Thermal ring-opening reaction of N-polynitromethyl tetrazoles: facile generation of nitrilimines and their reactivity

Article abstract of DOI:10.1016/j.tet.2009.02.032

Thermal ring-opening reaction of N-(R-dinitromethyl)-5-nitrotetrazoles (R=NO₂, F, Cl) yielded highly reactive N-(R-dinitromethyl)-nitrilimine intermediates under mild conditions. These species underwent facile and regiospecific reaction with ni

Full text of DOI:10.1016/j.tet.2009.02.032

Tetrahedron 65 (2009) 3441–3445
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Thermal ring-opening reaction of N-polynitromethyl tetrazoles:
facile generation of nitrilimines and their reactivity
y
*
V.V. Semenov , M.I. Kanischev , S.A. Shevelev, A.S. Kiselyov
N.D. Zelinsky Institute of Organic Chemistry, RAS, Moscow 119991, Leninsky Pr. 47, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
Thermal ring-opening reaction of N-(R-dinitromethyl)-5-nitrotetrazoles (R¼NO , F, Cl) yielded highly
2
Received 19 December 2008
Received in revised form 25 January 2009
Accepted 13 February 2009
Available online 24 February 2009
reactive N-(R-dinitromethyl)-nitrilimine intermediates under mild conditions. These species underwent
facile and regiospecific reaction with nitriles and acetylenes to afford the corresponding nitrotriazoles
and nitropyrazoles in 50–90% yields. Treatment of N-(chlorodinitromethyl)-5-nitrotetrazole with the
excess of azide led to a unique compound with the molecular formula C
it was assigned a structure of diazidomethylenecarbonohydrazonic diazide.
Ó 2009 Elsevier Ltd. All rights reserved.
2
N14. Based on the analytical data,
Keywords:
Nitronitrilimines
1,3-Dipolar cycloaddition
N-Polynitromethyl tetrazoles
1. Introduction
Electron-deficient substituents in position 2 of the tetrazole ring
were shown to lead to accelerated rates of this thermally induced
Polynitrated azoles continue to attract considerable amount of
interest as building blocks for the synthesis of a high-energy ma-
terials.1 Elevated acidity of these substances, as exemplified by
tetranitropyrrole, 2,4,5-trinitroimidazole, 3,5-dinitro-1,2,4-triazole,
ring-opening step, while electron-donating moieties slowed it
2
12,13
down.
For instance, 2-acyl-5-aryltetrazoles were reported to
ꢀ
10
eliminate N2 at 70
aryltetrazoles underwent this reaction at 140–160 and
ꢀ
220 C, respectively. Notably, the influence of the functionality in
C, whereas 2-phenyl-5-aryl- and 2-alkyl-5-
9
,10,13,14
4
,5-dinitro-1,2,3-triazole, and 5-nitrotetrazole historically limited
ꢀ
C
10
their practical utility. This issue has been somewhat addressed by
the modification of the acidic proton at the heterocyclic pyrrole
the position 5 of tetrazole was reciprocal, namely electron-donat-
ing groups facilitated the process. The overall effect of a 2-sub-
stituent on the rate of formation of nitrilimines was more profound
3
–8
(N-H) with the polynitromethyl moiety.
In the course of our
studies on polynitrated aromatics, we have developed the synthesis
of N-(polynitromethyl)tetrazoles and studied their thermal stability.
Literature data suggest that 2-substituted tetrazoles 1 feature
12,13
than that of a 5-group.
2
facile elimination of N under a variety of experimental conditions
to yield highly reactive nitrilimine intermediates 2. These species
2. Results and discussion
undergo 1,3-dipolar cycloaddition reaction with dipolarophiles to
9
,10
The desired N-dinitromethyl derivatives have been prepared by
yield diverse heterocyclic scaffolds
exemplified on the Scheme 1 for nitriles.
(e.g., 1,2,4-triazoles, 3) as
2
11
nitration of the easily available N-acetonyl-5-nitrotetrazole 4
3
(
Scheme 2). Considering our prior experience with this reaction,
we carried out the nitration of 4 in 75–80% H SO in order to both
enhance enolization of the acidic CH group and to reduce
2
4
R1
2
R1
5
N
3
R1
the amounts of side products. A similar strategy has been reported
R
R
2
N
N
N
2
N
Δ
R -CN
R1
N
N
in the synthesis of N-dinitromethylylides and other N-polynitro-
3
N
+
N
N
N
+
R
R
- N2
-
-
4–8
methylheterocycles.
Under the reaction conditions described in
at
of the N-acetonyl group. This was in contrast to the previously
2
R
3
3
our earlier studies, we observed a stepwise introduction of NO
CH
2
1
2
2
Scheme 1.
suggested mechanism involving initial formation of a nitroso de-
rivative followed by its oxidative nitration to the respective dini-
1
5–18
troketones.
Water quench of the nitration reaction after shorter
*
Corresponding author. Tel.: þ7499 1356343; fax: þ7499 1372966.
E-mail address: vs@zelinsky.ru (V.V. Semenov).
