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.

中文翻译：

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在绿色条件下合成一种可持续的多相催化剂，负载二氧化钛的羟基磷灰石，用于功能化色烯-二氢吡啶

我们已经描述了在羟基磷灰石 (TiO ₂/HAp）。它们的结构特性和形貌是通过粉末 X 射线衍射 (p-XRD)、扫描电子显微镜 (SEM)、Brunauer-Emmett-Teller (BET)、透射电子显微镜 (TEM) 和傅里叶变换红外 (FT-IR) 确定的分析。研究了所制备的复合材料的催化功效，通过四组分反应合成新型 4-氧代-色烯-二氢吡啶衍生物。在乙醇介质中的一锅融合包括色烯-3-甲醛、乙炔二甲酸二甲酯、丙二腈以及不同的芳香胺和杂芳基胺。该方法在室温下的短反应时间内（<21 分钟）提供了令人印象深刻的目标产物产率 (92–97%)。此外，我们检查了分离催化剂的效率，以类似的催化活性重复使用多达五次。