Microwave-assisted Biginelli Research Articles

Synthesis of 3,4-Dihydropyrimidin-2(1H)-one-phosphonates by the Microwave-Assisted Biginelli Reaction

The synthesis of novel 3,4-dihydropyrimidin-2(1H)-one-phosphonates was elaborated by the microwave (MW)-assisted three-component Biginelli reaction of β-ketophosphonates, aromatic or aliphatic aldehydes and urea derivatives. The condensation was optimized on a selected model reaction in respect of the reaction parameters, such as the heating method, the type of the catalyst and solvent, the temperature, the reaction time and the molar ratio of the starting materials. The fast and solvent-free MW-assisted procedure was then extended for the preparation of further new 3,4-dihydropyrimidin-2(1H)-one-phosphonate derivatives starting from different aromatic aldehydes, β-ketophosphonates and urea derivatives to prove the wide scope of the process. As a novel by-product of the Biginelli-type synthesis of 3,4-dihydropyrimidin-2(1H)-one-phosphonates, the 5-diethoxyphosphoryl-4-phenyl-6-styryl-3,4-dihydropyrimidin-2(1H)-one was also isolated and characterized. Our MW-assisted method made also possible the condensation of aliphatic aldehydes, diethyl (2-oxopropyl)phosphonate and urea, which reaction was previously reported to be impossible in the literature.

Ultrafast fabrication of fluorescent organic nanoparticles with aggregation-induced emission feature through the microwave-assisted Biginelli reaction

Because of its unique optical properties, the aggregation-induced emission (AIE) dye has attracted extensive attention for various applications. Especially, the utilization of AIE-active dyes for fabrication of fluorescent organic nanoparticles (FONs) has attracted the most research interest for biomedical applications. Therefore, the development of novel and effective strategies to design and prepare AIE-active FONs should be of great importance for the biomedical applications of AIE-active FONs. In this report, we reported an ultrafast strategy that based on the one-pot microwave-assisted Biginelli reaction for fabrication of AIE-active poly(AA-AEMA-TPE) copolymers, which use the 2-(methacryloyoxy) ethylacet, acrylic acid (AA) and 4′,4‴-(1,2-diphenylethene-1,2-diyl) bis([1,1′-biphenyl]-4-carbaldehyde) (TPE-CHO) as the substrates. The microwave-assisted Biginelli reaction is simple, efficient and atom-economical and can be accomplished within 3 min. Owing to their amphiphilicity, poly(AA-AEMA-TPE) copolymers will self-assemble into FONs with small size and high water dispersibility. The proton nuclear magnetic resonance (1H NMR) spectroscopy, UV-Vis spectrum and fluorescence spectrometer were used to characterize the resultant copolymers. We demonstrated that poly(AA-AEMA-TPE) FONs possess many excellent properties, such as high water dispersibility, intense fluorescence, obvious AIE feature and favorable biocompatibility. The above results suggest that poly(AA-AEMA-TPE) FONs are of great potential for fluorescent imaging. Moreover, the microwave-assisted Biginelli reaction can occur under a rather benign environment with high efficiency and good substrate adaptability. Therefore, we believe that the method developed in this work could greatly advance the applications of AIE-active functional materials.

Biginelli Reaction: Polymer Supported Catalytic Approaches.

The Biginelli product, dihydropyrimidinone (DHPM) core, and its derivatives are of immense biological importance. There are several methods reported as modifications to the original Biginelli reaction. Among them, many involve the use of different catalysts. Also, among the advancements that have been made to the Biginelli reaction, improvements in product yields, less hazardous reaction conditions, and simplified isolation of products from the reaction predominate. Recently, solid-phase synthetic protocols have attracted the research community for improved yields, simplified product purification, recyclability of the solid support, which forms a special economic approach for Biginelli reaction. The present Review highlights the role of polymer-supported catalysts in Biginelli reaction, which may involve organic, inorganic, or hybrid polymers as support for catalysts. A few of the schemes involve magnetically recoverable catalysts where work up provides green approach relative to traditional methods. Some research groups used polymer-catalyst nanocomposites and polymer-supported ionic liquids as catalyst. Solvent-free, an ultrasound or microwave-assisted Biginelli reactions with polymer-supported catalysts are also reported.

Microwave-Assisted Biginelli Reaction: An Old Reaction, a New Perspective

In this review, we tried to highlight the recent advances in the Biginelli reaction, leading to the synthesis of 3,4-dihydropyrimidin-2(1H)-ones, albeit only those conducted under microwave irradiation. The merits and drawbacks of these reactions are compared and discussed with those performed under conventional heating. Dedicated to kazem Kargosha, in the occasion of his honorable retirement as a Professor in Analytical Chemistry. I would like to open this essay by paying homage to Professor Kargosha, who was much inspirational to the establishment of the Iranian Chemical &Chemical Engineering Society (then, Iranian Chemical Society). Keywords: Biginelli reaction, dihydropyrimidines, DHPMs microwave irradiation, brønsted acid, lewis acid, ionic liquid, catalysis, multicomponent reactions, (MCRs).

