Nitropyrazoles 15.* Synthesis and some transformations of 1-(2,4-dinitrophenyl)-4-methyl-3,5-dinitropyrazole

Article abstract of DOI:10.1007/s11172-009-0288-8

The method for preparation of 1-(2,4-dinitrophenyl)-4-methyl-3,5- dinitropyrazole has been developed. Due to the larger CH-acidity of 4-Me-group compared to 1,4-dimethyl-3,5-dinitropyrazole, 1-(2,4-dinitrophenyl)-4-methyl-3, 5-dinitropyrazole is capable of reacting with substituted benzaldehydes to afford 4-[(E)-2-arylvinyl]-1-(2,4-dinitrophenyl)-3,5-dinitropyrazoles. Under the action of nucleophiles, dinitrophenyl group is detached from the former compounds leading to previously unknown N-unsubstituted 4-[(E)-2-arylvinyl]-3,5- dinitropyrazoles.

Full text of DOI:10.1007/s11172-009-0288-8

Russian Chemical Bulletin, International Edition, Vol. 58, No. 10, pp. 2109—2117, October, 2009
2109
Nitropyrazoles
15.* Synthesis and some transformations
of 1ꢀ(2,4ꢀdinitrophenyl)ꢀ4ꢀmethylꢀ3,5ꢀdinitropyrazole
A. A. Zaitsev,a I. A. Vatsadze,a I. L. Dalinger,a V. V. Kachala,a Yu. V. Nelyubina,b and S. A. Sheveleva
aN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5328. Eꢀmail: shevelev@ioc.ac.ru
bN. A. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation
The method for preparation of 1ꢀ(2,4ꢀdinitrophenyl)ꢀ4ꢀmethylꢀ3,5ꢀdinitropyrazole has
been developed. Due to the larger CHꢀacidity of 4ꢀMeꢀgroup compared to 1,4ꢀdimethylꢀ3,5ꢀ
dinitropyrazole, 1ꢀ(2,4ꢀdinitrophenyl)ꢀ4ꢀmethylꢀ3,5ꢀdinitropyrazole is capable of reacting with
substituted benzaldehydes to afford 4ꢀ[(E)ꢀ2ꢀarylvinyl]ꢀ1ꢀ(2,4ꢀdinitrophenyl)ꢀ3,5ꢀdinitroꢀ
pyrazoles. Under the action of nucleophiles, dinitrophenyl group is detached from the former
compounds leading to previously unknown Nꢀunsubstituted 4ꢀ[(E)ꢀ2ꢀarylvinyl]ꢀ3,5ꢀdinitroꢀ
pyrazoles.
Key words: nitropyrazoles, dinitropyrazoles, nitration, nucleophilic substitution, nucleoꢀ
philes, protective groups, enamines, Smiles rearrangement.
Previously,2 with the 1,4ꢀdimethylꢀ3,5ꢀdinitroꢀ
Scheme 1
pyrazole, we have demonstrated that introduction of two
nitro groups at the 3ꢀ and 5ꢀpositions of the pyrazole ring
activates the 4ꢀMe group in a fashion that enables its conꢀ
densation with dimethylformamide dimethyl acetal
(DMFꢀDMA) to yield (E)ꢀN,Nꢀdimethylꢀ2ꢀ(1ꢀmethylꢀ
3,5ꢀdinitropyrazolꢀ4ꢀyl)ethylеnamine.
This work focuses on the condensation of 1ꢀRꢀ4ꢀmeꢀ
thylꢀ3,5ꢀdinitropyrazoles with the organic electrophiles of
different type, namely, benzaldehydes. The 4ꢀMe group in
1,4ꢀdimethylꢀ3,5ꢀdinitropyrazole (1) was found to be inꢀ
sufficiently reactive to condense with various benzaldeꢀ
hydes: with a comprehensive set of substituted benzaldeꢀ
hydes, a single condensation product (with pꢀmethoxyꢀ
benzaldehyde) could be isolated, yet under rather forcing
conditions and in a small yield. The resulting 4ꢀ[(E)ꢀ2ꢀ(4ꢀ
methoxyphenyl)vinyl]ꢀ1ꢀmethylꢀ3,5ꢀdinitropyrazole (2)
was feasible only under heating (fusion) of reactants at
100—105 °C without solvent in the presence of piperidine
in a catalytic amount, in the isolated yield of only 15%.
(Scheme 1). The coupling constants for vinyl protons
3J = 16.5 Hz are indicative of the transꢀconfiguration of
C=C bond in 2.3
At the same time, our results obtained for the dinitroꢀ
pyrazole 2 have demonstrated the usefulness of synthesizꢀ
ing such unsaturated species. Characteristically, the nitro
i. Fusion, 10 h; ii. PhCH2SH, K2CO3, Nꢀmethylpyrrolidinꢀ1ꢀ
one (NMP), ∼20 °C, 6 h; iii. N2H4•H2O, FeCl3•6H2O, activatꢀ
ed carbon/MeOH, reflux, 3 h.
* For Part 14, see Ref. 1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2045—2053, October, 2009.
1066ꢀ5285/09/5810ꢀ2109 © 2009 Springer Science+Business Media, Inc.

2110
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 10, October, 2009
Zaitsev et al.
group in 2 is readily substituted by PhCH2S– in NMP at
a temperature as low as ∼20 °C (see Scheme 1). That is,
4ꢀ(pꢀmethoxyphenyl)vinyl group facilitates nucleophilic
substitution of NO2 group as opposed to 4ꢀMe substituꢀ
ent; with the latter, heating at 100 °C in the same solvent
was required.2 The attachment site of PhCH2S on the
uct by nitrating the 1ꢀ(2,4ꢀdinitrophenyl)ꢀ4ꢀmethylpyrꢀ
azole (5). The latter was derived from commercially availꢀ
able 1,1,3,3ꢀtetraethoxyꢀ2ꢀmethylpropane and 2,4ꢀdiꢀ
nitrophenylhydrazine (Scheme 2).
Scheme 2
1
pyrazole ring of 3 was deduced from longꢀrange Н—13С
couplings established using 2D correlation HMBC experꢀ
iments. As in our previous study,4 spinꢀspin coupling beꢀ
tween NMe protons and SCH2 protons was found at only
one pyrazole carbon (δ = 133.08 ppm) which is possible
exclusively in the case of PhCH2S group attached to C(5).
With the equivalent amount of the reducing agent
(hydrazine hydrate in the presence of FeCl3 and activated
carbon), 5ꢀNO2 group in 2 could be reduced selectively to
NH2 (see Scheme 1). The substitution pattern for the pyrꢀ
azole ring of 4 was identified as follows. Chemical shifts for
C(3) and C(5) carbons are 150.04 and 146.03 ppm, reꢀ
spectively (assignment of 1Н and 13С signals was based on
2D 1H—13C HMBC technique). Analogously with Ref. 4,
the signal of the carbon atom bonded to NO2 was assigned
from its correlation with the connectivity feature maniꢀ
fested in the slowing of quadrupolar relaxation of the niꢀ
troꢀgroup 14N nucleus (expressed as noticeable NO2 line
narrowing in 14N NMR spectrum) with a simultaneous
distinct broadening of CNO2 resonance in 13C NMR specꢀ
trum (associated with residual 14N—13C spinꢀspin couꢀ
pling) with increasing temperature. The only signal for
which this was observed was C(3) carbon resonance.
Chemical shift at δ 146.03 for C(5)—NH2 carbon comꢀ
pares favorably with the reported5 chemical shifts of
C—NH2 carbon atoms in 1ꢀmethylꢀ5ꢀaminopyrazoles,
ranging from 146.6 to 149.9 ppm.
i. 1) 2,4ꢀDinitrophenylhydrazine, conc. HCl/EtOH, reflux, 8 h,
2) KOH/H2O; ii. HNO3 (d = 1.5 g cm–3), H2SO4 (∼97.5%),
30—40 °C, 10 min; iii. HNO3 (d = 1.5 g cm–3), H2SO4
(~97.5%), 100—105 °C, 3 h.
