heterocycles

Multiwalled carbon nanotubes crowned with nickel‐ferrite magnetic nanoparticles assisted heterogeneous catalytic strategy for the synthesis of benzo[d]imidazo[2,1‐b]thiazole scaffolds

Multiwalled carbon nanotubes crowned with nickel‐ferrite magnetic nanoparticles assisted heterogeneous catalytic strategy for the synthesis of benzo[d]imidazo[2,1‐b]thiazole scaffolds

Abstract

Present manuscript elicits an account of the sonication promoted multicomponent reactions strategy assisted by multiwalled carbon nanotubes embraced with nickel‐ferrite (NiFe2O4‐CNTs) magnetic nanoparticles, as a heterogeneous catalyst to synthesize a novel series of pharmacologically active benzo[d]imidazo[2,1‐b]thiazole scaffolds. The synthesis of these biologically active derivatives was achieved via. A3 coupling involving 2‐aminobenzothiazole, pertinent aryl aldehydes and phenyl acetylene derivatives, proceeded in PEG 400 as green solvent under aerobic conditions to afford the products in good to excellent yields. The higher environmental compatibility and sustainability factors such as higher ecoscale score, smaller E‐factor and appreciable atom economy put this etiquette under the parasol of green chemistry precepts. The characterization of synthesized catalysts was attained through varied techniques viz. powder X‐ray diffraction, field emission scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, Raman, FT‐IR, VSM and TGA‐DTA‐DTG analyses, dispersion studies, and nitrogen porosimetry analyses. The structures of the synthesized compounds were also endorsed by extensive spectroscopic studies (FT‐IR, 1H and 13C NMR, Mass) and elemental analyses.

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Chemo‐ and diastereoselective synthesis of new oxa[3.3.3]propellane via a domino cascade four‐component reaction based on diketene

Chemo‐ and diastereoselective synthesis of new oxa[3.3.3]propellane via a domino cascade four‐component reaction based on diketene

Abstract

A highly convergent, eco‐friendly and straightforward synthesis of new O‐fused heterocycles, functionalized indeno[1,2‐b]furan derivatives was successfully accomplished through a one‐pot four‐component cascade reaction involving, ninhydrin, malononitrile, diketene and various primary amines in the presence of a catalytic quantity of triethylamine in ethanol at ambient temperature, in one pot fashion. This new efficient cascade reaction generates two rings by the simultaneous construction of C‐N (one), C‐O (two) and C‐C (two) multiple bonds, presumably through a sequence of Knoevenagel reaction/Michael addition/intramolecular O‐cyclization and imine‐enamine/keto‐enol tautomerization. The merits of this protocol are highlighted as utilization of inexpensive commercially accessible starting materials, operational simplicity, atom economy, clean reaction profile, simple work‐up procedure being conducted at ambient temperature in relatively short reaction times, preventing chromatographic purification, giving excellent yields, and tolerance to a wide variety of functional groups.

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Design, synthesis, and bioactivities of novel pyridazinone derivatives containing 2‐phenylthiazole or oxazole skeletons

Design, synthesis, and bioactivities of novel pyridazinone derivatives containing 2‐phenylthiazole or oxazole skeletons

Abstract

A series of novel pyridazinone derivatives were designed and synthesized by replacing 4‐(tert‐butyl)phenyl moiety of pyridaben with 2‐phenylthiazole or oxazole fragments via activity substructure connecting approach. The structures of all target compounds were characterized through NMR, MS, and elemental analysis. Bioassay results exhibit that most compounds showed potent bioactivities against Aphis fabae, Tetranychus urticae, Erysiphe graminis, and/or Puccinia polysora. Among the newly synthesized compounds, 2‐(tert‐butyl)‐4‐chloro‐5‐(((2‐phenylthiazol‐4‐yl)methyl)thio)pyridazin‐3(2H)‐one (12b) displays remarkable insecticidal activity against A fabae. Its LC50 value (2.73 mg/L) is better than that of pyridaben (5.46 mg/L), although inferior to that of imidacloprid (0.51 mg/L). In addition to its extraordinary insecticidal activity, compound 12b also exerts 96.9% fungicidal activities against P polysora at 500 mg/L in vivo, significantly superior to that of pyridaben (50.0%), while slightly lower than that of tebuconazole (100%). This article discusses the synthesis, bioassay results, and structure‐activity relationship of this series of novel pyridazinone derivatives.

