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Piperazinium nano silica sulfonate (PNSS) is simply prepared by the reaction of piperazine with nano sized silica sulfuric acid. After preparation it was completely characterized using different techniques including FT-IR, XRD, TGA, FESEM, EDS and TEM analysis. In continue PNSS was efficiently used for the promotion of the synthesis of polyhydroquinolines and 1,8-dioxo-decahydroacridines through unsymmetrical and symmetrical Hantzsch condensation reaction. High yields, short reaction times, ease of preparation and reusability of the catalyst, easy work-up procedure and solvent-free conditions are among the most important advantages of this method.

A green approach for the promotion of the synthesis of Hantzsch products using poly(vinylpyrrolidinium) perchlorate {[PVPH]ClO 4 } as a new modified polymeric catalyst in the absence of solvent is reported. The title catalyst is easily prepared and characterized using a variety of techniques including infrared spectra, X-ray diffraction, thermal gravimetric analysis, scanning electron microscopy, pH analysis, and Hammett acidity function. Some of the advantages of this novel synthetic method are: easy preparation of the catalyst, short reaction times, high to excellent yields of the products, simple and easy work-up procedure, and reusability of the catalyst.

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This article describes the use of Pregabalin as a commercially available chiral amino acid in the efficient synthesis of the Passerini‐type condensation products via two‐component condensation of aromatic aldehydes with cyclohexyl isocyanide. All reactions are accompanied with aerobic oxidation of aldehydes in water leading to chiral α‐acyloxycarboxamides with moderate to good enantioselectivities (up to 88 % ee) under green conditions such as nonmetal source. This is the first report of asymmetric synthesis of Passerini products in water.

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