The general approach to the synthesis of the species
analogous to 2 proposed herein is based on the idea
of introducing a strong electronꢀwithdrawing substituent
into the 1ꢀposition of the pyrazole ring of 4ꢀmethylꢀ3,5ꢀ
dinitropyrazole — on the one hand, to enhance reactiviꢀ
ty of the 4ꢀMe group as compared with 1 so to enꢀ
able synthesis of 4ꢀ[(E)ꢀ2ꢀarylvinyl]ꢀ3,5ꢀdinitropyrꢀ
azoles, and on the other hand, to exploit such substituꢀ
ent as readily removable protecting group thereby affordꢀ
ing Me group modification leading to NHꢀunsubstituted
products.
An examination of literature brought us to believe that
for this task 2,4ꢀdinitrophenyl would fit well, being a strong
electron acceptor, stable to HNO3/H2SO4 nitration (which
is a necessary step to synthesize dinitropyrazole moiety)
and easily removable by treatment with nucleophiles unꢀ
der mild conditions.6
Nitration of 5 with HNO3/H2SO4 acid under mild conꢀ
ditions (30—40 °C) leads to 5ꢀnitropyrazole 6 which is
formed rapidly (in 10 min) (see Scheme 2). It should be
noted that the reported data on the relative activity of 3
and 5 positions of the pyrazole ring (with the substituted
position 4) in the nitration reactions are much of contraꢀ
dictory. Thus, according to the literature, nitrations of
1ꢀmethylꢀ4ꢀpicrylpyrazole8 with 90% HNO3, 1ꢀmethylꢀ4ꢀ
pꢀtolylpyrazole9 with 70% HNO3, 4ꢀbromoꢀ1ꢀethylꢀ10 and
4ꢀmethylꢀ1ꢀ(4ꢀnitrophenyl)pyrazoles7 with HNO3/H2SO4
occur selectively in the 3ꢀposition of the pyrazole ring, as
do nitrations of 1ꢀmethylꢀ4ꢀphenylꢀ9, 1,4ꢀdimethylꢀ7,11
,
1ꢀmethylꢀ4ꢀethylꢀ11, 1ꢀphenylꢀ4ꢀethylꢀ11, and 4ꢀmethylꢀ
1ꢀ(4ꢀnitrophenyl)pyrazoles7 with acetyl nitrate. Nitrations of
4ꢀ(2,4ꢀdinitrophenyl)ꢀ1ꢀmethylpyrazole8 with 70% and 90%
HNO3 and of 1,4ꢀdimethylpyrazole7 with sulfuric—nitric
mixed acids lead to the mixture of products with the dominant
For the required precursor, 1ꢀ(2,4ꢀdinitrophenyl)ꢀ4ꢀ
methylꢀ3,5ꢀdinitropyrazole there is a known7 synthetic
method, however its overall yield in a twoꢀstep nitration of
4ꢀmethylꢀ1ꢀ(4ꢀnitrophenyl)pyrazole is 10—13%, so we
have developed the alternative method to prepare this prodꢀ
3ꢀnitropyrazole; nitration of 1ꢀmethylꢀ4ꢀchloropyrazole12
—
to the mixture with the dominant 5ꢀnitropyrazole; nitraꢀ
tion of 4ꢀbromoꢀ1ꢀmethylpyrazole12 — selectively to
5ꢀnitropyrazole; furthermore, the higher reactivity of the

1ꢀ(2,4ꢀDinitrophenyl)ꢀ4ꢀmethylꢀ3,5ꢀdinitropyrazole Russ.Chem.Bull., Int.Ed., Vol. 58, No. 10, October, 2009
2111
5 compared to 3 position was demonstrated in the study of
nitrodecarboxylation of isomeric 4ꢀhaloꢀ1ꢀmethylꢀ3ꢀ and
4ꢀhaloꢀ1ꢀmethylpyrazoleꢀ5ꢀcarboxylic acids, as well as
4ꢀhalopyrazoleꢀ3,5ꢀdicarboxylic acids.13
O(8)
N(6)
O(7)
As can be seen from the available 13C NMR spectral
data for 3ꢀNO2ꢀ5ꢀHꢀ and 5ꢀNO2ꢀ3ꢀHꢀpyrazoles with the
4ꢀposition occupied by hydrogen or an aliphatic carbon
atom,5a,14 chemical shifts for C(3) and C(5) in such
3ꢀnitropyrazoles fall in the ranges 148.9—160.1 and
124.4—137.1 ppm, respectively (the difference δ(C(3))
– δ(C(5)) = 20.0—27.9 ppm); for 5ꢀnitropyrazoles, chemꢀ
ical shifts for C(3) and C(5) lie in the ranges 133.6—139.6
and 142.3—146.6, respectively with |δ(C(3)) – δ(C(5))|
modulus ranging from 6.4 to 8.7 ppm. In the 13C NMR
spectrum of 6, chemical shifts of CH and CNO2 carbons
are 143.81 and 143.86 ppm, respectively (assignment based
on 2D correlation techniques with longꢀrange (HMBC)
C(5´)
C(6´)
C(4´)
C(3´)
C(1´)
N(1)
C(2´)
N(2)
O(1)
O(6)
C(3)
O(5)
N(5)
N(3)
C(5)
O(4)
C(4)
N(4)
O(2)
1
and direct (HSQC) H—13C spinꢀspin coupling conꢀ
stants), |δ(C(3)) – δ(C(5))| is 0.05 ppm. As the chemical
shifts in the 3ꢀnitropyrazoles considered are at least
148.9 ppm for C(3) and at most 137.1 ppm for C(5), the
nitro group in 6 is obviously attached to C(5) carbon.
Moreover, the replacement of Me with 2,4ꢀdinitrophenyl
group at the 1ꢀposition of the pyrazole ring results in the
lowꢀfield shift of C(3) carbon by 4.6—9.2 ppm,5a,b,15
hence, the chemical shift for C(3) in the spectrum
of 6 (143.81 ppm) exceeds the relevant literature values
(133.6—139.6 ppm).
Nitration of 1ꢀ(2,4ꢀdinitrophenyl)ꢀ4ꢀmethylpyrazole
(5) under more severe temperature conditions (∼100 °C)
leads to 1ꢀ(2,4ꢀdinitrophenyl)ꢀ4ꢀmethylꢀ3,5ꢀdinitropyrꢀ
azole (7) in a yield of 64% (see Scheme 2). Thus, compared
to the synthetic method of Ref. 7, the yield of the product
7 generated from 2ꢀmethylꢀ1,1,3,3ꢀtetraethoxypropane is
increased from 7—8 to 60%. We have also attempted prepꢀ
aration of 7 via nitration of 4ꢀmethylꢀ1ꢀphenylpyrazole,
yet its yield in this case was markedly lower. Finally, the
nitration sequence for 4ꢀmethylꢀ1ꢀphenylpyrazole is folꢀ
lowing: 4ꢀposition of phenyl → 5ꢀposition of pyrazole
and 2ꢀposition of phenyl (concurrently) → 3ꢀposition of
pyrazole.
O(3)
C(6)
Fig. 1. View of molecule 7 (thermal ellipsoids enclose 50% probꢀ
ability, hydrogen atoms are removed for clarity).
distance is close to the sum of the corresponding van der
Waals radii. Such proximity implies intramolecular interꢀ
action between O(4) and O(5) oxygen atoms.16 The nitro
groups in the structure 7, except for 4´ꢀNO2, are also enꢀ
gaged in O...O (2.821(3)—3.015(3) Å) contacts which link
the molecules to form a 3D framework (Fig. 2). The nitro
group at C(4´), in its turn, seems to interact with N(3)O2
and N(4)O2 groups in the O...π mode with O...N distancꢀ
es of 2.989(3) and 3.032(3) Å, respectively. Besides that,
c
Dinitropyrazole 7 was structurally characterized by
Xꢀray diffraction (Fig. 1); the obtained bond lengths and
angles are close to normal (Table 1).
