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ChemInform Abstract: A Green One-Pot Multicomponent Synthesis of 4H-Pyrans and Polysubstituted Aniline Derivatives of Biological, Pharmacological, and Optical Applications Using Silica Nanoparticles as Reusable Catalyst.
Abstract
A one-pot practical, efficient, and environmentally benign multicomponent synthesis of 4H-pyrans and polysubstituted aniline derivatives of biological, pharmacological, and optical applications has been developed using a very mild, neutral, and reusable silica nanoparticles as catalyst. The 4H-pyran derivatives were synthesized by a three component reaction of an aldehyde, malononitrile, and 5,5-dimethyl-1,3-cyclohexanedione or ethyl acetoacetate at room temperature or refluxing in ethanol. Alternatively, polysubstituted anilines were synthesized via a four component reaction of an aldehyde, a ketone, and two equivalents of malononitrile in ethanol.
... Multicomponent reactions (MCRs) are a type of reaction where at least three different starting materials are made to react in a single reaction vessel. [2][3][4][5] The availability of various reacting sites in the reaction mixture increases the chances of probable novelty in the desired product. Therefore, MCRs have expedited organic synthesis to a signicant level of novel compound formation. ...
... A pentacyclic product named as (7-benzoyl-6,7-dihydro- [1,3] low energy demand and economically affordable chemicals are the major advantages of this reaction protocol (Scheme 43). 73 Taheri and colleagues performed the same reaction in 2021 to develop an easy, efficient and straight-forward protocol for the synthesis of benzo solvent system at reux. ...
The category of bifunctional building blocks overrides many others because of their fascinating wide applicability in synthetic chemistry. Aryl glyoxal is one of the key molecules used extensively in heterocyclic chemistry to afford nearly all types of five- and six-membered heterocycles, which are the structural constituents of many natural products. The multicomponent reaction is a practical strategy to utilize this wonderful moiety with different types of starting materials to obtain numerous diverse oxygen heterocycles. This review covers the advancement of aryl glyoxal as a prime synthetic equivalent in recent years for the synthesis of oxygen heterocycles.
... 3 In the last few years, multicomponent reactions (MCRs) have proved themselves to be very effective bond-forming tools in synthetic organic chemistry with reference to green chemistry. 4 MCRs are one-pot reactions that involve at least three reactants to generate a single product. 5 These reactions are very effective, have high atom economy and are accomplished in a sequence to produce a single targeted product. ...
... 5 These reactions are very effective, have high atom economy and are accomplished in a sequence to produce a single targeted product. 4 One of the major advantages of the MCRs is the synthesis of heterocyclic compounds with a lesser number of steps as compared to the simple classical methods. 6,7 The heterocyclic compounds consisting of nitrogen, oxygen and/or sulfur constitute an important class of organic compounds. ...
A dioxomolybdenum(VI) complex has been successfully prepared by the reaction of an ONO donor Schiff base, derived by condensing 3-methoxysalicylaldehyde and 4-amino-2-hydroxybenzohydrazide, with MoO2(acac)2. The structures of synthesized products were explored spectroscopically through FT-IR, ¹H and ¹³C NMR and by elemental composition (CHN) through combustion analysis. The catalytic potential of the complex was explored to synthesize the substituted 4H-pyrans through the domino Knoevenagel condensation, Michael addition and cycloaddition reaction. In this method, three-component condensation of various aryl aldehydes with malononitrile and 1,3-dicarbonyl compounds was carried out in refluxed ethanol. The main advantages of the present catalytic work are less time required for the completion of the reaction, high percentage yield and simplicity in operation.
... Due to the fact that heterogeneous catalysts, which can be conveniently separated from the reaction ambient and reused, offer economic and biocompatible advantages over homogeneous catalysts. Recently, several heterogeneous catalysts, such as silica nanoparticles [22], CsF [23], Amberlyst A21 [24], MgO/SnO 2 solid superbase [25], nanocrystalline ZnO [26], [BMIm]BF 4 [27], and InCl 3 [28], have been proposed for these synthesis methods. Also, several catalysts have been designed for the production of spirooxindole derivatives, including surfactant metal carboxylates [29], ethylenediamine diacetate [30], carbon-SO 3 H [31], and ZnS nanoparticles [32]. ...
The use of solvents, catalysts, and electrolytes in industrial processes presents significant environmental challenges, particularly in wastewater management. This study introduces a novel and sustainable deep eutectic solvent (DES) composed of HNFM and FeCl4, designed as a reusable electrolyte, solvent, and catalyst aimed to rapid electro-organic synthesis of spirooxindole compounds 5(a–f) and 4H-pyran derivatives 6(a–h) with yields ranging from 90 to 97%. The synthesis is conducted at room temperature under a 5 mA current using graphite rods as low-cost and readily available anodes and cathodes, completing the process in just 20 min. The innovative 4-formylmorpholin-4-ium iron (III) chloride (HNFM@FeCl4) DES not only enhances the efficiency of electrochemical reactions but also addresses environmental concerns associated with conventional solvents, catalysts, and electrolytes. By utilizing low-cost electrodes, this DES is both biodegradable and nontoxic, making it a sustainable alternative in electro-organic synthesis. This synthesis method demonstrates significant progresses in the reaction procedure and yields, showcasing the potential of this DES in organic synthesis applications. This research highlights the dual advantage of utilizing a green electrolyte while producing biologically relevant compounds, paving the way for more sustainable practices in electro-organic synthesis. The synthesized derivatives were identified through melting point analysis, FT-IR, 1HNMR, and CHN analysis. Additionally, an in vitro cytotoxicity assessment of the synthesized compounds reveals promising results, indicating their potential therapeutic benefits. The synthesized spirooxindole 5(a–f) and 4H-pyran 6(a–h) derivatives were then assessed for in vitro cytotoxic effects on the human colorectal adenocarcinoma cell line (HT-29) and human breast cancer cell line (MCF-7). All compounds demonstrated IC50 values lower than 10 µM for the MCF-7 and HT-29 cell lines, indicating strong potential in anticancer activity. Remarkably, derivatives 5(a–f) demonstrated fantastic efficacy in inhibiting the viability of the HT-29 and MCF-7 cell line in comparison with commercial anticancer agent Doxorubicin which utilized as a positive control in this research.
Graphical abstract
... There are numerous catalysts available for the production of the synthetic tetrahydrobenzo[b]pyran scaffold. For example, CaHPO 4 [26], SiO 2 NPs [27], ethylenediamine diacetate [28], SBPPSP [29], I 2 [30], methylene blue [31], NH 4 H 2 PO 4 /Al 2 O 3 [32], ACoPc-MNPs [33], ZnO NPs [34], acridine yellow G [35], NiFe 2 O 4 @SiO 2 -H 3 PW 12 O 40 [36], theophylline [37], triethanolamine [38], sodium alginate [39], Fe 3 O 4 @SiO 2 @TiO 2 [40], MgFe 2 O 4 nanoparticles [41], trichloroisocyanuric acid [42], Na 2 eosin Y [43], and DABCO [44]. The prolongation of reaction times can be attributed to various factors such as the utilization of metal catalysts, the use of expensive reagents, the occurrence of complex reaction processes, and a reduction in yield, all of which can have adverse effects on waste management. ...