Microwave-assisted biginelli reaction: An old reaction, a new perspective

Microwave-assisted biginelli reaction: An old reaction, a new perspective

Efficient and Green Microwave-Assisted Multicomponent Biginelli Reaction for the Synthesis of Dihydropyrimidinones Catalyzed by Heteropolyanion-Based Ionic Liquids Under Solvent-Free Conditions

An efficient and green route for the synthesis of dihydropyrimidinones via microwave-assisted Biginelli reaction catalyzed by 3 mol% of heteropolyanion-based ionic liquids under solvent-free conditions has been reported. The practical reaction was found to be compatible with different structurally diverse substrates. Good to excellent yields, short reaction times, and operational simplicity are the main highlights of this protocol. Moreover, the heteropolyanion-based ionic liquids were easily reusable for this Biginelli reaction.

An Efficient Synthesis of New 3,4-Dihydropyrimidin- 2(1H)-ones Incorporating a Phenyl Moiety at C-5 and C-6 Catalyzed by TMSCl and Co(OAc)2.4H2O

New 3,4-dihydropyrimidin-2-ones having a phenyl moiety at C-5 and C-6 have been prepared by a microwave-assisted Biginelli–like reaction by a three-component, one-pot condensation of an aromatic aldehyde, deoxybenzoin and urea, or thiourea using TMSCl and Co(OAc) 2 .4H 2 O as an efficient Lewis acid catalyst.

Catalyst-Free, Rapid Synthesis of Fused Bicyclic Thiazolo-Pyrimidine and Pyrimido-Thiazine Derivatives by a Microwave-Assisted Method

The present investigation deals with the rapid microwave-assisted synthesis of compounds containing fused bicyclic systems. Dihydropyrimidines obtained via a microwave-assisted Biginelli reaction were treated with dibromo alkanes under microwave conditions to yield thiazolo-pyrimidine and pyrimido-thiazine systems. The usefulness of this method lies in carrying out the reaction without a catalyst and solvent in a shorter time. The reaction was successfully extended to develop fused systems from benzimidazole-2-thiol.

Solvent- and catalyst-free synthesis of dihydropyrimidinthiones in one-pot under focused microwave irradiation conditions

Fifteen dihydropyrimidinthiones have been synthesized by microwave-assisted Biginelli reactions without any solvent or catalyst. The advantages of this novel protocol include the excellent yield, operational simplicity, short time and the avoidance of the use of organic solvents and catalysts.

A microwave-assisted synthesis of 3,4-dihydro-pyrimidin-2-(1 H)-ones catalyzed by FeCl 3-supported Nanopore Silica under solvent-free conditions

Lewis acid supported Nanopore Silica catalysts for microwave-assisted Biginelli reaction under solvent-free conditions were prepared by impregnating FeCl 3 dissolved in ethanol to Nanopore Silica at 40 °C. Biginelli reaction under solvent-free conditions, one-pot three-component condensation of urea, benzaldehyde, and ethyl acetoacetate, catalyzed with porous material or Lewis acid supported porous material, such as MCM-41, SBA-15, VSB-5, Nanopore Silica, FeCl 3/MCM-41, FeCl 3/Nanopore Silica, CeCl 3/Nanopore Silica and InCl 3/Nanopore Silica, was investigated. Our recent results of the microwave-assisted Biginell reaction of some benzaldehyde derivatives starting materials using MCM-41, Nanopore Silica, FeCl 3/Nanopore Silica, under solvent-free conditions are also reported. Aromatic aldehydes carrying either electron releasing or electron withdrawing substituents in the ortho, meta, and para positions afforded good yields of the products using MCM-41 as a catalyst. When Nanopore Silica was used as a catalyst, the yield of the Biginelli product was in the range of 27–56%. However FeCl 3/Nanopore Silica has been employed as a catalyst, the yield of the Biginelli product was increased dramatically. Thus it has been found that the use of FeCl 3/Nanopore Silica as heterogeneous catalyst has made this method very cost effective.

New Three‐Component Cyclocondensation Reaction: Microwave‐Assisted One‐Pot Synthesis of 5‐Unsubstituted‐3,4‐dihydropyrimidin‐2(1H)‐ones under Solvent‐Free Conditions.

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New three-component cyclocondensation reaction: microwave-assisted one-pot synthesis of 5-unsubstituted-3,4-dihydropyrimidin-2(1 H)-ones under solvent-free conditions

Sixteen 5-unsubstituted-3,4-dihydropyrimidin-2(1 H)-ones have been synthesized by microwave-assisted Biginelli reactions in a short and concise manner employing ZnI 2 as a catalyst under solvent-free conditions. All products were identified by IR, NMR, elemental analysis and HRMS. The advantages of this novel protocol include the excellent yield, operational simplicity, short time and the avoidance of the use of organic solvents and expensive catalysts.

Building Dihydropyrimidine Libraries via Microwave-Assisted Biginelli Multicomponent Reactions

Building Dihydropyrimidine Libraries via Microwave-Assisted Biginelli Multicomponent Reactions