Search

A series of novel (3-aryl-1,2-oxazol-5-yl) methyl 6-fluoro-4-oxo-4H- -chromene-2-carboxylate derivatives (C1-C12) were synthesized by Cu (I) catalyzed reaction of in situ generated nitrile oxides with prop-2-yn-1-yl 6-fluoro-4-oxo-4H-chromene-2-carboxylate in good yields and investigated their antioxidant and antimicrobial activities. Among all the synthesized compounds, C1 (IC50: 16.43 ± 0.57 μM) and C12 (IC50:15.98 ± 0.72 μM) have registered good antioxidant activity as compared to the standard drug Trolox. Compound-C1, C3, and C6 have registered very good inhibition against all gram-positive and gram-negative bacterial strains with MIC values ranging from 9.375 to 37.5 (μg mL-1). Compound-C7, C8, C9, C10, and C11 have registered good inhibition against B. subtilis and S. aureus with MIC values ranging from 18.75 to 37.5 (μg mL-1). Compound-C10 and C11 against P. aero-ginosa have shown prominent activity than the standard drug Penicillin (MIC: 12.5 μg mL-1) with MIC 9.375 μg mL-1 (~ 1.33 fold potent than Penicillin). Compound-C7, C8, and C9 have registered good to moderate antifungal activity against four tested fungal strains with MIC values ranging from 18.75 and 37.5 μg mL-1

Due to the potential antimicrobial activity of pyranochromenones and pyrazolines moieties, hybrid compounds containing both, substituted 4-Chloro-8-methyl-2-(1,3-diphenyl- -1H-pyrazol-4-yl)-1,5-dioxa-2H-phenanthren-6-ones (4a-g), have been synthesized from substituted (E)-1-(7-Hydroxy-4-methyl-8-coumarinyl)-3-(1,3-diphenyl -1H-pyrazol-4-yl)-2-propen-1-ones (3a-g) in good yield using the Vilsmeier reaction, by microwave-assisted method. The structures of all the compounds have been established on the basis of analytical and spectral data. All the synthesized compounds were tested in vitro for their antibacterial and antifungal activities. Some of the compounds have shown very good activity compared to standard drugs against all pathogenic bacteria and fungi.

Chromenes are a significant family of heterocyclic chemicals that have a wide range of biological applications, a simple chemical structure, and only mildly undesirable side effects. The synthesis of a wide range of chromene analogs that displayed unexpected behaviors via numerous mechanisms was investigated by a number of different research teams, which led to the discovery of multiple pathways for their synthesis. In addition, different chromene-fused heterocycles exhibit a wide variety of fascinating biological actions, including those that are anticancer, anticonvulsant, antibacterial, anticholinesterase, antituberculosis, and anti-diabetic. In light of this, the purpose of this study is to highlight the many synthesis techniques and antibacterial activity associated with chromene-fused heterocyclic compounds. Moreover, such research can open avenues for exploring other therapeutic applications of these compounds in various disease areas, as their biological activities extend beyond antibacterial effects., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Some interesting nitrogen heterocycles, as well as other products, were synthesized by reactions of 2-cyano-N′-[(1,3-diphenyl-1H-pyrazol-4-yl)methylidene]acetohydrazide with phenyl isothiocyanate/elemental sulfur, 3,4,5-trimethoxybenzaldehyde, 4-hydroxy-1,1′-biphenyl-3-carbaldehyde, 2-oxoquinoline-3-caraldehyde, triethyl orthoformate, ethyl cyanoacetate, and thiosemicarbazide. The structures of all isolated compounds were established from their analytical and spectral data. [ABSTRACT FROM AUTHOR]

Novel chromenyl α-aminophosphonic acid 4 and dialkyl chromenyl phosphonate 6 have been obtained. In addition, some novel types of chromene fused with phosphorus heterocycles such as chromeno[4,3-c][1,2]azaphospholes 5 and 7, chromeno[2,3-d][1,3,2]diazaphosphinine 8 and 1,2-oxaphosphinino[3,4-c]pyridine 10 have been synthesized. The methodology depended on treatment of 2-imino-2H-chromene-3-carboxamide (1) with some phosphorus esters. The synthesized compounds were evaluated for antioxidant and cytotoxic activities. Among the synthesized compounds, compound 5 exhibited the most antioxidant activity with IC50 = 2.8 μg/mL in comparison with ascorbic acid as standard antioxidant. Also, compound 5 had significant cytotoxic effects against four cancer cell lines. Its IC50 values ranged between 4.96 and 7.44 μg/mL in comparison to doxorubicin (IC50 = 0.426–0.493 μg/mL). [ABSTRACT FROM AUTHOR]

A new series of chromene based 1,2,3-triazole derivatives has been synthesized by incorporating biologically active heterocyclic rings containing chromene and triazole moieties in one molecular structure. All newly synthesized compounds are characterized by 1H and 13C NMR, mass, and IR spectra. The title compounds are tested for their activity against different bacterial and fungal strains, and antioxidant activity. Several compounds are determined to be potent antimicrobial and antioxidant agents. [ABSTRACT FROM AUTHOR]

