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We have described the synthesis of composite materials with different titanium dioxide loading on hydroxyapatite (TiO2/HAp). Their structural properties and morphologies were established by powder X‐ray diffraction (p‐XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), transmission electron microscopy (TEM) and Fourier transform infrared (FT‐IR) analyses. The catalytic efficacy of the as‐prepared composite materials was explored to synthesise novel 4‐oxo‐chromen‐dihydropyridine derivatives by the four‐component reaction. The one‐pot fusion in ethanol medium involved chromene‐3‐carbaldehyde, dimethyl acetylenedicarboxylate, malononitrile and different aromatic and heteroaryl amines. The method provided impressive yields (92–97%) of the target products in a short reaction time (<21 min) at room temperature. Further, we examined the efficiency of the separated catalyst, reused up to five runs with similar catalytic activity. This sustainable protocol merits easy workup, fast reaction time, superior yields, catalyst reusability, mild reaction environment and column‐free purification.

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A facile, green and environmentally‐friendly protocol for the preparation of ceria doped multi‐walled carbon nanotubes (2.5%CeO2/MWCNTs) composite catalysts are developed. The synthesized catalyst materials have been characterized by using P‐XRD, SEM, TEM and BET analysis. Further, the composite was utilized as a highly efficient and reusable heterogeneous nano‐catalyst for the synthesis of pyridine‐3‐carboxamide derivatives by multicomponent condensation of acetoacetanilide, ammonium acetate, substituted aromatic aldehyde and ethyl cyanoacetate via one‐pot reaction under ethanol solvent conditions at R.T. The remarkable advantages of this green protocol exhibits operational simplicity, easy workup procedure, inexpensive, evading of toxic solvents, shorter reaction times (≤ 15 mins), excellent yields and also avoidance of column chromatography. Furthermore, the catalyst was recyclable and reusability endured for a minimum of six consecutive cycles without significant loss in the catalytic activity.

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