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Synthesis of glycolurils and hydantoins by reaction of urea and 1, 2‐dicarbonyl compounds using etidronic acid as a “green catalyst”

Synthesis of glycolurils and hydantoins by reaction of urea and 1, 2‐dicarbonyl compounds using etidronic acid as a “green catalyst”

Abstract

Most of the known methods for the synthesis of heterocyclic compounds have disadvantages, such as a long reaction time and aggressive conditions. We have developed a new, rather simple and efficient method for the synthesis of a number of glycoluryls and hydantoins in water using a etidronic acid (HEDP) as “Green catalyst.” So, for the first time, the condensation reaction of ureas with 1, 2‐dicarbonyl compounds was carried out in the presence of HEDP. Also based on NMR studies, a chemism of these reactions, which is stepwise, is proposed. It has been established that the optimal conditions for the synthesis of glycoluryls and hydantoins using HEDP are: temperature 80°C‐90°C, 40‐20 minutes, and the ratio of urea and HEDP is 1:1. In all cases, the remaining aqueous filtrate containing HEDP after the reaction can be reused for other cycles synthesis of glycoluril and other compounds, because HEDP is not converted during the reaction.

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Synthesis and anticancer evaluation of some new pyrazolo[3,4‐d][1,2,3]triazin‐4‐ones, pyrazolo[1,5‐a]pyrimidines, and imidazo[1,2‐b]pyrazoles clubbed with carbazole

Synthesis and anticancer evaluation of some new pyrazolo[3,4‐d][1,2,3]triazin‐4‐ones, pyrazolo[1,5‐a]pyrimidines, and imidazo[1,2‐b]pyrazoles clubbed with carbazole

Abstract

Carbazole represents as a promising template for cancer treatment as it exists in the skeleton of numerous man‐made and natural anticancer agents. In this regard, new sets of novel functionalized pyrazolo[3,4‐d][1,2,3]triazin‐4‐ones 6a‐e and 10a‐e, pyrazolo[1,5‐a]pyrimidines 16a,b and imidazo[1,2‐b]pyrazoles 20a,b and 23a‐c having carbazole moiety were efficiently synthesized, characterized, and mechanistically discussed. They were also evaluated against three human cancer cell lines (HCT‐116, HepG‐2, and MCF‐7) and one standard human cell line (REP1) for their in vitro anticancer activity. The results declared that seven compounds 10d, 10e, 12b, 12d, 12e, 16a, and 23a had potent anticancer activity, having IC50 values in the range 2.97 to 10.31 μM. The most effective compounds 10d and 10e inhibited the growth of all screened cancer cell lines and did not reveal human toxicity.

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Synthesis of Heterocycles by isothiourea organocatalysis

Synthesis of Heterocycles by isothiourea organocatalysis

Abstract

Isothiourea was first employed as catalyst by Birman in 2006 for the enantioselective acyl transfer reaction. The catalyst was then well explored in the course of kinetic resolution and desymmetrization studies. A few years later, Romo and Smith applied isothiourea catalysis in enantioselective cascade reactions to prepare carbocycles and heterocycles acessing new reactivities of isothiourea. Several research groups were then attracted toward this new field of organocatalysis, and applied isothioureas as nucleophilic catalysts in executing cascade methodologies to synthesize various intresteting molecular scaffolds including heterocycles. The present review documents a summary on the construction of heterocyclic molecules by isothiourea organocatalysis. Heterocycles are of prime interest to organic chemists due to their omnipresence in natural products and bioactive molecules. The Lewis basic nucleophilic catalyst isothioureas play a pivotal role in the cascades to generate either α,β‐unsaturated acyl isothiouronium ion or isothiouronium enolate as the prime reaction intermediate. We have covered the reactions involving two intermediates of opposite reactivities affording various heterocycles.