Deceased.
reaction times (e.g., 2–3 h vs 72 h) afforded both 2-dinitro (7a,
UVmax¼336 nm) and 2-nitro (8, UVmax¼312 nm at pH¼8)
y
0
040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.02.032

3442
V.V. Semenov et al. / Tetrahedron 65 (2009) 3441–3445
NO2
NO2
N
N
Hydrolysis N
N
N
-
M+ (a) M+ = H
+
NO2
Base
NO2
+
(b) M = K
NO2
+
N
2
N
O2N
+
+
HNO /H SO /H O
(c) M = NH NH
(d) M = NH4
3
2
4
2
N
N
O
2
3
N
N
7a-d
N
+
+
N
H O
X
2
i, ii, iii
NO2
O N
NO2
2
O
O
N
4
5
N
N
N
N
i) NO BF , - 20 °C, MeCN (9a, unstable) O N
O N
2
2
4
2
X
(a) X = NO2
ii) 10% F /N , H O, 0-5 °C (9b, 93%)
O N
2
2
2
2
(b) X = F
8
9a-c
iii) Cl , CH Cl , RT (9c, 70%)
2
2
2
(c) X = Cl
Scheme 2.
methyltetrazoles in ca. 45% overall yield and 2:1 ratio, respectively.
Product 8 likely resulted from the hydrolysis of unstable mono-
nitroketone intermediate 5. Monitoring of the reaction course by
UV spectroscopy suggested that 8 was not a direct precursor to 7a.
Moreover, we were not able to convert analytically pure 8 into 7a
under a variety of experimental conditions including direct addi-
tion of 8 to the nitrating mixture described above. Based on these
(X¼Cl) were relatively stable in both solid state and in solution
compared to 9a (X¼NO
2
).
Table 1
Correlation of thermal stability and electron withdrawing nature (
s
*
) of the poly-
nitro substituent X for 9a–c
Compound
9a, X¼NO
ꢁ20
2
9b X¼F
9c, X¼Cl
observations, we concluded that the nitration at CH
2
position of 4
ꢀ
Temperature of thermolysis, C
s*
25–30
60–65
proceeded sequentially, hydrolysis of the acetyl group occurring at
the respective dinitro derivative 6 stage.
20
20
21
4.54
4.4
4.2
Neither addition nor removal of nitric oxides with urea, hydra-
zine or sulfaminic acid affected the reaction course. A quantitative
In contrast, diarylnitrilimines available via thermolysis of the
respective diaryl tetrazoles were reported to be considerably less
reactive. For example, yields of the triazole products were ca. 15%,
acid–base equilibrium of 7 in H
spectroscopy (UVmax¼336 nM). As evidenced from the absorption
maximum, protonation of C(NO moiety versus basic N of the
2 4
SO was easily monitored using UV
11
decomposition being the main reaction course.
2 2
)
As evidenced from both chromatographic and NMR spectro-
scopic analyses, the reaction was regiospecific. It afforded a single
product, namely 1,2,4-triazole derivative 10a–c. This outcome was
tetrazole ring was the initial step at all pH values evaluated. The
ꢀ
respective pK
a
¼ꢁ1.7 measured at 20 C was comparable to that of
a strong mineral acid. In the course of our studies, we have pre-
11,13
þ
þ þ
in accordance with data reported in the literature.
Structures
pared K , NH , and NH NH salts 7b–d (50–85% yields). Salts 7b
4 2 3
1
of 10a–c have been confirmed by elemental analysis, IR, H, and
and 7d were subsequently converted to 2-trinitro- (9a), 2-(fluoro-
dinitro)- (9b, 93% yield), and 2-(chlorodinitro)- (9c, 70% yield)
tetrazoles by the treatment with NO BF , 10% F /N and Cl , re-
2 4 2 2 2
13
1
13
C NMR spectroscopy. For example, H and C NMR spectra of
derivative 10b (X¼F) featured relatively large spin–spin in-
teraction constants J (CH –F cou-
–F coupling)¼3 Hz and J (CH
pling)¼5 Hz, respectively, presumably due to the proximity of Me
and C(NO )F groups in the molecule. In addition, both derivatives
0a and 10c afforded the same salt 11 when treated with KI/
spectively. In our hands 9a was unstable at the temperatures
3
3
ꢀ
greater than ꢁ20 C and was used for further transformations in
situ.
2
1
We were interested in the thermal behavior of 9a–c. In our
hands, these molecules underwent thermal decomposition in
MeCN to afford the corresponding products of dipolar cycloaddi-
tion of the intermediate nitrilimines, 1-polynitromethyl-3-nitro-5-
methyl-1,2,4-triazoles (10a–c) in 80–90% isolated yields and high
purity (Scheme 3). Triazoles 10a and 10c were further converted to
19
MeOH.
Under the conditions described above, 9c reacted with other
nitriles to furnish the targeted triazole derivatives. Specifically, 12a
(
R¼CH COOEt) and 12b (R¼Ph) were formed in quantitative yields
2
and, without further purification converted to the dinitromethyl
derivatives 13a and 13b (Scheme 4, 70% and 75% yields for two
steps). In a similar fashion, thermally induced reaction of 9c with
malononitrile in dichloroethane (DCE) afforded bicyclic triazole 14
in a 60% yield.
the dinitromethyl salt 11 using KI/MeOH (80% and 90% yields,
respectively).19
C(NO ) X
2
2
O N
O N
2
O N
N
+
N
-
2
2
N
N
N
Δ
MeCN
NO
X
NO2
KI/MeOH
X = NO , Cl
NO2
O2N
O N
2
2
9a-c
N
N
N
-
+
N
N
N
N
-
N2
2
K
NO
Cl
NO
2
2
NO2
N
ii
N
(80-90%)
Me
11
-
K
+
O N
C(NO )X
Me
2
2
N
N
10 (a) X = NO (80%)
i
NO2
NO2
13 (a) R = CH COOEt (70%)
R
+
2
R
12a,b
-
(
b) X = F (85%)
c) X = Cl (90%)
9c
iii, ii
O N
NO2
2
(
- N2
(
b) R = Ph (75%)
Scheme 3.
