Fe3O4@SiO2@SH–SO3H as a heterogeneous acidic nanocatalyst for mild and facile synthesis of 2-arylbenzothiazoles under green conditions

چکیده مقاله

Benzothiazoles and their derivatives constitute a significant part of heterocyclic chemistry.1 They have gained considerable attention for their biological and pharmaceutical activities such as antitumor2, anticonvulsant, anthelmintic, antiviral, anti-inflammatory, fungicidal, antimalarial,antimicrobial3 activities. Magnetite, also known as ferrite (Fe3O4), can be applied as a support for functionalization of metals, N-heterocyclic carbenes, organocatalysts and chiral catalysts4. Magnetite is a sustainable catalyst because its preparation is easy, it has a very active surface and can be separated by magnetic decantation after the reaction5. The organocatalysts can be directly immobilized on the surface of magnetite or the homogeneous organocatalysts can be successfully decorated with linkers on the surface of magnetite4. Due to the importance of the described compounds, and in continuation of our previous studies on preparation and application of nanocatalysts6-8, herein, we report the one pot preparation of 2-substituted benzothiazoles by the condensation of 2-aminothiophenol with corresponding aldehydes using Fe3O4@SiO2@SH–SO3H as a novel heterogeneous nanocatalyst at room temperature (Scheme 1).