Calcined Layered Double Hydroxides: Catalysts for Xanthene, 1,4-Dihydropyridine, and Polyhydroquinoline Derivative Synthesis

Abstract

This work is generally focused on the synthesis of NiFeTi-layered double hydroxides (LDHs) using a hydrothermal route, which were calcined at various temperatures (varying from 200 to 600 °C). The synthesized materials were physicochemically characterized. Xray diffraction results revealed the loss of the layered structure on calcination resulting in the formation of layered double oxides (LDOs) or mixed metal oxides, which was also supported by Fourier transform infrared studies. Scanning electron microscopy results also show loss of the layered structure and the creation of LDOs on increasing the temperature. These LDOs were tested as the catalysts for the synthesis of biologically significant xanthene, 1,4-dihydropyridine, and polyhydroquinoline derivatives. Among all, NiFeTi LDH calcined at 600 °C proved to be the best catalyst for the synthesis of these derivative compounds under optimized conditions. The advantages obtained were excellent yields in a lesser reaction time. Stability and reusability were also assessed; the catalyst was stable even after five cycles. Furthermore, the memory effect of the obtained NiFeTi CLDH calcined at 600 °C confirms that the material so formed is a calcined state of LDH itself. High catalytic efficiency, easy fabrication, and recycling ability of NiFeTi CLDH calcined at 600 °C make it a potential catalyst for the synthesis of xanthene, 1,4-dihydropyridine, and polyhydroquinoline derivatives.

Fabrication of a Gold-Supported NiAlTi-Layered Double Hydroxide Nanocatalyst for Organic Transformations

“…The so-formed second intermediate further reacts with ammonium acetate to form enamine, which further results in the desired product after intramolecular cyclization and dehydration steps. 13 …”

Introduction of a trinuclear manganese(iii) catalyst on the surface of magnetic cellulose as an eco-benign, efficient and reusable novel heterogeneous catalyst for the multi-component synthesis of new derivatives of xanthene

“…A control experiment lumpish that no product was obtained when the reaction was accomplished in the absence of the catalyst (Table 1, entry 9). The effect of different temperatures was also examined on the model reaction progress (Table 1, entries [12][13][14] and found that the multi-component reaction proceeded surprisingly at 45 C (Table 1, entry 3). It is noteworthy that the MCR reaction has a small efficiency without temperature conditions (entry 12).…”

“…As a result, 40 C was selected as the optimum reaction temperature. Further investigation disclosed that the number of oxidizing agents is crucial to the product yield (entries [13][14]. When the oxidation of the model reaction was carried out using 1, 2, and 3 mmol of tert-butyl hydroperoxide, the product's yield increased as the concentration of tert-butyl hydroperoxide increased.…”

“…2H, Ar), 7.20-7.25 (m, 2H, Ar), 7.84-7.88 (m, 2H, Ar), 9.91 (s, 1H, COH) ppm 13. C NMR (DMSO, 75 MHz): d ¼ 20.3, 25.9, 27.1, 30.8, 37.0, 67.1, 67.9, 114.0, 114.7, 117.0, 117.1, 129.3, 129.8, 132.0, 136.8, 157.4, 163.7, 164.1, 190.9, 196.7 ppm.…”

Incorporation of Keggin-based H3PW7Mo5O40into bentonite: synthesis, characterization and catalytic applications

“…40 Various members of this family are currently used for cytostatic and antitumor activities (for example, nitracrine derivatives), 41 platelet antiaggregatory activities, the treatment of Alzheimer's disease, strong anti-cancer treatments (for example, amsacrine derivatives), cardiovascular diseases including hypertension and diabetes, and so on. 41,42 The structures of some xanthene and acridine derivatives are shown in Fig. 1.…”