0
b
The characteristic structural features of dinitropyrꢀ
azole 7 include, first, a rather large torsion angle between
pyrazole and phenyl planes (65.5(3)°) and, second, rather
small outꢀofꢀplane tilt angles of nitro groups with respect
to pyrazole and phenyl planes, namely, 4.7(3), 3.9(2), and
4.6(3)° for NO2 groups at 3, 2,´ and 4´ positions, respecꢀ
tively. For the most sterically hindered 5ꢀNO2 group, the
tilt angle is larger (10.3(3)°).
a
It should be noted that the orientation of the nitro
groups to C(5) and C(2´) carbons is such that the miniꢀ
mum O...O distance is 3.025(3) Å, that is, O(4)—O(5)
Fig. 2. Crystal packing of compound 7 projected along the c axis.

2112
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 10, October, 2009
Zaitsev et al.
Table 1. Selected bond lengths (d) and bond angles (ω) in dinitropyrazole 7 (from Xꢀray data)
Bond
d/Å
Bond angle
ω/deg
Dihedral angle
θ/deg
N(1)—N(2)
N(1)—C(5)
N(1)—C(1´)
N(2)—C(3)
C(3)—C(4)
C(4)—C(5)
C(4)—C(6)
C(1´)—C(6´)
C(1´)—C(2´)
C(2´)—C(3´)
C(3´)—C(4´)
C(4´)—C(5´)
C(5´)—C(6´)
N(3)—C(3)
N(4)—C(5)
N(5)—C(2´)
N(6)—C(4´)
1.347(2)
1.373(3)
1.437(3)
1.329(3)
1.408(3)
1.376(3)
1.498(3)
1.392(3)
1.401(3)
1.378(3)
1.387(3)
1.378(3)
1.393(3)
1.455(3)
1.441(3)
1.477(3)
1.474(3)
N(2)—N(1)—C(5)
N(2)—N(1)—C(1´)
C(5)—N(1)—C(1´)
C(3)—N(2)—N(1)
N(2)—C(3)—C(4)
C(5)—C(4)—C(3)
C(5)—C(4)—C(6)
C(3)—C(4)—C(6)
N(1)—C(5)—C(4)
C(6´)—C(1´)—N(1)
C(2´)—C(1´)—N(1)
С(2´)—C(1´)—С(6´)
C(3´)—C(2´)—C(1´)
C(2´)—C(3´)—C(4´)
C(5´)—C(4´)—C(3´)
C(4´)—C(5´)—C(6´)
C(1´)—C(6´)—C(5´)
110.11(17)
116.59(16)
133.27(17)
104.01(16)
115.18(18)
100.48(18)
129.3(2)
N(2)—N(1)—C(1´)—C(6´)
N(2)—N(1)—C(1´)—C(2´)
C(5)—N(1)—C(1´)—C(6´)
C(5)—N(1)—C(1´)—C(2´)
O(1)—N(3)—C(3)—N(2)
O(2)—N(3)—C(3)—N(2)
O(1)—N(3)—C(3)—C(4)
O(2)—N(3)—C(3)—C(4)
O(3)—N(4)—C(5)—N(1)
O(4)—N(4)—C(5)—N(1)
O(3)—N(4)—C(5)—C(4)
O(4)—N(4)—C(5)—C(4)
O(5)—N(5)—C(2´)—C(1´)
O(6)—N(5)—C(2´)—C(1´)
O(5)—N(5)—C(2´)—C(3´)
O(6)—N(5)—C(2´)—C(3´)
O(7)—N(6)—C(4´)—C(3´)
O(8)—N(6)—C(4´)—C(3´)
O(8)—N(6)—C(4´)—C(5´)
O(7)—N(6)—C(4´)—C(5´)
62.4(2)
–112.4(2)
–115.5(2)
69.7(3)
–4.7(3)
175.54(18)
175.0(2)
–4.7(3)
–173.43(18)
7.1(3)
12.4(3)
–167.1(2)
3.2(3)
–176.97(19)
–176.39(18)
3.5(3)
–5.1(3)
175.7(2)
–3.8(3)
130.2(2)
110.21(18)
115.81(18)
124.90(18)
119.09(18)
121.02(18)
118.11(19)
122.83(19)
118.21(19)
120.6(2)
175.3(2)
Scheme 3
crystal 7 incorporates various weaker O...C, O...H, and
H...H contacts with the minimum distances 2.872(3),
2.485(3), and 2.381(3) Å, respectively.
Dinitropyrazole 7 interacts with a series of anionic Sꢀ,
Nꢀ and Oꢀnucleophiles (in MeCN) always via regiospeꢀ
cific substitution of dinitropyrazole anion regardless of the
nucleophile nature (an attack on the C(1´) dinitropheꢀ
nyl carbon), while nitro groups on 3,5ꢀdinitropyrazole
and 2,4ꢀdinitrophenyl rings remain not involved. Thus,
the reaction of dinitropyrazole 7 with thioglycolic acid
Nꢀphenylаmide in the presence of K2CO3 is completed in
30 min at ∼20 °C; with sodium azide, full conversion of
dinitropyrazole 7 at ∼20 °C takes 15—20 h (30 min with
heating under reflux), and the reaction of dinitropyrazole
7 with glycolic acid Nꢀphenylаmide in the presence of
K2CO3 requires heating at reflux for several hours to comꢀ
plete. In all cases the reactions lead to 4ꢀmethylꢀ3,5ꢀdiꢀ
nitropyrazole (8) and the substituted derivatives 9a—c,
with product 9c of the reaction with glycolic acid Nꢀpheꢀ
nylаmide under basic conditions partially undergoing
Smiles rearrangement to yield substituted aniline 10
(Scheme 3). There is the literature precedent that 10 is
derived from 9c under treatment with sodium hydroxide
or ethoxide (Ref. 17).
days. Beside that, nitropyrazole 6 with a single nitro group
in the pyrazole ring does not react with DMFꢀDMA in
toluene at all, prolonged heating to reflux (50—60 h) failꢀ
ing to afford a product and leading only to slow decompoꢀ
sition of 6.
Enamine 11 can be further converted similarly with reꢀ
acting of the condensation product of 1 and DMFꢀDMA2
to give the derivatives 12 and 13 (see Scheme 4).
Reaction of dinitropyrazole 7 with DMFꢀDMA leads
to enamine 11 (Scheme 4). Note that dinitropyrazole 7
reacts with DMFꢀDMA under much milder conditions
than 1,4ꢀdimethylꢀ3,5ꢀdinitropyrazole (1): conversion of
7 at heating under reflux in toluene is completed in ∼8 h,
whereas reaction of 1 with DMFꢀDMA at heating under
reflux in toluene cannot go to completion even in several

1ꢀ(2,4ꢀDinitrophenyl)ꢀ4ꢀmethylꢀ3,5ꢀdinitropyrazole Russ.Chem.Bull., Int.Ed., Vol. 58, No. 10, October, 2009
2113
Scheme 4
Scheme 5
i. Me2NCH(OMe)2, PhCH3, reflux, 8 h; ii. NaNO2/HCl conc.,
∼20 °C; iii. MeONH2•HCl, EtOH, reflux, 30 min.
i. Me2C6H4, reflux, 40 h; ii. 1) NaN3/MeCN, ~20 °C, 20 h;
2) H+/H2O.
The enhanced reactivity of 4ꢀMe group is reflected in
both the conditions and results of the condensation of 7
with benzaldehydes. In contrast to 1,4ꢀdimethylꢀ3,5ꢀdiꢀ
nitropyrazole (1), its analog, dinitropyrazole 7, reacts with
various substituted benzaldehydes with the process run
not in a melt but under "classical" conditions (heating at
reflux with xylene in the presence of morpholine in a cataꢀ
lytic amount). The products formed are the presumed
4ꢀ[(E)ꢀ2ꢀarylvinyl]ꢀ1ꢀ(2,4ꢀdinitrophenyl)ꢀ3,5ꢀdinitropyrꢀ
azoles 14a—c (Scheme 5) with C=C bond configured trans
analogously to 2 (3J = 16.5—17.1 Hz).
The condensation products 14a—c, like dinitropyrꢀ
azole 7, lose pyrazolate anion when submitted to various
nucleophiles thereby generating 4ꢀ[(E)ꢀ2ꢀarylvinyl]ꢀ3,5ꢀ
dinitropyrazoles with unsubstituted nitrogen atom as shown
in Scheme 5 on example of interaction between 14a,b and
NaN3 leading to corresponding dinitropyrazoles 15a,b.