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Recent progress on coumarin scaffold‐based anti‐microbial agents (Part III)

Recent progress on coumarin scaffold‐based anti‐microbial agents (Part III)

Abstract

The biological, therapeutic, and medicinal properties of coumarins (chromen‐2‐ones), and its analogs have triggered enormous studies aimed toward growing synthetic routes to these heterocyclic compounds. This review presents a systematic and comprehensive survey of the method of preparation, the chemical reactivity, and the anti‐microbial properties associated with this system.

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Synthesis of a truncated tetradenolide

Synthesis of a truncated tetradenolide

Abstract

The enantiopure synthesis of a truncated tetradenolide is presented. Starting from the versatile Chiron 7,3‐lactone‐xylofuranose derivative (7,3‐LXF), the enantiomerically pure synthesis of the title compound is obtained in six steps with a 40% overall yield.

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An expedient multi‐component synthesis of pyridinyl‐spirooxindoles and their effect on proliferation of lung cancer A549 cells

An expedient multi‐component synthesis of pyridinyl‐spirooxindoles and their effect on proliferation of lung cancer A549 cells

Abstract

A series of new functionalized pyridinyl‐spirooxindoles have been synthesized through three‐component cyclization reactions. The selected compounds were screened for their in vitro antiproliferative activity against human lung cancer cell line A549. Among the candidate structures, compound 1o demonstrated maximum inhibitory activity against A549 cells with IC50 values of 28.38 μM. EdU (5‐Ethynyl‐2′‐ deoxyuridine, EdU) assay and cell colony formation test showed that cell proliferation of A549 cells was inhibited. In addition, Western blot analysis revealed that the phosphorylation levels of Akt, mTOR, 70S6, and S6 were down‐regulated. Thus, these results indicated that 1o may inhibit the proliferation of A549 cells through inhibiting the phosphorylation levels of Akt, mTOR, 70S6, and S6. 1o may be developed as a potential antitumor agent for lung cancer treatment.

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Microwave assisted synthesis, biological activities, and in silico investigation of some benzimidazole derivatives

Microwave assisted synthesis, biological activities, and in silico investigation of some benzimidazole derivatives

Abstract

Some derivatives of 2‐substituted benzimidazole were prepared via coupling of N‐methyl‐o‐phenylenediamine or o‐phenylenediamine with different aromatic aldehydes catalyzed by Ni(OAc)2 in the presence of chloroform under microwave‐assisted conditions. Structural confirmation of all synthesized molecules was investigated by FT‐IR, 13C NMR, 1H NMR, ESI‐MS, and Elemental analysis. All prepared molecules were examined for in‐vitro pharmaceutical activities like antibacterial, antifungal, antimalarial, antituberculosis, and anti‐oxidant. Additionally, in silico study was also carried out. We also evaluated the steadiness and molecular interaction of docked complex, that is, complex of molecule (7s) with PDB: 5ZNI and complex of derivative (7l) with PDB: 3VLN, we have established a molecular dynamics model on the best dock molecules. All newly prepared molecules were authenticated to have excellent pharmacokinetics stuffs via calculated ADME‐Tox descriptors, which signifying that these derivatives could be utilized as hit for the expansion of the some innovative active compounds.

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One‐pot homo‐ and cross‐coupling of diazanaphthalenes via C‐H substitution: Synthesis of Bis‐ and Tris‐diazanaphthalenes

One‐pot homo‐ and cross‐coupling of diazanaphthalenes via C‐H substitution: Synthesis of Bis‐ and Tris‐diazanaphthalenes

Abstract

The transition metal‐free coupling reactions of unactivated diazanaphthalenes were studied using only lithium tetramethylpiperidine (LiTMP) reagent. Symmetrical and nonsymmetrical bis‐diazanaphthalenes were synthesized in moderate to high yield by homo‐ and cross‐coupling of related monomers. In addition, the single‐step synthesis of diquinoxalino [2,3‐a: 2′, 3’c] phenazine and 2,2′: 3′, 2″ ‐ terquinoxaline using the appropriate equivalent amount of LiTMP was performed. The products were characterized by means of NMR spectroscopy and HRMS spectrometry.