Chiral chromene motifs are important heterocycles in numerous natural products and bioactive molecules. Among them, flavenes, flavanes, and flavanones, which consist of the 2‐aryl‐chromene skeleton are observed most frequently. As subgroups of flavonoids, they often occur in various plants and show many biological activities, such as antitumor, antioxidant, antibacterial, anti‐inflammatory, and anticoagulant properties. This Minireview summarizes recent reports on catalytic asymmetric synthesis of flavenes, flavanes, and flavanones. [ABSTRACT FROM AUTHOR]

Phenolic groups are responsible for the high clearance and low oral bioavailability of the estrogen receptor alpha (ERα) clinical candidate GDC-0927. An exhaustive search for a backup molecule with improved pharmacokinetic (PK) properties identified several metabolically stable analogs, although in general at the expense of the desired potency and degradation efficiency. C-8 hydroxychromene 30 is the first example of a phenol-containing chromene that not only maintained excellent potency but also exhibited 10-fold higher oral exposure in rats. The improved in vivo clearance in rat was hypothesized to be the result of C-8 hydroxy group being sterically protected from glucuronide conjugation. The excellent potency underscores the possibility of replacing the presumed indispensable phenolic group at C-6 or C-7 of the chromene core. Co-crystal structures were obtained to highlight the change in key interactions and rationalize the retained potency. [ABSTRACT FROM AUTHOR]

The Chromene derivatives having heteroatoms as active sites were investigated for scaling downthe corrosion process in mild steel (MS). The effectiveness of the inhibitors was monitored by gravimetric potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. Observations suggested that the mechanism of inhibition is mainly due to the adsorption of the inhibitor molecules on the MS surface. Adsorption of both inhibitors follows the Langmuir adsorption isotherm. Tafel curve shows that both inhibitors act as mixed type inhibitor. Morphological studies were done by FESEM and AFM instruments. These images indicated the formation of a protective layer on the MS surface which slows down the process of corrosion. DFT calculation provides the valuable quantum chemical parameters for both inhibitors which are supportive of the results obtained from gravimetric and EIS methods. [ABSTRACT FROM AUTHOR]

The expansion of proficient and environmentally benign synthetic protocols has engrossed increasing attention in recent organic syntheses in view of the mounting concern over the environment. As part of this green concept, our group designed novel LTTM by using Glycerol and proline (1:1) at reflux condition, and effectiveness of novel DES or LTTM has been studied for the synthesis of 7-(aryl)-10-methyl-6 H ,7 H -chromeno[4,3- d ]thiazolo[3,2- a ]pyrimidin-6-one derivatives via Multicomponent reaction. The synthetic methodology with the use of novel LTTM as green solvent and inexpensive, biodegradable, plays a dual role (recyclable catalyst and solvent) with its operational simplicity and maximum greener synthetic efficiency with green chemistry metrics calculations will be attractive for academic and industrial research. The synthesized derivatives have been evaluated for mosquito larvicidal bioassay using two mosquito species namely Aedes aegypti and Culex quinquefasciatus. Unlabelled Image • New entry of DES or LTTM. • Products with excellent yield with non-chromatographic purification, shorter reaction time. • Successively reused LTTM on the basis of Green chemistry. • Admirable green metric correlation with synthesized scaffolds with high atom economy. • Synthesized derivatives exhibit an excellent mosquito larvicidal activity. [ABSTRACT FROM AUTHOR]

A novel series of 3-amino-2,2-dialcoxy-7,7-dimethyl-5-oxo-4-phenyl-3,4,5,6,7,8-hexahydro-2H-chromene-3-carbonitriles are synthesized by oxidative difunctionalization (geminal dialkoxylation and migration of the amino group) of 2-amino-4-aryl-7,7-dimethyyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles in the presence of iodobenzenediacetate in water medium with excellent yields. All the newly synthesized compounds are characterized by IR, 1H and 13C NMR and Mass spectral data. The representative synthesized analogues are screened in vitro for antibacterial and antifungal activity using Gentamycin sulphate and Nystatin as standard drugs. [ABSTRACT FROM AUTHOR]

In this paper, we highlight some addition/cycloaddition reactions of allenylphosphonates and allenylphosphine oxides, mostly based on the work done in our laboratory. Thus the electrophilic addition of iodine monochloride (ICl) with allenylphosphine oxides affords cyclic phosphonium salts rather than γ-chloro-β-iodovinylphosphine oxides (NMR, HRMS, X-ray) that exhibit rather unusual downfield shifts in the 31P NMR spectra. These compounds undergo hydrolysis to afford γ-hydroxy-β-iodovinylphosphine oxides; the hydroxymethyl group in these compounds can be oxidized by Dess-Martin periodinane to afford the corresponding aldehyde-substituted vinylphosphine oxides. A [2+2] cycloaddition product of an allenylphosphonate has also been structurally characterized. Other reactions that are highlighted include those leading to (Z)/(E)-β-aminovinylphosphonates, β-ketophosphonates (and their utility in Horner-Wadsworth-Emmons reaction), indolyl/furanyl/isocoumaranyl/naphthyl phosphine oxides, thiophosphorylated phosphonates and azo-substituted coumarin phosphonates. [ABSTRACT FROM AUTHOR]

The baker's yeast catalyzed one-pot three-component cyclocondensation of salicylaldehyde, malononitrile or ethyl cyanoacetate, and nitroalkanes for the synthesis of substituted 2-amino-4H-chromene derivatives is presented. The highlights of the protocol is a use of a biodegradable catalyst which is inexpensive, having simple reaction conditions, in other words, at room temperature and neutral pH, good-to-excellent yield, and simple workup procedure. [ABSTRACT FROM AUTHOR]

