Highly Effective Synthesis of 1-thioamidoalkyl-2-naphthols and Tetrahy-dropyridines Using a Nanostructured Silica-based Catalyst Under Mild Conditions

Aim and Objective: Nano-2-[N',N'-dimethyl-N'-(silica-n-propyl)ethanaminium chloride]-N,N-dimethy laminium bisulfate (nano-[DSPECDA][HSO4]) was used as a highly effective and heterogeneous silica-based nanostructured catalyst for the synthesis of 1-thioamidoalkyl-2-naphthols and substituted tetrahydropyridines. Material and Methods: The expected products were prepared in mild conditions. In this work, three novel 1-thioamidoalkyl-2-naphthols and two new tetrahydropyridine derivatives were synthesized and characterized by IR, H-1 and C-13 NMR and Mass spectroscopy. Results: One-pot multi-component condensation of 2-naphthol with arylaldehydes and thioacetamide catalyzed by nano-[DSPECDA][HSO4] under green, mild and solvent-free conditions led to 1-thioamidoalkyl-2-naphthols in high yields. The nanocatalyst was also used for the preparation of functionalized tetrahydropyridines by the one-pot multi-component reaction of anilines, arylaldehydes and ethylacetoacetate under solvent-free and mild conditions. Conclusion: The reaction results were found to be better compared to the literature in terms of one or more of these factors: yield, time, and the reaction media. All the products were purified by recrystallization from EtOH, and without column chromatography, being in good agreement with the green chemistry protocols.

Automated summary

The study utilized nano-[DSPECDA][HSO4] as a catalyst for the synthesis of 1-thioamidoalkyl-2-naphthols and tetrahydropyridine derivatives under mild and solvent-free conditions. The products were characterized by IR, NMR, and Mass spectroscopy, showing better reaction results compared to literature, in line with green chemistry protocols.