Reaction of 2,2-dinitro-2-(3-phenyl-1,2,4-oxadiazol-5-yl)-acetonitrile with diazomethane and diazoethane

Full text of DOI:10.1134/S1070428007110309

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 11, pp. 1742–1744. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © I.A. Shevtsova, A.G. Tyrkov, 2007, published in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 11, pp. 1740–1741.
SHORT
COMMUNICATIONS
Reaction of 2,2-Dinitro-2-(3-phenyl-1,2,4-oxadiazol-5-yl)-
acetonitrile with Diazomethane and Diazoethane
I. A. Shevtsova and A. G. Tyrkov
Astrakhan State University, pl. Shaumyana 1, Astrakhan, 414000 Russia
e-mail: tyrkov@rambler.ru
Received January 5, 2007
DOI: 10.1134/S1070428007110309
It is known that chloro(dinitro)acetonitrile and tri-
nitroacetonitrile react with diazomethane to give
3-cyanodihydroisoxazole N-oxide [1] or N-methyl-
4-trinitromethyl-1,2,3-triazoles [2]. With the goal of
studying how the structure of substituted dinitroaceto-
nitrile affects the direction of their transformations in
reactions with diazoalkanes, we examined reactions of
2,2-dinitro-2-(3-phenyl-1,2,4-oxadiazol-5-yl)aceto-
nitrile (III) with diazomethane and diazoethane. We
found that, like trinitroacetonitrile, the behavior of
compound III is determined by dipolarophilic activity
of the cyano group. The reaction of nitrile III with
diazomethane followed the 1,3-dipolar cycloaddition
pattern to give a mixture of isomeric N-methyl-1,2,3-
triazol-4-yl(3-phenyl-1,2,4-oxadiazol-5-yl)dinitro-
methanes IVa and Va which were separated by column
chromatography. In the reaction of III with diazo-
ethane, the process stopped at the 1,3-dipolar cycload-
dition stage, and the product was dinitromethane VIa
(Scheme 1).
The structure of compounds III and IVa–VIa was
1
unambiguously confirmed by their IR and H NMR
spectra, as well as by the transformations of IVa–VIa
under the action of alcoholic potassium hydroxide
(Scheme 2). These reactions were accompanied by
elimination of the 1,2,4-oxadiazole heteroring, leading
to the formation of isomeric N-methyl-4-dinitrometh-
yl-1,2,3-triazole potassium salts IVb and Vb (from
IVa and Va) and 4-dinitromethyl-5-methyl-1,2,3-tri-
azole dipotassium salt (VIb; from VIa). In addition,
3-phenyl-1,2,4-oxadiazol-5-ol (VII) was isolated. Com-
pounds IVb–VIb and VII were reported previously.
Scheme 1.
N
O
N
O
N
O
AgNO3
–KNO3
BrCN
NO2
NO2
NO2
NO2
NO2
CN
K+
Ag+
Ph
Ph
Ph
–AgBr
N
N
N
NO2
I
II
III
Me
N
N
N
N
O
O
N
N
Ph
Me
Ph
CH2N2
+
N
N
N
N
O2N
NO2
O2N
NO2
IVa
Va
Me
N
N
O
CH3CHN2
NH
Ph
N
N
O2N
VIa
NO2
1742