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Design, synthesis and antibacterial activity evaluation of novel 2‐(4‐((1‐aryl‐1H‐1,2,3‐triazol‐4‐yl)methoxy)phenyl)2‐(2‐oxoazetidin‐1‐yl)acetamide derivatives

Design, synthesis and antibacterial activity evaluation of novel 2‐(4‐((1‐aryl‐1H‐1,2,3‐triazol‐4‐yl)methoxy)phenyl)2‐(2‐oxoazetidin‐1‐yl)acetamide derivatives

Abstract

In this paper, a novel series of 2‐(4‐((1‐aryl‐1H‐1,2,3‐triazol‐4‐yl)methoxy)phenyl)2‐(2‐oxoazetidin‐1‐yl)acetamide derivatives are synthesized in two steps. The first step involved Ugi multicomponent reaction of β‐alanine, o‐(propargyl)benzaldehyde and isocyanide derivatives. The product of this step, underwent a click 1,3‐dipolar cycloaddition reaction with benzyl azide derivatives. The 2‐(4‐((1‐aryl‐1H‐1,2,3‐triazol‐4‐yl)methoxy)phenyl)2‐(2‐oxoazetidin‐1‐yl)acetamide product was characterized and their antibacterial activities were evaluated against various G‐positive (Staphylococcus aureus and Bacillus subtilis) and G‐negative (Pseudomonas aeruginosa and Escherichia coli) bacteria, using minimal inhibition concentration. The compounds showed very good antimicrobial activity and a number of products have been more active than ciprofloxacin.

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Design, synthesis and insecticidal‐activity evaluation of N‐pyridylpyrazolo‐5‐methyl amines and its derivatives

Design, synthesis and insecticidal‐activity evaluation of N‐pyridylpyrazolo‐5‐methyl amines and its derivatives

Abstract

In searching for novel insecticidal leads, a series of N‐pyridylpyrazolo‐5‐methyl amines and their derivatives were designed and synthesized. Among the 22 target compounds obtained, bioassays indicated that some of the target compounds exhibited good insecticidal activities against Plutella xylostella (P. xylostella) and Spodoptera frugiperda (S. frugiperda). In particular, compound 9j revealed the best insecticidal activity against P. xylostella, with a LC50 value of 22.11 mg/L, and compound 9q had the best insecticidal activity against S. frugiperda which with 73.99% of mortality rate at 100 mg/L. Structure‐activity relationship (SAR) analysis showed that 4‐CF3 at the position of R1 linked with N‐pyridylpyrazole via amide bond could enhance the insecticidal activity of the target compounds. This study provides valuable clues for the further design and optimization of N‐pyridylpyrazole derivatives.

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Synthesis of N‐heterocycles via [4 + 3] cycloaddition of azomethine imine

Synthesis of N‐heterocycles via [4 + 3] cycloaddition of azomethine imine

Abstract

Di, tri and tetra‐nitrogen containing 7‐membered heterocycles are the key building blocks for natural and medicinally active compounds. They are using as antidepressants, antiulcer, antibiotics, antiemetic and also used as herbicides and insecticides. These building blocks can be synthesized easily from [4 + 3] cycloadditon reaction of azomethine imine with the other suitable reacting partner. Research on this area is very much important as this area is not much explored till now. Hence, the synthetic literature survey towards the di‐nitrogen containing heterocycles is paramount importance. Herein, we report numerous synthetic routes (metal catalyzed, metal free, asymmetric) of di‐nitrogen containing 7‐membered heterocycle through [4 + 3] cycloadditon reaction of the last 10 years (2011‐2019).

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One‐pot multicomponent synthesis and antimicrobial evaluation of novel tricyclic indenopyrimidine‐2‐amines

One‐pot multicomponent synthesis and antimicrobial evaluation of novel tricyclic indenopyrimidine‐2‐amines

Abstract

The synthesis of novel tricyclic indenopyrimidine‐2‐amines from 3,3‐dimethyl‐/3‐methyl‐2H‐indanones has achieved by base‐catalyzed one‐pot three‐component reaction. The desired products are formed within 10 hours after addition at reflux temperature. This multicomponent approach offers a viable protocol for the construction of indenopyrimidine‐2‐amines in single‐step without the isolation of the intermediates 3,3‐dimethyl/3‐methyl‐2‐(4‐substituted benzylidene)‐2,3‐dihydro‐1H‐inden‐1‐ones. All the synthesized compounds have been screened for antimicrobial activity and some of the derivatives show comparable activity against bacterial and fungal isolates.

