Synthesis and cytotoxicity evaluation of highly functionalized pyranochromenes and pyranopyrans

Ru(ii)-catalysed oxidative (4 + 2) annulation of chromene and coumarin carboxylic acids with alkynes/propargylic alcohols: isolation of Ru(0) complexes

Ru(ii)-catalysed oxidative (4 + 2) annulation of chromene and coumarin carboxylic acids with alkynes affords pyrano-chromones via vinylic C–H bond activation; use of methyl-tethered propargylic alcohols instead of alkynes gives Ru(0) complexes.

Crystal structures of two 4H-chromene derivatives: 2-amino-3-cyano-4-(3,4-di-chloro-phen-yl)-7-hy-droxy-4H-benzo[1,2-b]pyran 1,4-dioxane monosolvate and 2-amino-3-cyano-4-(2,6-di-chloro-phen-yl)-7-hy-droxy-4H-benzo[1,2-b]pyran

In the title compounds, C16H9Cl2N2O2·C4H8O2 and C16H9Cl2N2O2, the bicyclic 4H-chromene cores are nearly planar with maximum deviations of 0.081 (2) and 0.087 (2) Å. In both structures, the chromene derivative mol-ecules are linked into centrosymmetric dimers by pairs of N-H⋯O hydrogen bonds, forming R2 2 (16) motifs. These dimers are further linked in the 3,4-di-chloro-phenyl derivative by N-H⋯N hydrogen bonds into double layers parallel to (100) and in the 2,6-di-chloro-phenyl derivative by O-H⋯N hydrogen bonds into ribbons along the [10] direction. In the 3,4-di-chloro-phenyl derivative, the 1,4-dioxane solvent mol-ecules are connected to the chromene mol-ecules via O-H⋯O hydrogen bonds.

The chromene derivative 4-Clpgc inhibits cell proliferation and induces apoptosis in the K562 cell line

Chronic myeloid leukemia (CML) is a malignant blood disease with a particular chromosomal aberration that is known as a common form of leukemia. The chromene family exhibits strong anti-cancer effects. Therefore, the effects of six members of the dihydropyrano [2,3-g] chromene family on cell toxicity and apoptosis induction in K562 cancer cells were investigated and compared with those of normal peripheral blood mononuclear cells (PBMCs). The K562 cells were cultured in the presence of the aforementioned chromene derivatives at concentrations of 40 to 200 μM for 24 to 72 h. The effects of these compounds on the growth and viability of the K562 cell line and PBMCs were studied through MTT assay. Furthermore, apoptosis induction was investigated using flow cytometry. Real-time PCR was used for relative quantification of BCL2, Bax, TP53 and BCR- ABL genes after 48 h of exposing K562 cells and PBMCs to 4-Clpgc. Based on the results, these chromene derivatives inhibited the growth of K562 cells. According to the obtained data, 4-Clpgc was the strongest compound with IC50 values of 102 ± 1.6 μM and 143 ± 9.41 μM in K562 cells and PBMCs, while pgc was the weakest one with IC50 levels of 278 ± 2.7 μM and 366 ± 47 μM in K562 cells and PBMCs (after 72 h), respectively. The results demonstrated that the apoptotic cell percentage in the control group increased from 6.09% to 84.10% and 17.2% to 20.06% in K562 cells and PBMCs after 48 h of treatment, respectively. Moreover, 4-Clpgc treatment increased the expression of Bax and TP53 genes by 42.74 and 35.88 folds in K562 cells and 9.60 and 7.75 folds in PBMCs, respectively. On the other hand, the expression of BCL2 was reduced by 1.47 and 1.38 folds in K562 cells and PBMCs, respectively. These compounds were associated with less toxic effects on normal cells, compared to the cancer cells. In conclusion, these derivatives can be considered as appropriate candidates for leukemia treatment.

Synthesis and characterization of amino glucose-functionalized silica-coated NiFe2O4 nanoparticles: a heterogeneous, new and magnetically separable catalyst for the solvent-free synthesis of pyrano[3,2-c]chromen-5(4H)-ones

A novel, efficient and one-pot multi-component procedure for the synthesis of simple pyrano[3,2-c]chromen-5(4H)-ones or pyrazolyl pyrano[3,2-c]chromen-5(4H)-ones via reaction of aryl aldehydes, acetophenones and 4-hydroxycoumarin promoted by amino glucose-functionalized silica-coated NiFe₂O₄ nanoparticles under solvent-free conditions without using any other harmful organic reagents was reported. The structure of this nanoparticle was characterized by transmission electron microscopies, X-ray diffraction and Fourier transform infrared spectroscopies. The catalyst could easily be separated from the reaction mixture by using an external magnetic field and it was reusable. The high purity of the desired products, eco-friendliness, short reaction time and easy workup procedure can be mentioned as the other advantages of this method.

We have developed NiFe₂O₄@SiO₂@glucose amine as a new, mild and efficient avenue for the synthesis of pyrano[3,2-c]chromen-5(4H)-ones.

A Base-Catalyzed, Domino Aldol/hetero-Diels-Alder Synthesis of Tricyclic Pyrano[3,4-c]chromenes in Glycerol

The domino aldol/hetero-Diels-Alder synthesis of some new tricyclic pyrano[3,4-c]chromene derivatives has been achieved successfully after assembling a variety of acyclic or cyclic monoketones with prenyl ether-tethered aldehydes in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene in glycerol at 120 °C. The hitherto unreported stereochemical outcome of this synthetic sequence was studied and established on the basis of single-crystal X-ray diffraction data and 2D NMR NOESY spectroscopy along with the isolation and characterization of the intermediate Aldol condensation product.