A green radical synthetic approach for the production of tetrahydrobenzo[b]pyran scaffolds, which utilizes a Knoevenagel–Michael cyclocondensation reaction of aldehydes, malononitrile, and dimedone, has been devised. This innovative technique has been designed to achieve environmental sustainability. A novel single-electron transfer photocatalyst was employed for the synthesis in an aqueous ethanol solution under an air atmosphere at room temperature and stimulated with blue LED illumination serving as a renewable energy source. The objective of this undertaking is to cultivate a metal-free donor–acceptor (D–A) photocatalyst that is highly affordable and universally accessible. 9-Mesityl-10-methylacridinium perchlorate (Mes-Acr-Me⁺ClO4⁻) is recognized for its expeditious and effortless applicability, high efficiency in yielding products, low energy consumption, and commendable eco-friendliness. This capability facilitates the investigation into the temporal alterations of environmental and chemical constituents. A research inquiry was conducted with the primary objective of determining the turnover number and turnover frequency associated with tetrahydrobenzo[b]pyran scaffolds. Furthermore, the attainment of cyclization at a gram-scale level offers substantiation for its feasibility as a viable solution for industrial implementation.
... belong to an important class of heterocyclic compounds having important pharmacological and biological activities [5]. They have use in spasmolytic [6], diuretic [7], antiallergic, antibacterial [8], anticoagulant, anticancer and antianaphylactic activities [9]. ...
Glutamic acid is used as an efficient organocatalyst for one-pot synthesis of tetrahydrobenzo [b]pyran via condensation of an aromatic aldehyde, dimedone and malononitrile in ethanol: water (1:4) as solvent at reflux temperature. The short reaction time, cleaner reaction, and easy workup make this protocol practical and economically attractive.
... Finding alternatives to toxic solvents, developing recyclable green catalysts, and reducing reaction times are as many challenges as the researchers must overcome. 1 The importance of green catalysts is naturally obvious for the multicomponent reactions (MCRs), which have attracted growing attention from both organic and medicinal chemists as they possess the ability to build complex and highly functionalized molecules in one-pot reactions, 2,3 The strategies of MCR offer significant advantages over conventional syntheses in terms of the high degree of atom economy, reaction time, and quantities of solvent used. 1.4-dihydropyridines (DHPs) and their derivatives have attracted great attention because of their wide range of pharmacological and therapeutic properties, such as nifedipine, nicardipine, amlodipine, felodipine, and others that are useful as calcium channel blockers, 4-6 anticancer, 7 antitubercular agents, 8 antioxidant, 9 and antibacterial. ...
A green method for synthesizing 1,4-dihydropyridines (1a-j) by a one-pot reaction of various aldehydes, ethyl acetoacetate, and ammonium carbonate, catalyzed by a seashell and kaolin powders, mixed and calcined at 500 and 800 °C, under solvent-free conditions, has been developed. The catalyst was characterized by physicochemical techniques, namely, X-ray diffraction (XRD), electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The mixture composed of 20% seashell and 80% Kaolin (Q3-500), calcined at 500 °C, gave the best results (78 to 96% yields). Q3-500 separation from the reacting medium was carried out by filtration and reused several times with a slight decrease in yields. Compared with other conventional methods, the present method is inexpensive and offers advantages, namely: the catalyst is eco-friendly, recyclable, and gives high yields with shorter reaction time.
... Pyran and chromene also show potent medicinal properties. 8,22,[57][58][59][60][61][62][63][64][65] So, we focused on the comprehensive study of the synthesis of pyrano and chromeno fused benzophenazines which are termed as benzo[a]pyrano [2,3-c]phenazines and Benzo [a]chromeno [2,3-c]phenazines respectively ( Figure 1). ...
One of the important classes of aza-polycyclic compounds is Phenazine systems which are naturally present and synthetically derived. More than 6000 phenazine compounds are recognized; among them, pyran and chromene fused Benzo[α]phenazines have gained special attention due to their fascinating biological properties. In this regard, synthesizing these phenazinle derivatives by multicomponent reactions has gained much attention due to the advantages associated with the process. Hence seeing the contribution of pyran and chromene fused benzo phenazines to the pharmaceutical field, this review highlights the synthesis of these compounds by different catalytic conditions involving the use of nontoxic catalysts and solvents in a multicomponent system. This review evaluates studies reported since 2012 on the multicomponent green synthesis of pyran and chromene fused benzo phenazines.
... Multicomponent reactions (MCRs) are a type of reaction where at least three different starting materials are made to react in a single reaction vessel. [2][3][4][5] The availability of various reacting sites in the reaction mixture increases the chances of probable novelty in the desired product. Therefore, MCRs have expedited organic synthesis by a signicant level in novel compound formation. ...
The category of bifunctional building blocks overrides many others because of their fascinating wide applicability in synthetic chemistry. Aryl glyoxal is one of the key molecules that has been extensively used in heterocyclic chemistry to afford nearly all types of five- and six-membered heterocycles, which are the structural constituents of many natural products. The multicomponent reaction is a practical strategy to utilize this wonderful moiety with different types of starting materials to obtain numerous diverse oxygen heterocycles. This review covers the advancement of aryl glyoxal as a prime synthetic equivalent in recent years for the synthesis of oxygen heterocycles.
... Now a days, to stop the use and production of unsafe substances in the designing, making and use of chemical products, they are trying to develop new synthetic methods which solve environmental problems involves the designing and redesigning of chemical creation and chemical products. [26,27] The synthesis of dihydropyrano [3,2-c] chromenes derivatives by a three component condensation reaction of 4-hydroxycoumrin, aldehydes and malononitrile has been performed under various conditions by using different catalyst such as ammonium acetate, [28] piperidine in aqueous media, [29] DBU, [30] urea, [31] Na 2 HPO 4 , [32] K 2 CO 3 , [33] TBAB, [34] MgO, [35] (S)-proline, [36] [bmim]Br, [37] nano-Al 2 O 3 , [38] CuOnano, [39] Fe 3 O 4 @GO-naphthalene-SO 3 H nanocatalyst, [40] Fe 3 O 4 @SiO 2 -Poly acrylic acid nanocatalyst [41] MNPs@ Cu-nano catalyst, [42] H 6 P 2 W 18 O 62 .18H 2 O, [43] DMAP, [44] silica grafted IL, [45] DAHP, [46] TBBDA, [47] etc. SDS (20 mol %) mediated protocol for the synthesis of 2-amino 4H-chromene was also reported [48] but it take longer time to completion of the reaction. While these methods have achieved good results with their own advantages, but some of these procedures suffer from one or more limitations such as high cost, low yields, longer reaction times, use of toxic solvents, the requirement of special apparatus, tedious work-up and poor recovery and reusability of the catalyst. ...