2
N
N
N
N
N
K+
N
NO2
2
-
O N
NO2
4 (60%)
We observed a direct link between the thermolysis tempera-
ture required to generate the reactive nitrilimine intermediate
and the electron withdrawing effect of a polynitroalkyl sub-
2
-
O N
2
1
ꢀ ꢀ
2 2
Scheme 4. Conditions: (i) R-CN, DCE, 60 C; (ii) KI/MeOH, rt; (iii) CH (CN) , DCE, 60 C.
stituent in 9 (
s
*
, Table 1). For example, both 9b (X¼F) and 9c

V.V. Semenov et al. / Tetrahedron 65 (2009) 3441–3445
3443
Tetrazoles 9a–c reacted with acetylenes in dichloroethane (DCE)
at the temperatures summarized in Table 1 to led to 3-nitro-
pyrazoles 15a–c. Products 15a–c were converted to the respective
anion afforded highly unstable diazidomethylenecarbonohy-
drazonic diazide (23% yield).
1
-(dinitromethyl)-3-nitro-5-R pyrazoles 16a–c by treatment with
3
3
. Experimental
KI/MeOH (Scheme 4). Similar to the reaction of 9a–c with nitriles,
the process was regiospecific.
We conducted thermolysis of 9c in the presence of an equimolar
mixture of benzonitrile and phenyl acetylene (10-fold molar excess
each, Scheme 5). Upon completion of the thermolysis step, the
14
.1. General
NMR data were collected on a Bruker AM-300 instrument
1
13
1
(working frequencies of 300.13 MHz ( H) and 75.47 ( C)). Mass-
spectra were collected on a Finningan MAT/INCOS 50 instrument
reaction mixture was treated with KI/MeOH. H NMR spectroscopic
analysis of the crude reaction mixture revealed the presence of
both pyrazole 16a and triazole 13b in a 3:1 ratio and ca. 70% overall
yield. This outcome suggests higher reactivity of the intermediate
nitrilimine toward phenyl acetylene versus benzonitrile.
In our further investigations, we heated 9c in a mixture of or-
ganic solvent (MeOH, nBuOH, acetone) and water (2–30%). The only
detectable product in the reaction mixture was the hydrazone of
chloronitroformaldehyde 18 (52% yield) presumably formed via the
intermediate formation of hydrate 17 (Scheme 6). To the best of our
(70 eV) using direct probe injection. HRMS data were collected on
ꢀ
a KRATOS instrument (42 eV, source temperature 150 C). IR
spectra were collected on a UR-20 instrument. UV spectra were
collected on a SPECORD UV–vis instrument.
3.1.1. 2-Dinitromethyl-5-nitrotetrazole (7a)
ꢀ
Yield: 72%, white solid, mp 105–106 C. Water (10 mL) followed
by HNO
5
3
(10 mL, d¼1.5) was added to a cooled (ice bath) solution of
2
g (29.2 mmol) of 2-acetonyl-5-nitrotetrazole 4 in 24 mL of H SO
2 4
knowledge, this molecule is unattainable by alternative chemical
ꢀ
procedures.22
(d¼1.83). The reaction mixture was warmed and left at 40 C for
h. The resulting precipitate was filtered, washed with CF COOH,
and dried in vacuo over P to yield the targeted compound (5 g).
5
3
3
Reaction of 9c with NaN (6–9 M excess) in anhydrous MeOH at
2 5
O
rt followed by the water quench of the reaction mixture and or-
ganic extraction of aqueous phase yielded an unstable crystalline
compound. An IR spectrum of the molecule featured azide group
1
ꢁ1
H NMR (CF
CH(NO ), 1373, 1570 (aromatic NO
Anal. Calcd for C
10.97; H, 0.38; N, 45.04.
3
COOH): 8.47 (s, CH). IR (KBr, cm ): 1320, 1596, 1620
(
2
)
2
2
). pKa (H O–H SO
2
2
4
): ꢁ1.7.
ꢁ1
2
H
1
N
7
O
6
: C, 10.96; H, 0.46; N, 44.76. Found: C,
band (2160 cm ) along with strong bands at 1295, 1343, 1445,
ꢁ
1
1535, and 1600 cm corresponding to vibrations of imine bonds.
15
Notably, the same reaction with 9c labeled with N at the
C(NO Cl moiety yielded unlabeled compound with identical IR
spectrum. The compound did not contain Cl. HRMS analysis of the
3.1.2. Potassium salt (7b)
2 2
)
ꢀ
Yield: 85%, yellow crystals, mp 164 C (decomp.), d¼2.042
3
g/cm : Reaction of 7a (1 g) with saturated KOAc in water (1 mL)
followed by treatment of the resulting precipitate with water and
ether furnished the respective analytically pure potassium salt
(1 g). C NMR (DMSO-d
UVmax (H
sample afforded the exact mass of 220.0430ꢂ0.0002 correspond-
2
ing to the molecular formula of C N14. Electron impact mass spec-
trum (70 eV; m/z, I, %) featured peaks corresponding to fragments
composed of C and N atoms only, namely: 220 [M , 9%], 68 [CN
13
þ
6
): 131.5 (J13C–15N¼30.0 Hz), 166.2 (C5).
