ZrO2 and Rice-Husk-Xanthate Adduct: An Efficient Bioderived Catalyst for Synthesis of Spiro[4H-pyran-4,3′-indoline]s.

The reaction of dry and pulverized rice husk with alkaline CS2 followed by treatment of the resulting xanthate derivative with zirconyloxychloride at room temperature led to functionalization of the xanthated biomass with sodium zirconate grouping. The as-prepared sodium salt of the rice-husk xanthatozirconate was characterized physicochemically and found to be an efficient, robust, and recyclable catalyst for the three-component synthesis of some spiro[4H-pyran-4,3′-indoline]s in water. [ABSTRACT FROM AUTHOR]