A simple, efficient and rapid one pot green synthesis of pyrano‐chromene derivatives have been realized by using water‐SDS‐neutral ionic liquid ([BMIm]Br) miceller system via sequential addition of aromatic aldehyde, malonitrile (Knoevenagel condensation) followed by 4‐hydroxy coumarin. In all cases the obtained products were produced well to excellent yields. This protocol shifts a versatile solvent‐catalyst system, which has many advantages such as eco‐friendly condition, simple workup and reuse (recycle) of post reaction waste containing sodium dodecyl sulphate and ionic liquid without loss of catalytic activity. The efficacy of the synthesised compounds as inhibitors of the SARS‐CoV‐2 main protease (Mpro) was investigated through molecular docking studies. Our study showed that most of the synthetic compounds exhibited excellent capability to block the SARS‐CoV‐2 Mpro by binding with crucial amino acid residues in catalytic pockets, compared to naturally occurring known SARS‐CoV‐2 Mpro inhibitors, flavonoids like Baicalein, Quercetin, and Quercetagetin.
... In some occasions, prolonged reaction times were reported (Table 1; entries 1 , 4, 19). Few of them were definitely carried out in aqueous medium although they required either long reaction times or high temperature (Table 1; entries [17][18][19][20][21][22][23][24]. After analyzing the reported methods, we feel that there is still enough scope to design an environmentally benign general method for the synthesis of structurally diverse tetrahydrobenzo[b] pyrans in water. ...
A facile and convenient method has been developed for the one-pot three-component synthesis of 2-amino-3-cyano substituted tetrahydrobenzo[b]pyran derivatives from the reactions of aromatic aldehydes, malononitrile and dimedone or 1,3-cyclohexanedione in the presence of a catalytic amount of sodium dodecyl sulphate as an efficient surfactant type catalyst in water at room temperature. Synthesis of 2-amino-3-cyano substituted spiropyrans was also achieved under the same reaction conditions starting from ninhydrin/isatins, malononitrile and dimedone or 1,3-cyclohexanedione. All the reactions were completed within 2.5 h and the desired products afforded in good to excellent yields. Gram scale production of the desired compound was also achieved. Use of water as green solvent, commercially available low cost surfactant type catalyst, high atom economy, excellent yields, energy efficiency, no column chromatographic purifications, reusability of the solvent media, multiple carbon–carbon and carbon-heteroatom bond formations are some of the major advantages of this newly developed protocol.
Graphical Abstract
... Several methods for synthesizing tetrahydrobenzo[b]pyran scaffolds with MCRs in the presence of various catalysts have been published. For example, CaHPO 4 (Bodaghifard et al., 2016), SiO 2 NPs (Banerjee et al., 2011), ethylenediamine diacetate (Zhou et al., 2017), silica-bonded N-propylpiperazine sodium n-propionate (Niknam et al., 2013), I 2 (Bhosale et al., 2007), NH 4 Al(SO 4 ) 2 .12H 2 O FIGURE 1 | Photocatalytic cycles can be carried out with MB + (Patel et al., 2021). (Mohammadi et al., 2017), NH 4 H 2 PO 4 /Al 2 O 3 (Maleki and Sedigh Ashrafi, 2014), ACoPc-MNPs (Zolfigol et al., 2016), ZnO NPs (Banerjee and Saha, 2013), Fe 3 O 4 @SiO 2 -imid-PMA (Esmaeilpour et al., 2015), NiFe 2 O 4 @SiO 2 -H 3 PW 12 O 40 (Maleki et al., 2016), theophylline (Mohamadpour, 2021c), triethanolamine (Rahnamaf et al., 2020), sodium alginate (Mohamadpour, 2022a), Fe 3 O 4 @SiO 2 @ TiO 2 (Khazaei et al., 2015), MgFe 2 O 4 nanoparticles (Eshtehardian et al., 2020), trichloroisocyanuric acid (Hojati et al., 2018), Na2 eosin Y (Mohamadpour, 2021d), DABCO (Tahmassebi et al., 2011), and Pd nanoparticles (Saha and Pal, 2012). ...
In a green tandem reaction using aldehyde derivatives, malononitrile, and dimedone, a radical tandem Knoevenagel–Michael cyclocondensation reaction of tetrahydrobenzo[b]pyran scaffolds was developed. Using visible light as a sustainable energy source, methylene blue (MB⁺)-derived photo-excited state functions were employed in an aqueous solution as single-electron transfer (SET) and energy transfer catalysts. The range of yields is quite uniform (81–98%, average 92.18%), and the range of reaction time is very fast (2–7 min, average 3.7 min), and the point mentioned in the discussion is that the procedure tolerates a range of donating and withdrawing groups, while still giving very excellent yields. The reaction is fairly insensitive to the nature of the substituents. Research conducted in this project aims to develop a non-metallic cationic dye that is both inexpensive and widely available for more widespread use. In addition to energy efficiency and environmental friendliness, methylene blue also offers an excellent atom economy, time-saving features, and ease of use. As a result, a wide range of long-term chemical and environmental properties can be obtained. The turnover number and turnover frequency of tetrahydrobenzo[b]pyran scaffolds have been computed. Surprisingly, gram-scale cyclization is a possibility, implying that the technology may be applied in industries.
... Those are the building blocks and central part of many natural and synthetic molecules which display different pharmacological characteristics. 4H-pyrans in particular, exhibit many antifungal, antimicrobial, anticancer, spasmolytic, anti-anaphylactic, and anti-inflammatory properties (Green et al., 1995;Reddy et al., 2017;de Souza et al., 2004;Udhaya Kumar et al., 2019;Aytemir et al., 2004;Banerjee et al., 2011). Many naturally occurring products and medicinal compounds have the 4H-pyran core (Pratap and Ram, 2014;Sonsona et al., 2015). ...
Ultrasound-assisted multicomponent reactions in water are great implements for the development of bioactive compounds. The methodologies for the synthesis of different heterocyclic molecules have acquired enormous attention. Many such techniques are energy-intensive and associated with hazardous chemicals, solvents, expensive work-ups. Low yields and multi-step schemes generate huge organic waste. Hence, researchers thus focussed on benign and eco-friendly techniques to assemble heterocyclic analogs and drug molecules. The ultrasound-assisted synthesis of the target organic moieties frequently facilitates higher product yields than other methodologies. This review is focused on ultrasound-aided multicomponent reactions for synthesizing varied nitrogen-, oxygen-, and sulfur-containing heterocyclic compounds using water as the solvent. The advantages and limitations with respect to yields and reaction conditions are discussed. This evaluation covered the literature reports from 2014 to date.