4
,
ꢁ
1
2
O)¼336 nm ( ¼18,000). IR (KBr, cm ): 1260, 1300, 1493
3
3 2 2 2
57%], 54 [CN , 42%], 52 [C N , 9%], and 40 [CN , 100%]. The molecule
ꢁ
(C(NO
2
)
2
), 1350, 1587 (aromatic NO
2
2 7 6
). Anal. Calcd for C KN O : C,
was found to be extremely sensitive to both mechanical and thermal
stimuli. Based on the evidence listed above, we have assigned it the
structure of diazidomethylenecarbonohydrazonic diazide 22. The
suggested mechanism of this transformation involves the initial
nucleophilic displacement of 5-NO group in the tetrazole ring with
2
azide to furnish unstable 5-azidotetrazole 19. Thermally induced
ring-opening reaction of 19 followed by the sequential replacement
9.34; K, 15.20; N, 38.13. Found: C, 9.45; K, 15.11; N, 38.20.
3.1.3. Hydrazinium salt (7c)
ꢀ
Yield: 54%, yellow crystals, mp 130–140 C (decomp.), d¼1.818
3
g/cm . To a cooled solution (ice bath) of 7a (10 g, 46 mmol) in water
25 mL) wasadded aqueous NH NH (85% solution, 4 mL,100 mmol)
(
2
2
followed by of acetic acid (5.3 mL, 84 mmol) in water (4 mL). The
resulting mixture was kept at 0–5 C for 1 h, and then filtered. The
resulting precipitate was washed with ice-cold water (5 mL) and
recrystallized from water (25 mL) to afford 6.2 g of the corre-
sponding hydrazinium salts. UVmax (H
of Cl atoms with N
termediates 20 and 21 (observed in the UV spectrum only, UVmax
3
groups affords the key azidoimine in-
ꢀ
2
2–25
(
MeOH)¼284 nm) leading to the final molecule 22.
In conclusion, we have shown that thermal ring-opening
2
O)¼336 nm (
3
¼18,000). IR
reaction of N-(R-dinitromethyl)-5-nitrotetrazoles yielded highly
reactive N-(R-dinitromethyl)-nitronitrilimine intermediates under
mild conditions. These species underwent facile regiospecific re-
action with nitriles and acetylenes to yield the corresponding nitro
triazoles and pyrazoles in good to excellent yields. Heating of N-
ꢁ
1
ꢁ
(
(
KBr, cm ): 1300, 1365, 1375, 1380, 1493, 1520 (C(NO
aromatic NO
2
)
2
), 1585
þ
2
), 3000–3250 (br, NH
2
NH
3
). Anal. Calcd for C
2
H
5
N
9
O
6
:
C, 9.56; H, 1.99; N, 50.20. Found: C, 9.66; H, 1.88; N, 50.47.
3.1.4. Ammonium salt (7d)
(
chlorodinitromethyl)-5-nitro tetrazole in aqueous organic solvents
ꢀ
Yield: 50%, yellow crystals, mp 130–140 C (decomp.), d¼1.78
furnished the hydrazide of chloronitroformaldehyde (52% yield).
Ring-opening reaction of the same substrate with an excess of azide
3
i
g/cm . A solution of 7a (1 g, 4.56 mmol) in PrOH (3 mL) was treated
with solution of NH OAc in MeOH (2 mL). The resulting precipitate
4
O N
O N
2
2
N
N
N
N
NO2
DCE, 60-70 °C,
R
NO
Cl
2
KI, MeOH
-
+
9c
K
-
N2
NO2
R
NO2
R
Ph
Ph
1
5a-c
16 (a) R = Ph (75%)
b) CH Br (50%)
1
. DCE, 60-70 °C,
. KI, MeOH
N
(
2
2
(
c) R = CH Cl (60%)
16a
+
13b
2
(
70%, 3:1 ratio)
Scheme 5.

3444
V.V. Semenov et al. / Tetrahedron 65 (2009) 3441–3445
MeOH/H O, 35-40 °C O N
H O
Cl
2
2
2
9
c
N
N
H N
-
N2
- HNO , - CO
2
2
HO
N
C(NO)2Cl
NO2
2
-
H
MeOH (abs), N
18 (52%)
3
17
2
0 °C
N3
N
N
C(NO2)Cl
N
N3-
N3
N3-
N3
NO
2
N
+
N
N
Cl
N
N3
N
N3
-
Cl
- NO2, - Cl-
-
-
N2
- NO2
N
N
-
N3
N3
NO2
N3
NO2
2
2 (23%)
19
20
21
Scheme 6.
i
was filtered, washed with PrOH, ether, and dried in vacuo to yield
.54 g of the targeted salt. It was further dissolved in acetone (5 mL)
and triturated with ether to afford analytically pure material. UVmax
: C, 10.17; H,
mixture was concentrated in vacuo at rt and recrystallized from
CCl to afford 10a–c as analytically pure compound.
0
4
(
H
2
O)¼336 nm (
3
¼18,000). Anal. Calcd for C
2
H
4
N
8
O
6
3.2.1. 1-Trinitromethyl-3-nitro-5-methyl-1,2,4-triazole (10a)
ꢀ
1
.71; N, 47.46. Found: C, 10.22; H, 1.83; N, 47.58.
