Synthesis and Molecular Modeling Studies of 2-[2-(3-nitrophenyl)-1h-benzimidazol-1-yl]-acetamide Derivatives as Anthelmintic

Benzimidazole derivatives of substituted 2 [2-(3-nitrophenyl)-1H-benzimidazole-1-yl] acetamide analogues were synthesized and studied for antihelminthic activity. Compounds 3a–o were obtained in three steps, starting with the Oxidative Condensation of the appropriate 3-nitrobenzaldeyde, o-phenylenediamine and sodium hydrogen sulfite to form 2-(3-nitrophenyl)-1H-benzimidazole (1a). In second step Nucleophilic substitution, Chlorine atom of ethylchloroacetate will attach on nitrogen of benzimidazole by replacing hydrogen with elimination of hydrochloric acid to form ethyl [2-(3-nitrophenyl)-1H-benzimidazole-1-Yl acetate (2a).In third step amide formation from ester takes place by substitution of electrophilic with loss of ethanol to form substituted 2 [2-(3-nitrophenyl)-1H-benzimidazole-1-yl] acetamide 3a–o The antihelminthic activity showed that compounds 3f, 3h, 3i, 3j and 3k good activity against Indian earthworms (Pheretima posthuma) in comparison to albendazole.

Synthesis and Characterisation of 1,1′-{[3,5-Bis(dodecyloxy-carbonyl)-4-(thiophen-3-yl)-1,4-dihydropyridine-2,6-diyl]bis-(methylene)}bis(pyridin-1-ium) Dibromide

In the present work, construction of double-charged cationic amphiphilic 1,1′-{[3,5-bis(dodecyl¬oxy-carbonyl)-4-(thiophen-3-yl)-1,4-dihydropyridine-2,6-diyl]bis-(methylene)}bis(pyridin-1-ium) dibromide (7) was performed in four steps. Dodecyl 3-oxobutanoate (1) was condensed with thiophene-3-carbaldehyde (2) which was necessary for Hantzsch cyclisation dodecyl (E/Z)-3-oxo-2-(thiophen-3-ylmethylene)butanoate (3). Two-component Hantzsch type cyclisation of dodecyl (E/Z)-3-aminobut-2-enoate (4) and dodecyl (E/Z)-3-oxo-2-(thiophen-3-ylmethylene)butanoate (3) gave 3,5-bis(dodecyloxycarbonyl)-2,6-dimethyl-4-(thiophen-3-yl)-1,4-dihydropyridine (5). Bromination of compound 5 followed by nucleophilic substitution of bromine with pyridine gave the desired cationic amphiphilic 1,4-dihydropyridine 7. The obtained target compound 7 and new intermediates 3, 5 and 6 were fully characterised by IR, UV, 1H NMR, 13C NMR, HRMS or microanalysis. Characterisation of nanoparticles formed by the cationic 1,4-dihydropyridine 7 in an aqueous solution was performed by DLS measurements.

4,6-Dichloro-5-Nitrobenzofuroxan: Different Polymorphisms and DFT Investigation of Its Reactivity with Nucleophiles

This research focuses on the X-ray structure of 4,6-dichloro-5-nitrobenzofuroxan 1 and of some of its amino derivatives (4a, 4e, 4g, and 4l) and on DFT calculations concerning the nucleophilic reactivity of 1. We have found that by changing the solvent used for crystallization, it is possible to obtain 4,6-dichloro-5-nitrobenzofuroxan (1) in different polymorphic structures. Moreover, the different torsional angles observed for the nitro group in 1 and in its amino derivatives (4a, 4e, 4g, and 4l) are strictly dependent on the steric hindrance of the substituent at C-4. DFT calculations on the course of the nucleophilic substitution confirm the role of the condensed furoxan ring in altering the aromaticity of the carbocyclic frame, while chlorine atoms strongly influence the dihedral angle and the rotational barrier of the nitro group. These results corroborate previous observations based on experimental kinetic data and give a deep picture of the reaction with amines, which proceeds via a “non-aromatic” nucleophilic substitution.

Some Nitrogen Rich Energetic Material Synthesis by Nucleophilic Substitution Reaction from Polynitro Aromatic Compounds

Three new nitrogen-rich energetic compounds, N-(5-chloro-2,4-dinitrophenyl)hydrazine (1), N-(5-chloro-2,4-dinitrophenyl) guanidine (2) and N-(5-chloro-2,4-dinitrophenyl)-4-aminopyrazole (3) prepared by the nucleophilic substitution reaction of 1,3-dichloro-4,6-dinitrobenzene with hydrazine, guanidinium carbonate and 4-aminopyrazole. The compounds were characterized by 1H NMR, 13C NMR, IR and mass spectroscopy. Only compound 2 could be prepared in a suitable crystal and molecular model was determined by X-ray analysis. Compounds were investigated by TG and DSC. Thermal degradation and thermokinetic behavior were investigated by Ozawa–Flynn–Wall and Kissinger–Akahira–Sunose techniques. Compounds were observed to be prone to exothermical thermal decomposition. HOMO and LUMO levels, theoretical formation enthalpy and electrostatic maps were calculated by Gaussian09. The detonation velocity and pressure were calculated by Kamlet–Jacobs equation. The compounds were assayed for antimicrobial properties.