3,5-Bis(dimethylaminomethylene)amino-1-methyl-4-nitropyrazole (3). A suspension of compound 1
(3.0 g, 20.7 mmol) and DMF dimethylacetal (6.6 ml) was maintained at 100°C for 4 h. The reaction mixture was
evaporated in vacuum to an oily residue, which was treated with boiling hexane. The residual thick oil was
frozen in the refrigerator, and after crystallization from isopropyl alcohol a bright yellow substance (2.2 g, 39%)
1
was obtained; mp 185-186°C. M+· 267. H NMR spectrum (CDCl3), δ, ppm: 2.87, 2.91, 2.94 (12H, s, two
(N(CH3)2); 3.37 (3H, s, 1-CH3); 7.77, 7.91 (2H, s, two CH). Found, %: C 44.73; H 6.28; N 37.03. C10H17N7O2.
Calculated, %: C 44.94; H 6.41; N 36.68.
Reduction of 3,5-Bis(dimethylaminomethylene)amino-1-methyl-4-nitropyrazole 3. Palladium on
carbon (10%, 0.19 g) was added to a solution of compound 3 (2.0 g, 13.8 mmol) in methanol (60 ml) and the
mixture was reduced with hydrogen at normal pressure. After 3 h the reaction mixture was filtered and
evaporated in vacuum to a completely solid red residue, which was dried over P2O5, and analyzed.
Reactions of 3,5-Bis(dimethylaminomethylene)amino-1-methyl-4-nitropyrazole 3 with Amines. A
solution of compound 3 (0.35 g, 1.3 mmol) in methanol (30 ml) was heated with the appropriate amine
(4.0 mmol) until disappearance of the starting material according to TLC (72 h for p-anisidine, 24 h for
benzylamine, and 3 h for a methanolic solution of ammonia). The reaction mixture was cooled intensely and the
precipitated bright red solid 3-amino-5-(dimethylaminomethylene)amino-1-methyl-4-nitropyrazole 6A was
separated, and crystallized from ethanol; mp 191-193°C. M+· 212. 1H NMR spectrum (DMSO-d6), δ, ppm: 2.99,
3.08 (6H, s, N(CH3)2); 3.36 (3H, s, 1-CH3); 6.00 (2H, br. s, NH2); 8.12 (1H, s, CH). 13C NMR spectrum
(DMSO-d6), δ, ppm: 33.8 (N(CH3)2); 40.2 (CH3(1)), 110.0 (C(4)); 147.4(C(5)); 150.3 (C(3)); 159.1 (C(5a)).
Found, %: C 40.00; H 5.92; N 39.38. C7H12N6O2. Calculated, %: C 39.62; H 5.70; N 39.60.
The filtrate was evaporated to dryness and the oily residue treated with 6% methanolic hydrochloric
acid solution until a weakly acid reaction was obtained. The obtained hydrochlorides of substituted
formamidines of p-anisidine 7, 8, and benzylamine 9 were filtered off and crystallized from absolute alcohol.
N,N-Dimethylamino-N'-(4-methoxyphenyl)iminoformamide (7). Mp 126-128°C. M+· 178.
Found, %: C 55.86; H 6.97; N 13.31. C10H14N2.HCl. Calculated, %: C 55.94; H 7.04; N 13.05.
N,N'-Bis(4-methoxyphenyl)iminoformamide (8). Mp 134-138°C. M+· 256. Found, %: C 61.55;
H 6.01; N 9.39. C15H16N2O2.HCl. Calculated, %: C 61.54; H 5.85; N 9.57.
N,N''-Dibenzyliminoformamide (9). Mp 126-128°C. M+· 224. Found, %: C 66.55; H 6.79; N 9.93.
C15H16N2.HCl.½H2O. Calculated, %: C 66.78; H 6.72; N 10.38.
3,5-Diamino-1-methyl-4-nitropyrazole (10). A solution of pyrazole 6 (1.0 g, 4.7 mmol) in 20%
methanolic ammonia solution (4 ml) and methanol (40 ml) was heated in a bomb at 140°C for 24 h. The reaction
mixture was evaporated in vacuum and the residue recrystallized from isopropyl alcohol with a yield of 0.7 g
(97%) of a bright red crystalline substance; mp 181-183°C. M+· 157. Found, %: C 30.42; H 4.54; N 44.38.
C4H7N5O2. Calculated, %: C 30.58; H 4.49; N 44.57.
p
A
Reaction of 3,5-Bis(dimethylaminomethylene)amino-4-nitropyrazole (2) with -Anisidine.
solution of compound 2 (0.6 g, 2.4 mmol) and p-anisidine (0.6 g, 4.9 mmol) in methanol (40 ml) was refluxed
for 4 h. The reaction mixture was cooled, and compound 1 (0.3 g, 90%) was filtered off (bright red solid). The
filtrate was evaporated to dryness, and treated with 6% methanolic hydrochloric acid solution until a weakly
acid reaction was obtained. The solid compound 7 formed was separated, and crystallized from absolute alcohol.
X-ray Structural Investigation. A finely crystalline powder was synthesized for the determination of
the crystal structure. The powder diffraction spectrum was measured at room temperature in a Gine camera
(CuK/I radiation, the spectrum was plotted with a photofilm photodensitometer with a step of 0.01°, the sample
was prepared by a special procedure for smoothing out textural effects). The parameters of the triclinic unit cell
were determined with the ITO indexing program [6]. The crystal structure was solved by the systematic search
method of [7] and refined by the Ritveld method with the MRIA program [8] (all details of the experiment,
indexing, solution, and refinement of the structure, and also the coordinates and thermal parameters of atoms are
given in a separate publication [9]).
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