Yield: 85%, white crystals, mp 55–57 C. A suspension of 7d
(
NO
1.18 g, 5 mmol) in absolute MeCN (20 mL) was treated with
ꢀ
3
.1.5. 2-Nitromethyl-5-nitrotetrazole (8)
Yield: 14%, white crystals, mp 138–139 C. N-Acetonyl-5-nitro-
tetrazole 4 (1 g, 5.84 mmol) was dissolved in a vigorously stirred
mixture of HNO –H SO –H
O¼5:12:5 by volume (11 mL) at rt for
h. The reaction was poured into ca. 50 g of crushed ice. The
resulting precipitate was filtered, washed with water, recrystallized
2
BF
4
(0.95 g, 7 mmol) at ꢁ20 C under Ar. The reaction mixture
ꢀ
was stirred at this temperature for 15–20 min, diluted with CH
and filtered to remove inorganic salts. Organic phase was concen-
trated at rt and the residue was recrystallized from CCl to afford
): 2.67 (s, Me). C NMR (CDCl ): 14.7
2 2
Cl
3
2
4
2
4
1
13
2
1.2 g of 10a. H NMR (CDCl
(Me), 117.9 (C(NO ), 161.4 (C
1621 (C(NO ), 1298, 1580 (aromatic NO
2
3
3
ꢁ
1
2
)
3
5
), 161.8 (C
3
). IR (KBr, cm ): 1310,
). Anal. Calcd for
1
from MeOH/H
2
O (1:1) and dried in vacuo to yield 8 (0.14 g). H NMR
CN), 7.64 (s, CH ). UVmax (H ¼8600). IR
O, pH 8)¼312 nM (
KBr, cm ): 1305, 1560, 1590 (NO ). Anal. Calcd for C : C,
2
)
3
(
(
CD
3
2
2
3
C
4
H
3
N
7
O
8
: C, 17.34; H, 1.09; N, 35.38. Found: C, 17.08; H, 1.01; N,
ꢁ1
2
2
H
2
N
6
O
4
35.53.
ꢀ
13.80; H, 1.16; N, 48.28. Found: C, 13.71; H, 0.95; N, 47.93.
Reaction conducted at 20 C furnished the targeted 1-fluo-
rodinitromethyl-3-nitro-5-methyl-1,2,4-triazole (10b). Yield: 90%
ꢀ
1
3
.1.6. 2-(Trinitromethyl)-5-nitrotetrazole (9a)
Unstable at temperatures greater than ꢁ20 C; 9a was prepared
(1.13 g), white crystals, mp 55–57 C. H NMR (CDCl
3
): 2.74 (d,
ꢀ
13
J
1H–19F¼3.0 Hz, Me). C NMR (CDCl
113.5 (J13C–19F¼300.0 Hz, CF(NO ), 159.8 (C
NMR (CH Cl
): þ8.86 (F). IR (KBr, cm ): 1275, 1600, 1630
CF(NO ), 1310, 1570 (aromatic NO ). Anal. Calcd for
FN : C, 19.21; H, 1.21; N, 33.60; F, 7.60. Found: C, 19.02;
H, 1.03; N, 33.72; F, 7.36.
3
): 13.8 (J13C–19F¼5 Hz, Me),
19
and used in situ for the synthesis of respective triazole 10a (vide
supra).
2
)
2
5
), 162.1 (C
3
).
F
ꢁ1
2
2
(
2
)
2
2
3
.1.7. 2-(Fluorodinitromethyl)-5-nitrotetrazole (9b)
C
4
H
3
6 6
O
ꢀ
Yield: 93%, white crystals, mp 21–22 C. A solution of 7b (the
ꢀ
procedure was repeated several times at 5.1–12.9 g scale, 20–
5
Reaction conducted at 60–70 C furnished the targeted 1-
chlorodinitromethyl-3-nitro-5-methyl-1,2,4-triazole (10c). Yield:
85% (1.13 g), white crystals, mp 109–111 C. H NMR (CDCl
(s, Me). IR (KBr, cm ): 1310, 1612, 1625 (CCl(NO
(aromatic NO ). Anal. Calcd for C ClN
31.53; Cl, 13.30. Found: C, 18.19; H, 1.21; N, 31.58; Cl, 13.27.
ꢀ
0 mmol) in H
2
O (250 mL) was treated with F
2
(10% in N
2
) at 0–5 C
ꢀ
1
(
ice bath). Reaction completion was determined by UV (disap-
pearance of the absorption band at 336 nm). The resulting white
precipitate was filtered dried and recrystallized from CCl –hexanes
Cl
): þ9.8
), 1360, 1570 (aromatic
: C, 10.13; N, 41.36. Found: C, 10.01; N,
3
): 2.72
), 1360, 1570
6 6
O : C, 18.02; H, 1.13; N,
ꢁ1
2 2
)
4
2
4
H
3
19
(
1:1) to furnish the targeted 9b (4.4–11 g). F NMR (CH
2
2
ꢁ1
(
NO
F). IR (KBr, cm ): 1280, 1615 (CF(NO
). Anal. Calcd for C FN
1.59.
