Nitropyrazoles

Abstract

A method for the synthesis of 1 methyl 3,5 dinitropyrazole 4 carbonitrile from 1,4 di methyl 3,5 dinitropyrazole was developed. Nucleophilic substitution in 1,4 dimethyl 3,5 dinitropyrazole, 1 methyl 3,5 dinitropyrazole 4 carboxamide, and 1 methyl 3,5 dinitro pyrazole 4 carbonitrile involves solely the 5 NO 2 group in the ring. 1 Methyl 3,5 dinitro pyrazole 4 carbonitrile reacts with thioglycolic acid phenylamide and potassium carbonate to give 4 amino 1 methyl 3 nitro N phenyl 1H thieno[2,3 c]pyrazole 5 carboxamide. The use of glycolic acid phenylamide instead of thioglycolic acid N phenylamide under analogous conditions resulted in 5 anilino 1 methyl 3 nitro 1H pyrazole 4 carbonitrile. An explana tion for the regiospecificity of the nucleophilic substitution of the 5 NO 2 group in 4 R 1 methyl 3,5 dinitropyrazoles is given.

Nitropyrazoles 16. The use of methoxymethyl group as a protecting group for the synthesis of 4-methyl-3-nitro-5-R-pyrazoles

“…97-99 °С. Found (%):C, 49.32; H, 4.76; N, 17.74; S, 8.86. C 14 H 16 N 4 O 4 S. Calculated (%): C, 49.99; H, 4.79; N, 16.66; S, 9.53.…”

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

“…N 2 H 4 •H 2 O, FeCl 3 •6H 2 O, activat ed carbon/MeOH, reflux, 3 h. group in 2 is readily substituted by PhCH 2 S -in NMP at a temperature as low as ∼20 °C (see Scheme 1). That is, 4 (p methoxyphenyl)vinyl group facilitates nucleophilic substitution of NO 2 group as opposed to 4 Me substitu ent; with the latter, heating at 100 °C in the same solvent was required. 2 The attachment site of PhCH 2 S on the pyrazole ring of 3 was deduced from long range 1 Н-13 С couplings established using 2D correlation HMBC exper iments.…”

“…Found (%): C, 62.07; H, 5.01; N, 11.19; S, 7.68. C 20 H 19 (4). The mixture of dinitropyrazole 2 (0.55 g, 1.8 mmol), hydrazine hydrate (0.14 ml, 2.8 mmol), FeCl 3 •6H 2 O (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).…”

Nitropyrazoles 23. Synthesis of substituted N-amino-3-nitro-5-R-pyrazoles

“…The site of nucleophilic substitution was determined proceeding from the same specific features in the 1 H and 13 C NMR spectra, as for the N methyl derivatives of 5 substituted 3 nitropyrazoles synthesized by us earlier. 1,28,32 In fact, in the 1 H NMR spectra of compounds 2a-d an upfield shift of the signal for the NH 2 group from  7.84 (1) to  7.00-7.05 (2a-d) is observed due to the decrease in the electron accepting properties of the pyrazole ring. In the 13 C NMR spectra of compounds 2a-d, the most low field signal of the carbon atom is broadened due to the quadrupole relaxation on the 14 N nuclei of the NO 2 group, that, taking into account the known specifics in the se quence of chemical shifts for the carbon atoms in poly nitropyrazoles, allows us to assign them to the signal for the C(3) NO 2 fragment.…”