A new procedure for the preparation of 3,4-dihydropyrimidin-2(1H)-one and octahydroquinazolinone derivatives catalyzed by SCMNPs@CA-EA-SO3H under solvent-free conditions

Abstract:

Catalyzed with SCMNPs@CA-EA-SO3H, as a green and heterogeneous solid acid catalyst, 3,4-dihydropyrimidin-2(1H)-one and octahydroquinazolinone derivatives were obtained in high-to-excellent yields and in short reaction times via the one-pot multi-component condensation of ethyl acetoacetate or dimedone, urea, and aldehyde compounds under solvent-free conditions. More importantly, the green catalytic system could be easily collected from the reaction solution utilizing an external magnet and reused for five runs with a negligible decrease in yields and reaction rate.

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.

One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones catalyzed by SO3H@imineZCMNPs as a novel, efficient and reusable acidic nanocatalyst under solvent-free conditions

The synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives was accomplished efficiently via a three-component reaction between ethyl acetoacetate, various types of aldehydes, and urea in the presence of 10 mg SO₃H@imineZCMNPs as a novel, environment friendly, and reusable heterogeneous magnetic nanocatalyst under solvent-free conditions at 90 °C. The desired products were obtained with high quantitative yields. The catalyst was separated by simple isolation from the reaction mixture using a permanent magnet and reused several times without any significant loss of catalytic activity. The synthesized catalyst was fully characterized through various techniques including thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and the Hammett acidity test. This methodology tolerates most substrates and has the salient features of green reaction conditions, lower catalyst loading, high quantitative yields, low cost, the absence of solvents, and easy isolation and reusability of the catalyst.

Highly efficient, green, rapid, and chemoselective oxidation of sulfur-containing compounds in the presence of an MCM-41@creatinine@M (M = La and Pr) mesostructured catalyst under neat conditions

MCM-41@creatinnine@M (M = La and Pr) as a highly efficient and reusable heterogeneous catalyst prepared by a simple procedure for the oxidation of sulfur-containing compounds.

Efficient one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones catalyzed by a new heterogeneous catalyst based on Co-functionalized Na+-montmorillonite

A facile and efficient solvent-free protocol for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones by using Co@imine-Na⁺-MMT as a new, environmentally friendly and reusable heterogeneous catalyst is reported.

Synthesis and properties of novel reusable nano-ordered KIT-5-N-sulfamic acid as a heterogeneous catalyst for solvent-free synthesis of 2,4,5-triaryl-1 H-imidazoles

A novel silica-bonded propyl-

Sulfated polyborate: a new and eco-friendly catalyst for one-pot multi-component synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones via Biginelli reaction

A highly efficient and improved synthetic methodology for the preparation of 3,4-dihydropyrimidin-2(1H)-one derivatives in good to excellent yield via Biginelli reaction of β-ketoesters/β-diketone, urea/thiourea and various aldehydes using new, efficient and recyclable sulfated polyborate catalyst under the solvent-free condition is reported.

Graphite catalyzed solvent free synthesis of dihydropyrimidin-2(1H)-ones/thiones and their antidiabetic activity

A solvent free three component condensation reaction between an aldehyde, ethyl acetoacetate and urea catalyzed by graphite, a green catalyst is described for the synthesis of dihydropyrimidin-2(1H)-ones. This protocol is scalable and the catalyst is reusable. This method is also applied for the synthesis of dihydropyrimidin-2(1H)-thiones. α-Amylase, a key enzyme in carbohydrate metabolism is generally targeted for management of type 2 diabetes. The therapeutic potential of the dihydropyrimidinones and dihydropyrimidinthiones to inhibit α-amylase activity was evaluated by in vitro assay. Of the synthesized compounds 3,4-dihydropyrimidin-2(1H)-thione (1k) demonstrated highest inhibition of α-amylase activity.

Recent progress in asymmetric Biginelli reaction

The Biginelli reaction, which involves the interaction of ethyl acetoacetate, urea, and an appropriate aryl aldehyde, was first discovered by Pietro Biginelli about 120 years ago. The Biginelli products (3,4-dihydropyrimidin-2(1H)-ones) are interesting materials due to their significant pharmacological and structural profiles. In the last decades, the asymmetric synthesis as a powerful tool has an effective impact on the Biginelli products and has increased their potencies and applications as drugs. Having the importance of this subject in mind, in this review we wish to present the recent rapid progress of asymmetric Biginelli reaction.

Microwave-assisted synthesis and biological evaluation of dihydropyrimidinone derivatives as anti-inflammatory, antibacterial, and antifungal agents

A simple protocol for the efficient preparation of aryl and heteroaryl substituted dihydropyrimidinone has been achieved via initial Knoevenagel, subsequent addition, and final cyclization of aldehyde, ethylcyanoacetate, and guanidine nitrate in the presence of piperidine as a catalyst in solvent-free under microwave irradiation. The synthesized compounds showed a good anti-inflammatory, antibacterial, and antifungal activity.

Al(NO3)3 · 9H2O: An Efficient Catalyst for the One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Both under Reflux or Solvent-Free Conditions

Al(NO3)3 · 9H2O efficiently catalyzes the three-component Biginelli reaction between an aldehyde, aβ-dicarbonyl compound, and urea or thiourea in refluxing ethanol and solvent-free (SF) conditions to afford the corresponding dihydropyrimidinones in high yields. The advantages of this method involve the easy procedure, the environmentally friendly process, and the low cost of the Lewis acid catalyst.