A novel carbon-based solid-acid nanocatalyst (Sta-SO₃H) was simply prepared for the first time by the thermal treatment of sulfuric acid with starch at 180 °C in a sealed autoclave. The catalytic activities of Sta-SO₃H as an efficient and reusable catalyst were investigated by the condensation reaction of aldehyde, amine and β-keto ester for the synthesis of functionalized piperidines under solvent-free conditions at room temperature in good to high yields. Density functional theory calculations were used to study the structure of methyl 1,2,6-triphenyl-4-(phenylamino)-1,2,5,6-tetrahydropyridine-3-carboxylate (MPPC) as well as the thermochemistry of the multicomponent reaction. The theoretically calculated infrared and ¹H nuclear magnetic resonance spectra of MPPC were compared to the experimental data. It was found that the synthesis of MPPC is exothermic accompanied by a decrease