Synthesis of pyranopyrazoles using nano‐Fe‐[phenylsalicylaldiminemethylpyranopyrazole]Cl₂ as a new Schiff base complex and catalyst

Abstract

By the condensation reaction of benzaldehyde with ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of FeCl 2 , a pyranopyrazole derivative was prepared which was then reacted with salicylaldehyde to affordCl 2 ). The prepared nano-Schiff base complex was fully characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, differential thermogravimetry, scanning electron microscopy and UV-visible spectroscopy, and was used as an efficient and catalyst for the preparation of pyranopyrazoles.

Design and identification of nano‐Mg‐[4‐methoxy phenyl‐salicylaldimine–methyl‐pyranopyrzole] Cl2 and its catalytic application on the preparation of 1‐(α‐aminoalkyl)‐2‐naphthols

“…For the synthesis of nano‐Mg‐[4‐methoxy phenylsalicylaldiminemethylpyranopyrazole]Cl 2 (nano‐[Mg‐4MSMP]Cl 2 ), firstly, 4‐methoxybenzaldehyde was reacted with ethyl acetoacetate, malononitrile and hydrazine hydrate to afford the related pyranopyrazole according to previous literature . In the next step, the prepared amine was reacted with salicylaldehyde and MgCl 2 .6H 2 O to give nano‐Mg‐[4‐methoxy phenylsalicylaldiminemethylpyranopyrazole]Cl 2 (nano‐[Mg‐4MSMP]Cl 2 ) as a nano‐Schiff base complex (Scheme ).…”

“…For the synthesis of nano-Mg-[4-methoxy phenylsalicylaldiminemethylpyranopyrazole]Cl 2 (nano-[Mg-4MSMP]Cl 2 ), firstly, 4-methoxybenzaldehyde was reacted with ethyl acetoacetate, malononitrile and hydrazine hydrate to afford the related pyranopyrazole according to previous literature. [29][30][31][32][33] In the next step, the prepared amine was reacted with salicylaldehyde and MgCl 2 . [2,3-c]pyrazole-5-carbonitrile (4MSMP) as a Schiff base was prepared alone and its structure was studied by 1 HNMR and 13 CNMR spectra as well as mass analysis.…”

Catalytic Applications of Nano‐Fe‐[Phenyl‐Salicylaldimine‐Methylpyranopyrazole]Cl2 as a Schiff Base Complex and Nanostructured Catalyst for the Synthesis of Hexahydroquinolines

“…The prepared amine (1 mmol) and FeCl 2 .4H 2 O (1 mmol) were pulverized in a mortar for 10 min and then transferred to a 25‐mL round‐bottomed flask containing salicylaldehyde (1.5 mmol), which was connected to a reflux condenser, and stirred at 120°C for 24 h. After this time, the reaction was continued with excess salicylaldehyde for 48 h under the previous reaction condition. Finally, the reaction mixture was cooled and washed by ethyl acetate three times to purify nano‐[Fe‐PSMP]Cl 2 from excess salicylaldehyde …”

“…Finally, the reaction mixture was cooled and washed by ethyl acetate three times to purify nano-[Fe-PSMP]Cl 2 from excess salicylaldehyde. 25 General procedure for the synthesis of hexahydroquinolines A mixture of dimedone (1 mmol), aryl aldehyde (1 mmol), ethyl acetoacetate (1 mmol), ammonium acetate (1.2 mmol), and nano-[Fe-PSMP]Cl 2 (6 mol%) was added to a 25-mL round-bottomed flask connected to a reflux condenser and stirred at 60 C. After the completion of the reaction, as monitored by TLC, the reaction mixture was cooled to room temperature and the product and the remining starting materials were extracted with warm ethanol (20 mL) to separate the catalyst by filtration (the product is soluble in warm ethanol, but the catalyst is not). Then, the crude product was purified by recrystallization from ethanol (95%).…”

“…Hexahydroquinolines (HHQs) can be prepared by the condensation reaction of various aromatic aldehydes, dimedone, β‐ketoesters, and ammonium acetate via the one‐pot multicomponent condensation reaction using different catalysts . Because of the important properties of these compounds, and in continuation of our studies in the preparation of nano‐Schiff base complexes, we report here the synthesis of nano‐Fe‐[phenyl‐salicylaldimine‐methylpyranopyrazole]Cl 2 (nano‐[Fe‐PSMP]Cl 2 ) as an active complex and efficient catalyst for the preparation of hexahydroquinolines (Scheme ).…”