Polyphosphoric acid–zirconia pillared clay composite catalytic system for efficient multicomponent one pot synthesis of tetrahydropyridines under environmentally benign conditions.

Highlights: [•] Polyphosphoric acid–Zr-pillared clay composites prepared by different strategies. [•] Expansion of clay interlayer on intercalation of PPA and Zr-polycations. [•] Structural integrity of PPA confirmed from EDX, FTIR, UV–vis studies. [•] PPA–ZrP composite is highly active for the synthesis of tetrahydropyridines. [•] Structurally diverse tetrahydropyridines synthesized under mild condition. [Copyright &y& Elsevier]