Thus, introduction of 2,4ꢀdinitrophenyl substituent
into the 1ꢀposition of the pyrazole ring enhances reactivity
of the methyl group in the 4ꢀposition in the condensation
reactions with DMFꢀDMA and aromatic aldehydes.
2,4ꢀDinitrophenyl moiety can be readily removed by treatꢀ
ment with nucleophiles under mild conditions, which alꢀ
lows its employment as a protecting group so to synthesize
Nꢀunsubstituted 4ꢀ[(E)ꢀ2ꢀarylvinyl]ꢀ3,5ꢀdinitropyrazoles
unavailable by other means.
Experimental
1
Н and 13C NMR spectra were recorded on Bruker ACꢀ300
(300.13 MHz) and Bruker DRXꢀ500 (125 MHz) spectrometers,
respectively at 295 K (unless otherwise stated). Chemical shifts
for 1H and 13C are referred to Me4Si. IR spectra were measured
on Specord Mꢀ80 spectrometer from KBr tablets. Mass spectra
were recorded using Kratos MSꢀ30 instrument (direct insertion
probe, EI, electron energy 70 eV). TLC (Silufol UVꢀ254, eluent
CHCl3—Me2CO (10 : 1)) was used to monitor reaction evoluꢀ
tion and product purity. Elemental analysis was performed with
Perkin—Elmer Series II 2400 analyzer.
Xꢀray diffraction analysis of product 7 was performed on Smart
CCDꢀ1000 diffractometer (MoꢀKα radiation, graphite monoꢀ
chromator, ωꢀscans). The structure was solved by the direct
method and refined using the fullꢀmatrix leastꢀsquares on F 2
hkl
in anisotropic approximation. The hydrogen atoms were located
from difference Fourier syntheses and refined "riding" on the
corresponding carbon atoms, in isotropic approximation. Deꢀ
tails of crystal data, data collection and structure refinement are
listed in Table 2. All computations were performed on PC using
SHELXTL PLUS program package.18
Glycolic acid Nꢀphenylаmide19 and thioglycolic acid Nꢀpheꢀ
nylаmide20 were synthesized using the known procedures.
4ꢀ[(E)ꢀ2ꢀ(4ꢀMethoxyphenyl)vinyl]ꢀ1ꢀmethylꢀ3,5ꢀdinitropyrꢀ
azole (2). The mixture of 1,4ꢀdimethylꢀ3,5ꢀdinitropyrazole (1)
(1.00 g, 5.4 mmol), 4ꢀmethoxybenzaldehyde (1.0 mL, 8.2 mmol)

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Zaitsev et al.
Table 2. Crystallographic data and Xꢀray diffraction
experiment parameters for structure 7
(DMSOꢀd6), δ: 7.44 (d, 2 H, oꢀH, C6H4OMeꢀp, J = 8.5 Hz);
7.35 (d, 1 H, CH=CHC6H4OMeꢀp, J = 16.1 Hz); 7.24 (m, 3 H,
оꢀH, Ph + pꢀH, Ph); 7.10 (m, 2 H, mꢀH, Ph); 7.03 (d, 1 H,
CH=CHC6H4OMeꢀp, J = 16.1 Hz); 6.97 (d, 2 H, mꢀH,
C6H4OMeꢀp, J = 8.5 Hz); 4.07 (s, 2 H, CH2); 3.78 (s, 3 H,
OMe); 3.67 (s, 3 H, NMe). 13С NMR (DMSOꢀd6), δ: 159.53 (pꢀC,
C6H4OMeꢀp); 150.70 (C(3)); 136.80 (ipsoꢀC, Ph); 133.33
(CH=CHC6H4OMeꢀp); 133.08 (C(5)); 129.15 (ipsoꢀC,
C6H4OMeꢀp); 128.85 (mꢀC, Ph); 128.47 (оꢀC, Ph); 127.91 (oꢀC,
C6H4OMeꢀp); 127.52 (pꢀC, Ph); 119.86 (C(4)); 114.25 (mꢀC,
C6H4OMeꢀp); 113.32 (CH=CHC6H4OMeꢀp); 55.16 (OMe);
39.01 (CH2); 37.75 (NMe). IR, ν/cm–1: 1544, 1344 (NO2). MS,
m/z (Irel (%)): 381 [M]+
Parameter
Value
Molecular formula
Molecular weight
T/K
C10H6N6O8
338.21
120
Crystal system
Space group
Z
Monoclinic
P21/c
4
a/Å
b/Å
c/Å
α/deg
6.4237(6)
22.363(2)
9.2569(9)
90.00
4ꢀ[(E)ꢀ2ꢀ(4ꢀMethoxyphenyl)vinyl]ꢀ1ꢀmethylꢀ3ꢀnitropyrꢀ
azoleꢀ5ꢀamine (4). The mixture of dinitropyrazole 2 (0.55 g,
1.8 mmol), hydrazine hydrate (0.14 ml, 2.8 mmol), FeCl3•6H2O
(0.034 g, 0.1 mmol), and activated carbon (0.05 g) in methanol
(20 mL) was heated under reflux for 3 h (TLC monitoring).
Reaction mixture was cooled, filtered from activated carbon,
mother liquor was concentrated in vacuo to 10 mL, the residue
was filtered off to yield 0.32 g (65%) of rich redꢀcolored (crimꢀ
son) product 4. M.p. 193—195 °С. Found (%): C, 56.83; H, 5.29;
N, 20.58. C13H14N4O3. Calculated (%): C, 56.93; H, 5.14;
N, 20.43. 1Н NMR (DMSOꢀd6), δ: 7.45 (d, 2 H, oꢀH,
C6H4OMeꢀp, J = 8.8 Hz); 7.17 (d, 1 H, CH=CHC6H4OMeꢀp,
J = 16.9 Hz); 6.94 (d, 2 H, mꢀH, C6H4OMeꢀp, J = 8.8 Hz); 6.91
(d, 1 H, CH=CHC6H4OMeꢀp, J = 16.9 Hz); 6.15 (с, 2 H,
NH2); 3.76 (s, 3 H, OMe); 3.70 (s, 3 H, NMe). 13С NMR
(DMSOꢀd6), δ: 158.69 (pꢀC, C6H4OMeꢀp); 150.04 (C(3));
146.03 (C(5)); 130.45 (ipsoꢀC, C6H4OMeꢀp); 127.64 (CH=CHꢀ
C6H4OMeꢀp); 127.13 (oꢀC, C6H4OMeꢀp); 115.00 (CH=CHꢀ
C6H4OMeꢀp); 114.13 (mꢀC, C6H4OMeꢀp); 96.31 (C(4)); 55.12
(OMe); 35.72 (NMe). IR, ν/cm–1: 3428, 3348 (NH2); 1568,
1540, 1500, 1388, 1352 (NO2). MS, m/z (Irel (%)): 274 [M]+.
1ꢀ(2,4ꢀDinitrophenyl)ꢀ4ꢀmethylpyrazole (5). The mixture
of ethanol (1500 mL), 2,4ꢀdinitrophenylhydrazine (133.6 g,
0.674 mol), and conc. HCl (250 mL) was stirred while adding
1,1,3,3ꢀtetraethoxyꢀ2ꢀmethylpropane (171 g, 0.730 mol) over
30 min. The reaction mixture was refluxed for 8 h, then cooled
to ∼20 °C and poured into 2 L of water. The aqueous solution was
basified in portions with KOH to pH 8—9, the precipitate formed
was filtered off, washed with water and allowed to air dry. The
brownꢀcolored product 5 was isolated in a yield of 62.0 g (97%).
M.p. 159—162 °С. Found (%): C, 48.30; H, 3.20; N, 22.69.
C10H8N4O4. Calculated (%): C, 48.39; H, 3.25; N, 22.57. 1Н NMR
(DMSOꢀd6), δ: 8.80 (d, 1 H, H(3´), J = 2.3 Hz); 8.56 (dd, 1 H,
H(5´), J = 8.5 Hz, J = 2.3 Hz); 8.27 (с, 1 H, H(5)); 8.05 (d, 1 H,
H(6´), J = 8.5 Hz); 7.70 (с, 1 H, H(3)); 2.11 (s, 3 H, Me).