This article describes the amalgamated of polyboric acid (PBA) and Aminoethyl-3-Aminopropyltriethoxysilane (AEAPTES) by straightforward extrusion process to produce composite (PBA/AEAPTES). It showed basic nature due to amine functionalities on surface of PBA. The composite is applied for the fabrication of pyran derivatives. These reactions are noteworthy for their large product yields, environmental friendliness, quick reaction times, wide range of substrates and no need of hazardous solvents. Moreover, there is no discernible decrease in activity after four reuses of the catalyst and catalyst separated by simple filtration method without any extraction. The resultant composite is characterized by FT-IR, XRD and SEM analysis. In addition, the synthesized compounds characterized by FT-IR, ¹H, & ¹³C NMR analysis.
This study examined the investigation of one‐pot multicomponent reactions of actylacetone, 4‐hydroxy‐3‐methoxybenzaldehyde, primary amines, and activated acetylenic compounds in an aqueous medium at room temperature in the presence of catalytic amounts of Cu@Fe3O4/SiO2@MWCNTs. The responses that were employed As a result, high‐yielding bis‐1,4‐dihydropyridines and other novel compounds can be produced. Diphenyl‐picrylhydrazine (DPPH) radical trapping is being used in this field of study to examine the antioxidant characteristics of some bis‐1,4‐dihydropyridines that are produced. Scholarly research now underway has concentrated on examining the antibacterial characteristics of chemical substances that have been produced. The bis‐1,4‐dihydropyridines was synthesized by an experimental procedure that demonstrated several notable features, such as rapid reaction kinetics, substantial product yields, and effortless separation of the catalyst from the reaction mixture.
A novel Brønsted acidic nanocomposite, H 3 PMo 11 O 39 @SiO 2 @g-C 3 N 4 has easily prepared. This nanocomposite has characterized and identified using a Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX). Three-component condensation reaction of aldehyde, malononitrile, and dimedone carried out in the presence of the H 3 PMo 11 O 39 @SiO 2 @g-C 3 N 4 nanocomposite as a green catalyst under solvent-free conditions at room temperature. The experimental results show that the 4-hydropyran derivatives obtained in high yields and very short reaction times. Easy workup, reusability, and stability of the green catalyst are noteworthy advantages of this method. Moreover, this heterogeneous catalyst can be satisfactorily recovered by simple filtration and reused at least five times without loss of activity.
Due to their extensive applications in pharmaceuticals and natural substances, organic synthesis and heterocyclic compounds have been at the forefront of research for many years. Pyrimidine is one of the heterocyclic compounds that have various derivatives with promising biological and pharmacological properties. This review article covers the synthesis and biological effects of pyrimidine derivatives, such as pyrano[2,3‐d]pyrimidines, pyrido[2,3‐d]pyrimidines, and furo[2,3‐d]pyrimidines. The compounds discussed in this review have a wide range of biological activities. Recent advances in green chemistry have led to the development of eco‐friendly synthetic methods for producing these bioactive heterocycles. This review aims to present various synthetic methods and biological effects of these compounds and provide new opportunities for organic chemists to develop potent nitrogen‐ and oxygen‐containing heterocycles for future applications. The review highlights examples of successful syntheses and applications of pyrimidine derivatives in the fields of antibacterial, antifungal, anticancer, enzyme inhibition, and antiviral research.
Background
A number of research were conducted on the pyran and thiophene derivatives, which were attributed to have a wide range of biological activities, including anti-plasmodial, as well as acting as caspase, hepatitis C and cancer inhibitors.
Objective
The multicomponent reactions of the 5-acetyl-2-amino-4-(phenylamino)-thiophene-3-carbonitrile produced biologically active target molecules like pyran and their fused derivatives. Comparison between regular catalytic multi-component reactions and solvent-free ionic liquids immobilized multicomponent was studied.
Method
The multicomponent reactions in this work were carried out not only under the reflux conditions using triethylamine as a catalyst but also in solvent-free ionic liquids immobilized magnetic nanoparticles (MNPs) catalysts.
Results
Through this work, thirty-one new compounds were synthesized and characterized and were evaluated toward the six cancer cell lines, namely A549, HT-29, MKN-45, U87MG, and SMMC-7721 and H460. The most active compounds were further screened toward seventeen cancer cell lines classified according to the disease. In addition, the effect of compound 11e on the A549 cell line was selected to make further morphological changes in the cell line. The Molecular docking studies of 11e and 11f were carried and promising results were obtained.
Conclusion
The synthesis of heterocyclic compounds derived from thiophene derivatives has been receiving significant attention. After a detailed optimizing study, it has been found that the solvent-free ionic liquids immobilized multi-component syntheses afforded a high yield of compounds, opening a greener procedure for this synthetically relevant transformation. Many of the synthesized compounds can be considered anticancer agents, enhancing further studies
Increased energy consumption as a result of population growth and industrialization necessitates the use of renewable energy sources in the field of chemistry. Nonrenewable energy sources release not only greenhouse gases but also other hazardous pollutants that are damaging to all living things. This plainly mandates the researchers' use of a renewable energy source that is both environmentally friendly and cost-effective. This study shows that a renewable energy source (sunlight) can be used to synthesize tetrahydrobenzo[b]pyran scaffolds using the Knoevenagel–Michael cyclocondensation of aldehyde derivatives, malononitrile, and dimedone via a three-condensation domino reaction. This research establishes a new role for solar energy as a renewable energy source for the synthesis of tetrahydrobenzo[b]pyran scaffolds under catalyst-solvent-free conditions, with outstanding yields, shorter reaction time, and great atom economy. This cyclization may also be done on a gram scale with free, safe, and clean energy from concentrated solar radiation (CSR), indicating the reaction's potential for industrial applications.
In this work, a new Schiff base attached to an ionic liquid and a crown ether and coordinated to cobalt (II) was synthesized and then characterized by Fourier transform IR, inductively coupled plasma, X-ray diffraction, and thermogravimetric analyses. This catalyst was used in the synthesis of xanthenes and chromenes. In these syntheses, an alcohol was used instead of an aldehyde or a ketone. In all the reactions, the catalyst containing the crown ether and the ionic liquid exhibited greater activity than the analogs without them. The presence of the crown ether ring and the ionic liquid increases the solubility of the catalyst in the aqueous phase and increases its contact surface as a Lewis acid with the reactive species, increasing the alcohol oxidation process and, as a result, the speed of the reaction. Another advantage of this method is the reuse of the catalyst for up to at least six runs, the short reaction time, the use of environmentally friendly green solvents, and the good to excellent yields of products.
Background/Introduction
4-aryl-4H-chromenes have attracted attention as potential anticancer agents.
Objective
In an effort to discover effective compounds, we designed a new series of these chromenes with methoxy substitution at 2, 3, 4, 5, and 6 positions.
Methods
The synthesized compounds were tested for anticancer properties against two human cancer cell lines (MCF- 7 and PC3) as well as a normal cell line. Furthermore, induction of apoptosis was explored through various methods, such as flow cytometry analysis, morphological changes, activation of caspase 3, ROS, and MMP.