In this study, a series of novel chromene based 2,6-disubstituted-thiazolo[3,2-b] [1,2,4] triazole derivatives (7a-g) were synthesized by condensing 5-substituted-1,2,4-traizole-thione (6a-g) using poly phosphoric acid through one pot reaction. The structure of new compounds was supported by 1H NMR, 13C NMR and MS data. The synthesized compounds were evaluated using writhing assays for analgesic and carrageenan-induced rat paw edema method for anti-inflammatory activities respectively. Some of the newly synthesized compounds 7c, 7f and 7g showed very good anti-inflammatory activity with 90.83%, 85.81% and 88.40% protection respectively along with low GI toxicity as compared to standard drug ibuprofen while compounds 7a, 7b, 7d and 7f showed highest analgesic activity with 52.54%, 54.02%, 56.76% and 52.45% protection among them compound 7d showed better protection than standard drug ibuprofen. [ABSTRACT FROM AUTHOR]

Abstract: This work describes a new method for a one-pot multicomponent condensation of a variety of aldehydes with dimedone and malononitrile in water, providing a simple and effectual procedure for preparing 4H-chromene under reflux conditions with magnetic nanoparticles supported on functionalized 7-aminonaphthalene-1,3-disulfonic acid-functionalized silica as catalyst. (Fe3O4@SiO2@Propyl-ANDSA) has been investigated as a novel catalyst in this reaction. This protocol is novel in (1) avoiding toxic solvents (2) introducing a catalyst with ideal features such as chemical stability, low toxicity, cost-effectiveness and, most importantly, easy, fast and comfortable separation using an external magnet. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Series of novel 2-aryl-4 H -chromene and 3-aryl-1 H -benzo[ f ]chromenes were synthesized. • Four compounds were identified as potent α-glucosidase inhibitors. • Structure-activity relationships were derived via molecular modeling. • Lead compound 6a is superior to acarbose with IC 50 of 62.26 µM. • Lead compound 6a effectively prevents postprandial hyperglycemia in rats. Abstract Herein we report a study of novel arylchromene derivatives as analogs of naturally occurring flavonoids with prominent α-glucosidase inhibitory properties. Novel inhibitors were identified via simple stepwise in silico screening, efficient synthesis, and biological evaluation. It is shown that 2-aryl-4H-chromene core retains pharmacophore properties while being readily available synthetically. A lead compound identified through screening inhibits yeast α-glucosidase with IC 50 of 62.26 µM and prevents postprandial hyperglycemia in rats at 2.2 mg/kg dose. [ABSTRACT FROM AUTHOR]

Fe3O4 supported graphene quantum dots (GQDs) (Fe3O4@GQDs) was prepared under microwave irradiation. Piperidine was bound to Fe3O4@GQDs via its reaction with 3-piperidinopropyltrimethoxysilane and piperidine-functionalized Lewis basic nano-catalyst (Fe3O4@GQDs-Pip) was prepared. This freshly prepared catalyst was evaluated as a heterogeneous magnetic reusable catalyst for the one-pot synthesis of 2- aminochromenes under MW-assisted solvent-free conditions. Two composite particles, Fe3O4@GQDs and Fe3O4@GQDs-Pip were characterized by FT-IR, XRD, SEM, TGA and VSM analytical methods. The catalyst could be easily recovered by magnetic separation and recycled for 5 times without significant loss of its catalytic activity. [ABSTRACT FROM AUTHOR]

This work aimed to synthesis some new different heterocyclic compounds based on phenylpyrazole-4-carbaldehyde derivative (1) reacted with cyanoacetohydrazide to afford N'-[(5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)methylene]-2-cyanoacetohydrazide (2). It was cyclized by acetyl acetone, and aromatic aldehyde, respectively, to give pyrazolo-pyridone (4) and substituted pyrazolochromene (6 and 8), respectively. Pyrazolo triazole (10) was obtained by coupling of 1-azido-4-fluorobenzene with (2), which was diazotized by 3-(chlorodiazenyl)-4,6-dimethyl--1H-pyrazolo[3,4-b]pyridine to give pyrazolo pyridine derivative (11). N,N-Dimethylformamide dimethyl acetal reacted with (2) to afford [(5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)methylene]-2-cyano-3-(dimethylamino)-acrylohydrazide (13). The compound before compound yield substituted pyrazole-4-carbohydrazide (15). Also, compound (2) reacted with phNCS in the presence of KOH and furnish compound (22), which preferred over compound (20) All synthesized compounds were established using IR, ¹H-NMR. All synthesized compounds were screened for their antimicrobial activities. [ABSTRACT FROM AUTHOR]

Keywords: asymmetric synthesis; phosphite; chromene; organocatalysis; phospha-Michael; biological activity EN asymmetric synthesis phosphite chromene organocatalysis phospha-Michael biological activity 3181 3181 1 10/18/23 20231013 NES 231013 The inside cover picture is an artistic illustration of the bifunctional activation of the phosphite and the iminochromene by a chiral squaramide tattooed on the arm of a chemist. Asymmetric synthesis, phosphite, chromene, organocatalysis, phospha-Michael, biological activity Cover Picture: Asymmetric Organocatalyzed Phospha-Michael Addition for the Direct Synthesis of Biologically Active Chromenylphosphonates (Adv. [Extracted from the article]

