Sulfamic Acid‐functionalized Nano‐titanium dioxide as a Novel and Highly Efficient Heterogeneous Nanocatalyst for One‐pot and Solvent‐free Synthesis of Hexahydroquinolines

Abstract

Hexahydroquinolines are synthesized via one‐pot, four‐component condensation of 1,3‐cyclic diketones, aromatic aldehydes, malononitrile, and ammonium acetate in the presence of sulfamic acid‐functionalized nano‐titanium dioxide as a novel type of heterogeneous nanocatalyst. The optimized reaction condition is achieved using response surface method (Box–Behnken design [BBD]). Operational simplicity, low cost, nontoxic nature, and high reusability of the catalyst together with simple work‐up and excellent product yields are the main advantages of this methodology. Also, the nanocatalyst can be recovered easily by centrifugation and reused efficiently for at least seven consecutive runs.