DABCO catalyzed domino Michael/hydroalkoxylation reaction involving α-alkynyl-β-aryl nitroolefins: excellent stereoselective access to dihydropyrano[3,2-c]chromenes, pyranonaphthoquinones and related heterocycles

The stereoselective (up to ≤96 : 4 Z/E ratio) access to pyrano[3,2-c]chromenes and related scaffolds has been achieved in 72–89% yields via a domino reaction of enolizable cyclic 1,3-dicarbonyls and β-alkynyl nitroolefins.

Investigation on the Binding Mode of 3, 4-Dihydropyrano[c]Chromene Derivative with Double Strand DNA

PURPOSE

The study on the interaction between small molecules and DNA has been very useful for investigating the structure and physical properties of DNA, elucidating the damage mechanism of DNA and significant in the design of new drugs targeted to DNA. This article describes an interaction of native calf thymus DNA (ctDNA) with a new 3, 4-dihydropyrano[c]chromene derivative, 2-amino-4-(4- chlorophenyl)-5-oxo-4H, 5H-pyrano-[3, 2-c] chromene-3-carbonitrile (4-CC) by using spectroscopic and viscometric techniques.

METHODS

The interaction between 4-CC and ctDNA is realized from the UV absorption spectrophotometry, viscosimetry, circular dichroism and fluorescence spectroscopic techniques which shows that the successive interaction of 4-CC with ctDNA occurs.

RESULTS

The experimental results revealed that 4-CC can interact with DNA through non- intercalative mode and the intrinsic binding constant (Kb) for 4-CC with DNA was estimated to 2.37 (±0.001) ×103 M-1. Methylene blue (MB) displacement studies revealed that 4-CC did not have any effect on MB bound DNA which is indicative of groove binding mode. Furthermore, 4-CC induces detectable changes in the CD spectrum of ctDNA as well as changes in its viscosity study corroborate the above experimental results.

CONCLUSION

These results further advance our knowledge on the molecular aspects on the interaction of 4-CC to nucleic acids.

Crystal structure of ethyl (4R)-2-amino-7-hy-droxy-4-phenyl-4H-chromene-3-carboxyl-ate

In the title compound, C18H17NO4, the dihedral angle between the phenyl ring and the fused six-membered ring is 77.65 (4)°. The conformation of the mol-ecule is determined in part by an intra-molecular N-H⋯O hydrogen bond between the amino H atom and the carbonyl O atom, forming an S(6) motif. In the crystal, mol-ecules are linked into N-H⋯O hydrogen-bonded inversion dimers which are then connected into chains along [001], forming a two-dimensional network parallel to (100) via O-H⋯O hydrogen bonds. C-H⋯O interactions further contribute to the crystal stability. The ethyl group is disordered over two sets of sites in a 0.801 (5):0.199 (5) ratio.

Acid promoted synthesis of cyclic 1,3-dione fused symmetrical 2,8-dioxabicyclo[3.3.1]nonanes

Synthesis of symmetrical 2,8-dioxabicyclo[3.3.1]nonanes (4) is accomplished by the reaction of β-enamino ketones (1) and 1,3-cyclohexanediones (2) in AcOH. However, the presence of TFA in toluene gave xanthenes (5).

A remarkable solvent effect on the reaction of 4-hydroxycoumarin with (E)-3-aryl-2-nitroprop-2-enol: Facile synthesis of highly substituted furo/pyrano[3,2-c]chromenes

The solvent dependent reaction of 4-hydroxycoumarin with (E)-3-aryl-2-nitroprop-2-enol has been reported for the synthesis functionalized furo/pyrano[3,2-c]chromenes in water and DMSO media.

DABCO-functionalized mesoporous SBA-15: an efficient and recyclable catalyst for the synthesis of spiro-pyranoxindoles as antioxidant agents

A series of spiro-pyranoxindole derivatives were prepared in good yields via a three-component reaction of isatins with activated methylene reagents and kojic acid using 1,4-diazabicyclo[2.2.2]octane (DABCO) immobilized on mesoporous SBA-15 as a heterogenized organocatalyst in aqueous media. The synthesized compounds were evaluated for their antioxidant activity by a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay.

Regioselective synthesis of 3-benzyl substituted pyrimidino chromen-2-ones and evaluation of anti-microbial and anti-biofilm activities

Regioselective synthesis of a number of highly functionalized 3-benzylpyrimidino chromen-2-ones (4) were accomplished in a one pot three component reaction in acetic acid and determined their anti-microbial and anti-biofilm activities. Compounds 4o and 4p showed an excellent anti-microbial activity against Micrococcus luteus MTCC 2470 at a par with standard control (Ciprofloxacin) and exhibited best activity against Staphylococcus aureus MTCC 96 and Bacillus subtilis MTCC 121. Further, compounds 4h, 4i, 4m, 4n and 4q showed promising activity against Micrococcus luteus MTCC 2470, Staphylococcus aureus MTCC 96 and Bacillus subtilis MTCC 121. Whereas, compounds 4m showed very promising biofilm inhibition activity against Staphylococcus aureus MLS 16 MTCC 2940 and 4o, 4p showed very potent activity against Staphylococcus aureus MTCC 96 at a par with Ciprofloxacin used as standard control.