13С NMR (DMSOꢀd6), δ: 144.78 (C(3)); 144.66 (C(4´)); 142.04
(C(2´)); 135.83 (C(1´)); 128.78 (C(5)); 127.77 (C(6´)); 124.44
β/deg
100.374(5)
90.00
1308.0(2)
1.717
γ/deg
V/Å3
dcalc/g cm–3
μ/cm–1
1.52
F(000)
688
2θmax/deg
54
The number of measured reflections
The number of independent reflections
The number of reflections with I > 2σ(I)
The number of refined parameters
R1
9528
2981
2086
218
0.0532
0.1347
1.002
wR2
GOF
Largest difference peak and
hole/e Å–3, ρmin/ρmax
0.367/–0.248
and piperidine (several drops) was heated for 10 h at 100—105 °C.
The mixture was cooled to ∼20 °C and, after adding 20 mL
of nꢀhexane, triturated to achieve solid consistency. The preꢀ
cipitate was recrystallized from CCl4—MeOH (20 : 1) to yield
(0.25 g, 15%) canaryꢀcolored product 2. M.p. 154—157 °С.
Found (%): C, 51.02; H, 3.73; N, 18.75. C13H12N4O5. Calꢀ
culated (%): C, 51.32; H, 3.98; N, 18.41. 1Н NMR (DMSOꢀd6),
δ: 7.55 (d, 2 H, оꢀH, C6H4OMeꢀp, J = 8.5 Hz); 7.23 (d, 1 H,
CH=CHC6H4OMeꢀp,
J = 16.5 Hz); 7.10 (d, 1 H,
CH=CHC6H4OMeꢀp, J = 16.5 Hz); 6.99 (d, 2 H, mꢀH,
C6H4OMeꢀp, J = 8.5 Hz); 4.24 (s, 3 H, NMe); 3.79 (s, 3 H, OMe).
13С NMR (DMSOꢀd6), δ: 160.21 (C(4´)); 149.01 (C(3)); 142.67
(C(5)); 138.71 (CH=CHC6H4OMeꢀp); 128.59 (C(2´)); 128.47
(C(1´)); 114.49 (C(3´)); 114.31 (C(4)); 110.11 (CH=CHC6H4ꢀ
OMeꢀp); 53.33 (OMe); 42.68 (NMe). IR, ν/cm–1: 1576, 1568,
1560, 1384, 1320 (NO2). MS, m/z (Irel (%)): 304 [M]+.
5ꢀBenzylthioꢀ4ꢀ[(E)ꢀ2ꢀ(4ꢀmethoxyphenyl)vinyl]ꢀ1ꢀmethylꢀ3ꢀ
nitropyrazole (3). To a solution of dinitropyrazole 2 (0.61 g,
2.0 mmol) in NMP (50 mL) were added 0.24 mL (2.0 mmol) of
benzyl mercaptan and 0.30 g (2.2 mmol) of potassium carbonate.
The reaction mixture was stirred for 6 h at ∼20 °C (the course of
the reaction was followed by TLC), then poured into 400 mL of
water, acidified with hydrochloric acid to pH 2—3, precipitate
formed was filtered off, washed with water on the filter, airꢀdried
and recrystallized from ethanol. Product 3 was isolated as canaꢀ
ryꢀcolored crystals in a yield of 0.44 g (58%). M.p. 113—115 °С.
Found (%): C, 62.07; H, 5.01; N, 11.19; S, 7.68. C20H19N3O3S.
(C(5´)); 121.11 (C(3´)); 119.73 (C(4)); 8.53 (Me). IR, ν/cm–1
:
1548, 1532, 1512, 1344 (NO2). MS, m/z (Irel (%)): 248 [M]+.
1ꢀ(2,4ꢀDinitrophenyl)ꢀ4ꢀmethylꢀ5ꢀnitropyrazole (6). To 225 mL
of 92.5% sulfuric acid (d = 1.826 g cm–3) was added 90 mL of
41% oleum (d = 1.963 g cm–3) maintaining temperature at
30—40 °C, after which the solution was treated in portions with 5
(14.8 g, 59.6 mmol) at 30—40 °C and, subsequently, dropwise
with fuming nitric acid (24 mL, 0.571 mol) (d = 1.5 g cm–3). The
reaction mixture was stirred for 30 min at 30—40 °C (initial
pyrazole is completely converted by TLC within 10 min after
addition of HNO3), poured onto crushed ice (1 kg), then air was
1
Calculated (%): C, 62.97; H, 5.02; N, 11.02; S, 8.41. Н NMR

1ꢀ(2,4ꢀDinitrophenyl)ꢀ4ꢀmethylꢀ3,5ꢀdinitropyrazole Russ.Chem.Bull., Int.Ed., Vol. 58, No. 10, October, 2009
2115
bubbled through the suspension formed for 3—4 h until nitrose
gases were completely removed. The precipitate formed was filꢀ
tered off, washed with water and allowed to air dry. The tawnyꢀ
colored product 6 was obtained in a yield of 13.55 g (77%).
M.p. 137—139 °С. Found (%): C, 40.92; H, 2.30; N, 24.25.
C10H7N5O6. Calculated (%): C, 40.97; H, 2.41; N, 23.89.
1Н NMR (DMSOꢀd6), δ: 8.96 (d, 1 H, H(3´), J = 2.2); 8.74 (dd,
1 H, H(5´), J = 8.1 Hz, J = 2.2 Hz); 8.20 (d, 1 H, H(6´), J = 8.1 Hz);
8.04 (s, 1 H, H(3)); 2.43 (s, 3 H, Me). 13С NMR (DMSOꢀd6), δ:
147.69 (C(4´)); 144.44 (C(2´)); 143.86 (C(5)); 143.81 (C(3));
136.60 (C(1´)); 131.62 (C(6´)); 128.79 (C(5´)); 120.99 (C(3´));
120.07 (C(4)); 10.02 (Me). IR, ν/cm–1: 1544, 1520, 1336 (NO2).
MS, m/z (Irel (%)): 248 [M – NO2]+.
1ꢀ(2,4ꢀDinitrophenyl)ꢀ4ꢀmethylꢀ3,5ꢀdinitropyrazole (7). To
900 mL of 92.5% sulfuric acid (d = 1.826 g cm–3) was added
360 mL of 41% oleum (d = 1.963 g cm–3) with maintaining
temperature at 30—40 °C, after which the solution was treated in
portions with pyrazole 5 (60.0 g, 0.242 mol) at 30—40 °C
and, subsequently, dropwise with fuming nitric acid (100 mL,
2.38 mol) (d = 1.5 g cm–3). The reaction mixture was held for 3 h
with heating at 100—105 °C (TLC monitoring), cooled to ∼20 °C,
poured onto crushed ice (3—4 kg), then air was bubbled through
the suspension formed for 3—4 h until nitrose gases were comꢀ
pletely removed. The precipitate was filtered off, washed with
water, allowed to air dry and recrystallized from MeCN—EtOH
(1 : 1) to obtain light yellow product 7. Yield 52.2 g (64%).
M.p. 154—156 °С. Found (%): C, 35.54; H, 1.69; N, 25.40.
C10H6N6O8. Calculated (%): C, 35.51; H, 1.79; N, 24.85.
1Н NMR (DMSOꢀd6), δ: 9.05 (d, 1 H, H(3´), J = 2.4 Hz); 8.86
(dd, 1 H, H(5´), J = 8.5 Hz, J = 2.4 Hz); 8.30 (d, 1 H, H(6´),
J = 8.5 Hz); 2.72 (s, 3 H, Me). 13С NMR (DMSOꢀd6), δ: 153.74
(C(3)); 148.69 (C(4´)); 144.54 (C(5)); 144.04 (C(2´)); 135.26
(C(1´)); 132.13 (C(6´)); 129.65 (C(5´)); 121.41 (C(3´)); 115.54
(C(4)); 9.59 (Me). IR, ν/cm–1: 1548, 1524, 1336 (NO2). MS,
m/z (Irel (%)): 293 [M – NO2]+.
