH2, CH, OH); 1720 (CO);
1640, 1232, 880
—
—
3424, 3304 (NH2); 2896, 2552 (CH, OH); 1716
(CO); 1640, 1220, 984
6
7
3132, 3104 (СН); 1524, 1396, 1336, 1316, 972
—
—
3084, 2984 (CH); 1716 (CO); 1528, 1348, 1304,
1232, 992, 740
8
3450, 3116 (C(4´)H); 1536, 1512, 1400, 1352, 1304,
—
736

Synthesis of nitramino(triazolyl)furazans
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
1717
was filtered off, washed with water to a neutral reaction, and
dried in air.
4ꢀ(4ꢀEthoxycarbonylꢀ5ꢀmethylꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)ꢀ3ꢀ
nitraminoꢀ1,2,5ꢀoxadiazole (1a) was obtained from amine 2a
(0.3 g, 1.26 mmol) and NaNO3 (0.43 g, 5.1 mmol) at 50 °C for
4 h. The yield was 0.30 g.
4ꢀ[4ꢀEthoxycarbonylꢀ5ꢀ(3ꢀnitrophenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀ
yl]ꢀ3ꢀnitraminoꢀ1,2,5ꢀoxadiazole (1b) was obtained from amine
2b (0.4 g, 1.33 mmol) and NaNO3 (0.45 g, 5.29 mmol) at 50 °C
for 4 h. The yield was 0.28 g.
4ꢀ(5ꢀChloromethylꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)ꢀ3ꢀnitraminoꢀ1,2,5ꢀ
oxadiazole (1c) was obtained from amine 2c (0.2 g, 1 mmol) and
NaNO3 (0.34 g, 4 mmol) at 20 °C for 4 h. The yield was 0.08 g.
4ꢀ(5ꢀMethylꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)ꢀ3ꢀnitraminoꢀ1,2,5ꢀoxaꢀ
diazole (1d) was obtained from amine 2d (0.3 g, 1.8 mmol) and
NaNO3 (0.45 g, 5.29 mmol). The yield was 0.25 g.
3ꢀAminoꢀ4ꢀ[5ꢀ(4ꢀchlorophenyl)ꢀ4ꢀethoxycarbonylꢀ1Hꢀ1,2,3ꢀ
triazolꢀ1ꢀyl]ꢀ1,2,5ꢀoxadiazole (2h) was obtained from azide 4
(0.28 g, 2.23 mmol) and ethyl 4ꢀchlorobenzoylacetate (5a)
(0.53 g, 2.35 mmol) in EtOH (50 mL). The yield was 0.67 g.
3ꢀAminoꢀ4ꢀ(5ꢀtertꢀbutylꢀ4ꢀmethoxycarbonylꢀ1Hꢀ1,2,3ꢀtriꢀ
azolꢀ1ꢀyl)ꢀ1,2,5ꢀoxadiazole (2i) was obtained from azide 4 (0.38 g,
3 mmol) and methyl 4,4ꢀdimethylꢀ3ꢀoxopentanoate (5b) (0.5 g,
3.16 mmol) in MeOH (20 mL). Compound 2i was recrystallized
from MeOH—H2O (1 : 1). The yield was 0.65 g.
Synthesis of carboxylic acids 3a—c (general procedure).
Amino(triazolyl)furazan (2b,i,h) was added to a solution of
NaOH (1.2 molar excess) in water (30—50 mL) or H2O—EtOH
(1 : 1). The reaction mixture was refluxed for 30 min, cooled to
room temperature, and acidified by adding dropwise 2 M HCl to
an acidic reaction. Carboxylic acid (3a—c) that formed was filꢀ
tered off and washed with cold water.
3ꢀNitraminoꢀ4ꢀ[5ꢀ(3ꢀnitrophenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ
1,2,5ꢀoxadiazole (1e) was obtained from amine 2e (0.3 g, 1.32 mmol)
and NaNO3 (0.45 g, 5.29 mmol). The yield was 0.32 g.
4ꢀ(5ꢀtertꢀButylꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)ꢀ3ꢀnitraminoꢀ1,2,5ꢀ
oxadiazole (1f) was obtained from amine 2f (0.3 g, 1.44 mmol)
and NaNO3 (0.49 g, 5.76 mmol) at 20 °C for 4 h. The yield was
0.24 g.
4ꢀ[5ꢀ(4ꢀChloroꢀ3ꢀnitrophenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ3ꢀ
nitraminoꢀ1,2,5ꢀoxadiazole (1g) was obtained from amine 2g (0.4 g,
1.53 mmol) and NaNO3 (0.52 g, 6.12 mmol) in conc. H2SO4
(10 mL) at 20 °C for 1 h. The greasy product was filtered off,
dissolved in acetone (5 mL), and reprecipitated with water
(50 mL). After 24 h, compound 1g (0.34 g) was filtered off.
