Ionic liquid containing high-density polyethylene supported tungstate: a novel, efficient, and highly recoverable catalyst

Synthesis and catalytic application of polymeric-based nanocomposites are important subjects among researchers due to their high lipophilicity as well as high chemical and mechanical stability. In the present work, a novel nanocomposite material involving ionic liquid and high-density polyethylene supported tungstate (PE/IL-WO4 =) is synthesized, characterized and its catalytic application is investigated. The coacervation method was used to incorporate 1-methyl-3-octylimidazolium bromide ([MOIm] [Br]) ionic liquid in high-density polyethylene, resulting in a PE/IL composite. Subsequently, tungstate was anchored on PE/IL to give PE/IL-WO4 = catalyst. The PXRD, FT-IR, EDX, TGA, and SEM analyses were used to characterize the PE/IL-WO4 = composite. This material demonstrated high catalytic efficiency in the synthesis of bioactive tetrahydrobenzo[a]xanthen-11-ones under green conditions. The recoverability and leching tests were performed to investigate the stability and durability of the designed PE/IL-WO4 = catalyst under applied conditions.

Synthesis of Novel Diphenyl Ether-Based Bis-Heterocycles as Novel Hybrid Molecules via Michael and Other Cyclocondensation Reactions

Molecular hybridization is a technique used in drug creation that involves combining the pharmacophoric moieties of multiple bioactive compounds to create a new hybrid molecule with better affinity and effectiveness. In this regard, we created unique hybrid molecules out of diphenyl ether-linked fused pyrans and other heterocycles. The Michael reaction of 4,4'-oxydibenzaldehyde with malononitrile and various active methylene derivatives, as well as enaminone derivatives, produced the matching bis-fused pyrans and fused pyridines, both connected to a diphenyl ether moiety. Furthermore, the acid-catalyzed reaction of 4,4'-oxydibenzaldehyde with dimedone or β-naphthol produced the corresponding new bis(hexahydro-1H-xanthene-1,8-dione) and bis(14H-dibenzo[a,j]xanthene). The processes by which the target products are formed were also examined.

Solvent-Free, One-Pot, Multicomponent Synthesis of Xanthene Derivatives

An efficient and environmentally benign one-pot condensation of cyclic diketones, aldehydes and naphthols was achieved with 1,4-diazabicyclo[2-2-2]octane supported on Amberlyst-15 as a novel catalyst, producing a variety of benzoxanthenones in good to excellent yields. The advantages of this multicomponent reaction include the use of a heterogeneous catalyst, solventless conditions and a simple methodology that is atom-economical and results in low E-factor values. A total of 17 xanthene derivatives, including two novel molecules, were synthesized and then characterized. Aromatic aldehydes carrying an electron-withdrawing group provided excellent yields. Appreciable results were also obtained using aliphatic aldehydes. The catalyst is fully recyclable and can be reused up to six times.

An efficient and green one-pot synthesis of tetrahydrobenzo[a]xanthenes, 1,8-dioxo-octahydroxanthenes and dibenzo[a,j]xanthenes by Fe3O4@Agar-Ag as nanocatalyst

Agar-coated Fe₃O₄ nanoparticles (Fe₃O₄@agar) were prepared simply through in situ co-precipitation of Fe²⁺ and Fe³⁺ ions via NH₄OH in an aqueous solution of Agar. Coating of Ag⁺ ions on the surface of the latter followed by mild reduction of Ag⁺ with NaBH₄ gives Fe₃O₄@Agar-Ag NPs. The magnetic Fe₃O₄@Agar-Ag nanocatalyst was characterized thoroughly by FT-IR, XRD, SEM, TEM, VSM, EDX, TGA, and ICP analyses. Its catalytic activity was assessed in the synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-one, 14-aryl-14H-dibenzo[a,j]xanthenes, and 1,8-dioxo-octahydroxanthene derivatives through a one-pot condensation of dimedone, 2-naphthol, and aryl aldehydes in EtOH. This novel method represents lots of advantages compared to the previous researches, such as avoiding the toxic catalysts, easy method for isolation of the products, satisfying yields, totally clean conditions, and simplicity of the methodology. This catalytic system is attributed to an eco-friendly process, high catalytic activity, and facility of recovery using an external magnet. A novel and magnetically recyclable catalyst known as Fe3O4@Agar-Ag NPs as a heterogeneous catalyst were synthesized by a simple method. Using this facile, efficient, and eco-friendly Nanocomposite, for the different models of xanthene reaction was represented.