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Identification of novel thiourea‐stilbene‐triazine conjugates as persuasive lymphoid tyrosine phosphatase inhibitors

Identification of novel thiourea‐stilbene‐triazine conjugates as persuasive lymphoid tyrosine phosphatase inhibitors

Abstract

A library of novel thiourea‐based symmetrical stilbene‐triazines (5a‐i) was synthesized in an effort to develop new protein tyrosine phosphatase LYP inhibitors. The versatile nature of 2,4,6‐trichloro‐1,3,5‐triazine allows considerable scope for derivatization and hence exploration of structure activity relationships. A convenient and versatile three‐step synthetic approach involved the successive replacement of the two chloro groups of 2,4,6‐trichloro‐1,3,5‐triazine by a variety of substituents for structural modification. The newly synthesized derivatives were subjected to tyrosine phosphatase LYP inhibition studies. The results for the in vitro bioassays were promising with the identification of compound 5k and 5l having a 4‐methyl and 4‐methoxy substituent on phenyl ring, as the lead and selective candidate for LYP inhibition with an IC50 value of 2.1 ± 0.05 μM and 28 ± 3.3 μM, respectively. Moreover, docking studies were carried out to determine the possible interaction sites of thiourea‐based stilbene‐triazine compounds with Lymphoid Tyrosine Phosphatase. Results of docking computations further ascertained the inhibitory potential of compound 5k and 5l. The results indicated that the compound 5k may serve as a structural model for the design of most potent LYP inhibitors.

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An expedient and straightforward solvent‐free synthesis of 1,8‐dioxo‐octahydroxanthenes using eco‐friendly aluminized polyborate catalyst

An expedient and straightforward solvent‐free synthesis of 1,8‐dioxo‐octahydroxanthenes using eco‐friendly aluminized polyborate catalyst

Abstract

The present work deals with a catalytic application of aluminized polyborate as a mild solid acid catalyst for multicomponent synthesis of 1,8‐dioxo‐octahydroxanthenes under solvent‐free condition at 100°C‐110°C. It involves selective domino Knoevenagel‐Michael reaction of 1 mole of aromatic aldehyde with 2 moles dimedone. The aluminized polyborate is simply synthesized by using boric acid and aluminum trichloride and characterized by FT‐IR, XRD, SEM and EDAX techniques. The mild Lewis acidity, crystalline solid nature, stability and recyclability are significant features of the catalyst. The solvent‐free condition, clean reaction profile, inexpensive and non‐toxic catalyst, operational simplicity, good to excellent product yields, reduced reaction time and applicability to wide range of substrate are crucial features of this protocol.

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Green synthesis and investigation of antioxidant ability new pyrazines containing pyrrolo[2,1‐a]isoquinolines derivatives

Green synthesis and investigation of antioxidant ability new pyrazines containing pyrrolo[2,1‐a]isoquinolines derivatives

Abstract

In this study, a new, easy and high yield procedure is investigated for the generation of pyrazine containing pyrrolo[2,1‐a]isoquinoline derivatives using multicomponent reaction of phthalaldehyde or its derivatives, primary amines, α‐haloalketones, electron deficient acetylenic compounds, ammonium acetate and KF/Clinoptilolite nanoparticles (KF/CP NPs) as catalyst in water at room temperature. The reactions of 2‐hydroxy phthalaldehyde, primary amines, α‐haloketones, electron deficient acetylenic compounds, and ammonium acetate in the presence of KF/CP NPs as catalyst in water at room temperature produce pyrazine derivatives in good yields. Also, in this work, antioxidant ability was studied for a number of prepared compounds employing the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging and power of compounds for reducing of ferric ion experiments and evaluating results with synthetic antioxidants (TBHQ and BHT). Comfortable, simple, fast and fresh procedure is the advantages of this study.