[Display omitted] • A novel series of eighteen (3a-r) thiosemicarbazones was synthesized. • Characterization of (3a-r) was done by FTIR, 1HNMR, 13CNMR and Elemental analysis. • Probed for inhibition potential against α-Glycosidase. • Compound 3 g was proceeded for mechanistic studies. • Molecular docking studies were performed to find the binding mode of most potent inhibitor. • 2D-QSAR model was used to find profound influence on biological activity. Type-2 Diabetes Mellitus (T2DM) is one of the most common metabolic disorders in the world and over the past three decades its incidence has increased drastically. α -Glucosidase inhibitors are used to control the hyperglycemic affect of T2DM. Herein, we report the synthesis, α -glucosidase inhibition, structure activity relationship, pharmacokinetics and docking analysis of various novel chromone based thiosemicarbazones 3(a-r). The derivatives displayed potent activity against α -glucosidase with IC 50 in range of 0.11 ± 0.01–79.37 ± 0.71 µM. Among all the synthesized compounds, 3a (IC 50 = 0.17 ± 0.026 µM), 3 g (IC 50 = 0.11 ± 0.01 µM), 3n (IC 50 = 0.55 ± 0.02 µM), and 3p (IC 50 = 0.43 ± 0.025 µM) displayed higher inhibitory activity as compared to the standard, acarbose. Moreover, we have developed a statistically significant 2D-QSAR model (R2 tr :0.9693; F: 50.4647 and Q2 LOO :0.9190), which can be used in future to further design potent thiosemicarbazones as inhibitors of α -glucosidase. [ABSTRACT FROM AUTHOR]

In the present paper, an efficient one-pot synthesis of 7-alkyl-6H,7H-naphtho[1',2':5,6]pyrano[3,2-c]chromen-6-ones is described by three-component reaction of β-naphthol, aromatic aldehydes and 4-hydroxycoumarin using ZnO nanoparticles under solvent-free conditions. The present method provides a novel and efficient procedure for the synthesis of chromene derivatives with some advantageous such as short reaction times, easy workup, high yields, wide range of products, reusability of the catalyst, little catalyst loading and green conditions in the presence of ZnO nanoparticles (7 mol%) at 110 ºC.

A series of pyrimidine and thiazine derivatives synthesized by one pot reaction of cyclopentanone with a mixture of an aromatic aldehyde namely o-anisaldehyde and different ureas namely urea, guanidine and thiourea, respectively. Furthermore, cycloaddition reaction of active methylene reagents namely acetyl acetone, malononitrile, ethyl cyanoacetate, cyanoacetamide and N-phenyl cyanoacetamide with 2,6-bis(2-methoxybenzylidene)-cyclohexanone afforded chromene and quinoline derivatives in basic medium. The antitumor evaluation of some new compounds against three human cell lines namely MCF-7, NCI-H460 and SF-268 showed significant and moderate activity compared with the positive control doxorubicin.

In the title flavonoid derivative, C19H16O5, the chromene portion is planar (r.m.s. deviation = 0.022 Å) with the substituents lying closely to the same plane. The dihedral angle between its mean plane and that of the benzene ring is 4.9 (1)°. This planarity is due, in part, to the presence of a strong intramolecular C—H...O hydrogen bond and to two weak C—H...O contacts. In the crystal, neighboring molecules are linked by a C—H...O hydrogen bond and a C—H...π interaction, forming chains along the a-axis direction.

A new chromene derivative, alternapyran (1), along with three known compounds (2–4), was isolated from the Alternaria sp. ZG22 obtained from a Dasymaschalon rostratum collected from the Hainan. The structure of the new compound 1 was elucidated by NMR and mass spectroscopic data. Compounds 2 and 3 showed broad spectrum antibacterial activity against four terrestrial pathogenic bacteria. [ABSTRACT FROM AUTHOR]

A novel series of 5H-chromenopyridines was identified as anticancer agents in our continuing effort to discover and develop new small molecule anti-proliferative agents. Based on our initial lead SP-6-27 compound, we designed and synthesized novel tricyclic 5H-thiochromenopyridine and 5H-chromenopyridine analogs to evaluate the impact of an additional ring, as well as conformational flexibility on cytotoxic activity against human melanoma and glioma cell lines. All of the 5H-thiochromenopyridines have been achieved in good yields (89%–93%) using a single-step, three-component cyclization without the need for purification. The 5H-chromenopyridine analog of the potent 5H-thiochromenopyride was obtained in a good yield upon purification. All newly-prepared 5H-thiochromenopyridines showed good to moderate cytotoxicity against three melanoma and two glioma cell lines (3–15 μM). However, the 5H-chromenopyridine analogue that we prepared in our laboratory lost cytotoxic activity. The moderate cytotoxic activity of 5H-thiochromenopyridines shows the promise of developing chromenopyridines as potential anticancer agents.