2ꢀ[(2,4ꢀDinitrophenyl)thio]ꢀNꢀphenylacetamide (9a). To
a solution of dinitropyrazole 7 (0.124 g, 0.37 mmol) in acetoniꢀ
trile (15 mL) were added thioglycolic acid phenylamide (0.062 g,
0.37 mmol) and K2CO3 (0.066 g, 0.48 mmol). The mixture was
stirred for 30 min at ∼20 °C (TLC monitoring), poured into
50 mL of water, acidified with hydrochloric acid to pH 2—3, the
precipitate was filtered off, washed with water on the filter and
allowed to air dry to give light yellow product 9a. Yield 0.101 g
(83%). M.p. 194—196 °С. Found (%): C, 50.32; H, 3.48;
N, 12.21; S, 9.06. C14H11N3O5S. Calculated (%): C, 50.45; H,
3.33; N, 12.61; S, 9.62. 1Н NMR (DMSOꢀd6), δ: 10.44 (s, 1 H,
NH); 8.89 (d, 1 H, H(3), J = 1.5 Hz); 8.52 (dd, 1 H, H(5),
J = 9.5 Hz, J = 1.5 Hz); 7.95 (d, 1 H, H(6), J = 9.5 Hz); 7.57
(d, 2 H, оꢀH, Ph, J = 7.3 Hz); 7.32 (t, 2 H, mꢀH, Ph, J = 7.7 Hz);
7.08 (t, 1 H, pꢀH, Ph, J = 7.3 Hz); 4.24 (s, 2 H, CH2). 13С NMR
(DMSOꢀd6), δ: 165.22 (CO); 145.18; 144.43; 143.91 (C(4), C(2),
C(1)); 138.57 (ipsoꢀC, Ph); 128.80 (оꢀC, Ph); 128.48; 127.51
(C(6), C(5)); 123.72 (pꢀC, Ph); 121.24 (C(3)); 119.26 (mꢀC,
Ph); 36.84 (CH2). IR, ν/cm–1: 3380 (br.) (NH); 1648 (CO);
1548, 1344 (NO2). MS, m/z (Irel (%)): 333 [M]+.
and allowed airꢀdried. The product, 1ꢀazidoꢀ2,4ꢀdinitrobenzene
(9b) was isolated as light yellow crystals. Yield 0.099 g (83%).
Found (%): C, 34.62; H, 1.72; N, 33.40. C6H3N5O4. Calculatꢀ
ed (%): C, 34.46; H, 1.45; N, 33.49. 1Н NMR (CDCl3), δ: 8.81
(d, 1 H, H(3), J = 2.6 Hz); 8.49 (dd, 1 H, H(5), J = 8.8 Hz,
J = 2.6 Hz); 7.52 (d, 1 H, H(6), J = 8.8 Hz). MS, m/z (Irel (%)):
181 [M – N2]+.
Hydrochloricꢀacid solution formed on acidification of the
reaction mixture poured into water was extracted into ethyl
acetate (2×30 mL), washed with water (2×10 mL), dried over
Na2SO4; the solvent was removed in vacuo, and the residue was
recrystallized from ethanol. Whiteꢀcolored product, 4ꢀmethylꢀ
3,5ꢀdinitropyrazole (8) was isolated in a yield of 0.054 g (53%).
The properties of dinitropyrazole 8 are described in Ref. 21.
Interaction of dinitropyrazole 7 with glycolic acid phenylamide.
To a solution of dinitropyrazole 7 (0.500 g, 1.5 mmol) in
acetonitrile (30 mL) were added glycolic acid phenylamide (0.225 g,
1.5 mmol) and K2CO3 (0.230 g, 1.7 mmol). The mixture was
heated under reflux for 4 h (TLC monitoring), poured into
100 mL of water, acidified with hydrochloric acid to pH 2—3,
extracted with ethyl acetate (2×30 mL), washed with water
(2×10 mL), dried over Na2SO4, the solvent was removed
in vacuo, the residue was chromatographed on silica, eluting
with CHCl3 → CHCl3—Me2CO (10 : 1) to isolate 2ꢀ(2,4ꢀdiꢀ
nitrophenoxy)ꢀNꢀphenylacetamide (9c) as canaryꢀcolored crysꢀ
tals (yield 0.245 g, 52%), 2,4ꢀdinitroꢀNꢀphenylaniline (10) as
orangeꢀred crystals (yield 0.095 g, 25%) and product 8 as white
solid (yield 0.143 g, 56%). For the properties of dinitropyrazole 8
see Ref. 21. Intermediary between 9c and 10 fractions contain
inconsiderable amount (∼0.015 g, 5—6%) of 2,4ꢀdinitrophenol.
2ꢀ(2,4ꢀDinitrophenoxy)ꢀNꢀphenylacetamide (9c). Found (%):
C, 53.21; H, 3.56; N, 13.01. C14H11N3O6. Calculated (%):
1
C, 53.00; H, 3.49; N, 13.24. Н NMR (DMSOꢀd6), δ: 10.23
(s, 1 H, NH); 8.79 (d, 1 H, H(3), J = 1.5 Hz); 8.51 (dd, 1 H,
H(5), J = 9.5 Hz, J = 1.5 Hz); 7.56 (m, 3 H, H(6) + оꢀH, Ph);
7.33 (t, 2 H, mꢀH, Ph, J = 7.0 Hz); 7.09 (t, 1 H, pꢀH, Ph, J = 6.6 Hz);
5.15 (s, 2 H, CH2). IR, ν/cm–1: 3376 (br) (NH); 1700 (CO);
1544, 1524, 1344 (NO2).
2,4ꢀDinitroꢀNꢀphenylaniline (10). M.p. 156—157 °C (cf.
Ref. 22: m.p. 156 °C). Found (%): C, 55.31; H, 3.57; N, 15.85.
C12H9N3O4. Calculated (%): C, 55.60; H, 3.50; N, 16.21.
1Н NMR (DMSOꢀd6), δ: 10.17 (s, 1 H, NH); 8.89 (d, 1 H, H(3),
J = 2.9 Hz); 8.22 (dd, 1 H, H(5), J = 9.5 Hz, J = 2.9 Hz); 7.52
(t, 2 H, mꢀH, Ph, J = 7.7 Hz); 7.38 (m, 3 H, оꢀH, Ph + pꢀH, Ph);
7.10 (d, 1 H, H(6), J = 9.5 Hz). IR, ν/cm–1: 3320 (NH); 1548,
1520, 1340, 1324 (NO2). MS, m/z (Irel (%)): 259 [M]+.
(E)ꢀ2ꢀ[1ꢀ(2,4ꢀDinitrophenyl)ꢀ3,5ꢀdinitropyrazolꢀ4ꢀyl]ꢀN,Nꢀ
dimethylethenꢀ1ꢀamine (11). To the mixture of toluene (200 mL)
and dinitropyrazole 7 (12.0 g, 35.5 mmol) was added DMFꢀDMA
(12 mL, 90.5 mmol), then the mixture was refluxed for 8 h (TLC
monitoring), cooled to ∼20 °C, and toluene was removed in vacꢀ
uo. The residue was recrystallized from EtOH to yield (10.9 g,
78%) maroonꢀcolored product 11. M.p. 192—194 °С (decomp.).
Found (%): C, 40.57; H, 2.77; N, 25.32. C13H11N7O8. Calculatꢀ
1
ed (%): C, 39.70; H, 2.82; N, 24.93. Н NMR (DMSOꢀd6), δ:
Interaction of dinitropyrazole 7 with sodium azide. To a soluꢀ
tion of dinitropyrazole 7 (0.200 g, 0.59 mmol) in acetonitrile
(20 mL) was added sodium azide (0.045 g, 0.69 mmol). The
mixture was stirred for 20 h at ~20 °C (TLC monitoring), poured
into 75 mL of water, acidified with hydrochloric acid to pH 2—3,
the precipitate was filtered off, washed with water on the filter
8.99 (d, 1 H, H(3´), J = 2.9 Hz); 8.79 (dd, 1 H, H(5´), J = 8.8 Hz,
J = 2.9 Hz); 8.24 (d, 1 H, H(6´), J = 8.8 Hz); 8.20 (d, 1 H,
CH=CHNMe2, J = 13.2 Hz); 5.82 (d, 1 H, CH=CHNMe2,
J = 13.2 Hz); 3.10 (br.s, 6 H, 2 Me). 13С NMR (DMSOꢀd6), δ:
154.13 (CH=CHNMe2); 150.91 (C(3)); 147.95 (C(4´)); 143.75
(C(2´)); 139.10 (C(5)); 136.77 (C(1´)); 131.47 (C(6´)); 129.43

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Russ.Chem.Bull., Int.Ed., Vol. 58, No. 10, October, 2009
Zaitsev et al.