Results
The MTT assay showed that the 5g derivative, with methoxy groups at ortho and meta positions, exhibited the highest potency (IC50 = 40 μM) against the PC3 cell line. Our findings revealed that compound 5g induced apoptosis in the PC3 cell line, which was demonstrated by activation of caspase 3, an increase in ROS levels, and early apoptosis percentage.
Conclusion
These results suggest that compound 5g holds promise as a potential therapeutic approach to cancer treatment.
This expansive and practical textbook contains organic chemistry experiments for teaching in the laboratory at the undergraduate level covering a range of functional group transformations and key organic reactions.The editorial team have collected contributions from around the world and standardized them for publication. Each experiment will explore a modern chemistry scenario, such as: sustainable chemistry; application in the pharmaceutical industry; catalysis and material sciences, to name a few. All the experiments will be complemented with a set of questions to challenge the students and a section for the instructors, concerning the results obtained and advice on getting the best outcome from the experiment. A section covering practical aspects with tips and advice for the instructors, together with the results obtained in the laboratory by students, has been compiled for each experiment.
Targeted at professors and lecturers in chemistry, this useful text will provide up to date experiments putting the science into context for the students.
CoCeO2 NPs were successfully synthesized and confirmed using XRD, FESEM and HRTEM techniques. The catalytic performance of the synthesized CoCeO2 NPs catalyst was examined during the one‐pot multicomponent synthesis of biologically significant 2‐amino‐3‐cyano‐4H‐pyran derivatives. The reaction was easily accomplished using a one‐pot, three‐component reaction of dimedone, aryl aldehydes and malononitrile in ethanol under reflux, with excellent yields and short reaction time. The current catalytic system is more appealing because of its simple reaction conditions, uncomplicated product isolation, economic feasibility, and reusability of the catalyst with free from significant loss of activity. This process offers an effective strategy for the synthesis of 2‐amino‐3‐cyano‐4H‐pyran derivatives. This article is protected by copyright. All rights reserved.
A novel heterogeneous pumice supported perchloric acid catalyzed synthesis of tetrahydrobenzo[b]pyran has developed via multi-component condensation of aromatic aldehydes, dimedone and malononitrile. The catalyst was characterized by IR, XRD, EDS, SEM, and TGA techniques which confirmed the formation novel pumice supported perchloric acid. The present protocol proved to have numerous advantages like one-pot reaction, good yield, short reaction time, inexpensive catalyst, recyclability and reusability of the catalyst, simple experimental and work up procedure, and purification of targeted molecules without column chromatography.
We are reporting a simple and efficient synthesis of highly functionalized aniline by the reaction of 2H‐pyran‐2‐ones and benzyl cyanide in presence of sodamide in dioxane under reflux conditions. Various 4‐sec.amino‐2H‐pyran‐2‐ones, 4‐methylsulfanyl‐2H‐pyran‐2‐ones and 2‐oxobenzo[h[chromones were used as a substrate. Further, synthetic application of obtained arylated aniline was carried out to afford multifunctional carbazoles (13). 2′′‐Bromo‐[1,1′ : 2′,1′′‐teraryl]‐3′‐amines (6) and 4‐(2‐bromoarylyl)‐9,10‐dihydrophenanthren‐3‐amines (11) was used to demonstrate the the synthesis of carbazoles. The structure of isolated product 11 d was ascertained by spectroscopic and single crystal X‐ray diffraction analyses. We have explained the role of nonpolar solvents in the synthesis of arylated aniline.
We established a green approach for the radical synthesis of tetrahydrobenzo[b]pyran scaffolds by using Knoevenagel-Michael tandem cyclocondensation of aldehyde derivatives, malononitrile, and dimedone. Using visible light as a renewable energy source, a photo-induced electron transfer (PET) photocatalyst was exploited in an aqueous solution. A low-cost, readily available non-metal dye is the goal of this research. The photochemically catalyzed acridine yellow G (AYG) exhibits high yields, energy efficiency, and environmental friendliness, as well as speed-saving characteristics and ease of use. This allows for tracking of environmental and chemical variables over time. In this study, turnover number (TON) and turnover frequency (TOF) of tetrahydrobenzo[b]pyran scaffolds were determined. It is remarkable that gram-scale cyclization is feasible, indicating that it can be applied to industry.
Organic Synthesis is a branch of chemical synthesis which concerns with preparation of new organic molecules through organic reactions. These reactions require reagents and conditions which are so designed so as to give maximum product with little efforts. The conventional multistep methodologies employ toxic and hazardous reagents, solvents which evolve copious amount of waste which is of prime concern to human health and environment. Green chemistry practices aim to invent novel reactions mediated with technologies that go for efficient yield of the desired products preferably from renewable raw materials and reduce by-products. Innovation in such synthetic schemes which reduce operations and seek sustainable media is environmentally and ecologically benign. This chapter gives a comprehensive collection of tools and strategies for organic transformations contributed by researchers promoting Green Chemistry. The write-up covers a broad overview of novel and efficient methodologies ranging from catalytic approaches to microwave-induced synthesis, ultrasonics, solvent-free reactions and practice of unconventional media such as ionic liquids and deep eutectic solvents.
Graphical abstract
Organic-inorganic nanohybrid ionic liquid based on polyoxometalate [H2 [MIMBS]4 [P2W18O62].11H2O] (MIMB-P2W18) has been synthesized and characterized by elemental analysis technique, Fourier transform infrared (FT-IR), ¹H, ¹³C, and ¹⁵P nuclear magnetic resonance (NMR), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The catalytic activity of this nanohybrid ionic liquid has been studied in multi-component reactions to generate pyran and spiro indoline derivatives. Tetrahydrobenzo[b]pyrans have been successfully synthesized by one-pot three-component condensation of aldehyde, malononitrile and dimedone (or cyclohexane-1,3-dione/3-methyl-2-pyrazoline-5-one) using MIMB-P2W18 as a heterogeneous nano-catalyst. Furthermore, a set of multi-substituted spiro[indoline-3,4׳-pyrano[2,3-c]pyrazole] has been synthesized from isatin, hydrazinehydrate/phenylhydrazine, ethyl acetoacetate and malononitrile/ethyl cyanoacetate in the presence of the same catalyst via one-pot four-component method at room temperature. These procedures have several advantages such as high yields of product, easy work-up procedure, short reaction time and stability, non-toxicity, cheapness and reusability of the catalyst.
Triethylenetetramine-grafted magnetic graphene oxide (Fe3O4@GO-NH2) was used as a reusable heterogeneous catalyst in the preparation of 2-amino-4H-benzopyran derivatives. The characteristics of this method include green reaction conditions, easy separation, compatibility with the environment, the cost-effectiveness of the catalyst, and high yield (85–98%) in a short reaction time. It was also found that it could be reused for at least seven cycles without significant performance degradation.