2 2
)
2
2
7
O
6
3.2.2. Potassium salt of 1-dinitromethyl-3-nitro-5-methyl-1,2,4-
triazole (11)
Yield: 80% (1.22 g from 10a), 91% (1.23 g, from 10c), yellow
crystals, mp 182–190 C (decomp.). Triazole (10a or 10c, 2 mmol)
was dissolved in MeOH (5 mL) and treated with solution of KI
(0.664 g, 4 mmol) in MeOH (5 mL) at rt. The resulting mixture was
4
3
1
ꢀ
.1.8. 2-(Chlorodinitromethyl)-5-nitrotetrazole (9c)
ꢀ
Yield: 70%, white crystals, mp 65 C (decomp.). A suspension of
2 2 2
g of 7b in CH Cl (30 mL) was treated with Cl at rt until yellow
solid was replaced with colorless precipitate of KCl (5–10 min). The
precipitate was filtered, mother liquor was concentrated in vacuo at
stirred at rt for 40 min and triturated with 10 mL of Et
cipitate was collected, washed with ice-cold water, recrystallized
2
O. Pre-
ꢀ
ꢀ
1
2
0 C and the residue was recrystallized from CCl
4
at 50 C to afford
analytically pure 9c (0.69 g). IR (KBr, cm ): 1275, 1300, 1610
CCl(NO ), 1340, 1560 (aromatic NO ). Anal. Calcd for C ClN : C,
.48; N, 38.68. Found: C, 9.41; N, 38.18. Both formation and purity of
c were further confirmed by the treatment with KI/MeOH (20 mL
with Na
from water and washed with EtOH followed by Et
2
O to afford 11. H
): 11.6 (Me), 129.6
O)¼343 nm ( ¼16,400).
).
ꢁ1
13
NMR (DMSO-d
6
): 2.38 (s, Me). C NMR (DMSO-d
6
ꢁ
(
2
)
2
2
2
7
O
6
2
(C(NO )
2
), 160.4 (C
5
), 162.1 (C
3
). UVmax (H
2
3
ꢁ
1
ꢁ
9
9
IR (KBr, cm ): 1230, 1475 (C(NO
Anal. Calcd for C KN
17.92; H, 1.20; N, 31.29.
2
)
2
), 1540, 1562 (aromatic NO
2
4
H
3
6 6
O : C, 17.78; H, 1.12; N, 31.10. Found: C,
solution) followed by titration of I
2
2 2 3
S O .
3.2.3. Potassium salt of 1-dinitromethyl-3-nitro-5-
3
.2. General procedure for the thermal ring-opening reaction
carbethoxymethyl-1,2,4-triazole (13a)
of 2-(polynitromethyl)-5-nitrotetrazoles (9a–c)
Yield: 70%, yellow crystals, decompose upon heating. Ethyl ester
of cyanoacetic acid (5.65 g, 50 mmol) was added to solution of 1d
Tetrazole (2 mmol) was dissolved in absolute MeCN (10 mL).
The resulting solution was kept at the temperatures summarized in
(1.28 g, 5 mmol) in 10 mL of dichloroethane (DCE). The reaction
ꢀ
mixture was heated to 60–65 C for 15 min until N
2
evolution
Table 1 for 15–20 min until N
2
evolution stopped. The resulting
stopped. Vigorously stirred mixture was brought to rt and treated

V.V. Semenov et al. / Tetrahedron 65 (2009) 3441–3445
3445
ꢁ
dropwise with solution of KI (1.66 g, 10 mmol) in MeOH (10 mL)
followed by CH Cl (30 mL). The resulting precipitate was collected,
washed with ice-cold water, MeOH, and Et O to furnish 1.13 g of
), 4.1
1285, 1478 (C(NO
BrKN
20.32.
2
)
2
), 1540, 1568 (aromatic NO
2
). Anal. Calcd for
2
2
C
5
H
3
5 6
O : C, 17.25; H, 0.87; N, 20.12. Found: C, 17.14; H, 0.91; N,
2
1
1
3a. H NMR (DMSO-d
6
): 1.18 (t, J¼7.2 Hz, Me), 3.86 (s, CH
2
ꢁ1
(
q, J¼7.2 Hz, CH
2
). UVmax (H
2
O)¼341 nm (
3
¼16,700). IR (KBr, cm ):
3
.4. Synthesis of hydrazones from 2-(chloronitromethyl)-5-
ꢁ
1
235,1480 (C(NO
for C KN
N, 24.71.
2
)
2
), 1568 (aromatic NO
2
), 1731 (C]O). Anal. Calcd
nitrotetrazole (9c)
7
H
7
6 8
O : C, 24.56; H, 2.06; N, 24.55. Found: C, 24.69; H, 2.18;
3
.4.1. Chloronitroformaldehyde hydrazone (18)
Yield: 52%, yellow solid, mp 50 C (decomp.). A solution of 9c
2 g, 7.9 mmol) in MeOH (40 mL) was heated at 45 C for 4 h until
disappearance of the starting material. The reaction mixture was
concentrated in vacuo at rt, the residue was redissolved in water
ꢀ ꢀ
5 mL) at 50 C. The resultant mixture was filtered, cooled to 0–5 C,
ꢀ
3
.2.4. Potassium salt of 1-dinitromethyl-3-nitro-5-phenyl-1,2,4-
triazole (13b)
Yield: 75% (1.25 g), yellow crystals, decompose upon heating. H
ꢀ
(
1
13
NMR (DMSO-d
azole-C ), 127.6 (m-C), 129.4 (o-C), 131.1 (C(NO
59.7 (Triazole-C
6
): 7.95 (m, Ph). C NMR (DMSO-d
6
): 125.3 (C-Tri-
(
ꢁ
5
2 2
) ), 132.2 (p-C),
the resultant crystals were collected and dried to furnish 18
1
5
), 162.4 (Triazole-C
3
). UVmax (H
2
O)¼345 nm
ꢁ1
(0.51 g). UVmax (H
2
O)¼314.5 nm (
3
¼10,200). IR (KBr, cm ): 1235,
ꢁ
1
ꢁ
(
3
¼16,200). IR (KBr, cm ): 1230, 1490 (C(NO
NO ). Anal. Calcd for C KN
C, 32.70; H, 1.61; N, 25.39.
