Efficient synthesis of multiply substituted 7H-indeno[2,1-c]quinolines using LDHs supported 7‐aminonaphthalene‐1,3‐disulfonic acid as catalyst

The layered double hydroxides@Propyl-7‐aminonaphthalene‐1,3‐disulfonic acid used as a new catalyst for synthesis of 7H-indeno[2,1-c]quinoline derivatives. The catalyst was synthesized according to two-step synthesis. Zn-Cr layered double hydroxides (LDHs) with molar ratio 2:1 by the co-precipitation method. The main advantages of LDHs are their easy preparation, reusability and giving a visible active catalyst. The synthesized LDH was characterized by FE-SEM, TEM, TGA, XRD, and FT-IR techniques. LDHs have been known for over than 150 years since the discovery of the layered double hydroxide of general formula Mg6Al2CO3(OH)16•4(H2O), which were primarily described by Manasse in 1915. By co-precipitation method, the various forms of anionic species can be directly intercalated or modified with the hydroxide layers, and also, this artificial pathway is often the best method for the preparation of LDHs containing organic bonds which are difficult to attain by other methods. In the work reported here, in continuation of our research on the synthesis of heterocyclic compounds, a mixture of aryl amine (1.0 mmol) and aromatic aldehyde (1.0 mmol) and LDHs@Propyl–ANDSA (0.06 g) in anhydrous CH3CN (5 mL) was stirred at 60 °C for 30 min. 1-Indanone (1.0 mmol) was then added, and the resulting mixture was stirred at 60 °C.