(C(5´)); 121.94 (C(4)); 121.21 (C(3)´); 80.26 (CH=CHNMe2);
the broadened signal from methyl carbons is hidden under the
solvent signal at δ 40.5—38.5. IR, ν/cm–1: 1560, 1544, 1372,
1340, 1324 (NO2). MS, m/z (Irel (%)): 393 [M]+.
(DMSOꢀd6), δ: 160.59 (pꢀC, C6H4OMeꢀp); 152.30 (C(3));
148.69 (C(4´)); 143.98 (C(2´)); 142.96 (C(5)); 140.76
(CH=CHC6H4OMeꢀp); 135.35 (C(1´)); 132.07 (C(6´)); 129.82
(C(5´)); 128.94 (oꢀC, C6H4OMeꢀp); 128.21 (ipsoꢀC, C6H4OMeꢀp);
121.58 (C(3´)); 115.66 (C(4)); 114.53 (mꢀH, C6H4OMeꢀp);
108.91 (CH=CHC6H4OMeꢀp); 55.32 (Me). IR, ν/cm–1: 1572,
1540, 1520, 1344 (NO2). MS, m/z (Irel (%)): 456 [M]+.
(Hydroxyimino)[1ꢀ(2,4ꢀdinitrophenyl)ꢀ3,5ꢀdinitropyrazolꢀ4ꢀ
yl]acetaldehyde (12). To 18 mL of conc. hydrochloric acid,
enamine 11 (1.01 g, 2.6 mmol) was added. The resulting solution
was treated dropswise over 30 min with a solution of sodium
nitrite (0.358 g, 5.2 mmol) in 3.0 mL of water maintaining temꢀ
perature at 20—25 °C, this followed by stirring for 1 h and then
for additional 1 h after adding 100 mL of water. The precipitate
formed was filtered off, washed with water on the filter and air
dried. The product 12 representing the 17.5 : 1 mixture of Z and
E isomers (as detected by 1H NMR in DMSOꢀd6) was isolated as
yellow solid, yield 0.91 g (90%). M.p. 114—117 °С. Found (%):
C, 32.75; H, 1.30; N, 23.97. C11H5N7O10. Calculated (%):
C, 33.43; H, 1.28; N, 24.81. 1Н NMR (DMSOꢀd6), Z isomer, δ:
14.46 (s, 1 H, OH); 9.86 (s, 1 H, CH=O); 9.06 (d, 1 H, H(3´),
J = 2.4 Hz); 8.90 (dd, 1 H, H(5´), J = 8.5 Hz, J = 2.4 Hz); 8.50
(d, 1 H, H(6´), J = 8.5 Hz); E isomer, δ: 13.91 (s, 1 H, OH);
10.48 (s, 1 H, CH=O); the other signals are coincident (or very
close) with the signals from the Z isomer. 13С NMR (DMSOꢀd6),
Z isomer, δ: 188.39 (CHO); 151.99 (C(3)); 149.08 (C(4´)); 145.17
(C=NOH); 144.04 (C(5)); 143.95 (C(2´)); 134.18 (C(1´)); 132.45
(C(6´)); 129.96 (C(5´)); 121.62 (C(3´)); 103.05 (C(4)); E isoꢀ
mer, δ: 182.51 (CHO); the other signals are coincident (or very
close) with the signals from the Z isomer. IR, ν/cm–1: 3410
(OH); 1704 (CO); 1612 (C=N); 1536, 1340 (NO2). MS, m/z
(Irel (%)): 274 [M – 2 NO2 – CHO]+.
(Hydroxyimino)[1ꢀ(2,4ꢀdinitrophenyl)ꢀ3,5ꢀdinitropyrazolꢀ4ꢀ
yl]acetaldehyde Oꢀmethyloxime (13). To a solution of 12 (0.735 g,
1.9 mmol) in EtOH (50 mL) was added Oꢀmethylhydroxylamine
hydrochloride (0.157 g, 1.9 mmol). The mixture was heated to
reflux for 30 min (TLC monitoring), cooled to ∼20 °C, concenꢀ
trated in vacuo. The residue was filtered off and air dried to yield
(0.724 g, 92%) product 13. M.p. 100—103 °С. Found (%):
C, 33.34; H, 1.85; N, 26.07. C12H8N8O10. Calculated (%): C,
33.97; H, 1.90; N, 26.41. 1Н NMR (DMSOꢀd6), δ: 13.02 (с, 1 H,
OH); 9.05 (d, 1 H, H(3´), J = 2.2 Hz); 8.87 (dd, 1 H, H(5´),
J = 8.8 Hz, J = 2.2 Hz); 8.53 (d, 1 H, H(6´), J = 8.8 Hz); 8.21
(s, 1 H, CH=N); 3.78 (s, 3 H, Me). 13С NMR (DMSOꢀd6), δ:
151.99 (C(3)); 149.05 (C(4´)); 145.27 (C=NOH); 144.17 (C(2´));
143.89 (C(5)); 139.95 (C=NOMe); 134.27 (C(1´)); 132.52
(C(6´)); 129.89 (C(5´)); 121.59 (C(3´)); 105.37 (C(4)); 62.49
(Me). IR, ν/cm–1: 3480 (OH); 1612 (C=N); 1536, 1336 (NO2).
MS, m/z (Irel (%)): 424 [M]+.
4ꢀ[(E)ꢀ2ꢀ(3,4ꢀDimethoxyphenyl)vinyl]ꢀ1ꢀ(2,4ꢀdinitropheꢀ
nyl)ꢀ3,5ꢀdinitropyrazole (14b) was synthesized as described for
14a. Based on starting dinitropyrazole 7 (3.50 g, 10.3 mol), prodꢀ
uct 14b was isolated as brick redꢀcolored crystals in a yield of
1.90 g (38%). M.p. 224—226 °С. Found (%): C, 47.08; H, 2.72;
N, 17.09. C19H14N6O10. Calculated (%): C, 46.92; H, 2.90;
N, 17.28. 1Н NMR (DMSOꢀd6), δ: 9.06 (d, 1 H, H(3´), J = 2.4 Hz);
8.88 (dd, 1 H, H(5´), J = 9.2 Hz, J = 2.4 Hz); 8.36 (d, 1 H,
H(6´), J = 9.2 Hz); 7.44 (d, 1 H, CH=CHC6H3(OMe)2ꢀ3,4,
J = 16.5 Hz); 7.27 (d, 1 H, CH=CHC6H3(OMe)2ꢀ3,4,
J = 16.5 Hz); 7.28 (d, 1 H, H(2)—C6H3(OMe)2ꢀ3,4, J = 1.9 Hz);
7.21 (dd, 1 H, H(6)—C6H3(OMe)2ꢀ3,4, J = 8.5 Hz, J = 1.9 Hz);
7.05 (d, 1 H, H(5)—C6H3(OMe)2ꢀ3,4, J = 8.5 Hz); 3.85 (s, 3 H,
Me); 3.82 (s, 3 H, Me). 13С NMR (DMSOꢀd6), δ: 152.28 (C(3));
150.40; 149.12; 148.74 (C(3)—C6H3(OMe)2ꢀ3,4, C(4)—
—C6H3(OMe)2ꢀ3,4, C(4´)); 144.01 (C(2´)); 142.97 (C(5));
141.11 (CH=CHC6H3(OMe)2ꢀ3,4); 135.26 (C(1´)); 132.06
(C(6)´); 129.88 (C(5´)); 128.47 (C(1)—C6H3(OMe)2ꢀ3,4);
121.65; 121.26 (C(3´), C(6)—C6H3(OMe)2ꢀ3,4); 115.68
(C(4)); 111.88; 109.89; 109.15 (C(2)—C6H3(OMe)2ꢀ3,4,
C(5)—C6H3(OMe)2ꢀ3,4, CH=CHC6H3(OMe)2ꢀ3,4); 55.63
(2 Me). IR, ν/cm–1: 1548, 1512, 1340, 1328 (NO2). MS, m/z
(Irel (%)): 486 [M]+.