2
)
2
), 1572 (aromatic
1
258, 1300, 1520 (NO
2
), 1560, 1620 (N]C), 3220, 3280, 3420 (NH
2
).
EIMS (70 eV, 20 C) (m/z, I, %): 125 [M , 3], 79 [33]. Anal. Calcd for
CH ClO : C, 9.73; H, 1.63; N, 34.02; Cl, 28.71. Found: C, 9.60; H,
.83; N, 33.86; Cl, 29.07.
H
5
6
O
6
: C, 32.53; H, 1.52; N, 25.29. Found:
ꢀ
þ
2
9
2
N
3
2
1
3
.2.5. Bis-potassium salt of bis-(1-dinitromethyl-3-nitro1,2,4-
triazolyl-5)methane (14)
Yield: 60% (0.79 g), yellow crystals, decompose upon heating. H
3
.4.2. Diazidomethylenecarbonohydrazonic diazide (22)
Caution! The molecule easily decomposes upon mechanical
treatment when completely dry. Yield: 22%, white needles, 76–
7 C (decomp.). Dry NaN
portionwise (8–10) to a vigorously stirred solution of 9c (0.3 g,
.18 mmol) in absolute MeOH (10 mL). In 3 h the reaction mixture
was treated with 5 mL of water, concentrated in vacuo at rt to 3–
1
13
NMR (DMSO-d
6
): 4.90 (s, CH
2
). C NMR (DMSO-d
), 154.2 (Triazole-C ), 161.9 (Triazole-C
O)¼341 nm (
580 (aromatic NO
N, 32.05. Found: C, 16.23; H, 0.41; N, 32.24.
6 2
): 16.0 (CH ),
ꢁ
129.0 (C(NO
2
)
2
5
3
). UVmax
ꢀ
7
3
(0.6 g, 9.23 mmol) was cannulated
ꢁ
1
ꢁ
(
H
2
3¼29,900). IR (KBr, cm ): 1240, 1492 (C(NO
2
)
2
),
1
2
). Anal. Calcd for C
7
2
H KN12
O
12: C,16.03; H, 0.38;
1
4
mL, and extracted with Et
2
O (3ꢃ20 mL). Organic extract was
3
1
.3. Synthesis of 1-(dinitromethyl)-pyrazoles 16a–c via the
,3-dipolar cycloaddition reaction of nitrilamines to
acetylenes. Representative protocol
ꢀ
concentrated in vacuo at rt, cooled to ꢁ30 C (water–ethylene
glycol–dry ice bath) and the resulting crystals were expeditiously
2 14
filtered to yield 22 (0.06 g). HRMS (42 eV), calcd for C N :
2
20.0434, found: 220.0430ꢂ0.0002. EIMS (70 eV) (m/z, I, %): 220
3
.3.1. Potassium salt of 1-(dinitromethyl)-3-nitro-5-chloromethyl
þ
[M , 9], 68 [CN
4
, 57], 54 [CN
3
, 42], 52 [C
2
N
2
, 9], 40 [CN
2
, 100]. IR
pyrazole (16c)
ꢁ1
(CHCl
3
, cm ): 1295, 1343, 1445, 1535, 1587, 1600, 1612 (conjugated
Yield: 60%, yellow crystals, decompose upon heating. Propargyl
chloride (3 mL, 41 mmol) was added to a solution of 2-(chloro-
dinitromethyl)-5-nitrotetrazole (1.014 g, 4 mmol) in DCE (10 mL) in
C]N), 2160 (N
3
).
ꢀ
References and notes
a Teflon tube. The tube was sealed and heated at 70 C for 15 min
(
water bath). The reaction mixture was brought to rt and trans-
1. Ilyushin, M. A.; Tselinsky, I. V. Russ. Chem. J. (Russ.) 1997, 4, 3.
ferred to a 100 mL glass flask. Ether (20 mL) followed by suspension
of KI (1.33 g, 8 mmol) in MeOH (10 mL) was added to a vigorously
stirred mixture. After 20 min the solid residue was filtered and
2. Semenov, V. V.; Ugrak, B. I.; Shevelev, S. A.; Kanishchev, M. I.; Baryshnikov, A. T.;
Fainzilberg, A. A. Russ. Chem. Bull. 1990, 39, 1658.
3
4
. Semenov, V. V.; Shevelev, S. A.; Melnikova, L. Mendeleev Commun. 1993, 58.
. Kofman, T. P.; Kartseva, G. Y.; Glazkova, E. Y.; Krasnov, K. N. Russ. J. Org. Chem.
1
recrystallized from water to yield the targeted 16c (0.64 g). H NMR
(
Engl.) 2005, 41, 753.
5. Kofman, T. P.; Kartseva, G. Y.; Glazkova, E. Y. Russ. J. Org. Chem. 2008, 44, 870.
. Newton, C. G.; Ollis, W. D.; Wright, D. E. J. Chem. Soc., Perkin Trans. 1 1984, 69.