In this article, a green and recoverable heterogeneous phase-transfer catalyst containing silica-coated magnetite nanoparticles functionalized by polyethylene glycol and ethylenediamine was synthesized. After full characterization, the catalytic activity of the bifunctional magnetic nanocomposite was investigated in the straightforward synthesis of 2-amino-3-cyano-4H-pyrans under mild and green conditions through the one-pot reaction of aryl aldehydes with malononitrile and dimedone or 1,3-cyclohexanedione. Significant features such as mild reaction conditions, simple work-up, short reaction time, high product yield, and reusability of the catalyst, enhance the efficiency of this catalytic procedure economically and environmentally benefits.
[Cu(bpdo)2·2H2O]²⁺/Montmorillonite was successfully prepared by impregnation method and characterized by XRD, FESEM, EDS, ICP, FT-IR, and TGA. The XRD patterns show swelling of montmorillonite layers, leading more absorption of the Cu (II) complexes. The catalytic activity of this novel nanocomposite was investigated in the efficient synthesis of 2-amino-4H-chromene and 2-amino-4H-benzopyran derivatives via Multicomponent Reactions (MCRs). A wide range of substituted benzaldehyde, malononitrile (or ethyl cyanoacetate), and diverse enolizable C–H activated acidic compounds were reacted in the presence of [Cu(bpdo)2·2H2O]²⁺/Mont, in EtOH/H2O under reflux conditions to afford the corresponding 2-amino-4H-chromene and 2-amino-4H-benzopyran derivatives. In addition, spirochromene and spiroacenaphthylene derivatives were synthesized successfully in the presence of [Cu(bpdo)2·2H2O]²⁺/Mont under reflux conditions in EtOH/H2O. Some advantages of this method involved efficiency and rapidness leading to short reaction times, easy workup procedure, high yields, and recyclable green catalyst and being performed under eco-friendly conditions. This novel nanocatalyst was easily separated, recovered, and reused at least for five times without noteworthy loss in its catalytic activity and performance.
Aim
The research work aims to develop sustainable microwave-assisted scheme for the synthesis of 4-(benzylidene amino)-6-phenylpyrimidine-5-carbonitrile congeners.
Background
4-(benzylidene amino)-6-phenylpyrimidine-5-carbonitrile scaffolds are novel molecules having various pharmacological activities such as neurodegenerative, anti-microbial, anti-cancer. Schiff base congeners are considered as efficient pharmacophores for research. These activities are due to the presence of azomethine (CH=N) group in the Schiff base compounds.
Objectives
To synthesise different novel Schiff base scaffolds of pyrimidine nuclei by green chemistry with good yield.
Methods
The 4-(benzylidene amino)-6-phenylpyrimidine-5-carbonitrile scaffolds were prepared by two step reactions. Both steps were microwave assisted. The first step was to synthesize 4-amino-6-phenylpyrimidine-5-carbonitrile as intermediate compound. This compound was synthesized by using benzaldehyde, malononitrile and formamidine hydrochloride. The reaction conditions are as following: temperature- 1010C, pressure- 300W, time- 50min. The final Schiff base congeners were obtained by reacting it with various aromatic aldehydes in the second step. The yield, reaction condition, and time consumption all were very acceptable for the green synthetic methods rather than the conventional schemes.
Results
Microwave assisted method was more efficient. The reactions were less time consuming and the overall yield of the all-synthesized compounds was in the range of 72-81%. The synthesized congeners were characterized by different spectroscopic methods. The main functional group [azomethine] was considered by the IR peak at 1611 cm-1 wavelength.
Conclusions
This microwave assisted synthetic method thus emerges as more eco-friendly due to a much-reduced usage of organic solvents, leading to less harmful residues. Using this scheme, we synthesized different Schiff base congeners with satisfactory chemical yields.
A pseudo-five-component reaction leading to efficient synthesis of dicyanoanillines was developed using only aromatic aldehydes and malononitrile as the starting reactants. Mechanistic studies suggested that a malononitrile dimer and the Knoevenagel condensation product of benzaldehyde, initially formed in the reaction mixture, combine with a fourth equivalent of malononitrile to form the final product. X-ray crystallography analysis of one of the derivatives confirmed the structure of the products.
We report the fabrication of self-assembled Co3O4 nano-flake material by dissociation of CoCl2.6H2O under basic medium using co-precipitation method. The electronic/crystalline structure and morphology and elemental purity of Co3O4 material have been analyzed by UV–Vis, fluorescence, powder X-ray diffraction, field emission scanning electron microscopy, and energy dispersive X-ray measurement. The Co3O4 nano-flake has demonstrated excellent catalytic activity in the one-pot multicomponent synthesis of tetrahydrobenzo[b]pyran and 2-aryl-1,3-benzothazole derivatives under neat conditions in excellent yields. The Co3O4 nano-flake material was recovered from the reaction mixture and reused for at least ten runs without appreciable loss of catalytic activity.
A catalyst-free and solvent-free three-component tandem strategy for synthesizing tetrahydrobenzo[b]pyran scaffolds through Knoevenagel–Michael cyclocondensation is reported using visible light irradiation as a green promoter at room temperature. The prominent benefits of the existing protocol are catalyst-free, solvent-free, using commercially accessible, inexpensive preliminary substances, operational simplicity, energy-effectiveness, great yields, high atom-economy, thus meeting some features of sustainability and green chemistry.
Background
eosin Y is a metal-free organic dye with easy availability that has gained a wide application in recent years, having economic and ecological superiority for substituting transition-metal-based photocatalysts.
Method
a green three-component tandem strategy for synthesizing tetrahydrobenzo[b]pyran scaffolds through Knoevenagel-Michael cyclocondensation is reported using Na2 eosin Y-derived photoexcited states functions as a direct hydrogen atom transfer (HAT) catalyst via visible light-mediated in aqueous ethanol at ambient temperature under air atmosphere.
Findings
this study paves the new role for further use of a metal-free organic dye with commercial availability and inexpensiveness, Na2 eosin Y in photochemical synthesis with use of the lowest amount of catalyst, energy-effectiveness, excellent yields, operational simplicity, time-saving aspects of the reaction and high atom economy, thus meeting some features of sustainable and green chemistry.
A simple and straightforward route for the synthesis of thioethers, thioesters, vinyl thioethers and thio-Michael adducts has been demonstrated using silicananoparticles (NPs) as a reusable catalystvia the 1,2-addition of thiols to alkenes, alkynes and alkyl/acyl halides, and the 1,4-addition of thiols to conjugated alkenes at room temperature.
Synthesis of 2-amino-4-aryl-3-carbalkoxy-7,7-dimethyl-5-oxo-5,6,7,8-tertrahydrobenzo[b]pyran derivatives was carried out in 81-98% yields by one-pot condensation of aromatic aldehydes with cyanoacetic esters and 5,5-dimethyl-1,3-cyclohexanedione catalyzed by KF/basic Al2O3 at room temperature under ultrasound irradiation.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Optoelectronic components require materials with large second-order nonlinearities. Recently, various types of non-classsical chromophores have been developed, in the hope that they have improved physical properties for materials formation. The main research directions and latest developments reviewed here include multi-dipolar chromophoric assemblies, multiple donor and acceptor chromophores, non-rod-shaped dipolar chromophores, and non-conjugated donor-acceptor chromophores, in which the charge transfer process is through space instead of the pi-conjugated bridge.
