N-(2,4,6-Trinitrobenzylidene)phenylamine (2b). Yield 83%; mp 169-170°C (methanol) (according to
1
data in [4], mp 170-171°C). H NMR spectrum (DMSO-d6), , ppm, J, Hz: 7.20 (2H, d, Ph); 7.32 (1H, t, Ph);
δ
7.45 (2H, t, Ph); 8.92 (1H, s, CH=N); 9.10 (2H, s, 3-H, 5-H).
N-(2,4,6-Trinitrobenzylidene)-4-methylphenylamine (2c). Yield 90%; mp 193-194°C (methanol)
(according to data in [4], mp 177-178°C). 1H NMR spectrum (DMSO-d6), , ppm, J, Hz: 2.39 (3H, s, CH3); 7.13
δ
(2H, d, J = 7.27, Ph); 7.29 (2H, d, J = 6.37, Ph); 8.93 (1H, s, CH=N); 9.11 (2H, s, 3-,5-H).
N-(2,4,6-trinitrobenzylidene)-4-nitrophenylamine (2d). Yield 78%; mp 171-172°C (methanol).
1H NMR spectrum (DMSO-d6), , ppm, J, Hz: 7.38 (2H, d, J = 8.24, Ph); 8.35 (2H, d, J = 8.12, Ph); 9.06 (1H, s,
δ
CH=N); 9.17 (2H, s, 3-,5-H). Found, %: C 42.67; H 2.01; N 19.42. C13H7N5O8. Calculated, %: C 43.21; H 1.94;
N 19.39.
2-N-Phenyl-6-nitroindazole (3a). Azomethine 2a (0.813 g, 3 mmol) was suspended in DMF (0.5 ml).
Sodium azide (0.234 g, 3.6 mmol) was added, and the mixture was heated at 115-120°C until evolution of
nitrogen ceased (40-60 min). The solution was cooled and the completely solidified mass was filtered off and
washed with water. After recrystallization from acetone, 0.453 g (63%) of white powder was obtained;
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mp 137-138°C. H NMR spectrum (DMSO-d6), , ppm, J, Hz: 7.51 (1H, t, Ph); 7.62 (2H, m, Ph); 7.86 (1H, d,
δ
J = 9.23, Ph); 8.02 (1H, d, J = 9.23, Ph); 8.12 (2H, d, J = 8.30, Het); 8.70 (1H, s, Het); 9.30 (1H, s, Het).
Found, %: C 65.13; H 3.92; N 17.71. C13H9N3O2. Calculated, %: C 65.27; H 3.77; N 17.57.
General Procedure for Obtaining 2-N-Aryl-4,6-nitroindazoles (3b-d). Azomethine 2b-d (3 mmol)
was suspended in DMF (1-2 ml). Sodium azide (3.15 mmol) was added at ~20°C and the mixture was stirred
until completely solidified (3-5 min). The azide formed was converted to indazole by one of the following
methods. A. The solidified mass was heated to 60°C and held at this temperature for 40-50 min. The residue was
filtered off on cooling, washed with water and recrystallized from chloroform.
B. The azide was filtered off, dissolved in chloroform, and boiled for 20-30 min. The solution was
evaporated down to a fairly small volume and cooled. The residue of indazole was filtered off and dried.
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2-N-Phenyl-4,6-dinitroindazole (3b). Yield 68%; mp 203-204°C (chloroform). H NMR spectrum
(DMSO-d6), , ppm, J, Hz: 7.55-7.65 (3H, m, Ph); 8.25 (2H, d, J = 9.68, Ph); 8.80 (1H, s, Het); 9.15 (1H, s,
δ
Het); 9.63 (1H, s, Het). Found, %: C 54.52; H 3.06; N 19.97. C13H8N4O4. Calculated, %: C 54.93; H 2.82;
N 19.72.
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2-N-(4-Methylphenyl)-4,6-dinitroindazole (3c). Yield 64%; mp 237-238°C (chloroform). H NMR
spectrum (DMSO-d6), , ppm, J, Hz: 2.45 (3H, s, CH3); 7.45 (2H, d, J = 7.09, Ph); 8.13 (2H, d, J = 6.07, Ph);
δ
8.76 (1H, s, Het); 9.19 (1H, s, Het); 9.60 (1H, s, Het). Found, %: C 56.15; H 3.42; N 19.02. C14H10N4O4.
Calculated, %: C 56.37; H 3.35; N 18.79.
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2-N-(4-Nitrophenyl)-4,6-dinitroindazole (3d). Yield 62%; mp 253-254°C (chloroform). H NMR
spectrum (DMSO-d6), , ppm, J, Hz: 8.49 (2H, d, J = 8.03, Ph); 8.60 (2H, d, J = 9.04, Ph); 8.79 (1H, s, Het);
δ
9.22 (1H, s, Het); 9.89 (1H, s, Het). Found, %: C 47.32; H 2.28; N 21.36. C13H7N5O6. Calculated, %: C 47.42;
H 2.13; N 21.28.
REFERENCES
1.
2.
3.
A. G. Mohan, US Pat. 3833606; Chem. Abstr. 82:43410u (1975).
J. I. G. Cadogan, M. Cameron-Wood, R. K. Mackie, and R. J. G. Searle, J. Chem. Soc., 4831 (1965).
V. Marshalkin, D. Brovko, A. Samet, S. Zlotin, V. Semenov, A. Gakh, and A. Buchanan, J. Heterocycl.
Chem. (in press); V. V. Semenov, S. G. Zlotin, A. A. Gakh, and A. C. Buchanan, in: Seventeenth
International Congress of Heterocyclic Chemistry, Vienna, August 1-6, 1999, PO-337 (Internet:
http://www.ioc.tuwien.ac.at/ichc/).
4.
S. Secareanu, Bull. Soc. Chim. France, 51, 591 (1932).
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