The structural motif that results from the fusion of a benzene ring to a heterocyclic pyran ring, known as chromene, is broadly found in nature and it has been reported to be associated with a wide range of biological activity. Moreover, asymmetric organocatalysis is a discipline in expansion that is already recognized as a well-established tool for obtaining enantiomerically enriched compounds. This review covers the particular case of the asymmetric synthesis of 2-amino-3-cyano-4H-chromenes using organocatalysis. Herein, we show the most illustrative examples of the methods developed by diverse research groups, following a classification based on these five different approaches: (1) addition of naphthol compounds to substituted α,α-dicyanoolefins; (2) addition of malononitrile to substituted o-vinylphenols; (3) addition of malononitrile to N-protected o-iminophenols; (4) Michael addition of nucleophiles to 2-iminochromene derivatives; and (5) organocatalyzed formal [4+2] cycloaddition reaction. In most cases, chiral thioureas have been found to be effective catalysts to promote the synthetic processes, and generally a bifunctional mode of action has been envisioned for them. In addition, squaramides and cinchona derivatives have been occasionally used as suitable catalysts for the substrates activation.

Nano tin dioxide was employed as a catalyst for efficient and facile preparation of pyran derivatives via the one-pot three component condensation reaction of various aldehydes with malononitrile and dimedone. Chromene derivatives via the one-pot three component condensation reaction of various aldehyde with malononitrile and 4-hydroxycoumarin were also synthesized by this novel catalyst. The described novel synthesis method proposes several advantages of mild condition, safety, high yields, short reaction times compared to the traditional method of synthesis.

In this study, new quinazoline-chromene hybrid compounds were synthesized. The cytotoxic effects on cell viability of the hybrid compounds were tested against A549 human lung adenocarcinoma and BEAS-2B healthy bronchial epithelial cell lines in vitro. In addition, the ability of the active compounds to inhibit cell migration was tested. Molecular docking studies were performed to evaluate the ligand-protein interactions, and molecular dynamics simulations were performed to determine the interactions and stability of ligand-protein complexes. In silico absorption, distribution, metabolism, and excretion (ADME) studies were conducted to estimate the drug-likeness of the compounds. Compounds 4 (IC 50  = 51.2 µM) and 5 (IC 50  = 44.2 µM) were found to be the most active agents against A549 cells. They are found to be more selective against A549 cells than the reference drug doxorubicin. They also have the ability to significantly inhibit cell migration. They have the best docking scores against epidermal growth factor receptor (EGFR) (-11.300 and -11.226 kcal/mol) and vascular endothelial growth factor receptor 2 (VEGFR2) (-10.987 and -11.247 kcal/mol), respectively. In MD simulations, compounds 4 and 5 have strong hydrogen bond interactions above 80% of simulation times and showed a low ligand root mean square deviation (RMSD) around 2 Å. According to the ADME analysis, compounds 4 and 5 exhibit excellent drug-likeness and pharmacokinetic characteristics., (© 2023 Deutsche Pharmazeutische Gesellschaft.)

A series of chromene derivatives (5a-f) were prepared by multistep synthesis process using 2-[3-phenyl prop-2-ene nitrile] 1,3-benzothiazole and dimedone using piperidine as catalyst in ethanol. The reaction was found to proceed via Knoevenagel condensation of aldehydes with benzothiazole, followed by the elimination to afford the 2-(benzo[d]thiazol-2-yl)-3-(aryl)acrylonitrile, which then undergoes Michael addition with 5,5-dimethyl-1,3-cyclohexanedione, followed by intramolecular O-cyclization to give the products. The structures of all novel constructed derivatives were corroborated by elemental analysis and spectral data (FT-IR, 1H-NMR, 13C-NMR and Mass). Subsequently, the compounds were tested for their in-vivo anti-inflammatory activity. This study revealed that these synthesized derivatives tend to have significantly anti inflammatory activity and shall prove as structural templates in the design and development of new anti inflammatory drugs. [ABSTRACT FROM AUTHOR]

Two new chromene derivatives, songaricachromenes A (1) and B (2), were isolated from Artemisia songarica, along with 10 known compounds (3-12). The structures and stereochemistry of the new compounds were elucidated by analyses of the NMR, MS, and electronic circular dichroism (ECD) data. All the isolates (1-12) were evaluated for their NO inhibitory effects on LPS-stimulated BV-2 microglial cells. [ABSTRACT FROM AUTHOR]

Novel 2-sulfido-2,3-dihydro-4H-chromeno[2,3-d][1,3,2]diazaphosphinines are obtained in a simple one-pot procedure via treatment of 2-imino-2H-chromene-3-carboxamide with various phosphorus sulfides. Possible reaction mechanisms are proposed. The structure of the obtained products is confirmed by elemental analyses and spectral tools. [ABSTRACT FROM AUTHOR]