Continuing our research on the synthesis and biological activity of heterocyclic compounds synthesized by carbon suboxide, we prepared and screened some 2-oxo (2H) 1-benzopyran-3-carboxamide derivatives. The results of pharmacological assays are reported and discussed.
A stereoselective chiral synthesis of (–)-methyl elenolate has been achieved by employing a newly developed method for the construction of substituted 3-methoxycarbonyldihydropyrans based on a radical cyclisation reaction.
Following the increased interest from the pharmaceutical industry for the generation of diverse libraries of heterocyclic compounds, scientific efforts have become more and more focused on the development of novel multi-component procedures as a means of gaining rapid access to such compounds. Initially, the development of solid-phase procedures received considerable attention. However, current efforts are increasingly concerned with the development of solution-phase procedures. The latter will be the subject of discussion in this review, which aims to give an overview of the progress made in the past decade.
After a general introduction, non-catalyzed, acid-catalyzed, and transition metal-catalyzed solution-phase multi-component procedures for the preparation of a wide range of heterocycles will be discussed. The last chapter discusses the role of cycloaddition reactions in the development of novel MCRs for the synthesis of heterocyclic compounds.
In spite of their important role in the synthesis of heterocyclic compounds, MCRs involving isocyanides are not discussed in this review, since the topic has been exhaustively reviewed several times.
• 1Introduction
• 2Non-Catalyzed MCRs
• 3Acid-Catalyzed MCRs
• 4Transition Metal-Catalyzed or -Mediated MCRs
• 5MCRs Involving Cycloaddition Reactions
• 6Conclusions and Outlook
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
A novel heterogeneous hydrid catalyst is developed and applied for the Friedel—Crafts-type alkylation of arenes.
The development of highly efficient methodologies for constructing heterocyclic compounds is a major challenge in organic chemistry. This Account presents the recent progresses on cascade strategies for heterocyclic synthesis based on ketenimine intermediates. Three types of cascade reactions for the synthesis of a variety of heterocycles, involving nucleophilic addition to the central carbon of ketenimine, radical addition to the central carbon of ketenimine, and pericyclic reaction of ketenimine, are highlighted in this Account. A brief discussion on the mechanism of copper-catalyzed azide-alkyne cycloaddition (CuAAC) providing ketenimines is also included.
1 Introduction
2 Nucleophilic Addition to the Central Carbon of Ketenimines
3 Radical Addition to Ketenimines
4 Pericyclic Reactions of Ketenimines: Cycloaddition Reaction
4.1 Ketenimine-Imine [2+2] Cycloadditions
4.2 Ketenimine-Alkene [2+2] Cycloadditions
5 Pericyclic Reactions of Ketenimines: Electrocyclic Ring Closure
6 Pericyclic Reactions of Ketenimines: Sigmatropic Migration
7 Conclusions and Outlook
Abstract An efficient, rapid, one-pot synthesis of tetrahydrobenzo[b]pyran is achieved via a three-component reaction of aldehydes, 1,3-diketone, malononitrile in 20% ethanol using anhydrous
potassium phosphate as a catalyst at room temperature. The key advantages are the short reaction time, high yields, simple
work-up, inexpensive catalyst and purification of products by non-chromatographic methods, i.e. by simple recrystallization
from ethanol.
Graphical Abstract An efficient, rapid, one-pot synthesis of tetrahydrobenzo[b]pyran is achieved via a three-component reaction of aldehydes, dimedone, malononitrile in 20% ethanol using anhydrous potassium phosphate as a
catalyst at room temperature. The key advantages are the short reaction time, high yields, simple work-up, inexpensive catalyst
and purification of products by non-chromatographic methods, i.e. by simple recrystallization from ethanol.
One-step synthesis of ‘privileged medicinal scaffolds’, 2-amino-3,5-dicarbonitrile- 6-sulfanylpyridines, has been demonstrated via a multicomponent reaction of aldehydes, malononitrile, and thiols using silica nanoparticle (NP) as catalysts. The silica NP catalysts are very mild (nearly neutral in nature), effective, environmentally benign, and retain most of their activities after being reused for three times.
We have demonstrated the remarkable catalytic activity of silica nanoparticles (NPs) in the unusual bis-Michael addition of active methylene compounds to conjugated alkenes at room temperature. The catalyst silica NPs were reused up to seven runs without appreciable loss of catalytic activity.
An efficient synthesis of polyfunctionalized 4H-pyrans is carried out in one pot through condensation of an aldehyde, malononitrile, and an active methylenic diketo compound using a heterogeneous strong basic Mg/La mixed oxide catalyst. The protocol offers advantages in terms of higher yields, short reaction times, and mild reaction conditions, with reusability of the catalyst.
Acid catalysed condensations of various 2 substituted 1,3-oxazinanes 3 and 1,3-oxazolidines 4 with cyclic carbon nucleophiles viz. 5,5-dimethyl-1,3-cyclohexanedione and 1,3-cyclohexanedione furnish xanthene derivatives, whereas a Knoevenagel reaction proceeds with acyclic nucleophiles. In case of 4b and 4c, a unique synthesis of functionalised α-tetralones has emerged. Reactions of mixtures of cyclic and acyclic carbon nucleophiles with 3 provide some functionalised and partially reduced benzopyran derivatives.
The discovery of novel chemical reactions or reaction sequences that are able to generate useful chemical products may be regarded as the heart of organic chemistry. We present here concepts and methods on how to find and explore new multi component reactions, especially with automated combinatorial methods. This combinatorial reaction finding" provides also a powerful tool to the understanding of the rules of organic chemistry, especially structure-reactivity relationships.
Photosynthesis is one of the fascinating fields of current interdisciplinary research. It seems miraculous that nature, in the process of evolution, has managed to bring about the process of photosynthesis. The first step involves a charge separation at the reaction centers, which proceeds with 100% quantum yield from the photoexcited singlet state of the bacteriochlorophyll donor, despite the fact that the wasteful deactivation of the electron into the ground state should be highly favored. Biomimetic model compounds (that is, those which resemble the pigments nature has developed) have been constructed from porphyrins and quinones. These model systems have allowed the study of the factors contributing to the highly efficient charge separation. This report focuses on recent developments in the study of electron transfer in porphyrinoquinones. Some of the results of these investigations may not be not fully understood and are often the subject of controversial discussions.
