Carbon-based nanocatalyst: An efficient and recyclable heterogeneous catalyst for one-pot synthesis of gem-bisamides, hexahydroacridine-1,8-diones and 1,8-dioxo-octahydroxanthenes

In this abstract, we discuss the progress related to sulfonated carbon-based materials in various acid-catalyzed organic transformations which are then further utilized in medicinal field, laboratories and industries. A simple and novel methodology was employed to prepare carbon-based nanocatalyst, i.e. cellulose[2-(sulfooxy)ethyl]mercaptosulfonic acid as a solid acid catalyst. This nanocatalyst is recyclable and also exhibited very high activity. Novel carbon-based nanocatalyst, i.e. cellulose[2-(sulfooxy)ethyl]mercaptosulfonic acid[SEMSA] was successfully synthesized by reacting mercaptoethanol and chlorosulfonic acid, and the catalytic activity of the prepared catalysts was evaluated for the one-pot synthesis of gem-bisamides from various aldehydes and benzamide, hexahydroacridine-1,8-diones via three-component condensation of aromatic aldehyde, dimedone and ammonium acetate or aromatic amine and 1,8-dioxo-octahydroxanthenes using aldehyde and dimedone. Application of this new heterogeneous nanocatalyst system offered the advantages of high yields, short reaction times, eco-friendly nature and easy work-up procedure compared to the conventional methods of the synthesis, and confirmation of products synthesized has been done using studies like H-1 NMR and C-13 NMR. Among the various catalysts, this nanocatalyst, i.e. cellulose [2-(sulfooxy)ethyl]mercaptosulfonic acid[SEMSA], was found to be the most active and selective and could be recycled several times without significant loss of activity. Also, scanning electron microscopy and transmission electron microscopy of the catalyst have been performed to know the internal and external morphology, size, thermo-gravimetric analysis to study the thermal stability and Fourier transform infrared spectroscopy to study the modification pattern of the catalyst have been undertaken and presented in this work. Due to its simple and inexpensive solid support, i.e. cellulose and environmentally benign toluene, ethanol and acetonitrile as solvents in three different transformations which are less toxic, easily available and less expensive than other solvents. Graphic abstract We reported here a novel route for the synthesis of gem-bisamides, hexahydroacridine-1,8-diones and 1,8-dioxo-octahydroxanthenes [GRAPHICS] .