No abstract

Synthesis of pyranopyrazoles using heterogeneous catalysts is among the most executed synthetic approaches in organic chemistry and has attracted much attention because of the atom economy and environmentally benign issues. Magnetite dopamine‐supported copper nanoparticles were created using a simple co‐precipitation technique and characterized by Fourier‐transform infrared spectroscopy (FTIR), x‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and vibrating sample magnetometry (VSM). The catalytic activity of the Fe3O4@PDA/CuCl2 system was probed in the synthesis of structurally diverse pyranopyrazoles. It′s worth mentioning that the catalyst could be used at low loadings to produce pyranopyrazoles with high to acceptable in the absence of an external reducing agent. Additionally, the produced heterogeneous catalyst can be reused (by extracting with an external magnet) in six subsequent cycles without suffering a significant loss in catalytic activity. The high efficiency of the derivatives from about 70 % to 98 %, as well as the fact that the TON)1000–2500( and TOF)1000–5000 h−1) have attained the optimal amount, indicate the catalyst‘s high efficiency.

A one‐pot and efficient catalytic protocol has been developed to synthesize pharmaceutically critical 2‐substituted benzimidazoles and benzothiazoles using magnetite dopamine‐supported copper nanoparticles (Fe3O4@PDA/CuCl2) as a heterogeneous catalyst. This selective transformation proceeds via oxidative cross‐coupling of readily available benzylic amines with o‐phenylenediamine/2‐aminothiophenol. This one‐pot green method proceeds smoothly, under mild conditions, avoids the usage of toxic metals, tolerates a variety of functionalities, and is amenable to gram scale. Furthermore, this easy‐to‐prepare magnetic nanocatalyst can be separated by magnetic decantation after the reaction, thereby making it more sustainable.