Formation Of Chalcones Research Articles

One-Step, Low-Cost, Operator-Friendly, and Scalable Procedure to Synthetize Novel Tetrazolopyrimidinylbenzopyran-2-ones by Benign Protocol

Abstract: New coumarin chalcones 3j–p were conveniently obtained in high yields via Claisen-Schmidt condensation reaction, when acetyl coumarin 1 reacted with 3-aryl-1-phenyl pyrazole-4-carbaldehydes 2j–p in boiling ethanol in the presence of triethyl amine as a catalyst. Also, two synthetic pathways were afforded for the synthesis of novel tetrazolo[1,5-a]pyrimidinyl-2H-chromen-2-ones 5a-p. The first pathway is a multistep process including formation and separation of chalcones, which then were allowed to react with 5-aminotetrazole 4. While, the second pathway is a highly efficient one-pot three-component condensation reaction of 3-acetyl coumarin 1, aromatic aldehydes 2a-p and 5-aminotetrazole 4 under green and mild reaction conditions by using acetic acid (AcOH) as a catalyst and solvent. The molecular structure of products was established on the basis of their NMRs, IR and elemental analysis data. Solvent optimization was carried out in the reaction producing 3-(5-Phenyl-4,5-dihydrotetrazolo[1,5-a]pyrimidin-7-yl)-2H-chromen-2-one (5a). The advantages to using environmental-friendly acetic acid are simple operation, short reaction time, high efficient (97%), operationally facile and wide tolerance of starting materials. objective: The advantages of using environmental-friendly AcOH are simple operation, short reaction time, high efficient (97%), operationally facile and wide tolerance of starting materials.

In vitro anti-cancer, anti-inflammatory and anti-oxidant studies of novel oxazine derivatives

The ability to inhibit oxidative stress has been established as the prime mechanism in treatment of several disease conditions. Condensation of substituted acetophenones and Ferrocene aldehyde resulted in the formation of various Chalcones (I-III). The resulting various Chalcones (I-III) react with urea to form various oxazines ((Ia-IIIa). The reaction was monitored by TLC and synthesized products were characterized by physical, Elemental analysis, Spectral studies UV, FT-IR, C13 and 1H-NMR Spectroscopy. When these compounds were screened for antioxidant susceptibilities by FRAPAssay, anti-inflammatory and anti-cancer activities.

One-Pot Synthesis of Aminoindolizines and Chalcones Using CuI/CSP Nanocomposites with Anomalous Selectivity under Green Conditions

CuI/CSP nanocomposites were found to be efficient and recyclable nanocatalysts for one-pot synthesis of aminoindolizines via A3 coupling reaction in the presence of ethylene glycol (EG) as a recyclable solvent. In contrast, chalcones were isolated when the reaction was performed in the presence of secondary amines such as piperidine, 3-methylpiperidine, pyrrolidine, and piperazine under solvent free conditions. The CuI/CSP was recycled for five times without significant loss in its catalytic activity. The anomalous selectivity in the formation of aminoindolizines and chalcones was dependent on solvents and secondary amines used for the reaction. The present methodology is facile and follows green principles with higher atom economy (94%) and smaller E-factor (0.06).

Synthetic and Mechanistic Studies on the Solvent-Dependent Copper-Catalyzed Formation of Indolizines and Chalcones

Copper nanoparticles supported on activated carbon have been found to catalyze the multicomponent synthesis of indolizines from pyridine-2-carbaldehyde derivatives, secondary amines, and terminal alkynes in dichloromethane; in the absence of solvent, however, heterocyclic chalcones are formed. We provide compelling evidence that both processes take place through aldehyde–amine–alkyne coupling intermediates. In contrast to other well-known mechanisms for chalcone formation from aldehydes and alkynes, a new reaction pathway involving propargyl amines as intermediates that do not undergo rearrangement is presented. The formation of indolizines or chalcones is driven by inductive and solvent effects, with a wide array of both being reported. In both reactions, the nanoparticulate catalyst has been shown to be superior to some commercially available copper catalysts, and it could be recycled in the case of the chalcone synthesis.

SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY OF NOVEL PYRAZOLO[3,4-b]PYRIDINES AND THEIR SPIRO-HETEROCYCLIC DERIVATIVES

The present work describes the synthesis of a novel series of heterocyclic moieties derived from 5-acetylpyrazolo[3,4-b]pyridine (1). The formation of chalcones (2a-d) was utilized to synthesize pyrazoline, isoxazoline and pyrimidine derivatives (3-10). Thiosemicarbazone and semicarbazone (11, 17) were utilized to synthesize other new triazolethiones, thiadiazole and selenadiazole derivatives (11-19). Some new spiro derivatives (22-25) were synthesized by the reaction of chalcone (21) of 1 and isatine with hydrazines, hydroxyl amines and thiourea. Also, The reaction of 1 with cyanoacetyl hydrazine gave the hydrazide-hydrazone derivative 26, which was allowed to react with aromatic aldehydes and α-cyanocinnamonitrile to afford coumarine and substituted pyridine derivatives (28, 29). The structures of all the new compounds have been established on the basis of their analytical and spectral data. Twenty two of the synthesized compounds were also evaluated for their antibacterial and antifungal activity against various strains of bacteria and fungi and most are found to possess promising antimicrobial activity when compared with Chloramphenicol and Clotrimazole

Lithium hydroxide mediated synthesis of 3,4-disubstituted pyrroles

LiOH·H2O in ethanol was found to be an effective reagent for the synthesis of 3,4-disubstituted pyrrole derivatives by the van Leusen method. In situ formation of chalcones from aromatic aldehydes and enolisable ketones, and their subsequent reaction with tosylmethyl isocyanide resulted in the formation and precipitation of pyrrole derivatives from the reaction medium, in good yields. The solvation effect of the polar medium facilitates the reaction.

ChemInform Abstract: Graphite Oxide as an Auto‐Tandem Oxidation—Hydration—Aldol Coupling Catalyst.

Graphite oxide (GO) was found to function as an auto-tandem oxidation-hydration-aldol coupling catalyst for the formation of chalcones in a single reaction vessel. Various alkynes or alcohols were hydrated or oxidized in situ to their corresponding methyl ketones or aldehydes, respectively, which underwent a subsequent Claisen-Schmidt condensation. Each of the aforementioned reactions proceeded in the absence of metals (confirmed by inductively coupled plasma mass spectrometry, ICP-MS) and afforded a range of chalcone products in good to excellent yields from commercially available starting materials.

Graphite Oxide as an Auto‐Tandem Oxidation–Hydration–Aldol Coupling Catalyst

AbstractGraphite oxide (GO) was found to function as an auto‐tandem oxidation–hydration–aldol coupling catalyst for the formation of chalcones in a single reaction vessel. Various alkynes or alcohols were hydrated or oxidizedin situto their corresponding methyl ketones or aldehydes, respectively, which underwent a subsequent Claisen–Schmidt condensation. Each of the aforementioned reactions proceeded in the absence of metals (confirmed by inductively coupled plasma mass spectrometry, ICP‐MS) and afforded a range of chalcone products in good to excellent yields from commercially available starting materials.

Multistate reaction kinetics of 6-hydroxy-4′-(dimethylamino)flavylium driven by pH. A stopped-flow study

The synthetic flavylium salt 6-hydroxy-4'-(dimethylamino)flavylium hexafluorophosphate displays a set of pH-driven chemical reactions in aqueous solutions, involving the formation of hemiketal species and chalcones with cis and trans configurations. Such reactions were studied by steady-state and transient UV-Vis spectroscopy and by stopped-flow techniques. A novel and more generalized kinetic scheme is developed, in order to take account of possible acid/base pairs that occur in the network of chemical reactions as the pH is changed. It is found that the formation of the hemiketal species by hydration of the flavylium is slow, and it is not possible to isolate each process that leads to the formation of the cis-chalcone (hydration and tautomerization reactions). The cis/trans isomerization reaction of cis-chalcone is slow, and the system takes several hours to reach equilibrium after a pH jump at room temperature. In basic conditions, negatively charged trans-chalcones are dominant. Comparison with other flavylium compounds shows that the hydration process is affected mainly by the amino group, while the hydroxyl group influences the tautomerization and isomerization reactions.

Surface and catalytic properties of acid metal–carbons prepared by the sol–gel method

The sol–gel method has been applied for the synthesis of a series of acid metal–carbon xerogels (with M = V, Cr, Mo and Ni) by polymerisation of resorcinol with formaldehyde in the presence of metallic precursors. A blank sample was also prepared without any metal addition. The xerogels were heated in nitrogen at 1000 °C to obtain the pyrolysed products. The samples were characterised by different techniques such as thermal-mass spectrometry analysis, gas physisorption, and mercury porosimetry. In addition, the acid character of the pyrolysed products was tested by the Claisen–Schmidt condensation between benzaldehyde and acetophenone for the formation of chalcones.

Structure elucidation and DFT-study on substrate-selective formation of chalcones containing ferrocene and phenothiazine units. Study on ferrocenes, Part 17

By means of base-catalysed condensation of 1-acyl-/1,1′-diacylferrocenes (acyl formyl or acetyl) with 3-formyl- and 3,7-diacetylphenothiazines a series of novel mono- and bis-chalcones were prepared. The enhanced reactivity of the enolate anions of the mono-chalcone intermediates relative to that of the enolates of the corresponding diacetyl-substituted precursor was interpreted by the electron-releasing effect of the ferrocenyl- or phenothiazinyl group present in the β position of the enone subunit. The structures of the novel products were evidenced by IR, 1H and 13C NMR spectroscopy including 2D-COSY, 2D-HSQC and 2D-HMBC measurements.

