New iron(iii) complex of bis-bidentate-anchored diacyl resorcinol on a Fe3O4 nanomagnet: C–H bond oxygenation, oxidative cleavage of alkenes and benzoxazole synthesis ?

RSC Advances Pub Date: 2023-01-30 DOI: 10.1039/D2RA06818D

Abstract

We have synthesized a novel, bis-bidentate, covalently anchored, 4,6-diacetyl resorcinol (DAR) ligand on silica-coated magnetic Fe3O4 nanoparticles and the corresponding bi-metallic iron(III) complex (Fe3O4@SiO2-APTESFe2LDAR). Both the chemical nature and the structure of the homogeneously heterogenized catalyst were investigated using physico-chemical techniques. The results obtained by XPS, XRD, FT-IR, TGA, VSM, SEM, TEM, EDX, ICP and AAS revealed a magnetic core, a silica layer and the grafting of a binuclear iron complex on the Fe3O4@SiO2-APTES, as well as its thermodynamic stability. Despite many reports of metal complexes on different supports, there are no reports of anchored, bi-metallic complexes. To the best of our knowledge, this is the first report of a bi-active site catalyst covalently attached to a support. This study focuses on the catalytic activity of an as-synthesized, bi-active site catalyst for C–H bond oxygenation, the oxidative cleavage of alkenes, and the multicomponent, one-pot synthesis of benzoxazole derivatives with excellent yields from readily available starting materials. Our results indicated high conversion rates and selectivity under mild reaction conditions and simple separation using a magnetic field. The leaching and recyclability tests of the catalyst were investigated for the above processes, which indicated that all the reactions proceed via a heterogeneous pathway and that the catalyst is recyclable without any tangible loss in catalytic activity for at least 8, 5 and 5 cycles for C–H bond oxygenation, C[double bond, length as m-dash]C bond cleavage and benzoxazole synthesis, respectively.

Graphical abstract: New iron(iii) complex of bis-bidentate-anchored diacyl resorcinol on a Fe3O4 nanomagnet: C–H bond oxygenation, oxidative cleavage of alkenes and benzoxazole synthesis
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