Asymmetric synthesis and biological evaluation of 3-nitro-2H-chromenes as potential antibacterial agents

Halogenated 3-Nitro-2H-Chromenes as Potential Agents Against Multidrug-Resistant Bacteria

Introduction/Objectives: Nosocomial infections caused by S. aureus and S. epidermidis resistant strains are an important cause of morbidity and mortality worldwide. Due to the increasing rate of resistance to conventional antibiotics, the discovery of new antibiotic drugs is crucial to keep pace with the evolution of these pathogenic bacterial species. Methods: The 3-nitro-2H-chromene moiety is present in several compounds with potent antibacterial activity; based on these previous studies, we report herein the synthesis of 20 new 2-aryl-3-nitro-2H-chromene derivatives and the evaluation of their antibacterial potential in vitro. Results: Mono-halogenated nitrochromenes showed moderate anti-staphylococcal activity with MIC values of 8-32 μg/mL, whereas tri-halogenated 3-nitro-2H-chromenes displayed potent anti-staphylococcal activities with MIC values of 1-8 μg/mL. Notably, 2-(4-bromophenyl)-6-bromo-8-chloro-3-nitro-2H-chromene 5s was the best antibacterial agent in the series against multidrug-resistant strains of S. aureus and S. epidermidis with MIC values of 4 μg/mL and 1-4 μg/mL, respectively. Conclusions: nitrochromene 5s shows a good safety profile, so it can be considered as a lead for further development.

Design, spectroscopic characterizations, and biological investigation of oxospiro[chromine-4,3-indolene]-based compounds as promising antiproliferative EGFR inhibitors and antimicrobial agents

Utilizing microwave heating and an aqueous saturated solution of K2CO3 as a catalyst, a rapidone-pot synthesis of oxospiro[chromene-4.3-indoline] derivatives was produced in high yields. The experimental results confirmed that the saturated solution of K2CO3 gives outstanding yield to dangerous metals and strong bases during investigations into high-performance catalysts. The used catalyst is green, affordable, incredibly mild, and widely accessible. However, it generates samples, reduces the amount of byproducts, and is expected to be used in industrial-scale heterocyclic derivatives. New oxospiro[chromene-4.3-indoline] derivatives have been created from various isatin by condensing with various phenols. The biological activities results showed that when compared to erlotinib, the derivatives 3b, 4b, 5b, and 6b were the most effective analogues on A549, MCF-7, HepG-2, and HCT-116 cells, with an IC50 range of 3.32 to 11.88 µM. In A549 cells, compounds 3b, 4b, 5b, and 6b induced apoptosis, as shown by the up-regulation of Bax, the up-regulation of Bcl-2, and the stimulation of caspase-3 and -9. With IC50 value of 0.19 ± 0.09, compound3b was demonstrated to be the most effective against EGFRWT. Compounds 4b and 6b have good antibacterial activity toward Staphylococcus aureus, comparable to ciprofloxacin, and about half as much activity as ampicillin, according to the MIC value. Compound 6b's MIC is about 25% lower than clotrimazole drug. The in silico molecular docking outcomes of compounds 3b, 4b, 5b, and 6b in the EGFR active site depicted their ability to adopt essential binding interactions compared to the reference Erlotinib. Moreover, the investigation of the physicochemical properties of the most promising dual acting antiproliferative and antimicrobial compounds 4b and 6b through the egg-boiled method illustrated acceptable lipophilicity, GIT absorption, and blood-brain barrier penetration characteristics.

Cs2CO3-Catalyzed Rauhut-Currier-Type Reaction for the Synthesis of 2,3-Dihydrobenzo[b]oxepin Derivatives

The synthesis of fused benzoxepines relies on the use of complex substrates and methodologies. Herein, we report our experimental and theoretical findings about an unprecedented Rauhut-Currier-type reaction catalyzed by Cs2CO3 to access these important compounds. The developed methodology avoids the use of phosphine- or amine-based catalysts and additives. The reaction can be performed under microwave irradiation and proceeds with complete chemoselectivity.

The Chromenopyridine Scaffold: A Privileged Platform in Drug Design

The chromenopyridine scaffold represents an important class of heterocyclic compounds exhibiting a broad spectrum of biological properties. This review describes novel and efficient procedures for the synthesis of this scaffold. Herein, several methods were detailed and grouped according to their starting material (e.g., salicylaldehydes, chromones, chromanones and coumarins) and respective biological activity, when reported. This review highlights the potential of the reported synthetic strategies for preparing chromenopyridine derivatives with promising biological activity, paving the way for further developments in drug discovery.