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An efficient green synthesis and antibacterial activity of 1,3‐benzoxazine and 1,3‐naphthoxazine using NaCl.SiO2 as solid catalyst in neat condition

An efficient green synthesis and antibacterial activity of 1,3‐benzoxazine and 1,3‐naphthoxazine using NaCl.SiO2 as solid catalyst in neat condition

Abstract

A series of 1,3‐oxazine derivatives were synthesized by a one‐pot three‐component (ie, phenol, formaldehyde, amine) method where SiO2 bonded with NaCl was used as a reusable, more efficient, easily prepared, and available solid catalyst. The reactions were also carried out at room temperature for greener approach. in vitro studies for the synthesized compounds were also done against two gram‐positive (Bacillus subtilis and Staphylococcus aureus ) and two gram‐negative bacteria (Escherichia coli and Klebsiella pneumonia ) to check for their applicability as an antibacterial agent where some of the synthesized compounds gives the best antibacterial activity against selected bacterial strains. Streptomycin was used as a standard control for all the microbial test.

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Synthesis and cytotoxic activity of some new heterocycles incorporating cyclohepta[b]thiophene‐3‐carboxamide derivatives

Synthesis and cytotoxic activity of some new heterocycles incorporating cyclohepta[b]thiophene‐3‐carboxamide derivatives

Abstract

A series of 2‐amino‐5,6,7,8‐tetrahydro‐4H‐cyclohepta[b]thiophene‐3‐carboxamide‐heterocyclic hybrids were synthesized, characterized and their cytotoxic potencies were assessed on four human cell lines. Cyanoacetamide derivative (5 ) was used as the key synthetic intermediate for the synthesis many derivatives in this study, derivatives 9 , 11 , 12 were formed by coupled compound 5 with different aryl/heteryl diazonium chlorides, Gewald reaction and Knoevenagel condensation were used for synthesis derivatives 13 , 14 , 16 by treated cyanoacetamide (5 ) with different reagents. In another route, compound 5 treated with phenyl isothiocyanate give thiocarbamoyl derivative (7 ) which used as intermediate underwent oxidative cyclization with different moieties to offer the corresponding thiazoles and thiophene 18 , 19 , 20 , 21 , respectively. in vitro cytotoxic activity of prepared compounds were tested against four human tumor cell lines. The result revealed that compound 11a displayed promising cytotoxic activity against HepG2, HCT‐116, MCF‐7, and PC3 cancer cell lines comparing to the positive control (Doxorubicin).

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Regioselective aza‐Michael additions of 2‐arylidene‐1,3‐diphenylpropan‐1,3‐diones with isatins: Synthesis of N‐diketone‐functionalized isatins

Regioselective aza‐Michael additions of 2‐arylidene‐1,3‐diphenylpropan‐1,3‐diones with isatins: Synthesis of N‐diketone‐functionalized isatins

Abstract

The efficient aza‐Michael additions of isatins to 2‐arylidene‐1,3‐diphenylpropan‐1,3‐diones at room temperature in the presence of cesium carbonate are described. The salient features of this protocol are no transition‐metal catalysts, mild conditions, high regioselectivity, high atom economy, satisfactory yield and simple work‐up procedures.

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Synthesis, reactions, and antimicrobial activity of 2‐cyano‐N′‐(4‐(2‐oxo‐2‐phenylethoxy)benzylidene)acetohydrazide derivatives

Synthesis, reactions, and antimicrobial activity of 2‐cyano‐N′‐(4‐(2‐oxo‐2‐phenylethoxy)benzylidene)acetohydrazide derivatives

