Abstract
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.
Highlights
4H-chromenes represent an important class of oxygen-containing heterocycles and a key building block of many natural products
The FTIR spectrum is shown in Fig. 4. demonstrates the formation of desired bonds and the presence of new functional groups of Magnetic nanoparticles (MNPs)·Graphene Oxide (GO)-CysA
In the studies of different green catalysts such as ethylenediaminetetraacetic acid on (EDTA), cysteic acid, graphene oxide, and Fe3O4 nanoparticles on the model reaction, it was found that the best yield of desired product 5e (43%) was obtained when the cysteic acid was used as the catalyst in ethanol–water under reflux conditions (Table 1, entry 7–10)
Summary
4H-chromenes represent an important class of oxygen-containing heterocycles and a key building block of many natural products. We designed a magnetic nano-scaled catalyst which has been functionalized by cysteic acid to improve the catalytic activity.
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