MAKAROVA et al.
942
stretching vibrations of conjugated nitro groups in IIIa
and IIIb appear at 1540 and 1360 cm–1.
Found, %: C 50.29, 50.30; H 4.00, 4.02; N 21.40,
21.41. C11H10N4O4. Calculated, %: C 50.38; H 3.82;
N 21.37. Pure isomer IIIa was isolated in 35% by
repeated chromatographic separation of a mixture of
compounds IIIa and IIIb using carbon tetrachloride as
eluent. Rf 0.77, mp 33–35°C.
1
The H NMR spectral parameters of the isolated
compounds are consistent with the assumed structures
and are analogous to the spectra of structurally related
model compounds [8–10]. The spectra contain two set
of signals with different signal intensity ratios. The
main criteria for the structure of isomer a or b were the
chemical shifts of the CH (olefinic) and ethyl protons
in the ester group. These groups in isomers a and b
appear at different distances from the phenyl group.
The phenyl and ethoxycarbonyl groups in isomers b
are attached to the neighboring atoms, while the corre-
sponding groups in isomers a are more distant from
each other. Due to effect of the benzene ring, the 5-H
proton in the spectrum of IVa resonates in a weaker
field (δ 8.50 ppm) than the corresponding proton in
IVb (δ 8.18 ppm). The CH2 protons of the ester group
in molecule IVb are located below the benzene ring
plane (i.e., they fall into the area shielded by the ben-
zene ring), and their signal appears in a stronger field
(δ 4.20 ppm) relative to the corresponding signal of
isomer IVa (δ 4.40 ppm) [11, 12]. Likewise, we dis-
tinguished between regioisomeric dihydrotriazoles IIa
and IIb and triazoles IIIa and IIIb.
Ethyl 1-phenyl-1H-1,2,3-triazole-4-carboxylate
(IVa) and ethyl 1-phenyl-1H-1,2,3-triazole-5-car-
boxylate (IVb). Yield 15% (from benzene fraction),
Rf 0.73, 0.65; ratio IVa:IVb = 7:2. IR spectrum, ν,
1
cm–1: 1735 (C=O). H NMR spectrum, δ, ppm: IVa:
1.15 t (3H, CH3), 4.40 q (2H, OCH2), 7.60 m and
7.80 m (5H, C6H5), 8.50 s (1H, 5-H); IVb: 1.40 t (3H,
CH3), 4.20 q (2H, OCH2), 7.30–7.60 m (5H, C6H5),
8.18 s (1H, 4-H). Found, %: C 60.41, 60.45; H 5.27,
5.28; N 19.69, 19.65. C11H11N3O2. Calculated, %:
C 60.83; H 5.07; N 19.35. Pure isomer IVa was isolat-
ed in 10% yield by repeated chromatography of a mix-
ture of isomers IVa and IVb using benzene as eluent.
Rf 0.73, mp 75–77°C.
Ethyl 2-nitro-1-phenylaziridine-3-carboxylate
(V) was isolated in 7% yield as an inseparable mixture
of diastereoisomers (by repeated chromatographic
separation of a mixture of compounds IIa, IIb, and V
using carbon tetrachloride as eluent), Rf 0.64, 0.42.
IR spectrum, ν, cm–1: 1750 (C=O); 1550, 1385 (NO2).
1H NMR spectrum, δ, ppm: 1.25 t (3H, CH3), 4.25 q
(2H, OCH2), 2.75–3.16 m (1H, 2-H), 4.45–4.80 m (1H,
3-H), 7.20–7.70 m (5H, C6H5). Found, %: C 55.78,
55.69; H 4.84, 4.87; N 11.76, 11.89. C11H12N2O4. Cal-
culated, %: C 55.93; H 5.08; N 11.86.
The IR spectra were recorded on an InfraLYuM
FT-02 spectrometer from solutions in chloroform (c =
0.1–0.001 M). The 1H NMR spectra were measured on
a Bruker AC-200 instrument (200 MHz) using chloro-
form-d as solvent. The chemical shifts were measured
relative to hexamethyldisiloxane (external reference)
with an accuracy of ±0.5 Hz. The products were isolat-
ed and purified by column chromatography on silica
gel (Chemapol, 100/200 μm) using the Trappe solvent
series. The purity of the products was checked, and
the progress of the reaction was monitored, by thin-
layer chromatography on Silufol UV-254 plates using
hexane–acetone (3:2) as eluent; development with
iodine vapor.
Initial nitroalkene I was synthesized by improved
procedure [13], and phenyl azide was prepared as
described in [14].
Ethyl 5-nitro-1-phenyl-4,5-dihydro-1H-1,2,3-tri-
azole-4-carboxylate (IIa) and ethyl 4-nitro-1-phe-
nyl-4,5-dihydro-1H-1,2,3-triazole-5-carboxylate
(IIb). Yield 7%. Isomer mixture IIa/IIb was isolated
by repeated chromatographic separation of a mixture
of compounds IIa, IIb, and V using benzene as eluent.
Rf 0.56, 0.52; ratio IIa:IIb = 5:2. IR spectrum, ν, cm–1:
1745 (C=O); 1545, 1390 (NO2). 1H NMR spectrum, δ,
ppm: IIa: 1.26 t (3H, CH3), 4.30 q (2H, OCH2), 5.24 m
(1H, 5-H, J4,5 = 4.0 Hz), 4.41 m (1H, 4-H, J4,5
4.0 Hz), 7.20–7.60 m (5H, C6H5); IIb: 1.30 t (3H,
CH3), 4.20 q (2H, OCH2), 4.47 m (1H, 5-H, J4,5
=
=
6.0 Hz), 5.12 m (1H, 4-H, J4,5 = 6.0 Hz), 7.20–7.60 m
(5H, C6H5). Found, %: N 21.60, 21.64. C11H12N4O4.
Calculated, %: N 21.21.
Ethyl 5-nitro-1-phenyl-1H-1,2,3-triazole-4-car-
boxylate (IIIa) and ethyl 4-nitro-1-phenyl-1H-1,2,3-
triazole-5-carboxylate (IIIb). Yield 45% (eluent
hexane), Rf 0.77, 0.71; ratio IIIa:IIIb = 4:1. IR spec-
trum, ν, cm–1: 1740 (C=O); 1540, 1360 (NO2).
1H NMR spectrum, δ, ppm: IIIa: 1.30 t (3H, CH3),
4.45 q (2H, OCH2), 7.65 m (5H, C6H5); IIIb: 1.40 t
(3H, CH3), 4.30 q (2H, OCH2), 7.60 m (5H, C6H5).
REFERENCES
1. Comprehensive Organic Chemistry, Barton, D. and
Ollis, W.D., Eds., Oxford: Pergamon, 1979, vol. 4.
Translated under the title Obshchaya organicheskaya
khimiya, Moscow: Khimiya, 1985, vol. 8, p. 429.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 6 2005