. Khisamutdinov, G. K.; Korolev, V. L.; Kondyukov, I. Z.; Abdrakhmanov, I. S.;
1
3
(
(
(
DMSO-d
6
): 4.73 (s, 2H), 7.62 (s, 1H). C NMR (DMSO-d
6
): 33.8
), 130.7
¼16,300).
). Anal.
6
7
t, J¼152.6 Hz, CH
2
Cl), 103.2 (d,
J
13C–1H¼188.6 Hz,
C
4
ꢁ
C(NO
2
)
2
), 145.9 (C
5
), 155.9 (C
3
). UVmax (H
2
O)¼345 nm (
3
Smirnov, S. P.; Fainzilberg, A. A. Russ. Chem. Bull. (Engl.) 1993, 9, 1559.
8. Katritzky, A. R.; Sommen, G. L.; Gromova, A. V.; Witek, R. M.; Steel, P. J.;
Damavarapu, R. Khim. Geterocycl. Soed. (Engl.) 2005, 41, 111.
ꢁ
1
ꢁ
IR (KBr, cm ): 1221, 1483 (C(NO
Calcd for C ClKN
H, 1.11; N, 23.17.
2
)
2
), 1549 (aromatic NO
O : C, 19.78; H, 1.00; N, 23.06. Found: C, 19.82;
5 6
2
H
5 3
9
. Huisgen, R. Angew. Chem., Int. Ed. Engl. 1963, 2, 633.
0. Benson, F. R. In Heterocyclic Compounds; Elderfield, R., Ed.; Wiley: New York, NY,
London, Sydney, 1967; Vol. 8.
1
1
1. Huisgen, R.; Grashey, R.; Seidel, M.; Wallbillich, G.; Knupfer, H.; Schmidt, R.
Liebigs Ann. 1962, B653, 105.
3
.3.2. Potassium salt of 1-dinitromethyl-3-nitro-5-phenyl-
pyrazole (16a)
Yield: 75% (0.99 g), yellow crystals, decompose upon heating. H
12. Baldwin, J.; Hong, S. J. Chem. Soc., Chem. Commun. 1967, 1136.
1
13. Hong, S.; Baldwin, J. Tetrahedron 1968, 24, 3787.
13
1
1
1
4. Huisgen, R.; Seidel, M.; Wallbillich, G.; Knupfer, H. Tetrahedron 1962, 17, 3.
5. Parker, C. Tetrahedron 1962, 17, 109.
6. Grakauskas, V.; Guest, A. J. Org. Chem. 1978, 43, 3485.
NMR (DMSO-d
6
): 7.73 (s, 1H), 7.77 (m, 5H). C NMR (DMSO-d
6
):
), 127.5 (m-C),
), 156.0 (C ).
1
03.2 (d, J13C–1H¼186.6 Hz, C
4
), 126.2 (Pyrazole-C
5
ꢁ
129.1 (o-C), 131.8 (p-C), 132.8 (C(NO
2
)
2
), 146.2 (C
5
3
17. Ershova, L. V.; Gogitidze, V. N.; Belikov, V. M.; Novikov, S. S. Russ. Chem. Bull.
(Engl.) 1959, 8, 910.
18. Ungnade, H.; Kissinger, L. J. Org. Chem. 1959, 24, 666.
ꢁ
1
UVmax (H
2
O)¼348 nm (
3
¼16,500). IR (KBr, cm ): 1222, 1270, 1492
ꢁ
(
C(NO
2
)
2
), 1559 (aromatic NO ). Anal. Calcd for C KN : C,
2
5
H
4
5 6
O
19. Kofman, T. P.; Trubitsyn, A. E.; Dmitrienko, I. V.; Glazkova, E.; YuTselinskii, I. V.
2
2.32; H, 1.50; N, 26.01. Found: C, 22.45; H, 1.61; N, 26.22.
Russ. J. Org. Chem. (Engl.) 2007, 43, 758. KI protocol.
0. Hine, J.; Baily, W. J. Org. Chem. 1961, 26, 2098.
2
2
2
1. Kaplan, J.; Pickard, H. J. Org. Chem. 1970, 35, 2044.
2. Krayushkin, M. M.; Andreeva, T. G.; Shvarts, I. Sh.; Sevost’yanova, V. V.; Yar-
ovenko, V. N.; Novikov, S. S. Russ. Chem. Bull. (Engl.) 1980, 29, 462.
3
.3.3. Potassium salt of 1-dinitromethyl-3-nitro-5-bromomethyl-
pyrazole (16b)
Yield: 50% (0.70 g), yellow crystals, decompose upon heating. H
1
23. Pupko, L. S.; Dichenko, A. I.; Pelkis, P. S. Russ. J. Org. Chem. 1972, 8, 39; Chem.
Abstr. 1972, 76, 112852.
1
3
NMR (DMSO-d
CH
56.0 (C
6
): 4.83 (s, 2H), 7.60 (s, 1H). C NMR (DMSO-d
6
): 19.1
),
2
2
4. Dichenko, A. I.; Pelkis, P. S. Ukr. Chem. J.1979, 45, 451; Chem. Abstr.1979, 91,107741y.
5. Grundmann, C.; Schnabel, W. U.S. Patent 2,990,412, June 27, 1961; Chem. Abstr.
1961, 55, 25256e.
ꢁ
(
2
Br), 103.2 (d, J13C–1H¼186.0 Hz, C
4
), 130.8 (C(NO
¼16,200). IR (KBr, cm ): 1228,
2
)
2
), 146.6 (C
5
ꢁ
1
1
3
). UVmax (H
2
O)¼346 nm (
3