Abstract
ABSTRACTA novel Wells–Dawson heteropolyacid-based magnetic Inorganic–organic nanohybrid, Fe3O4@SiO2@ADMPT/H6P2W18O62, was fabricated and used as a green, efficient, eco-friendly, and highly recyclable catalyst for the one-pot and multi-component synthesis of 1,4-Dihydopyridine (1,4-DHP) derivatives from the reaction of various aromatic aldehydes with ethyl acetoacetate and ammonium acetate with good to excellent yields and in a short span of time. The nanohybrid catalyst was prepared by the chemical anchoring of Wells–Dawson heteropolyacid H6P2W18O62 onto the surface of functionalized Fe3O4 nanoparticles with 2,4-bis(3,5-dimethylpyrazol)-triazine (ADMPT) linker. These nanocatalysts were identified by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and vibrating sample magnetometer (VSM). This protocol is developed as a safe, cost-effective and convenient alternate method for the synthesis of 1,4-DHP derivatives utilizing an eco-friendly, and a highly reusable catalyst.
Highlights
Nitrogen-containing heterocycles often play important roles as the scaffolds of biological compounds
After completion of the reaction confirmed by thin-layer chromatography (TLC), solid catalyst was separated by an external magnet and the solution was cooled to room temperature and extracted with 15 ml water and dichloromethane (3 × 10 mL) and dried with anhydrous Na2SO4, the products were purified by recrystallized from ethanol, gave the pure products in 87–98% yields based on the starting aldehyde
FT-infrared spectroscopy (IR) spectroscopy The Wells–Dawson structure of H6P2W18O62 consists of two half units composed of a central tetrahedral PO4 surrounded by nine octahedral WO6
Summary
Nitrogen-containing heterocycles often play important roles as the scaffolds of biological compounds. The pyridine infrastructure is one of the most common heterocycles found in functional products, pharmaceuticals, and natural materials [1,2]. 1 ,4 -Dihydopyridines (1 ,4 -DHPs) have attracted much attention because they include a great family of medicinally active compositions with various therapeutic and pharmacological properties such as MDR reversal [3], vasodilation [4], HIV protease inhibition [5], radioprotection [6], bronchodilator, antitumor, and hepatoprotective activities [7]. Recent studies have shown that these compounds have various medicinal applications such as neuroprotectants, compounds with platelet antiaggregatory, cerebral anti-ischemic agents, and chemosensitizers [8]. Due to their wide range of pharmacological activity and applications, a number of methods have been reported for their synthesis. More than a century ago the first 1,4-DHPs were
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