1ꢀ(2,4ꢀDinitrophenyl)ꢀ4ꢀ[(E)ꢀ2ꢀ(4ꢀfluorophenyl)vinyl]ꢀ3,5ꢀ
dinitropyrazole (14c) was synthesized analogously to 14a. Based
on starting dinitropyrazole 7 (3.50 g, 10.3 mol), product 14c was
isolated as brick redꢀcolored crystals in a yield of 1.47 g (32%).
M.p. 168—170 °С. Found (%): C, 45.76; H, 2.21; N, 19.04.
C17H9N6O8F. Calculated (%): C, 45.96; H, 2.04; N, 18.92.
1Н NMR (DMSOꢀd6), δ: 9.06 (d, 1 H, H(3´), J = 2.4 Hz); 8.88
(dd, 1 H, H(5´), J = 8.5 Hz, J = 2.4 Hz); 8.35 (d, 1 H, H(6´),
J = 8.5 Hz); 7.64 (dd, 2 H, oꢀH, C6H4Fꢀp, J = 8.5 Hz,
J = 5.5 Hz); 7.49 (d, 1 H, CH=CHC6H4Fꢀp, J = 17.1 Hz);
7.38—7.25 (m, 3 H, CH=CHC6H4Fꢀp + mꢀH, C6H4Fꢀp).
1
13С NMR (DMSOꢀd6), δ: 162.83 (pꢀC, C6H4Fꢀp, JC,F
=
= 247.0 Hz); 152.33 (C(3)); 148.75 (C(4´)); 144.01 (C(2´));
143.22 (C(5)); 139.55 (CH=CHC6H4Fꢀp); 135.21 (C(1´));
132.24 (ipsoꢀC, C6H4Fꢀp, 4JC,F = 2.8 Hz); 132.13 (C(6´)); 129.85
(C(5´)); 129.46 (oꢀC, C6H4Fꢀp, 3JC,F = 8.5 Hz); 121.61 (C(3´));
2
1ꢀ(2,4ꢀDinitrophenyl)ꢀ4ꢀ[(E)ꢀ2ꢀ(4ꢀmethoxyphenyl)vinyl]ꢀ
3,5ꢀdinitropyrazole (14a). The mixture of dinitropyrazole 7 (5.00 g,
14.8 mmol), 4ꢀmethoxybenzaldehyde (2 mL, 16.4 mmol), and
morpholine (0.1 mL, 1.1 mmol) in the mixture of isomeric xyꢀ
lenes (200 mL) was refluxed for 40 h, cooled to ∼20 °C, concenꢀ
trated in vacuo to 100 mL. After addition of nꢀhexane (300 mL),
the precipitate was recrystallized from EtOH. The product 14a
was isolated as brick redꢀcolored crystals, yield 2.02 g (30%).
M.p. 177—179 °С. Found (%): C, 47.85; H, 2.66; N, 18.50.
C18H12N6O9. Calculated (%): C, 47.38; H, 2.65; N, 18.42.
1Н NMR (DMSOꢀd6), δ: 9.05 (d, 1 H, H(3´), J = 2.4 Hz); 8.88
(dd, 1 H, H(5´), J = 9.2 Hz, J = 2.4 Hz); 8.35 (d, 1 H, H(6´),
J = 9.2 Hz); 7.64 (d, 2 H, oꢀH, C6H4OMeꢀp, J = 8.9 Hz); 7.48
(d, 1 H, CH=CHC6H4OMeꢀp, J = 16.8 Hz); 7.25 (d, 1 H,
CH=CHC6H4OMeꢀp, J = 16.8 Hz); 7.04 (d, 2 H, mꢀH,
C6H4OMeꢀp, J = 8.9 Hz); 3.82 (s, 3 H, Me). 13С NMR
116.1 (mꢀC, C6H4Fꢀp, JC,F = 21.3 Hz); 115.06 (C(4)); 111.51
(CH=CHC6H4Fꢀp). IR, ν/cm–1: 1572, 1544, 1344 (NO2). MS,
m/z (Irel (%)): 444 [M]+.
4ꢀ[(E)ꢀ2ꢀ(4ꢀMethoxyphenyl)vinyl]ꢀ3,5ꢀdinitropyrazole (15a).
To a solution of nitropyrazole 14a (0.200 g, 0.44 mmol) in acetoꢀ
nitrile (20 mL) was added sodium azide (0.040 g, 0.62 mmol).
The mixture was stirred for 20 h at ~20 °C, poured into 75 mL of
water, acidified with hydrochloric acid to pH 2—3, extracted
with ethyl acetate (2×25 mL), washed with water (2×10 mL),
dried over Na2SO4, the solvent was removed in vacuo, the preꢀ
cipitate was chromatographed on silica (with CHCl3 → CHCl3—
—Me2CO (5 : 1) as the eluent) to yield (0.122 g, 96%) product
15a (brownꢀcolored). M.p. 215—217 °С. Found (%): C, 49.84;
H, 3.22; N, 19.01. C12H10N4O5. Calculated (%): C, 49.66;
H, 3.47; N, 19.30. 1Н NMR (DMSOꢀd6), δ: 7.54 (d, 2 H, oꢀH,
C6H4OMeꢀp, J = 6.3 Hz); 7.38 (d, 1 H, CH=CHC6H4OMeꢀp,

1ꢀ(2,4ꢀDinitrophenyl)ꢀ4ꢀmethylꢀ3,5ꢀdinitropyrazole Russ.Chem.Bull., Int.Ed., Vol. 58, No. 10, October, 2009
2117
J = 16.2 Hz); 7.20 (d, 1 H, CH=CHC6H4OMeꢀp, J = 16.2 Hz);
7.00 (d, 2 H, mꢀH, C6H4OMeꢀp, J = 6.3 Hz); 3.79 (s, 3 H, Me).
13С NMR (DMSOꢀd6), δ: 159.61 (С(4´)); 148.14 (C(3), C(5));
137.88 (CH=CHC6H4OMeꢀp); 128.27 (С(1´)); 128.07 ((С2´));
114.11 (С(3´)); 112.17 (C(4)); 110.24 (CH=CHC6H4OMeꢀp);
55.18 (Me). IR, ν/cm–1: 3464 (NH); 1568, 1328 (NO2). MS,
m/z (Irel (%)): 290 [M]+.
4ꢀ[(E)ꢀ2ꢀ(3,4ꢀDimethoxyphenyl)vinyl]ꢀ3,5ꢀdinitropyrazole
(15b) was synthesized as described for 15a. Starting from 14b
(0.215 g, 0.44 mmol), product 15a (brownꢀcolored) was isolated
in a yield of 0.133 g (94%). Found (%): C, 49.02; H, 3.73; N, 17.82.
C13H12N4O6. Calculated (%): C, 48.75; H, 3.78; N, 17.49. 1Н NMR
(DMSOꢀd6), δ: 7.36 (d, 1 H, CH=CHC6H3(OMe)2, J = 16.5 Hz);
7.24 (s, 1 H, H(2)—C6H3(OMe)2ꢀ3,4); 7.15 (d, 1 H, CH=CHꢀ
C6H3(OMe)2ꢀ3,4, J = 16.5 Hz); 7.14 (d, 1 H, H(6)—C6H3ꢀ
(OMe)2ꢀ3,4, J = 7.9 Hz); 7.01 (d, 2 H, H(5)—C6H3(OMe)2ꢀ
3,4, J = 7.9 Hz); 3.83 (s, 3 H, Me); 3.81 (s, 3 H, Me).
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Received March 11, 2009;
in revised form September 9, 2009