Fe₃O₄@SiO₂–imid–PMAⁿmagnetic porous nanospheres as recyclable catalysts for the one-pot synthesis of 14-aryl- or alkyl-14H-dibenzo[a,j]xanthenes and 1,8-dioxooctahydroxanthene derivatives under various conditions

Abstract

Synthesis of 14-aryl- or alkyl-14H-dibenzo[a,j]xanthenes and 1,8-dioxooctahydroxanthene derivatives by Fe3O4@SiO2–imid–PMA nanocatalysts.

A convenient, simple and one-pot synthesis of dibenzoxanthenes and tetrahydrobenzoxanthenes by nanotitania-supported sulfonic acid as an efficient and highly reusable nanocatalyst

“…The proposed mechanism for the formation of dibenzoxanthenes is depicted in Scheme 2 [31]. Due to hydrogen bonding between carbonyl oxygen of aldehyde and sulfonic acid groups of the n-TSA, the electron density of carbonyl decreases, which results in higher susceptibility to nucleophilic attack on carbonyl groups.…”

A green one-pot three-component synthesis of tetrahydrobenzo[b]pyran and 3,4-dihydropyrano[c]chromene derivatives using a Fe3O4@SiO2–imid–PMAn magnetic nanocatalyst under ultrasonic irradiation or reflux conditions

“…Some of these compounds exhibit spasmolytic, diuretic, anticoagulant, anticancer, andantianaphylactic activity [28].Moreover they can be used as cognitive enhancers, for the handling of neurodegenerative diseases, including amyotrophic lateral sclerosis, Alzheimer's disease, Parkinson's disease, Huntington's disease, AIDS associated dementia and Down's syndrome as well as for the treatment of schizophrenia and myoclonus [29].Despite their importance from pharmacological, industrial and synthetic point of views, comparatively few methods for the preparation of dihydropyrano[3,2-c]chromenederivatives have been reported [30].Some of the reported procedures require long reaction times; afford products with only modest yields and non-reusability of the catalyst. The use of support allows the heteropolyacids to be dispersed over a large surface area and increases their catalytic activity [33].In previous work[34], we introduce a simple, repaid, inexpensiveand one step method, solvothermal, for synthesis ofH 3 PMo 12 O 4 nanoparticles (PMA n ) from H 3 PMo 12 O 4 bulk particles (PMA b ). In recent years, brønsted acids such as Keggin-type heteropolyacids(HPAs) have been used as efficient catalysts for a variety of organic reactions because of their redox properties and superacidic, high thermal stability, ease of handling, high proton mobility, stronger acids than homogeneous acid catalysts, low toxicity, development of clean technologies and low cost [31].Although HPAs are versatile compounds intheir acidic form, their main disadvantages are high solubility inpolar solvents and low surface area (<10 m 2 /g).…”

One-pot synthesis of multisubstituted imidazoles catalyzed by Dendrimer-PWAn nanoparticles under solvent-free conditions and ultrasonic irradiation

“…Although these materials are versatile compounds in their acidic form, their main disadvantages are high solubility in polar solvents and low surface area (\10 m 2 /g). Therefore, in a homogeneous reaction, the isolation of the products and the reuse of the catalyst after reaction become difficult [30][31][32][33]. Therefore, in order to overcome this problem, these materials are dispersed on supports (such as silica, acidic ionexchange resins, active carbon, etc.)…”