γ‐Fe₂O₃@Cu₃Al‐LDH‐TUD as a new Amphoteric, Highly Efficient and Recyclable Heterogeneous Catalyst for the Solvent‐free Synthesis of Dihydropyrano[3,2‐c]pyrazoles and dihydropyrano[3,2‐c]chromens

Abstract

Thiourea dioxide was immobilized on γ‐Fe2O3@Cu3Al‐LDH magnetic nanoparticles to prepare the γ‐Fe2O3@Cu3Al‐LDH‐TUD MNPs. The structure and properties of these magnetic nanoparticles were established by FT‐IR, EDX, SEM, XRD, and hystogram of particle size analytical methods. The results obtained from these analytical methods confirmed the successful immobilization of the thiourea dioxide onto the magnetic support. The synthesized magnetic nanoparticles (MNPs) exhibited high catalytic activity in one‐pot three‐component reactions under mild and solvent‐free conditions for the synthesis of diverse ranges of dihydropyrano[3,2‐c]pyrazoles and dihydropyrano[3,2‐c]chromens. All the reactions proceeded smoothly to furnish the respective products in excellent yields. Simple isolation of the products, avoidance of harmful organic solvents, versatility of the catalyst and its easy magnetic separation and reusability with no significant loss of activity are the main advantages of the present method.

Ternary Hydrotalcites in the Multicomponent Synthesis of 4H-Pyrans

“…MCRs have proven to be a tool for the formation of strong and efficient bonds in organic, medical chemistry and in the context of green chemistry. Several investigations using hydrotalcites as heterogeneous catalysts have been reported in the field of MCRs [4,[7][8][9]. It has been found that the ratio and type of metal cations, as well as the formation of mixed oxides (LDO) by calcination processes, are useful parameters for obtaining highly selective products.…”

“…In addition, the incorporation of V 2+ and Zn 2+ improves the catalytic performance, but when Co 2+ or Ni 2+ is incorporated, it decreases [4]. The synthesis of dihydropyran-chromenes is favored by the replacement of Cu 2+ in the brucite layer [9].…”

Heterogenized magnetic graphene oxide‐supported N6‐Schiff base Cu (II) complex as an exclusive nanocatalyst for synthesis of new pyrido[2,3‐d]pyrimidine‐7‐carbonitrile derivatives

“…In recent years, the search for extension of new and effective synthetic approaches toward the preparation of various biologically active heterocyclic compounds has been motivated on highly active and reusable catalysts under eco‐friendly conditions. [ 61–64 ] In this regard, and as our ongoing research program directed on the preparation and application of new and reusable magnetic nanoparticles as catalysts, [ 65–73 ] herein we wish to report the coating of Cu (II) N 6 ‐Schiff base complex on the surface of Fe 3 O 4 ‐magnetized graphene oxide nanosheets as a new support in order to prepare GO/Fe 3 O 4 @SPNC nanoparticles as a novel catalyst. The catalytic activity of this magnetically GO/Fe 3 O 4 ‐supported Cu (II) Schiff base complex was explored as an efficient, recyclable and sustainable catalyst in the synthesis of new pyrido[2,3‐ d ]pyrimidine‐7‐carbonitrile derivatives (Scheme 1).…”

β‐Alanine‐functionalized magnetic graphene oxide quantum dots: an efficient and recyclable heterogeneous basic catalyst for the synthesis of 1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione and 2,3‐dihydroquinazolin‐4(1H)‐one derivatives

“…Following our ongoing efforts for the development of more benign and efficient heterogeneous nanocatalysts and their catalytic applications in organic transformation reactions, including the synthesis of heterocyclic compounds, [ 57–61 ] herein we report the novel synthesis of magnetic β‐alanine‐functionalized GO quantum dot (GOQD), Fe 3 O 4 @GOQD‐ N ‐(β‐alanine), nanoparticles as a novel catalyst. This magnetic Fe 3 O 4 @GOQD‐ N ‐(β‐alanine) nanoparticle was explored as an efficient, recyclable, and sustainable catalyst for one‐pot synthesis 1 H ‐pyrazolo[1,2‐ b ]phthalazine‐5,10‐diones ( 4a–i ) and 2,3‐dihydroquinazolin‐4(1 H )‐ones ( 7a–h ) (Scheme 1).…”