4ꢀ[5ꢀ(4ꢀChloroꢀ3ꢀnitrophenyl)ꢀ4ꢀethoxycarbonylꢀ1Hꢀ1,2,3ꢀ
triazolꢀ1ꢀyl]ꢀ3ꢀnitraminoꢀ1,2,5ꢀoxadiazole (1h) was obtained
from amine 2h (0.3 g, 0.9 mmol) and NaNO3 (0.31 g, 3.6 mmol)
at 20 °C. The yield was 0.27 g.
4ꢀ(5ꢀMethylꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)ꢀ3ꢀnitraminoꢀ1,2,5ꢀoxaꢀ
diazole, potassium salt (6). A solution of nitramine 1d (0.1 g,
0.474 mmol) in acetone (5 mL) was refluxed for 1 h in the presꢀ
ence of K2CO3 (0.04 g, 0.29 mmol). The reaction mixture was
cooled, the precipitate that formed was filtered off, and the mother
liquor was evaporated to dryness in vacuo. The yield of salt 6
was 0.1 g.
4ꢀ[4ꢀEthoxycarbonylꢀ5ꢀ(3ꢀnitrophenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀ
yl]ꢀ3ꢀnitraminoꢀ1,2,5ꢀoxadiazole, sodium salt (7). A solution of
NaHCO3 (0.4 g, 4.76 mmol) in water (1 mL) was added to
a solution of nitramine 1b (0.5 g, 1.28 mmol) in acetone (5 mL).
The reaction mixture was stirred for 1 h and evaporated to dryness
in vacuo. The residue was refluxed in acetone (5 mL) for 5 min,
the precipitate that formed was filtered off, and the mother liquor
was evaporated to dryness in vacuo. The yield of salt 7 was 0.5 g.
3ꢀNitraminoꢀ4ꢀ[5ꢀ(3ꢀnitrophenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ
1,2,5ꢀoxadiazole, ammonium salt (8). Five drops of concentrated
aqueous ammonia were added to a solution of nitramine 1e
(0.05 g, 0.16 mmol) in EtOH (3 mL) to a basic reaction. The
solvents were removed at room temperature. The resulting solid
residue was washed with a small amount of ethanol. The yield of
salt 8 was 0.07 g.
1ꢀ(4ꢀAminoꢀ1,2,5ꢀoxadiazolꢀ3ꢀyl)ꢀ5ꢀphenylꢀ1Hꢀ1,2,3ꢀtriꢀ
azoleꢀ4ꢀcarboxylic acid (3a) was obtained from ester 2b (1 g,
3.33 mmol) and NaOH (0.16 g, 4 mmol). The yield was 0.85 g.
1ꢀ(4ꢀAminoꢀ1,2,5ꢀoxadiazolꢀ3ꢀyl)ꢀ5ꢀtertꢀbutylꢀ1Hꢀ1,2,3ꢀ
triazoleꢀ4ꢀcarboxylic acid (3b) was obtained from ester 2i (0.5 g,
1.88 mmol) and NaOH (0.1 g, 2.5 mmol). The yield was 0.41 g.
1ꢀ(4ꢀAminoꢀ1,2,5ꢀoxadiazolꢀ3ꢀyl)ꢀ5ꢀ(4ꢀchlorophenyl)ꢀ1Hꢀ
1,2,3ꢀtriazoleꢀ4ꢀcarboxylic acid (3c) was obtained from ester 2h
(0.63 g, 1.87 mmol) and NaOH (0.08 g, 2 mmol). The yield was 0.51 g.
Synthesis of 5ꢀsubstituted amino(triazolyl)furazans 2e—g
(general procedure). Carboxylic acid (3a,b,c) was dissolved in
AcOH (15 mL). The resulting solution was refluxed for 30—60 min
and cooled to room temperature. Water (45—60 mL) was added
in small portions with stirring. The decarboxylation product
(2e,f,g) was filtered off, washed with water, and dried in air.
3ꢀAminoꢀ4ꢀ(5ꢀtertꢀbutylꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)ꢀ1,2,5ꢀoxaꢀ
diazole (2f) was obtained from acid 3b (0.3 g, 1.19 mmol). The
yield was 0.21 g.
3ꢀAminoꢀ4ꢀ(5ꢀphenylꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)ꢀ1,2,5ꢀoxadiꢀ
azole (2e) was obtained from acid 3a (1.82 g, 6.69 mmol). The
yield was 1.35 g.
3ꢀAminoꢀ4ꢀ[5ꢀ(4ꢀchlorophenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ1,2,5ꢀ
oxadiazole (2g) was obtained from acid 3c (0.43 g, 1.41 mmol).
The yield was 0.25 g. In the synthesis of compounds 2e and 2g,
the reaction mixtures were refluxed for 5 min upon the addition
of water and cooled to 20 °C. The precipitates that formed were
filtered off and washed with water.
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Received September 28, 2010;
in revised form March 17, 2011