Efficient four‐component synthesis of spiroindole derivatives catalysed by a versatile and reusable nano‐paramagnetic catalyst

Abstract

A simple, efficient and environmentally benign route was developed for the preparation of spiro(indoline-3,4-pyrano[2,3-c]pyrazole) derivatives with good yields from condensation of isatins, malononitrile (or ethyl cyanoacetate), hydrazine hydrate and ethyl acetoacetate catalysed by PFu@Fe 3 O 4 nanocomposite. The use of easily available catalyst, shorter reaction times, better yields, simplicity of reaction, heterogeneous system and easy work-up are the advantages of the method presented. Characterization of the catalyst was performed using Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy.

The application of copolymer‐coated graphene oxide‐Fe3O4 in the highly efficient synthesis of 2′‐aminospiro[indeno[1,2‐b]quinoxaline‐11,4′‐[4'H] pyran]‐3′‐carbonitrile and 2′‐aminospiro[indeno‐2,4′‐[4'H]pyran]‐3′‐carbonitrile

“…The development of a simple and green method for the synthesis of 2 0 -aminospiro[indeno [1,2-b] quinoxaline-11, 4 0 -[4'H]pyran]-3 0 -carbonitrile using an inexpensive and environmentally benign catalyst is therefore in demand. In continuation of our interest in the development of green catalytic methods for the preparation of biologically active heterocycles, [33][34][35][36][37][38][39] we report here for the first time the application of magnetically separable copolymer (polyaniline-polypyrrole)@GO-Fe 3 O 4 in the four-and three-component synthesis of…”