REACTION OF 2,2-DINITRO-2-(3-PHENYL-1,2,4-OXADIAZOL-5-YL)ACETONITRILE
1743
Scheme 2.
N
N
O
NO2
KOH, EtOH
K+
N
+
IVa, Va
Ph
OH
N
N
Me
NO2
IVb, Vb
VII
Me
NO2
NO2
KOH, EtOH
2K+
+
VII
VIa
N
N
N
VIb
nD20 = 1.4815. IR spectrum CHCl3), ν, cm–1: 1580, 1300
(NO2). H NMR spectrum, δ, ppm: 8.13 s (1H, CH),
7.75 m (5H, Harom), 4.22 s (3H, CH3). Found, %:
C 43.42; H 2.67; N 29.48. C12H9N7O5. Calculated, %:
C 43.50; H 2.72; N 29.61.
Dinitroacetonitrile III was synthesized from 5-di-
nitromethyl-3-phenyl-1,2,4-oxadiazole potassium salt
(I) [3] as shown in Scheme 1, and diazomethane and
diazoethane were prepared as described in [4, 5].
1
5-Dinitromethyl-3-phenyl-1,2,4-oxadiazole silver
salt (II). A solution of 15 mmol of AgNO3 in a mini-
mal volume of water was added to 10 mmol of potas-
sium salt I in 10 ml of water, heated to 40°C. The mix-
ture was cooled to 0°C, and the precipitate was filtered
off, washed with water, and dried in air. Yield 80%,
decomposition point 156°C. Found, %: N 15.56.
C9H5AgN4O5. Calculated, %: N 15.69.
1-Methyl-1H-1,2,3-triazol-4-yl(dinitro)(3-phen-
yl-1,2,4-oxadiazol-5-yl)methane (Va). Yield 24%,
mp 96°C. IR spectrum (CHCl3), ν, cm–1: 1580, 1300
1
(NO2). H NMR spectrum, δ, ppm: 8.20 s (1H, CH),
7.73 m (5H, Harom), 4.11 s (3H, CH3). Found, %:
C 43.44; H 2.63; N 29.52. C12H9N7O5. Calculated, %:
C 43.50; H 2.72; N 29.61.
2,2-Dinitro-2-(3-phenyl-1,2,4-oxadiazol-5-yl)-
acetonitrile (III). A thick-walled glass ampule was
charged with a mixture of 5 mmol of salt II and
6 mmol of cyanogen bromide. The ampule was sealed,
placed into an explosion-safe box, and heated for 20 h
at 80°C. After cooling, the ampule was opened, the
mixture was extracted with acetone (2×10 ml), the ex-
tract was evaporated, and the residue was subjected to
chromatography in a 500×10-mm column filled with
activated silica gel (Silicagel, 100–400 μm) using ben-
zene as eluent. Yield 68%, mp 52°C. IR spectrum
(CHCl3), ν, cm–1: 2250 (CN); 1600, 1290 (NO2).
1H NMR spectrum, δ, ppm: 7.76 m (5H, Harom). Found,
%: C 43.52; H 1.68; N 25.30. C10H5N5O5. Calculated,
%: C 43.64; H 1.82; N 25.45.
5-Methyl-2H-1,2,3-triazol-4-yl(dinitro)(3-phenyl-
1,2,4-oxadiazol-5-yl)methane (VIa). Yield 63%, nD20 =
1.4795. IR spectrum (CHCl3), ν, cm–1: 1580, 1300
(NO2). 1H NMR spectrum, δ, ppm: 9.41 br.s (1H, NH),
7.76 m (5H, Harom), 2.34 s (3H, CH3). Found, %:
C 43.40; H 2.69; N 29.50. C12H9N7O5. Calculated, %:
C 43.50; H 2.72; N 29.61.
4-Dinitromethyl-N-methyl-1,2,3-triazole potas-
sium salts IVb and Vb and 3-phenyl-1,2,4-oxadi-
azol-5-ol (VII). A saturated solution of potassium hy-
droxide in ethanol was added dropwise under stirring
at 0°C to a solution of 5 mmol of isomer mixture
IVa/Va in 10 ml of ethanol until the corresponding
potassium salts no longer separated. The precipitate
was filtered off and recrystallized from ethanol. The
filtrate was evaporated, and the residue was subjected
to column chromatography on silica gel using diethyl
ether as eluent to isolate 23% of compound VII,
mp 202°C [6].
Dinitro(3-phenyl-1,2,4-oxadiazol-5-yl)(1,2,3-tri-
azol-4-yl)methanes IVa–VIa. A solution of excess di-
azomethane or diazoethane in diethyl ether was added
in portions to a mixture of 7 mmol of compound III
and 20 ml of anhydrous diethyl ether, cooled to 0°C,
until nitrogen no longer evolved. The mixture was kept
for 24 h at 25°C and evaporated, and the residue was
subjected to column chromatography on silica gel
using benzene (IVa, VIa) or diethyl ether (V) as eluent.
4-Dinitromethyl-2-methyl-1,2,3-triazole potassi-
um salt (IVb). Yield 72%, decomp. point 198°C [2].
4-Dinitromethyl-1-methyl-1,2,3-triazole potassi-
um salt (Vb). Yield 78%, decomp. point 182°C [2].
2-Methyl-2H-1,2,3-triazol-4-yl(dinitro)(3-phenyl-
1,2,4-oxadiazol-5-yl)methane (IVa). Yield 46%,
4-Dinitromethyl-5-methyl-1,2,3-triazole dipotas-
sium salt (VIb) and 3-phenyl-1,2,4-oxadiazol-5-ol
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007

SHEVTSOVA, TYRKOV
1744
REFERENCES
(VII). A solution of 5 mmol of compound VIa in
10 ml of ethanol was cooled to 0°C, a solution of
potassium hydroxide in ethanol was added to pH 9,
and the mixture was kept for 1 h at 0°C. The solvent
was removed, and the residue was subjected to column
chromatography on silica gel. Elution with diethyl
ether gave compound VII, yield 20%, mp 202°C [6],
and the subsequent elution with ethanol gave di-
potassium salt VIb, yield 52%, decomp. point 205°C
(from water) [7].
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The IR spectra were recorded on an IKS-29 spec-
trometer from solutions in chloroform with a concen-
tration of 40 mg/ml (cell path length 0.1 mm). The
1H NMR spectra were measured on a Tesla BS-487C
instrument at 80 MHz using acetone-d6 as solvent and
HMDS as internal reference. The purity of the isolated
compounds was checked by TLC on Silufol UV-254
plates using acetone–hexane (2:3) as eluent; develop-
ment with iodine vapor.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007