Silica immobilized nickel complex: An efficient and reusable catalyst for microwave-assisted one-pot synthesis of dihydropyrimidinones

Chiral Separation of 3,4-dihydropyrimidin-2(1H)-ones and 3,4-di -hydropyrimidin- 2(1H)-thiones Enantiomers by HPLC on Chiralcel®OD-H

Objective:

Ten racemic 3,4-dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidin- 2(1H)-thiones were separated by liquid chromatography on Chiralcel®OD-H column containing cellulose tris(3, 5-dimethylphenylcarbamate).

Methods:

The enantioseparation was carried out using Chiralcel®OD-H polysaccharide-type chiral stationary phase to resolve such enantiomers under normal-phase mode.

Results:

Complete separations of the 3,4-dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidin- 2(1H)-thiones derivatives with good resolution (RS= 1.04-2.80) were achieved within a short time (10-15 min).

Conclusion:

An optimal baseline separation (Rs> 1.5) was achieved using Chiralcel®OD-H under normal-phase mode. Structure-retention relationships have also been discussed.

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.

1,3,5-Tris(2-hydroxyethyl)isocyanurate functionalized graphene oxide: a novel and efficient nanocatalyst for the one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones

The preparation and characterization of a novel 1,3,5-tris(2-hydroxyethyl)isocyanurate functionalized graphene oxide (GO–THEIC) nanomaterial and its catalytic application for the Biginelli reaction are described.

Nickel stabilized by triazole-functionalized carbon nanotubes as a novel reusable and efficient heterogeneous nanocatalyst for the Suzuki–Miyaura coupling reaction

The synthesis of a MWCNT-grafted nickel catalyst through “click” reaction of azide-functionalized carbon nanotubes with propargyl alcohol, for the Suzuki–Miyaura coupling reaction.

Inorganic-organic hybrid silica based tin complex as a novel, highly efficient and recyclable heterogeneous catalyst for the one-pot preparation of spirooxindoles in water

In the present study, a tin complex immobilized on silica gel as a novel, green, highly efficient and heterogeneous reusable catalyst was synthesized by grafting 2-amino benzamide onto the silica gel surface as a result of the reaction between isatoic anhydride and 3-aminopropyl-functionalized silica gel, followed by complexing with tin chloride. The resulting organic-inorganic hybrid material was evaluated in the one-pot three-component synthesis of spiro[indoline-pyrazolo[4',3':5,6]pyrido[2,3-d]pyrimidine]trione derivatives in water via the condensation reaction of isatins, barbituric acids, and 1H-pyrazol-5-amines. All the reactions were completed in short reaction times and all the products were obtained in high to excellent yields with high purity. In addition, the synthesized novel catalyst could be separated from the reaction mixture by simple filtration and can be reused up to seven runs without significant loss in activity.

Magnetically retrievable silica-based nickel nanocatalyst for Suzuki–Miyaura cross-coupling reaction

A new magnetically recoverable silica-based nickel nanocatalyst was synthesized, characterized and applied for the first time as a catalyst in Suzuki–Miyaura cross-coupling reaction.

Anchoring of ruthenium onto imine-functionalized zeolite beta: an efficient route for the synthesis of 4H-benzo[b]pyrans and pyrano[c]chromenes

The synthesis and characterization of a highly efficient and reusable catalyst, ruthenium immobilized in zeolite beta, are reported. The catalyst was characterized by powder X-ray diffraction, BET surface area measurements, scanning electron micrographs, Fourier-transform infrared spectroscopy, inductive coupled plasma, and elemental analysis. The supported material was used as an efficient catalyst for the one-pot three-component synthesis of 4H-benzo[b]pyrans and pyrano[c]chromenes in good yields. The catalyst was separated from the reaction mixture and reused up to five runs without significant loss of activity.

Titanium dioxide supported on MWCNTs as an eco-friendly catalyst in the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones accelerated under microwave irradiation

Some transition metal oxides supported on MWCNTs were prepared as novel heterogeneous catalysts using the facile processes. These catalysts were used for the synthesis of Biginelli compounds under microwave irradiation.