Applications of novel composite UiO-66-NH2/Melamine with phosphorous acid tags as a porous and efficient catalyst for the preparation of novel spiro-oxindoles

In this study, we introduce a novel approach for incorporating phosphorus acid tags into a UiO-66-NH2/Melamine-based metal–organic framework (MOF). The structure and morphology of UiO-66-NH2/Melamine/[N(CH2PO3H2)2]2 as a catalyst were characterized using various techniques. The presented catalyst was used in the synthesis of novel spiro-oxindoles via a condensation reaction of isatin derivatives, acenaphthylene-1,2-dione or 11H-indeno[1,2-b]quinoxalin-11-one, barbituric acid derivatives, 5-(1H-indol-3-yl)-2H-pyrazol-3-ylamine and 3-(1H-indol-3-yl)-1-phenyl-1H-pyrazol-5-amine under green and mild conditions.