A Laccase Heterogeneous Magnetic Fibrous Silica‐Based Biocatalyst for Green and One‐Pot Cascade Synthesis of Chromene Derivatives

Abstract

Green cascade approaches, which utilize sustainable and recyclable heterogeneous biocatalysts, can be used in the catalysis of multicomponent organic reactions to synthesize biologically important substances. Three magnetic nanoparticles, iron (II, III) oxide, cobalt ferrite, and nickel ferrite, were prepared by co‐precipitation and functionalized with fibrous silica (KCC‐1), and characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), and vibrating sample magnetometry (VSM). Laccase immobilized on CoFe2O4‐KCC‐1 was used as a heterogeneous biocatalyst for green and one‐pot cascade synthesis of 2‐amino‐5‐oxo‐4‐aryl‐4H,5H‐pyrano[3,2‐c]chromene‐3‐carbonitriles. The reaction was performed in the presence of 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) as a synthetic redox mediator. The optimum reaction conditions were found to be as immobilized laccase (100 mg, 95 U) and TEMPO (2 mol‐%) in a 100 mm sodium citrate buffer (pH 4.5), 40 °C, and incubation time 17 h. About 80 % of initial activity of the immobilized laccase was retained after 15 independent runs.