The Hantzsch three-component condensation reaction of various aromatic aldehydes, 1,3-dione and aniline derivatives in the presence of 2-methylpyridinium trifluoromethanesulphonate ([2-MPyH]OTf) as green and highly efficient catalysts in water affords 1,8-dioxodecahydroacridine derivatives in good to excellent yields. This reaction has been carried out in the presence of 1 mol% of [2-MPyH]OTf at room temperature. The described novel synthesis method proposes several advantages of mild condition, short reaction times, high yields, simplicity and easy workup compared to the traditional method of synthesis.

In this paper, we explore the catalytic activity of SiO₂ nanoparticles (NPs) as an eco-friendly, efficient and reusable catalyst in the synthesis of 2,3-dihydro-1H-perimidines as well as tetraketones. For tetraketones syntheses, a simple tandem Knoevenagel condensation following Michael addition procedure is performed by the reaction between benzaldehydes and 5,5-dimethyl-1,3-cyclohexanediones under solvent-free condition using SiO₂ NPs as an efficient solid catalyst. In addition, for 2,3-dihydro-1H-perimidines syntheses, cyclocondensation of various aldehydes with 1,8-diaminonaphthalene is achieved under solvent-free condition using SiO₂ NPs as a catalyst at room temperature. The results showed catalytic enhancement in both synthetic procedures.In this work,4-(2,3-dihydro-1H-perimidin-2-yl)benzonitrileand2-(pyridin-4-yl)-2,3-dihydro-1Hperimidine are synthesized as new compounds. Also, reusability study of SiO₂ NPs was done to ensure its applicability as a recycled catalyst in this work.