I. L. Dalinger

Novel Highly Energetic Pyrazoles: N-Trinitromethyl-Substituted Nitropyrazoles.

A new family of energetic compounds, nitropyrazoles bearing a trinitromethyl moiety at the nitrogen atom of the heterocycle, was designed. The desirable high-energy dense oxidizers 3,4-dinitro- and 3,5-dinitro-1-(trinitromethyl)pyrazoles were synthesized in good yields by destructive nitration of the corresponding 1-acetonylpyrazoles. All of the prepared compounds were fully characterized by multinuclear NMR and IR spectroscopy, as well as by elemental analysis. Single-crystal X-ray diffraction studies show remarkably high density. Impact sensitivity tests and thermal stability measurements were also performed. All of the pyrazoles possess positive calculated heats of formation and exhibit promising energetic performance that is the range of 1,3,5-trinitroperhydro-1,3,5-triazine and pentaerythritol tetranitrate. The new pyrazoles exhibit positive oxygen balance and are promising candidates for new environmentally benign energetic materials.

A Direct Approach to a 6-Hetarylamino[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine Library

The synthesis of 6-hetarylamino[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazines is reported. The functionalized secondary amines were constructed via a K2CO3-mediated SNAr reaction of weakly basic hetarylamines with 3-(3,5-dimethylpyrazol-1-yl)[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazines, which allowed displacement 3,5-dimethylpyrazolyl leaving group. Significantly, the reaction exhibited a broad substrate scope and proceeded in good yields.

3-R-4-Nitro-6,7-furoxanobenzo[ d ]isoxazoles – a new type of condensed nitroarenes capable of Diels–Alder reaction

Pericyclic [4+2] cycloaddition (Diels–Alder reaction) of nitrofuroxanobenzo[d]isoxazoles, capable of acting both as dienophiles (at the C=CNO2 bond) or heterodienes (at the C=C–N(O)=O fragment) was used to synthesize a new type of condensed polycyclic systems. The obtained compounds combining in one molecule two pharmacophore moieties, furoxan (nitric oxide donor) and substituted isoxazole, may be considered as a potential basis for the design of compounds with dual biological activity.

Regiospecific substitution of the 4-nitro group in 3-amino-4,6-dinitrobenzo[b]thiophene-2-carboxylates: unexpected activating effect of the amino group

Abstract The cyclocondensation of 2,4,6-trinitrobenzonitrile with the esters of thioglycolic acid results in the formation of 3-amino-4,6-dinitrobenzo[ b ]thiophene-2-carboxylates 3 . The interaction of 3 with anionic nucleophiles RO − (R=CF 3 CH 2 , CHCCH 2 ), RS − (R=Ph, PhCH 2 , (CH 3 ) 2 CHCH 2 ), N 3 − in NMP or DMF leads to the substitution of only the 4-NO 2 group. The replacement of the electron-donating NH 2 group in 3 with hydrogen unexpectedly and significantly hampers nucleophilic substitution of the nitro group. It is assumed that increased reactivity of the 4-NO 2 in 3 is connected with the twist of this group with respect to the plane of the aromatic ring under the influence of the NH 2 group as indicated by semi-empirical quantum chemical calculations.

Regioselectivity of nucleophilic substitution of the nitro group in 2,4,6-trinitrobenzamide

Abstract Under the action of anionic nucleophiles RO − (R=Ph, HCF 2 CF 2 CH 2 ), R′S − (R′=Ph, PhCH 2 , C 2 H 5 OC(O)CH 2 ), N 3 − on 2,4,6-trinitrobenzamide in MeCN or DMF, the ortho -nitro group is substituted with high selectivity. Intramolecular cyclisation involving ortho- positioned fragments SX and -CONH 2 (XC 2 H 5 OC(O)CH 2 , Cl) has been achieved with the formation of 2-ethoxycarbonyl-3-hydroxy-4,6-dinitrobenzo[ b ]thiophene and 4,6-dinitro-2 H -benzo[ b ]isothiazol-3-one correspondingly.

Effects of N-nitropyrazoles on ocular blood flow of rabbits and retinal function recovery of rat eyes after ischemic insults.

Twelve compounds of N-nitropyrazoles were studied for their effects on ocular blood flow in rabbits and retinal function recovery in rat eyes after ischemic insults. Of the twelve N-nitropyrazoles examined, nine increased choroidal blood flow while five increased retinal blood flow significantly. On the other hand, all twelve compounds increased blood flow in iris and ciliary muscle without exception. As for retinal function recovery after ischemic insult in rat eyes, eight out of the twelve compounds showed more significant facilitation than the control. The structure activity relationship of the N-nitropyrazoles to increase ocular blood flow and to facilitate retinal function recovery after ischemic insults were discussed.

1,3-Disubstituted and 1,3,3-trisubstituted adamantyl-ureas with isoxazole as soluble epoxide hydrolase inhibitors

Adamantyl ureas are good soluble epoxide hydrolase (sEH) inhibitors; however they have limited solubility and rapid metabolism, thus limiting their usefulness in some therapeutic indications. Herein, we test the hypothesis that nodal substitution on the adamantane will help solubilize and stabilize the compounds. A series of compounds containing adamantane derivatives and isoxazole functional groups were developed. Overall, the presence of methyl on the nodal positions of adamantane yields higher water solubility than previously reported urea-based sEH inhibitors while maintaining high inhibition potency. However, it did not improve microsomal stability.

Synthesis and investigation of isomeric mono- and dinitro derivatives of 3-methyl-4-(pyrazol-3-yl)furazan

The regioselective introduction of nitro groups in pyrazoles, containing a furazanyl substituent at position 3(5) was investigated. All synthetically accessible isomeric mono- and dinitropyrazole derivatives were obtained. X-ray structural investigation was performed for all mononitroisomers and a dinitro derivative.

Synthesis of 4,6-dinitro-3-R-benzo[d]isoxazoles and their transformations under the action of nucleophiles

A new procedure was developed for the preparation of 4,6-dinitro-3-R-benzo[d]isoxazoles (R are derivatives of the aldehyde group) based on 2,4,6-trinitrophenylacetaldehyde. The resulting compounds are characterized by the regiospecific substitution of the nitro group at position 4 under the action of anionic nucleophiles RS–, RO–, F–, or N3–, which allowed the development of a new method for the preparation of previously unknown 4-Nu-6-nitro-3-R-benzo[d]isoxazoles (Nu is the residue of a nucleophile). At the same time, oxidative nucleophilic substitution under the action of anions of some β-dicarbonyl compounds leads to the replacement of the hydrogen atom at position 7 with the corresponding C-nucleophiles.

Pyrazole‐Tetrazole Hybrid bearing the Trinitromethyl, Fluorodinitromethyl or (Difluoroamino)dinitromethyl Groups: High‐Performance Energetic Materials

High-nitrogen-content compounds have attracted great scientific interest and technological importance because of their unique energy content, and they find diverse applications in many fields of science and technology. Understanding of structure-property relationship trends and how to modify them is of paramount importance for their further improvement. Herein, the installation of oxygen-rich modules, C(NO2 )3 , C(NO2 )2 F, or C(NO2 )2 NF2 , into an endothermic framework, that is, the combination of a nitropyrazole unit and tetrazole ring, is used as a way to design novel energetic compounds. Density, oxygen balance, and enthalpy of formation are enhanced by the presence of these oxygen-containing units. The structures of all compounds were confirmed by XRD. For crystal packing analysis, it is proposed to use new criterion, ΔOED , that can serve as a measure of the tightness of molecular packing upon crystal formation. Overall, the materials show promising detonation and propulsion parameters.