GO Treated with Aminoethyl‐Piperazine as a Reusable and Eco‐friendly Organocatalyst for Synthesis of Some Xanthen and Pyran Derivatives.

Graphene Oxide (GO) containing 1‐(2‐aminoethyl) piperazine as a reusable, highly efficient and heterogeneous organocatalyst was prepared using a simple and green way. Epoxide groups on the surface of GO layers were replaced with 1‐(2‐aminoethyl) piperazine by an easy and green technique in a mild condition. The prepared catalyst (GO‐A.P.) was characterized using diverse microscopic and spectroscopic techniques. The presence of organic functional groups on the surface of GO‐A.P. was confirmed by Fourier transform infrared and Raman spectroscopy. X‐ray diffraction analysis showed an increase in the catalyst's interlayer spaces which confirm the successful presence of 1‐(2‐aminoethyl) piperazine molecules on the GO surface. Also interaction between the organic molecules and GO was established by thermogravimetric analysis via weight loss steps. Then, the capability of this catalyst was evaluated in a three‐component coupling reaction for one‐pot synthesis of 12‐aryl‐8,9,10,12‐tetrahydrobenzo[a]xanthen‐11‐one (A1–A7) and also 2‐amino‐4H‐pyrans (B1–B8) derivatives. The target products were obtained in high isolated yields. Furthermore, our catalyst was reusable at least for 5 runs with no significant decrease in its activity. [ABSTRACT FROM AUTHOR]