A simple and green approach for the synthesis of substituted dihydro-2-oxypyrroles catalyzed by nano-Fe3O4@SiO2/SnCl4 super paramagnetic nanoparticles

Heterocyclic rings are important fundamental cores in most biologically active compounds. As a significant class of these heterocycles, nitrogen-containing heterocycles as identified pharmacophores have received much attention in medicinal chemistry and drug discovery [1–2]. In this context, the presence of pyrrol- 2-ones in pharmaceuticals and natural products has continued to stimulate much interest in the development of new methods for their synthesis [3]. To develop compound libraries based on this fused heterocyclic scaffold, we considered an efficient and green procedure for the synthesis of dihydro-2- oxypyrroles has been developed. One-pot four-component condensation reaction of aniline derivatives (2 mmol), dialkyl acetylene dicarboxylate (1 mmol), and aldehydes ( 1 mmol) was done in ethanol at 65 °C in the presence of nano-Fe3O4@SiO2/SnCl4 as a magnetically reusable heterogeneous acid catalyst (Fig. 1). The obtained dihydro-2-oxypyrroles were purified without any chromatography techniques. The structure of obtained pure products were identified by physical properties and spectroscopic data such as FT-IR, 1H NMR, 13C NMR and mass spectroscopy. This protocol, consistently has the advantages of excellent yields, short reaction time, simple workup, recyclability of the catalyst up to six runs without appreciable loss ofactivity.