The N‐substituted exo‐2‐oxazolidinone dienes are versatile molecules that undergo a variety of reactions. To further explore this versatility, Diels‐Alder reactions were carried out with novel naphthalene chalcones. Upon attempting the Diels‐Alder reaction with 2‐hydroxy‐1,4‐naphthoquinone, the formation of chromene unexpectedly took place via a formal [3+3] cycloaddition reaction. The observed reaction was then achieved with other 1,3‐dicarbonyl compounds. Cycloaddition Tales: Versatile N‐substituted exo‐2‐oxazolidinone dienes underwent different cycloaddition reactions, including the famous Diels‐Alder reaction, with novel chalcones to synthesize benzoxazole‐2‐ones and [3+3] formal cycloaddition with 1,3‐dicarbonyl compounds to synthesize chromenes. Both displayed interesting regio‐ and diastereoselectivity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • One-pot synthesis of 6-oxo-7-aryl-6,7-dihydrochromenopyrano[2,3- b ]pyridines was described. • Guanidine hydrochloride as the organocatalyst was used. • Aromatic aldehydes containing various functional groups are well tolerated in the reaction. • Double heterocyclization was carried out in the reaction. Abstract A simple and efficient protocol has been developed for the construction of novel 6-oxo-7-aryl-6,7-dihydrochromenopyrano[2,3- b ]pyridine derivatives using one-pot, three-component cyclocondensation of 4-hydroxycoumarin, various aromatic aldehydes and 2-aminoprop-1-ene-1,1,3-tricarbonitrile using 10 mol % guanidine hydrochloride as the organocatalyst under solvent-free conditions at 90 °C for the first time. The significant features of this protocol are operational simplicity, provide good to high yields, avoidance of toxic solvents, straightforward work-up, no column chromatographic purification and atom-economy which is considered to be relatively environmentally benign. [ABSTRACT FROM AUTHOR]

Abstract: Acid‐modified halloysite nanotubes were used for the first time as a stereoselective catalyst for synthesis of oxygen‐containing heterocycles applying of allyl alcohol (−)‐isopulegol condensation with aldehydes to the octahydro‐2H‐chromenol (4R‐ and 4S‐diastereomers) as an example. The catalysts were characterized by XRF, XRD, N2‐adsorption, FTIR with pyridine and MAS NMR methods. A high ratio of 4R/4S diastereomers (7.6–14.5) under mild conditions in cyclohexane was considerably exceeding previously reported results. Unprecedented selectivity (79–83 %) to 4R isomer of thiophenyl‐substituted chromenol exhibiting high analgesic activity was achieved. An increase in stereoselectivity with a decrease in the halloysite drying temperature and catalyst acidity clearly indicates formation of 4R diastereomer on the weak Brønsted sites. This work is an example that control of the stereoselectivity of acid‐catalyzed organic reactions can be effectively carried out by varying water content on the aluminosilicate surface. Modified halloysite nanotubes can be considered as extremely promising catalysts for stereoselective synthesis of heterocyclic compounds. [ABSTRACT FROM AUTHOR]

Abstract: A convenient and practical synthesis of 4H‐chromenes from the readily accessible o‐hydroxybenzhydryl alcohols and vinyl azides has been achieved. The transformation proceeds through a cascade that involves formation of an ortho‐quinone methide, [4+2]‐cycloaddition and elimination of hydrazoic acid. The reaction is well tolerated with respect to both the o‐hydroxybenzhydrols and the vinyl azides and affords the products in moderate to good yields. [ABSTRACT FROM AUTHOR]

In the present study, we have designed and synthesized indole derivatives by coalescing the indole nucleus with chromene carbonitrile and dihydropyridine nucleus. Two compounds 5c and 6d were selected from series I and II after sequential combinatorial library generation, docking, absorption, distribution, metabolism and excretion (ADME) filtering, anti-proliferative activity, cytotoxicity, and ER-α competitor assay kit by utilizing estrogen receptor-α (ER-α) dominant T47D BC cells line and PBMCs (Peripheral Blood Mononuclear Cells). Cell imaging experiment suggested that both the compounds successfully cross cellular biomembrane and accumulate in nuclear, cytoplasmic and plasma membrane region. Semiquantitative RT-PCR and Western blotting experiments further supported that both compounds reduced the expression of mRNA and receptor protein of ER-α, thereby preventing downstream transactivation and signaling pathway in T47D cells line. Current findings imply that 5c and 6d represent novel ER-α antagonists and may be used in the development of chemotherapy for the management of BC. [ABSTRACT FROM AUTHOR]

Ethyl 2-[(2-amino-3-cyano-4-phenethyl-4 H-naphtho[1,2- b]pyran-8-yl)oxy]acetate has been synthesised by condensation of ethyl 2-chloroacetate with the hydroxy group of 2-amino-8-hydroxy-4-phenethyl-4 H-naphtho[1,2-b]pyran-3-carbonitrile. The latter was prepared from cinnamaldehyde, malononitrile and naphthalene-1,6-diol through Knoevenagel condensation and cyclisation reaction and then reduction with hydrogen in the presence of Pd/C at room temperature. The crystal structure of the title compound was determined. In addition, the compound showed distinct inhibition of the proliferation of some cancer cell lines. [ABSTRACT FROM AUTHOR]

Abstract: An eco‐friendly reaction protocol was developed for the synthesis of heterocyclic hybrid scaffolds through bioisosteric replacement and scaffold hopping approach. The isosteric analogues of salicylaldehyde were designed, identified/synthesized and employed in a three component reaction to afford bioisosteric analogues of 4‐aryl‐4H‐chromenes. Thus central core swapping of benzene‐pyridine/pyrazole ring on 4‐aryl‐4H‐chromenes was achieved under simple one‐pot reaction conditions and easy work‐up. Docking studies show that almost all the compounds possess good binding affinities at the colchicine binding site of tubulin. [ABSTRACT FROM AUTHOR]