The importance of nonlinear optical phenomena has been known for some time, however, since the mid-1980s, there has been an explosion of interest in the search for and development of non-linear optical materials that possess commercial device applications. To date, the systems have been utilized in information processing, optical switching, optical frequency conversion, and telecommunications, and with the advancing development of optotechnology, burgeoning demands for suitable materials are becoming apparent. Of the many systems studied for example inorganic crystals and semiconductors, organic crystalline monomers, and long-chain polymers with delocalized π electrons, no one species has proved to be all-encompassing, with advantages for one application being negated by disadvantages for another. This is likely to remain the case for the foreseeable future with the criteria of the application governing the type of material used. However, chemists are gradually elucidating what actually governs second- and third-order nonlinear activity and thereby, tailoring species to show greater effects. In recent years, organometallic compounds, through their unique characteristics such as diversity of metals, oxidation states, ligands, and geometries, have found success and brought a new dimension to the area. This review attempts, with critical appraisal, to bring the discussion of organometallic nonlinear optical systems up to date, as well as giving a brief but general introduction to the field of nonlinear optics.
For corrigendum see DOI:10.1002/anie.199508261
The current status of organic low-molecular weight and polymeric materials for third-order nonlinear optics is reviewed. The importance of organic materials lies in their promise of large nonlinear optical figure of merit, high optical damage thresholds, ultrafast optical responses, architectural flexibility, and ease of fabrication. Organic materials exhibiting interesting third-order nonlinear optical properties are discussed to illustrate the importance of structure–property correlations. Results on emerging organic materials that include liquids, dyes, fullerenes, charge-transfer complexes, π-conjugated polymers, dye-grafted polymers, organometallic compounds, composites, and liquid crystals are presented. Organic nonlinear optical materials seem promising for a wide range of applications and their potential for integrated optics should be further explored.
A series of 2-amino-5,6,7,8-tetrahydro-5-oxo-4-aryl-7,7-dimethyl-4H-benzo-[b]-pyran-3-carbonitrile were synthesized by reaction of benzylidenemalononitrile derivatives and 5,5-dimethyl-1,3-cyclo-hexanedione under microwave irradiation without catalyst and solvent free.
A series of 5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran derivatives were prepared by the reaction of arylmethylidenemalononitriles or 2-cyano-3-aryl-1-acrylate with 5,5-dimethyl-1,3-cyclohexanedione (dimedone) in DMF at room temperature catalyzed by KF-alumina. The structure of the product was confirmed by x-ray analysis.
A one-pot synthesis of a series of 5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran derivatives via three-component coupling reactions of aldehydes, dimedone and malononitrile in room temperature ionic liquids (RTILs) without any catalyst has been reported. In the meantime, the reuse of ionic liquids and the effect of different ionic liquids as solvent on the reaction have also been investigated.
(S)-Proline has been used as a mild, efficient and neutral catalyst for synthesis of various 4H-benzo[b]pyran derivatives via a one-pot three-component condensation of aromatic aldehydes, active methylene compounds, and dimedone in aqueous media. This method offers the advantages of proceeding and neutral and mild conditions, giving high to excellent yields of the products and simple workup.
A new route for the synthesis of linear and vinyl thioethers has been demonstrated using bare silica nanoparticle as catalyst at room temperature under solvent-free conditions. The catalyst can be reused up to six times without loss of catalytic activity.
A novel, heterogeneous Pd-MCM-48 catalyst has been developed by encapsulating palladium nanoparticles into the cubic phase of mesoporous MCM-48 matrix at room temperature. The catalyst demonstrated excellent chemo- and regioselectivity for the hydrogenation of olefins at room temperature within 30-80 min. The turnover frequency for the hydrogenation is very high (4400 h(-1)). Interestingly, selectivity of the catalyst was significantly influenced by the mode of addition of palladium precursor. Moreover, the catalyst was also very effective for the coupling reactions with the formation of carbon-carbon and carbon-nitrogen bonds under ligand-free and aerobic conditions.
By generating structural complexity in a single step from three or more reactants, multicomponent reactions (MCRs) make it possible to synthesize target compounds with greater efficiency and atom economy. The history of such reactions can be traced to the mid-19th century when Strecker first produced alpha-aminonitriles from the condensation of aldehydes with ammonia and hydrogen cyanide. Recently, academic chemists have renewed their interest in MCRs. In part, the pharmaceutical industry has fueled this resurgence because of the growing need to assemble libraries of structurally complex substances for evaluation as lead compounds in drug discovery and development programs. The application of MCRs to that increasingly important objective remains limited by the relatively small number of such reactions that can be broadly applied to prepare biologically relevant or natural-product-like molecular frameworks. We were interested in applying logic-based approaches, such as our single reactant replacement (SRR) approach, as a way both to improve known MCRs and to design new multiple-component routes to bioactive structures. This Account provides several examples that illustrate the use of SRR with known MCRs as starting points for synthetic innovation in this area. As part of our working hypothesis, we initially explored strategies for engineering improvements into known MCRs, either by increasing the dimensionality--that is, changing an n-component to an (n + 1)-component reaction--or broadening the scope of useful input structures, or both. By exhaustively applying retrosynthetic analysis to the cognate MCR to identify and exploit alternative entry points into the overall reaction manifold, we have devised several such re-engineered MCRs. Serendipitous findings have also augmented the yield of useful developments from our logic-inspired approach. In some cases, we have identified surprising links between different compound families that provide useful new entry points for chemical library synthesis. In other cases, the same re-engineering logic made it possible (sometimes in unexpected ways) to transform certain nonelementary two-component reactions into higher order MCRs. While logic may also inspire the search for new MCRs, the design process requires added chemical creativity, which cannot be reduced to a simple formula. The long-term goal of our research is to expand the useful repertoire of such reactions, which are important as complexity-generating tools in both combinatorial and diversity-oriented synthesis.
It was recently recognized that three different types of multi-component reactions (MCRs) exist. In preparative chemistry, the MCRs of type II form their products particularly efficiently. These reactions correspond to equilibria of educts and intermediate products, whose final products are formed practically irreversibly. In recent years, the four component reaction of the isocyanides (U-4CR) of type II and their unions with various reactions and MCRs have become an important industrial process for preparing products and their libraries. It has been demonstrated that all conceivable collections of U-4CR educts can be converted into the corresponding products. In the usual chemical reactions, only the substituents of the products can be varied, whereas the U-4CR and related reactions can also produce skeletally different types of products with diverse substituents. The preparative advantages of forming products by the one-pot MCRs and the great variety of the possible products are illustrated in this review.
Asymmetric multicomponent reactions involve the preparation of chiral compounds by the reaction of three or more reagents added simultaneously. This kind of addition and reaction has some advantages over classic divergent reaction strategies, such as lower costs, time, and energy, as well as environmentally friendlier aspects. All these advantages, together with the high level of stereoselectivity attained in some of these reactions, will force chemists in industry as in academia to adopt this new strategy of synthesis, or at least to consider it as a viable option. The positive aspects as well as the drawbacks of this strategy are discussed in this Review.
[reaction: see text] A facile parallel synthesis of polysubstituted 2,6-dicyanoanilines via microwave-promoted three-component reaction of aldehydes, ketones, and propanedinitrile in solution and also on polymer support has been developed. The screening for optical properties identified two new compounds with high fluorescence quantum yields.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
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