Abstract

Knӧvenagel condensation of the starting 2‐cyano‐N ′‐(4‐(2‐oxo‐2‐phenylethoxy)‐benzylidene)acetohydrazide with different aromatic aldehydes produced the comparable arylidenes derivatives. Else way, 2‐cyano‐N ′‐(4‐(2‐oxo‐2‐phenylethoxy)‐benzylidene)‐acetohydrazide condensed with o ‐hydroxybenzaldehydes affording the respective chromenes which latter underwent acid hydrolysis giving the oxo‐chromenes analogues. Moreover, the reaction of 2‐cyano‐N ′‐(4‐(2‐oxo‐2‐phenylethoxy)benzylidene)acetohydrazide with istain yielded the respective indeno[2,1‐b ]furan derivative that was converted to its oxo‐analogue through acid hydrolysis. The treatment of 2‐cyano‐N ′‐(4‐(2‐oxo‐2‐phenylethoxy)benzylidene)acetohydrazide with α ‐halocompounds produced the relevant thiazoles. The enamine 2‐cyano‐3‐(dimethylamino)‐N ′‐(4‐(2‐oxo‐2‐phenylethoxy)benzylidene)acrylohydrazide underwent nucleophilic substitution reaction with guanidine hydrochloride followed by heterocyclization to get the relative aminopyrimidine. Contrarily, the reaction with various 4‐arylazo‐3,5‐diaminopyrazoles provided the relative pyrazolo[1,5‐a ]pyrimidines. The antimicrobial investigation was carried out for some of the newly synthesized compounds using agar well diffusion method.

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Mechanochemical synthesis of 5‐acetylthiazole: A step toward green and sustainable chemistry

Mechanochemical synthesis of 5‐acetylthiazole: A step toward green and sustainable chemistry

Abstract

Mechanochemical synthesis of 5‐acetylthiazole derivatives by one‐pot three‐component procedure over Silica Sulfuric acid under solvent‐free conditions, has been developed. The durability of the catalyst was tested. The environmentally benign protocol introduced herein characterized by no hazardous organic solvent used, recyclability of the catalyst up to five runs without loss of its catalytic activity and high yields of products that confirm the utilization of some green chemistry principles in the mentioned protocol.

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Biomimetic synthesis of carthamin, a red pigment in safflower petals, via oxidative decarboxylation

Biomimetic synthesis of carthamin, a red pigment in safflower petals, via oxidative decarboxylation

Abstract

Carthamin, a natural red pigment derived from safflower, was discovered centuries ago and has been utilized in several industries such as dye, food coloring, and natural medicine industries. Although it has been used since Egyptian times, its structural features were only determined in the mid‐1900s when pioneering studies were conducted to elucidate the carthamin structure and assign its stereochemistry. Reproducing the complex biosynthesis of carthamin has been a common research goal since then. However, this has been rendered complex because of the unstable precursors and low yields from the multiple steps involved in the synthesis. Herein, we report the total synthesis of carthamin via a four‐step procedure using (S )‐C β ‐D‐glucosylquinochalcone as the starting compound. The synthesis involves mild conditions, short reaction time, and readily available compounds. After de‐O ‐methylation, condensation, oxidative decarboxylation, and saponification, carthamin was obtained in an overall yield of 9.5% through the proposed method.

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Synthesis and antimicrobial evaluation of the novel heteroannulated furo[3′,2′:6,7]chromeno[2,3‐b]pyridines: Part 1

Synthesis and antimicrobial evaluation of the novel heteroannulated furo[3′,2′:6,7]chromeno[2,3‐b]pyridines: Part 1

Abstract

The chemical behavior of 4,9‐dimethoxy‐5‐oxo‐5H ‐furo[3,2‐g ]chromene‐6‐carbonitrile (1 ) was investigated toward some acyclic and cyclic active methylene ketones namely acetylacetone, ethyl acetoacetate, ethyl benzoylacetate, acetoacetanilide, dimedone, indanedione, pyrazolidine‐3,5‐dione and 5‐methyl‐2‐phenyl‐2,4‐dihydro‐3H ‐pyrazol‐3‐one, barbituric acid and 1‐allylthiobarbituric acid, and hippuric acid. A variety of novel heteroannulated furochromenopyridines were efficiently synthesized through a cascade reactions between 4,9‐dimethoxy‐5‐oxo‐5H ‐furo[3,2‐g ]chromene‐6‐carbonitrile (1 ) and the carbon nucleophilic reagents. Structures of the new products were inferred based on their analytical and spectral data.

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