A new chromene pyrazoline derivatives fluorescent probe L was designed and synthesized. The probe L appears in a 55-fold fluorescence enhancement after 5 equiv. Zn 2+ was added, and it also exhibits high sensitivity and selectivity for response to Zn 2+ in ethanol-water (V:V = 1:1) solution through “OFF-ON” type process and a possible photoinduced electron transfer (PET). Notably, the probe L distinguishes between Zn 2+ and Cd 2+ . The association constant was considered as 2.38 × 10 3  M −1 via fluorescence titration experiments. The probe L-Zn 2+ complex forms a 1:1 binding stoichiometry which was discussed by Job’s plot. The probe is very highly sensitive with fluorometric detection limit of 1.603 × 10 −10  M. It also shows good reversibility upon addition of EDTA. Furthermore, the viability of L to Zn 2+ has practical application in live cell imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • Acid-modified illite clay as a catalyst for synthesis of octahydro-2 H -chromenol. • Increase of stereoselectivity to 4 R diastereomer with decreasing catalyst acidity or its drying temperature. • Decrease of overall chromenol yield and increase of 4 R /4 S ratio at lower initial concentrations of reagents. • Kinetic modeling of Prins reaction of isopulegol with thiophene-2-carbaldehyde. Prins reaction of (−)-isopulegol with thiophene-2-carbaldehyde to physiologically active substituted octahydro-2 H -chromenol (as 4 R and 4 S diastereomers) was studied in the presence of commercial montmorillonites K-10 and K-30, acid-treated illite and glauconite clays as well as synthetic aluminosilicate AS-36 without of any solvent and in cyclohexane solution. The effect of the reaction temperature, catalyst/reagents ratio, solids drying conditions, and the initial concentrations of reagents on the yield of the desired chromenol and selectivity to diastereomers formation was studied for the first time. The catalysts were characterized by XRF, XRD, MAS NMR, FTIR with pyridine and nitrogen low-temperature sorption methods In the absence of any solvent after 1 h 70.8–99.0% conversion of isopulegol depending on the catalyst was achieved with 78.5–82.0% overall selectivity to octahydro-2 H -chromenol. Ratio of 4 R /4 S diastereomers increased from 3.7 to 4.9 with decrease of the acid sites concentration in the catalyst from 153 to 47 μmol/g. The overall selectivity to chromenol and 4 R /4 S ratio increased with decreasing the drying temperature of illite clay which indicates preferable formation of 4 R isomer in the presence of weak Brønsted acid sites. In cyclohexane as a solvent at same substrate conversion the yield of octahydro-2 H -chromenol on illite clay decreases with a decrease in the catalyst/reagents ratio. At 50% isopulegol conversion the 4 R /4 S ratio increased from 5.7 to 6.8 with a decrease in the initial concentration of reagents from 0.5 to 0.05 mol/l, while the overall selectivity to chromenol decreased from 84.9 to 76.1%. It is established that formation of chromenol and dehydration byproducts (chromenes) occurs both in consecutive and parallel pathways, with only 4 R diastereomer undergoing dehydrated. Kinetic modeling was performed to describe quantitatively observed regularities for the first time. Acid-modified illite L-1 clay is a promising catalyst for the synthesis of octahydro-2 H -chromenol exhibiting analgesic activity. [ABSTRACT FROM AUTHOR]

A set of (−)-isopulegol derived octahydro-2 H -chromen-4-ols was synthesized and evaluated in vitro for antiviral activity against panel of reference influenza virus strains differing in subtype, origin (human or avian) and drug resistance. Compound (4 R )- 11a produced via one-pot synthesis by interaction between (−)-isopulegol and acetone was found to exhibit an outstanding activity against a number of H1N1 and H2N2 influenza virus strains with selectivity index more than 1500. (4 R )- 11a was shown to be most potent at early stages of viral cycle. Good correlation between anti-viral activity and calculated binding energy to hemagglutinin TBHQ active site was demonstrated. [ABSTRACT FROM AUTHOR]

New chromene derivatives, 9H-furo[2,3-f]chromene-7,8-dicarboxylates, have been synthesized in high yields by a three-component reaction of euparin (isolated from Petasites hybridus), an aldehyde, and dialkyl acetylenedicarboxylate in the presence of PPh3 and catalytic amount of ZnO nanorods under solvent-free conditions at room temperature. ZnO nanorods showed a strong effect on improving the yield of the desired products. Chromene derivatives can be easily separated from the reaction mixture in a simple work-up, and the catalyst may be recovered and reused without considerable loss of activity. [ABSTRACT FROM AUTHOR]

Dodecanoyl isothiocyanate 1 was utilized for the construction of thioureido, 2-thioxo-2,3-dihydroquinazolin-4(1H)-one, benzo[d]-1,3-thiazin-4(H)-one and 3-amino quinazolin-4(3H)-one derivatives 2, 3, 4, and 5 respectively. However, N′-(2-cyanoacetyl) dodecanehydrazide 6 was also used as a key starting material for the construction of a variety of new pyrazolone, pyrazole, thiadiazole, pyridazine, chromeno[2,3-c]pyrazole, and dithiolane derivatives 7, 9, 12, 15, 18, and 20, respectively. The newly synthesized compounds were characterized by elemental analyses and spectral data (IR, 1H NMR, and mass spectra). Some of the newly synthesized compounds bearing heterocyclic moieties were tested for antioxidant activity as reflected in their ability to inhibit oxidation in rat brain and kidney homogenates using 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) inhibition. Also, in vitro anticancer activity was examined using the standard (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) (MTT) method against a panel of two human tumor cell lines namely; hepatocellular carcinoma HepG2 and mammary gland breast cancer MCF-7. Compounds 12 and 16b exhibited the highest activities as antioxidant and antitumor agents. Meanwhile, compounds 7 and 20 showed moderate activities and the rest of the tested compounds showed weak activities. [ABSTRACT FROM AUTHOR]

