Molecular Hybrid Design, Synthesis, In Vitro Cytotoxicity, In Silico ADME and Molecular Docking Studies of New Benzoate Ester-Linked Arylsulfonyl Hydrazones

In this paper, we present the synthesis and characterization of two known sulfonyl hydrazides (1 and 2) and their new sulfonyl hydrazone derivatives (9-20), as well as in vitro and in silico investigations of their cytotoxic properties against human lung (A549) and human breast (MCF-7) cancer cell lines. The target compounds (9-20) obtained in high yields were synthesized for the first time by a multi-step reaction, and their structures were confirmed by elemental analysis and various spectral techniques, including FT-IR, 1H-, and 13C-NMR. The antiproliferative profiles of these compounds (1, 2, and 9-20) in this study were determined at concentrations of 200, 100, 50, and 25 µM against selected cancer cell lines for 72 h using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method. Except for compounds 1 and 2, other compounds (9-20) demonstrated cytotoxic activity at concentrations lower than 200 µM. The newly synthesized compounds (9-20) demonstrated antiproliferative activities at a micromolar level, with IC50 values in the range of 29.59-176.70 μM for the A549 cell line and 27.70-170.30 μM for the MCF-7 cell line. Among these compounds, compound 15 (IC50 = 29.59 μM against A549 cell line and IC50 = 27.70 μM against MCF-7 cell line) showed the highest cytotoxic activity against these two cancer cell lines compared to the reference drug cisplatin (IC50 = 22.42 μM against A549 cell line and IC50 = 18.01 μM against MCF-7 cell line). From docking simulations, to establish a plausible binding mode of compounds, we noticed that compound 15 demonstrated the highest affinity (-6.8508 kcal/mol) for estrogen receptor-beta (ERbeta) compared to others, suggesting promising ERbeta binding potential. Most compounds followed Lipinski's rule of five, with acceptable logP values. Additionally, all had mixed gastrointestinal absorption and limited blood-brain barrier permeability. Overall, our study proposed new sulfonyl hydrazones as a potential class of anticancer agents.

Divergent Transformations of 2-Nitro-1H-benzo[f]chromenes in Reactions with Alkylidenemalononitriles: Access to Naphtho[2,1-b]furans via Base-Mediated Pyran Ring Contraction

The action of 2-(1-arylethylidene)malononitriles on 2-nitro-1H-benzo[f]chromenes in the presence of Et3N and MoO3·2H2O results in naphtho[2,1-b]furans containing an allylidenemalononitrile unit in the α-position. The reaction proceeds with contraction of the pyran ring via a cascade carba-Michael addition/retro-oxa-Michael reaction/tautomerization/SN2/oxidation process. In contrast, the reaction of 2-nitro-1H-benzo[f]chromenes with the cyclic Knoevenagel adduct derived from 1-indanone and malononitrile leads to dihydroindeno[1,2-c]xanthenes. The possibility of further transformations of naphtho[2,1-b]furan derivatives as useful precursors and their optical properties were also investigated.

Tunable Zinc-Mediated Reductive Cyclization of Diastereomeric 3-Nitro-4-phenacyl-2-(trihalomethyl)chromanes to Fused Pyrroline N-Oxides, Pyrrolines, and Pyrrolidines

Reductive cyclization of trans,trans- and trans,cis-isomers of the 2-CF3-substituted 3-nitro-4-phenacylchromanes with Zn-based reductive systems, depending on the conditions, affords 4-CF3-substituted 1,3a,4,9b-tetrahydrochromeno[3,4-b]pyrrole 3-oxides, 1,3a,4,9b-tetrahydrochromeno[3,4-b]pyrroles, or 1,2,3,3a,4,9b-hexahydrochromeno[3,4-b]pyrroles in good yields without changing the relative configuration of the pyran ring. A similar process involving the 2-CCl3-substituted 3-nitro-4-phenacylchromanes is accompanied by reductive dehalogenation to form the corresponding 4-dichloromethyl-substituted fused chromanes along with the 3-(2-hydroxyaryl)-2-(2,2-dichlorovinyl)-5-phenyl-2H-pyrroline 1-oxides as pyran ring opening products. The structure and relative configuration of the obtained products was reliably confirmed by X-ray diffraction analysis and 2D NMR spectroscopy.

Regio- and stereoselective synthesis of functionalized tetrahydro-benzochromenes and hexahydrochromenochromenones via [4 + 2] annulation of curcumins with nitrochromenes

A base-mediated regio- and stereoselective synthesis of functionalized tetrahydro-6H-benzo[c]chromenes and hexahydro-1H,6H-chromeno[6,5-c]chromenone is disclosed here. It involves a [4 + 2] annulation via cascade double and triple Michael reactions between curcumins and nitrochromenes in the presence of Cs₂CO₃ and DBU, respectively, at room temperature, and it offers a diverse array of products as single regio- and diastereomers in excellent yields under mild conditions. Preliminary studies towards developing an enantioselective version under organocatalytic conditions met with only limited success but revealed a potentially interesting kinetic resolution pathway.