Application of cyclohexane-1,3-diones for six-membered oxygen-containing heterocycles synthesis

Cyclohexan-1,3-dione derivatives are versatile scaffolds for the synthesis of a variety of value-added organic molecules including heterocycles and natural products. Six-membered oxygen heterocycles prepared from cyclohexan-1,3-diones are of much importance as they are intermediate for the synthesis of a number of natural products and several other valuable bioactive molecules which shows anti-viral, anti-bacterial, analgesic, antimalarial, anti-inflammatory, anti-allergic, anti-tumor and anti-cancer activities. These advantages have inspired us to write a detailed survey on the newly developed methods which are very essential in the construction of six-membered oxygen heterocycles. Further, the versatility in the chemistry of cyclohexan-1,3-dione and its derivatives is due to the presence of highly active methylene moiety and its active di-carbonyl groups. Recently, reactions of cyclohexane-1,3-dione and its derivatives with other substrates for instance aldehydes, malononitriles, NMSM, chalcones, isatin etc. have been established for the construction of a variety of six-membered oxygen heterocycles. The studies reported in this review article involved the synthesis of six-membered oxygen-containing heterocycles which includes 4H-chromen-5(6H)-one, 2H-xanthen-1(9H)-one, 2H-xanthen-1,8(5H,9H)-dione, 6H-chromen-2,5-dione derivatives and natural products having six-membered oxygen heterocycles from cyclohexane-1,3-dione and its derivatives as one of the substrate.

Recent development in the synthesis of heterocycles by 2-naphthol-based multicomponent reactions

2-Naphthol or β-naphthol is an important starting material that has drawn great attention in various organic transformations because of its attributes, such as low cost, easy to handle and eco-friendliness. The electron-rich aromatic framework of 2-naphthol with multiple reactive sites allows it to be utilized in several kinds of organic reactions eventuated to several organic molecules with potent biological properties. Multicomponent reaction approach has been tremendously utilized to explore the synthetic utility of 2-naphthol for the construction of diverse N/O-containing heterocyclic framework. In this review, we summarize recent data pertaining to multicomponent reactions, wherein heterocyclic compounds are synthesized utilizing 2-naphthol as one of the starting materials. It is anticipated that this review will stimulate the researchers to design new multicomponent strategies complying with the Green Chemistry principles for the further exploitation of 2-naphthol for the rapid synthesis of versatile biologically relevant heterocycles. This review provides a concise overview of the different 2-naphthol based multicomponent reactions utilized for the construction of diverse bioactive heterocyclic scaffold.

An efficient and reusable nano catalyst for the synthesis of benzoxanthene and chromene derivatives

Potassium fluoride impregnated on clinoptilolite nanoparticles (KF/CP NPs) was investigated as an efficient solid base catalyst for multicomponent condensation reaction. A broad range of aromatic aldehydes and enolizable compounds were condensed with 2-naphthol or 4-hydroxycumarine. The reaction was carried out under a solvent-free condition to give the corresponding benzoxanthene and pyrano [3,2-c]chromene derivatives in high yields. The low cost and availability of catalyst, novel and green procedure makes this strategy more useful for the preparation of tetrahydrobenzo[a]-xanthene-11-one and pyrano [3,2-c]chromene derivatives.

The preparation and characterization of boehmite nanoparticles-TAPC: a tailored and reusable nanocatalyst for the synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones

TAPC supported on boehmite nanoparticles (BNPs-TAPC) as novel, eco-friendly, and recyclable nanocatalyst for the synthesis of title compounds under solvent-free conditions is reported.