RuIII@CMC/Fe3O4 hybrid: an efficient, magnetic, retrievable, self-organized nanocatalyst for green synthesis of pyranopyrazole and polyhydroquinoline derivatives

Abstract

RuIII incorporated with magnetic nanosized CMC/Fe3O4 hybrid (RuIII@CMC/Fe3O4) has readily developed by a very simple self-organized procedure of RuCl3 and Na-CMC/Fe3O4 organic/inorganic hybrid. The self-organized fresh and recovered catalyst was well characterized by ICP-AES, FTIR, XRD, TGA-DSC-DTG, SEM-EDS-mapping, TEM, and XPS techniques. The elemental maps confirmed that the RuIII species are well dispersed in a homogeneous manner on the surface of CMC/Fe3O4 magnetic hybrid nanoparticles. After full characterization, its catalytic activity was investigated in the synthesis of pyranopyrazole and polyhydroquinoline derivatives. Under optimal conditions, all reactions proceeded well and afforded the desired products in excellent yields. There was no significant effect of electron withdrawing or donating nature of substituent on aryl aldehydes in the formation of these target compounds. The salient features of the present new protocol are broad substrate scope, mild reaction conditions, good-to-excellent yields, operational simplicity, energy-efficiency, high atom-economy, easy isolation of products and no column chromatographic separation. Moreover, RuIII@CMC/Fe3O4 can be easily recovered by using a magnetic field and directly reused for several cycles without significant loss of its activity. The recovered catalyst was confirmed by TEM, XPS, XRD, and SEM-EDS analyses. One-pot multicomponent reactions for green synthesis of pyranopyrazole and polyhydroquinoline derivatives have been performed using a self-organized RuIII@CMC/Fe3O4 nanocatalyst.