Silver-Catalyzed Chlorocyclization for the Synthesis of 3-Chloro-2H-chromenes

A silver-catalyzed chlorocyclization reaction of aryl 3-aryl-2-propyn-1-yl ethers in the presence of NCS under darkness was accomplished, which provides a straightforward and efficient access to 3-chloro-2H-chromenes.

Synthesis of 2H-chromenes: recent advances and perspectives

As one type of chromene, 2H-chromenes represent important oxygen heterocycles, which not only widely exist in natural products, pharmaceutical agents and biologically relevant molecules, but have also been used broadly in materials science and organic synthesis. Two major synthetic strategies have been developed towards such compounds. This review mainly focuses on the recent advances in this field, including benzopyran ring formation involving cyclization reactions and the late-stage functionalization of the parent 2H-chromenes.

Asymmetric organocatalysis: an enabling technology for medicinal chemistry

The efficacy and synthetic versatility of asymmetric organocatalysis have contributed enormously to the field of organic synthesis since the early 2000s. As asymmetric organocatalytic methods mature, they have extended beyond the academia and undergone scale-up for the production of chiral drugs, natural products, and enantiomerically enriched bioactive molecules. This review provides a comprehensive overview of the applications of asymmetric organocatalysis in medicinal chemistry. A general picture of asymmetric organocatalytic strategies in medicinal chemistry is firstly presented, and the specific applications of these strategies in pharmaceutical synthesis are systematically described, with a focus on the preparation of antiviral, anticancer, neuroprotective, cardiovascular, antibacterial, and antiparasitic agents, as well as several miscellaneous bioactive agents. The review concludes with a discussion of the challenges, limitations and future prospects for organocatalytic asymmetric synthesis of medicinally valuable compounds.

Heterocyclization of 2-(2-phenylhydrazono)cyclohexane-1,3-dione to Synthesis Thiophene, Pyrazole and 1,2,4-triazine Derivatives with Anti-Tumor and Tyrosine Kinase Inhibitions

BACKGROUND

Recently tetrahydrobenzo[b]thiazole derivatives acquired a special attention due to their wide range of pharmacological activities especially the therapeutic activities. Through the market it was found that many pharmacological drugs containing the thiazole nucleus were known.

OBJECTIVE

This work aimed to synthesize target molecules not only possess anti-tumor activities but also kinase inhibitors. The target molecules were obtained starting from the arylhydrazonocyclohexan-1,3-dione followed by their heterocyclization reactions to produce anticancer target molecules.

METHODS

The arylhydrazone derivatives 3a-c underwent different heterocyclization reactions to produce thiophene, thiazole, pyrazole and 1,2,4-triazine derivatives. The anti-proliferative activity of twenty six compounds among the synthesized compounds toward the six cancer cell lines namely A549, H460, HT-29, MKN-45, U87MG, and SMMC-7721 was studied.

RESULTS

Anti-proliferative evaluations, tyrosine and Pim-1 kinase inhibitions were perform for most of the synthesized compounds where the varieties of substituent through the aryl ring and the thiophene moiety afforded compounds with high activities.

CONCLUSION

The compounds with high anti-proliferative activity towards the cancer cell lines showed that compounds 3b, 3c, 5e, 5f, 8c, 9c, 11c, 12c, 14e, 14f and 16c were the most cytotoxic compounds. Further tests of the latter compounds toward the five tyrosine kinases c-Kit, Flt-3, VEGFR-2, EGFR, and PDGFR and Pim-1 kinase showed that compounds 3c, 5e, 5f, 8c, 9c, 12c, 14e, 14f and 16c were the most potent of the tested compounds toward the five tyrosine kinases and compounds 6d, 11a, 20b and 21e were of the highest inhibitions towards Pim-1 kinase. Pan Assay Interference Compounds (PAINS) for the most cytotoxic compounds showed zero PAINS alert and can be used as lead compounds.

Synthesis of 2H-Chromenes via Unexpected [4 + 2] Annulation of Alkynyl Thioethers with o-Hydroxybenzyl Alcohols

A novel Brønsted acid-catalyzed reaction of alkynyl thioethers with o-hydroxybenzyl alcohols via an unexpected formal [4 + 2] annulation has been developed. This metal-free protocol leads to the facile and practical synthesis of valuable polysubstituted 2H-chromenes in mostly good to excellent yields under mild reaction conditions and features a wide substrate scope and excellent functional group tolerance.

Diastereoselective synthesis of 3,3-disubstituted 3-nitro-4-chromanone derivatives as potential antitumor agents

We report an efficient and highly diastereoselective protocol for the rapid construction of 3-nitro substituted 4-chromanones by an intramolecular Michael-type cyclization of α-nitro aryl ketones bearing unsaturated ester units.