Highly Monodispersed PEG-stabilized Ni Nanoparticles: Proficient Catalyst for the Synthesis of Biologically Important Spiropyrans

A convenient and efficient synthesis of biologically and pharmacologically important spiropyrans from the condensation of malononitrile, 1,3-dicarbonyl compounds and ninhydrin/acenaphthequinone/isatin has been reported using recyclable heterogeneous polyethylene glycol (PEG)-stabilized Ni nanoparticles in ethylene glycol. This new protocol affords products in high yields and less reaction time.