A chalcone synthase with an unusual substrate preference is expressed in barley leaves in response to UV light and pathogen attack.

A cDNA clone was isolated by differential hybridization from a library prepared from barley leaves inoculated with the fungus Blumeria graminis f.sp. hordei (Bgh). The open reading frame of the insert (designated HvCHS2) encoded a polypeptide with 72-79% identity to chalcone synthases (CHS) and 65-68% identity to stilbene synthases. Alignments of the amino acid sequence of HvCHS2 with the consensus sequence of naringenin-CHS (EC 2.3.1.74) reveals significant differences between HvCHS2 and naringenin-CHS. HvCHS2 transcripts accumulate strongly in barley leaves in response to inoculation with Bgh, whereas only insignificant accumulation of barley naringenin-CHS (CHS1) transcripts is seen upon the inoculation. The accumulation of HvCHS2 transcripts is also elicited by UV light. To compare the activity of HvCHS2 with the activity of CHS1, the two enzymes were expressed in Escherichia coli. Both HvCHS2 and CHS1 catalyse the formation of chalcones. However, HvCHS2 and CHS1 differ in their substrate requirements. CHS1 uses cinnamoyl-CoA and 4-coumaroyl-CoA at comparable rates whereas feruloyl-CoA is a poor substrate for this enzyme. In contrast, HvCHS2 converts feruloyl-CoA and caffeoyl-CoA at the highest rate whereas cinnamoyl-CoA is a poor substrate. Thus, HvCHS2 is a novel pathogen and UV light induces homoeriodictyol/eriodictyol CHS involved in the direct production of flavonoids possessing multi-substituted B-rings.

Wounding‐ and Elicitor‐induced Formation of Coloured Chalcones and Flavans (as Phytoalexins) in Hippeastrum x hortorum*

Abstract:Hippeastrum x hortorum bulbs produce red pigments upon wounding. Analysis by TLC, HPLC, MS and NMR revealed that this pigment, which is absent in unwounded tissue, is a mixture composed of an orange‐coloured chalcone (3,2′4′‐trihydroxy‐4‐methoxychalcone) and 3 flavans (7,4′‐dihydroxy‐8‐methylflavan, 7,3′‐dihydroxy‐4′‐methoxyflavan and 7‐hydroxy‐3′‐4′‐methylenedioxyflavan). The colourless flavans can be oxidised to red‐coloured dimers or polymers. The induction of these “phytoalexins” is achieved by wounding and can be further amplified by biotic and abiotic elicitors; e.g. cell walls of yeast appeared to be a potent elicitor. Immediately after wounding or elicitation the apparent activities of phenylalanine ammonium lyase (PAL) and peroxidase, which are probably involved in the biosynthesis of the red pigments increase substantially (both enzymes are hardly measurable in unwounded tissue) and reach a transient maximum after 2 − 3d whereas pigment formation becomes visible after 2d and reaches a maximum after 9 to 12 d. Since cycloheximide inhibits the formation of the phytoalexins, a de novo synthesis of the corresponding enzymes is likely. Total phytoalexin extracts showed an inhibition of bacterial growth (e.g. of Bacillus subtilis, B. megaterium) and of feeding by polyphagous larvae of the moth Syntomis mogadorensis. These data imply that the wounding‐ and elicitor‐induced phytoalexins appear to function as defence compounds against microorganisms and herbivores.

A novel reaction of some [formula omitted](aroylmethyl) sulfoxides with aromatic aldehydes and ammonium acetate

On reaction with aromatic aldehydes and ammonium acetate, bis (aroylmethyl) sulfoxides lead to the formation of chalcones in good yield, which is in striking contrast to the behaviour of its sulfide and sulfone counterparts and a hypothetical pathway for this reaction is suggested.

Formation of chalcones and isoflavones by callus culture of Glycyrrhiza uralensis with different production patterns.

Formononetin (1), isoliquiritigenin (2), echinatin (3), liquiritigenin (4), p-hydroxybenzoic acid (5), 3'-hydroxyformononetin (6) and isobavachalcone (7) were isolated from callus culture of Glycyrrhiza uralensis which was established on Murashige-Skoog's medium containing naphthaleneacetic acid (NAA, 2ppm), (2, 4-dichlorophenoxy) acetic acid (2, 4-D, 1ppm) and benzyladenine (0.1ppm). Formononetin (1), 3'-hydroxyformononetin (6) and isobavachalcone (7) showed different patterns of production.