The role of hydrazide compounds in asymmetric synthesis

Designing Functionally Substituted Pyridine-Carbohydrazides for Potent Antibacterial and Devouring Antifungal Effect on Multidrug Resistant (MDR) Strains

The emergence of multidrug-resistant (MDR) pathogens and the gradual depletion of available antibiotics have exacerbated the need for novel antimicrobial agents with minimal toxicity. Herein, we report functionally substituted pyridine carbohydrazide with remarkable antimicrobial effect on multi-drug resistant strains. In the series, compound 6 had potent activity against four MDR strains of Candida spp., with minimum inhibitory concentration (MIC) values being in the range of 16-24 µg/mL and percentage inhibition up to 92.57%, which was exceptional when compared to broad-spectrum antifungal drug fluconazole (MIC = 20 µg/mL, 81.88% inhibition). Substitution of the octyl chain in 6 with a shorter butyl chain resulted in a significant anti-bacterial effect of 4 against Pseudomonas aeruginosa (ATCC 27853), the MIC value being 2-fold superior to the standard combination of ampicillin/cloxacillin. Time-kill kinetics assays were used to discern the efficacy and pharmacodynamics of the potent compounds. Further, hemolysis tests confirmed that both compounds had better safety profiles than the standard drugs. Besides, molecular docking simulations were used to further explore their mode of interaction with target proteins. Overall results suggest that these compounds have the potential to become promising antimicrobial drugs against MDR strains.

A Systematic Review on Synthetic and Antimicrobial Bioactivity of the Multifaceted Hydrazide Derivatives

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To overcome the upsurge of antimicrobial resistance that has emerged in recent years, there is a need for the development of newer hits having satisfying anti-infective activity. Hydrazides incorporated with an azomethine hydrogen account for a cardinal class of molecules for the development of newer derivatives. Hydrazide derivatives have gained considerable interest of medicinal chemists owing to their diverse bioactivity. In the present review, we have attempted to compile the recent trends in the synthesis of hydrazides and their substituted derivatives. The structural features that lead to the desired antimicrobial activity are highlighted, which will lead the way for synthetic and medicinal chemists to focus on newer designs in this arena.

One-Pot Synthesis and in Silico Molecular Docking Studies of Arylselanyl Hydrazides as Potential Antituberculosis Agents

The present study reports a simple two-step method for the synthesis of arylselanyl hydrazide derivatives using hypophosphorous acid and polyethylene glycol (H₃ PO₂ /PEG-400) as an alternative reducing system and hydrazine hydrate (NH₂ NH₂ ⋅xH₂ O/50-60 %). This single-vessel procedure was employed with methyl acrylate 2a and methyl bromoacetate 2b using diaryl diselenides to generate the nucleophile species to produce, respectively, 3-(arylselanyl)propane-hydrazides 4a-e and 2-(arylselanyl)acetohydrazides 5a-e with good yields by accelerating the reduction of -Se-Se- bond, when compared to available methods. The synthesized molecules are structurally similar to the isoniazid (INH). Therefore, we perform in silico molecular docking studies, using the lactoperoxidase enzyme, in order to verify whether the INH Se derivatives could interact in a similar way to INH at the active site of the mammalian enzyme. The in silico results indicated a similar type of interaction of the arylselanyl hydrazide derivatives with that of INH. In view of the similar in silico interaction of the selenium derivatives of INH, the arylselanyl hydrazide derivatives reported here should be tested against Mycobacterium tuberculosis in vitro.

Catalytic Enantioselective Synthesis of C–N Atropisomeric Heterobiaryls

Molecules containing an atropisomeric C–N biaryl axis are gaining increasing attention in catalytic and medicinal chemistry. Despite this rising interest, relatively few approaches towards their catalytic enantioselective synthesis have been reported. Here we review these approaches, with a focus on the mechanism of asymmetric induction. Some common themes emerge: Brønsted acid catalysed cyclo-condensation and palladium-catalysed ring-closure are the most common and successful approaches. Meanwhile, the more direct but challenging axial C–N bond formation strategy remains in its infancy, with just two reports to-date. We hope this review will inform and inspire other researchers to develop new creative approaches to this important chemical motif.

1 Introduction

2 Cyclo-Condensation

3 Proximal C–N Bond Formation

4 Desymmetrisation of Intact Axes

5 ortho-C–H Functionalisation

6 Cycloaddition

7 Axial C–N Bond Formation

8 Atropisomeric N–N Axes: An Emerging Class of Heterobiaryls

9 Conclusion and Outlook

Infrared Fingerprints of nN → σ*NH Hyperconjugation in Hydrazides

An earlier study demonstrated that hyperconjugation operates in hydrazides by analyzing the N-H stretching mode in gas phase infrared (IR) spectroscopy, and then observing two very distinct bands corresponding to isolated isomers experiencing or not the n_N → σ*_N-H electron delocalization. The present work reports a chemical method to obtain insight on the hyperconjugation in hydrazide derivatives from solution IR spectroscopy. The analogous amides did not show a ν_N-H red-shifted band, as the electron donor orbital in the above hyperconjugative interaction does not exist. In addition, the effect of electron withdrawing groups bonded to a nitrogen atom, namely the trifluoroacetyl and the methanesulfonyl groups, was analyzed on the conformational isomerism and on the ability to induce a stronger hyperconjugation in the resulting compounds.