β-Cyclodextrin nanosponge polymer: a basic and eco-friendly heterogeneous catalyst for the one-pot four-component synthesis of pyranopyrazole derivatives under solvent-free conditions

Abstract

β-Cyclodextrin-epichlorohydrin nanosponge polymer, β-CD/EP, was prepared from the stepwise polymerization of β-cyclodextrin with epichlorohydrin under basic conditions and characterized by FT-IR spectroscopy, thermogravimetric analysis, scanning electron microscopy and Brunauer–Emmett–Teller. An efficient synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazole] and pyranopyrazole derivatives is described using β-CD/EP as a stationary micro-vessel and basic heterogeneous catalyst via a four component reaction under solvent-free conditions.