Vilsmeier–Haack reaction of (E)-1-(1-(3,5-difluorophenyl)ethylidene)-2-phenylhydrazine (1) using dimethyl formamide in excess of phosphorous oxychloride by conventional method, resulted in the synthesis of title compound 3-(3,5-difluorophenyl)-1-phenyl-1H-pyrazole-4- carbaldehyde (2) in good yield and high purity. Structure characterization of the novel title compound was done by IR, ¹H NMR, ¹³C NMR and mass spectral analysis.

We report an unusual transformation where a transient formation of a nitrene moiety initiates a sequence of steps where leading to a remote oxidative C-H functionalization (R-CH3 to R-CH2OC(O)R’) and concomitant reduction of the nitrene into an amino group. No external oxi-dants or reductants are needed for this formal molecular com-proportionation. Detected and iso-lated intermediates and computational analysis suggest that the process occurs with pyrazole ring opening and recyclization.

DFT calculations on the photoisomerization reactions of pyridazine N-oxide derivatives are presented. The irradiation of 3,6-diphenylpyridazine N-oxide allowed to obtain the first excited singlet state that underwent to a ring opening reaction induced to the oxygen migration to the adjacent carbon atom, with the formation of a diazo derivative. This intermediate can give a ring closure reaction to give a pyrazole derivative, or, with a higher transition energy, it can lose nitrogen allowing the formation of 2,5-diphenylfuran. The irradiation of 3-phenylpyridazine N-oxide allowed the formation only of 2-phenylfuran. In this case, calculations allowed to explain this behavior. The first excited singlet state gave a photoisomerization reaction with the formation of the corresponding diazo intermediate. This intermediate could not be converted into the corresponding pyrazole derivative because it was converted into a N-formyl pyrazole never reported in literature. The only possible reaction is the loss of nitrogen and the formation of 2-phenylfuran.

To make low-cost catalytic materials that mimic the activity of tyrosinase enzymes (Catechol oxidase) is an exciting challenge of biochemical technology. Herein, we report the synthesis of a series of acylhydrazone-pyrazoles based biomolecule materials (L1-L7) with superior catecholase activity. These biomolecules were synthesized by a one pot chemical condensation between 5-methyl-1H-pyrazole-3-carbohydrazide and benzaldehyde derivatives. The X-ray single crystal diffraction (XRD) for two ligands L1 and L2 have been studied and the molecular structures were optimized and confirmed using the density functional theory (DFT/B3LYP) method. Copper (II) complexes of the biomolecules (L1-L7), generated in-situ, and were studied for their catalytic activities towards the oxidation reaction of catechol to ortho-quinone according to two parameters: the nature of the ligand and the nature of counter anion. The L7-CuSO4 was found to have an excellent catalytic activity (105.42 μmol·L−1·min−1) among the catalysts recently reported in the existing literature.

It is at the chemistry-biology interface that this work that we have carried out takes place. Indeed, the expected goal is to develop simple molecules, capable of activating the catalytic action of certain metalloenzymes such as tyrosinase. The official name of an enzyme includes the type of reaction catalyzed, the name of the substrates involved. In this work, we carried out the study of the catalytic activity of the complexes of organotin carboxylates synthesized vis-à-vis the oxidation of 3,5-di-tert-butylcatecchol. The results obtained show that the various complexes exhibit good catalytic activity for the oxidation of 3,5-di-tert-butylcatecchol under mild conditions. The complexes that showed good catalytic activity are the compounds C1 and C2.

The alarming rise of antibiotic resistance has made it imperative to find novel antimicrobial medications. This study reports the design and synthesis of new molecules based on benzofuran-pyrazole scaffolds hybridized with various N/O heterocycles using the molecular hybridization process. The newly synthesized candidates were confirmed using micro-analytical and spectral analyses, and their antimicrobial characteristics were assessed against different bacterial and fungal isolates in comparison with novobiocin and clotrimazole as antibacterial and antifungal standards, respectively. In addition, the new compounds were further evaluated as in vitro antioxidants and anti-inflammatory congeners. The most promising broad spectrum antimicrobial compounds 9, 10 with values ranging from 2.50-20.60 μg/mL were further examined as E. coli DNA gyrase B enzyme suppressors using novobiocin as a reference drug. In silico computational studies revealed that compound 9 produced a good fit in the active site of E. coli DNA gyrase B in comparison to novobiocin. Additionally, the drug similarity and ADMET parameters of compound 9 were examined in conjunction with the antibiotic ciprofloxacin, making it a potential candidate for further development as a promising antimicrobial agent.

Diisocyanates, particularly toluene diisocyanate (TDI) are useful for the preparation of various polyurethanes with specific applications as leather-like materials, adhesives, insoles etc. Blocking agents can be used for the operational simplicity and reducing the hazards of TDI. In this paper we reported the use of 3-(4-bromo-phenyl)-1H-pyrazole to block toluene diisocyanate (TDI). FTIR, NMR, thermogravimetric analysis, contact angle and differential scanning calorimetry (DSC) and were used for characterization. Effectiveness of blocking was confirmed by spectroscopic techniques. DSC thermogram shows that blocked adducts deblock at 240 °C causing the regeneration of TDI and blocking agents to react with polyols of different molecular weights forming polyurethanes. The characterization of polyurethanes has been done by Infrared spectroscopy, Nuclear magnetic resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry and contact angle study.

This paper presents the work done to transition the lab scale synthesis (1 g) to a large scale (400 g) synthesis of the 3-5-diamino-1H-Pyrazole Disperazol; a new pharmaceutical for treatment of antibiotic resistant Pseudomonas aeruginosa biofilm infections. The potentially hazardous diazotisation step in the lab scale synthesis was transformed to a safe and easy to handle flow chemistry step. Additionally, the paper presents an OSHA recommended safety assessment of the active compound E, performed by Fauske and Associates, LLC.

In this paper, we present the interaction results of 1,2-dibromo-3-isothiocyanatopropane with some pyrazoles and cytisine and salsoline alkaloids. It has been shown that the reaction results in the one-step and rather mild method for the preparation of the corresponding 1,3-thiazoline bromomethyl derivatives. The yield of this reaction is affected by the presence of a base and the order in which the reagents are added. Molecular docking of the synthesized 1,3-thiazoline derivatives for putative antibacterial activity has been carried out using the penicillin-binding target protein (PBP4) of the bacteria E. coli “Homo sapiens” and S. aureus “Homo sapiens” as an example. Molecular docking shows that the compounds have insignificant binding energies at the level of selected reference drugs (Cephalotin and Chloramphenicol). The presence of natural alkaloids in the structure of thiazoline derivatives somewhat increases the affinity of these substrates for target proteins selected.