Sodium ethylene diamine tetraacetate catalyzed synthesis of chromene derivatives via multi-component reactions at low catalyst loading

Zr@IL-Fe3O4 MNPs as an efficient and green heterogeneous magnetic nanocatalyst for the one-pot three-component synthesis of highly substituted pyran derivatives under solvent-free conditions

The present study was conducted to synthesize Zr@IL-Fe3O4 MNPs as a new magnetically recoverable heterogeneous catalyst, which was then characterized by Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray spectroscopy (EDX), vibrating sample magnetometry (VSM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The catalytic behavior of the Zr@IL-Fe3O4 MNPs was efficiently used for the synthesis of highly substituted pyran derivatives via a one-pot three-component condensation of 4-hydroxycoumarin/dimedone, malononitrile, and arylaldehydes under solvent-free conditions. This new methodology demonstrated some important features, including short reaction times, excellent yields, lower loading of the catalyst, easy work-up, and recyclability of the catalyst for a minimum of six times without any noticeable decrease in catalytic activity.

Cysteic acid grafted to magnetic graphene oxide as a promising recoverable solid acid catalyst for the synthesis of diverse 4H-chromene

4H-chromenes play a significant role in natural and pharmacological products. Despite continuous advances in the synthesis methodology of these compounds, there is still a lack of a green and efficient method. In this study, we have designed cysteic acid chemically attached to magnetic graphene oxide (MNPs·GO-CysA) as an efficient and reusable solid acid catalyst to synthesize 4H-chromene skeletons via a one-pot three components reaction of an enolizable compound, malononitrile, an aldehyde or isatin, and a mixture of water-ethanol as a green solvent. This new heterogeneous catalyst provides desired products with a good to excellent yield, short time, and mild condition. This procedure presents an environmentally friendly approach for the synthesis of a great number of 4H-chromene derivatives.

The molecular diversity scope of 4-hydroxycoumarin in the synthesis of heterocyclic compounds via multicomponent reactions

4-Hydroxycoumarins are some of the most versatile heterocyclic scaffolds and are frequently applied in the synthesis of various organic compounds. 4-Hydroxycoumarin-based compounds are important among heterocyclic structures due to their biological and pharmaceutical activities. In this study, we provide an overview on the recent applications of 4-hydroxycoumarin in multicomponent reactions for the synthesis of various heterocyclic compounds during the time period of 2015-2018.