Different Behavior of 2-Substituted 3-Nitro-2H-chromenes in the Reaction with Stabilized Azomethine Ylides Generated from α-Iminoesters

The AgOAc-catalysed reaction of 3-nitro-2-phenyl-2H-chromenes with stabilized azomethine ylides generated from the imines based on methyl glycinate and arylaldehydes leads to a mixture of endo and endo' isomers of the corresponding chromeno[3,4-c]pyrrolidines in a ratio of 2.0-2.3:1 in 85-93% total yields as a result of a Michael addition/Mannich reaction sequence. In a similar reaction involving 2-trifluoromethyl-3-nitro-2H-chromenes, only endo chromeno[3,4-c]pyrrolidines are formed in 85-94% yields. 3-Nitro-2-(trichloromethyl)-2H-chromenes under the same conditions react with these azomethine ylides to give the corresponding Michael adducts as individual anti-isomers with the cis,trans-configuration of the chromane ring in 40-67% yields. Some 4-CF₃-substituted chromano[3,4-c]pyrrolidines exhibited high cytotoxic activity against HeLa human cervical carcinoma cells.

Green and Efficient Construction of Chromeno[3,4-c]pyrrole Core via Barton-Zard Reaction from 3-Nitro-2H-chromenes and Ethyl Isocyanoacetate

A regioselective one-pot method for the synthesis of 1-ethyl 2,4-dihydrochromene[3,4-c]pyrroles in 63-94% yields from available 2-phenyl-, 2-trifluoro(trichloro)methyl- or 2-phenyl-2-(trifluoromethyl)-3-nitro-2H-chromenes and ethyl isocyanoacetate through the Barton-Zard reaction in ethanol at reflux for 0.5 h, using K₂CO₃ as a base, has been developed.

The Diverse Biological Activity of Recently Synthesized Nitro Compounds

The search for new and efficient pharmaceuticals is a constant struggle for medicinal chemists. New substances are needed in order to treat different pathologies affecting the health of humans and animals, and these new compounds should be safe, effective and have the fewest side effects possible. Some functional groups are known for having biological activity; in this matter, the nitro group (NO₂) is an efficient scaffold when synthesizing new bioactive molecules. Nitro compounds display a wide spectrum of activities that include antineoplastic, antibiotic, antihypertensive, antiparasitic, tranquilizers and even herbicides, among many others. Most nitro molecules exhibit antimicrobial activity, and several of the compounds mentioned in this review may be further studied as lead compounds for the treatment of H. pylori, P. aeruginosa, M. tuberculosis and S. mutans infections, among others. The NO₂ moiety triggers redox reactions within cells causing toxicity and the posterior death of microorganisms, not only bacteria but also multicellular organisms such as parasites. The same effect may be present in humans as well, so the nitro groups can be considered both a pharmacophore and a toxicophore at the same time. The role of the nitro group itself also has a deep effect on the polarity and electronic properties of the resulting molecules, and hence favors interactions with some amino acids in proteins. For these reasons, it is fundamental to analyze the recently synthesized nitro molecules that show any potential activity in order to develop new pharmacological treatments that enhance human health.

Highly diastereoselective annulation of 2-substituted 3-nitro-2H-chromenes with hemicurcuminoids and curcuminoids via a double and triple Michael reaction cascade

The K2CO3-catalysed double Michael addition of (E)-1,5-diaryl- and 1-alkyl-5-arylpent-4-ene-1,3-diones to 2-trifluoromethyl- and 2-phenyl-substituted 3-nitro-2H-chromenes in dichloromethane at room temperature for 48 h results in 10-aroyl(acyl)-7-aryl-6a-nitro-6,6a,7,8,10,10a-hexahydro-9H-benzo[c]chromen-9-ones in 75-98% yields as individual...

Synthesis of 5H-chromeno[3,4-b]pyridines via DABCO-catalyzed [3 + 3] annulation of 3-nitro-2H-chromenes and allenoates

The DABCO-catalyzed [3 + 3] annulation between 3-nitro-2H-chromenes and benzyl 2,3-butadienoate has been developed as a route to 5H-chromeno[3,4-b]pyridine derivatives. Under optimal reaction conditions, 5H-chromeno[3,4-b]pyridines incorporating two allenoate units were obtained in moderate to good yields (30-76%). The same type of transformation could be carried out using butynoates as allene surrogates. Mechanistic studies by mass spectrometry allowed the identification of the key intermediates involved in the reaction mechanism. The reported synthetic methodology represents an entirely new approach for the synthesis of the 5H-chromeno[3,4-b]pyridine core structure based on allene chemistry.

Synthesis of chromans and kinetic resolution of 2-aryl-3-nitro-2H-chromenes via the NHC-bound azolium homoenolate pathway

Herein, an effective kinetic resolution (KR) of racemate 2-aryl-3-nitro-2H-chromenes to afford synthetically valuable chromans and 2H-chromenes through an NHC-bound acyl azolium homoenolate pathway has been demonstrated.

A regio- and stereocontrolled approach to the synthesis of 4-CF3-substituted spiro[chromeno[3,4-c]pyrrolidine-oxindoles]viareversible [3+2] cycloaddition of azomethine ylides generated from isatins and sarcosine to 3-nitro-2-(trifluoromethyl)-2H-chromenes

The first example of regio- and stereocontrolled synthesis of 4-CF₃-spiro[chromeno[3,4-c]pyrrolidine-oxindoles] with anticancer activity.