Mild preparation of 2-amino-3-cyano-4-aryl-4H-benzo[h]chromenes and 2-amino-3-cyano-1-aryl-1H-benzo[f]chromenes, under solvent-free conditions, catalyzed by recyclable basic ionic liquids

The L-proline modified Zr-based MOF (Basu-proline) catalyst for the one-pot synthesis of dihydropyrano[3,2-c]chromenes

A novel, reusable, and efficient L-proline-modified Zr-based metal-organic framework (Basu-proline) was designed, synthesized, and characterized by Fourier Transform-Infrared spectroscopy (FT-IR), Energy-Dispersive X-ray spectroscopy (EDX), elemental mapping, Field Emission Scanning Electron Microscopy (FE-SEM), X-ray Diffraction analysis (XRD), Thermo-Gravimetric-Differential Thermal Analysis (TGA-DTA), and N2 adsorption-desorption isotherms. Then, its catalytic performance was assessed in the synthesis of dihydropyrano[3,2-c]chromenes via the one-pot, three-component tandem condensation reaction of 4-hydroxycoumarin, aromatic aldehydes and malononitrile. The Basu-proline catalyst exhibited a better efficiency than some reported protocols regarding higher yields, lower reaction times, and simple separation.

Preparation and characterization of Pd supported on 5-carboxyoxindole functionalized cell@Fe3O4 nanoparticles as a novel magnetic catalyst for the Heck reaction

Pd supported on 5-carboxyoxindole functionalized cell@Fe₃O₄ nanoparticles (Pd@CAI@cell@Fe₃O₄), a new magnetic nanocatalyst, was prepared and characterized using inductively coupled plasma atomic emission spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and energy-dispersive X-ray spectroscopy techniques. The synthesized nanocatalyst (Pd@CAI@cell@Fe₃O₄) was employed for Heck-type arylation of different substituted maleimides with iodoarenes in good to excellent yields. This green catalyst was easily recovered and reused several times with no substantial loss of activity, providing a clean and efficient synthetic procedure with excellent yield and reduced time.

Recent development in the synthesis of heterocycles by 2-naphthol-based multicomponent reactions

2-Naphthol or β-naphthol is an important starting material that has drawn great attention in various organic transformations because of its attributes, such as low cost, easy to handle and eco-friendliness. The electron-rich aromatic framework of 2-naphthol with multiple reactive sites allows it to be utilized in several kinds of organic reactions eventuated to several organic molecules with potent biological properties. Multicomponent reaction approach has been tremendously utilized to explore the synthetic utility of 2-naphthol for the construction of diverse N/O-containing heterocyclic framework. In this review, we summarize recent data pertaining to multicomponent reactions, wherein heterocyclic compounds are synthesized utilizing 2-naphthol as one of the starting materials. It is anticipated that this review will stimulate the researchers to design new multicomponent strategies complying with the Green Chemistry principles for the further exploitation of 2-naphthol for the rapid synthesis of versatile biologically relevant heterocycles. This review provides a concise overview of the different 2-naphthol based multicomponent reactions utilized for the construction of diverse bioactive heterocyclic scaffold.

Nanofibre Sepiolite Catalyzed Green and Rapid Synthesis of 2-Amino-4H-chromene Derivatives

Nanofibre sepiolite catalyzed the rapid, clean, and highly efficient synthesis of 2-amino-4H-chromene derivatives by a one-pot, three-component condensation of a series of aldehydes, various enolizable C–H bonds (such as dimedone, α-naphthol, resorcinol, and 4-hydroxy-2H-chromen-2-one), and malononitrile in a mixture of water/ethanol. The present method offers several advantages such as high to excellent yields, short reaction times, mild reaction conditions, simple procedure, use of inexpensive, non-toxic, and naturally available catalyst, easy isolation of the products, and no need for column chromatography. The catalyst could be easily separated from the reaction mixture and can be reused for many consecutive trials without a significant decline in its reactivity.