A diverse library of chromene-xanthene hybrids were synthesized through intramolecular Friedel-Crafts reaction of the arenoxy carbinols. Examples include first incorporation of amino acid tyrosine into xanthene skeletons with polar functionalities. A careful structural evaluation revealed that tyrosine crafted chromene-xanthene hybrids exhibited good activities against breast cancer cell lines MCF-7, MDA-MB-231. The lead compound 16 displays significant cell cycle arrest at G1 phase and induces apoptosis in MDA-MB-231 cells. [ABSTRACT FROM AUTHOR]

A series of novel azo group fused 2H-chromenes and 4H-chromenes were synthesised as well as pyranopyrazole derivatives via the Knoevenagel condensation reaction of C–H acid compounds with 5-(arylazo)salicylaldehydes by a nucleophilic addition to the carbonyl group followed cyclisation. [ABSTRACT FROM AUTHOR]

Thiosemicarbazone ligand, 2-((4,9-dimethoxy-5-oxo-5H-furo[3,2-g]chromen-6-yl)methylene) hydrazinecarbothioamide and its Cd(II), Cu(II), Zn(II), Ni(II), Co(II), VO(II), and Mn(II) complexes have been prepared and characterized by various spectroscopic and analytical techniques. Complexes molar conductance measurements displayed that all complexes (2-8) are non-electrolyte. With general composition [M(H3L)(CH3COO)2H2O].nH2O, where M = Cd(II), Cu(II), Zn(II), Ni(II), Co(II) and Mn(II) while complex (8) has [VO(H3L)(SO4)H2O].2H2O formula. Based on analytical and spectral measurements, the octahedral or distorted octahedral geometries suggested for complexes. Ligand and complexes anti-proliferative activities were assessed against three various human tumor cell lines including breast cancer (MCF-7), liver cancer (HepG2) and lung cancer (A549) using SRB fluorometric assay and cis-platin as positive control. The anti-proliferative activity result indicated that the ligand and its complexes have considerable anti-proliferative activity analogous to that of ordinarily utilized anti-cancer drug (cis-platin). They do their anti-cancer activities by modifying free radical's generation via raising the superoxide dismutase activity and depletion of intracellular reduced glutathione level, catalase, glutathione peroxidase activities, escorted by highly generation of hydrogen peroxide, nitric oxide and other free radicals leading to tumor cells death, as monitoring by decreasing the protein and nucleic acids synthesis. [ABSTRACT FROM AUTHOR]

Imidazolium room temperature ionic liquids (RTIL s) were used as solvents in the Lewis acid-catalyzed cycloaddition reactions of D-glucal with substituted salicylaldehydes. These reactions selectively led to various, novel, cis -pyrano [4,3- b ]benzopyrans in modest yields, different products than those isolated from analogous solution studies. Furan diol was isolated as the major byproduct from all the reactions. The use of RTIL s facilitated the use of unprotected sugars in these reactions. [Display omitted] • Chromane. • Cycloaddition. • RTIL. • D-Glucal. [ABSTRACT FROM AUTHOR]

Herein, the building block synthon cyano-(furan-2-ylmethylene)-acetohydrazide (3) was synthesized and utilized for constructing a wide variety of nitrogen heterocyclic compounds. Cyclization of acetohydrazide 3 in boiling EtOH and 0.5 ml piperidine afforded 2-cyano-(furan-2-ylmethylene)-3-phenylacrylohydrazide (5). Also, a new series of a new chromen-2-imine derivatives 8a-d have been synthesized via stirring starting moiety 3 with 2-hydroxy-5-(phenyldiazenyl)benzaldehyde derivatives 6a-d under heating at 50 °C in the presence of piperidine as a catalyst. Moreover, coupling of active methylene 3 with arylamine diazonium salts 10 a-h formed the corresponding 2-(2-furan-2-ylmethylene)hydrazineyl)-N-(4-substitutedphenyl)-2-oxoaceto-hydrazonoyl cyanide derivatives 11a-h in overall good yields. Furthermore, creating molecules with pyrazole rings was prepared by coupling acetohydrazide 3 with heterocyclic amine diazonium salts 14–16. The structural elucidation was achieved for the target molecules by different spectral parameters such as FTIR, 1H NMR, and 13C NMR spectra. Molecular modeling studies displayed the geometrical structures for the investigated compounds by using the geometrical studies (DFT) of the synthesized molecules that were investigated by the initio/3021 G quantum mechanical method. The in vitro cytotoxic activity of new furan-hydrazide derivatives against the HepG-2 cell line was evaluated using the reference doxorubicin. Compounds 8a and 8b exhibited high reactivity against the HepG-2 cell line, with IC-50 values of 9, and 8.1 μM, respectively. Cell cycle studies indicate that the most potent furan derivatives 8a and 8b arrested cells at the G2/M phase and induced apoptosis. [Display omitted] [ABSTRACT FROM AUTHOR]