Three-component reactions of kojic acid: Efficient synthesis of dihydropyrano[3,2-b]chromenediones and aminopyranopyrans catalyzed with Nano-Bi2O3-ZnO and Nano-ZnO

Abstract

Synthesis of pyrano-chromenes and pyrano-pyrans was developed by three-component reactions of kojic acid and aromatic aldehydes with dimethone and malononitrile, catalyzed with nano-Bi 2 O 3 -ZnO and nano-ZnO, respectively. Reactions proceeded smoothly and the corresponding heterocyclic products were obtained in good to high yields. Nano ZnO and nano Bi 2 O 3 -ZnO were prepared by sol-gel method and characterized by X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. Supporting Bi 3+ on ZnO nanoparticles as Bi 2 O 3 , is the main novelty of this work. The simple reaction procedure, easy separation of products, low catalyst loading, reusability of the catalyst are some advantageous of this protocol.