Phosphotungstic acid grafted zeolite imidazolate framework as an effective heterogeneous nanocatalyst for the one‐pot solvent‐free synthesis of 3,4‐dihydropyrimidinones

Abstract

Phosphotungstic acid (H 3 PW 12 O 40 , PTA) supported on ZIF-9(NH 2 ) was synthesized for the first time and performed as an effective and environmental friendly catalyst in the one-pot three component Biginelli condensation of different substituted benzaldehydes with ethyl acetoacetate and urea to afford the corresponding 3,4-dihydropyrimidin-2-(1H)-ones under solvent-free conditions. ZIF-9(NH 2 ) and the prepared nanocatalyst PTA@ZIF-9(NH 2 ) were characterized by XRD, FESEM, TEM, EDX, BET, AAS, TGA, UV-Vis, and FT-IR. After reaction, the nanocatalyst can be easily separated from the reaction mixture by centrifuge and the recovered catalyst can be reused for at least five times with a 14% reduction in yield after the fifth run. This study showed that ZIF-9(NH 2 ) can be utilized as a promising support for PTA and developed a highly active, stable and reusable heterogeneous catalyst under easy reaction condition in the multi-component organic synthesis.

Air‐stable zirconium (IV)‐salophen perfluorooctanesulfonate as a highly efficient and reusable catalyst for the synthesis of 3,4‐dihydropyrimidin‐2‐(1H)‐ones/thiones under solvent‐free conditions

“…In show the merit of the present study, the results of using complex 1 for the synthesis of product 5a by reacting benzaldehyde, ethyl acetoacetate, and urea with other homogeneous and heterogeneous catalysts were compared (Table , entries 3–14). According to the obtained results our catalyst shows better catalytic activity with a shorter reaction time using solvent‐free conditions with good recyclability. Apparently, the long fluoroalkyl chain in the sulfonate must be responsible for the hydrophobicity and increasing the catalytic activity.…”

“…Generally, dihydropyrimidinones are synthesized by the three‐component Biginelli reaction of aldehyde, 1,3‐dicarbonyl compound and urea, and much work on improving these protocols towards reaching milder reaction conditions and higher yields has been actively pursued. Until now, various catalysts and catalytic systems have been developed, including BF 3 ·OEt 2 , ZrCl 4 or ZrOCl 2 , InCl 3 , InBr 3 , YCl 3 , TaBr 5 , VCl 3 , metal triflates (Y, Sr, In, Cu), Fe (OTs) 3 · 6H 2 O, Mn (OAC) 3 · 2H 2 O, Y (NO 3 ) 3 · 6H 2 O, H 3 BO 3 , PPh 3 , Cp 2 Ti‐based Lewis acids, TBAB, Ag 3 PW 12 O 40 , SiO 2 ‐Cl, Fe 3 O 4 /PAA‐SO 3 H, nanomagnetic supported sulfonic acid, FeCl 3 ‐supported nanoporous silica, precious metals (Pt, Pd, Ru) on graphene oxide nanoparticle catalyst, zirconium porphyrin graphene oxide, H 3 PW 12 O 40 supported on ZIF‐9(NH 2 ), Cu@SBA‐15, and others . However, these catalysts of the Biginelli reaction procedures are associated with harsh reaction conditions, expensive and corrosive reagents, the use of volatile organic solvents, poor substrate generality, unsatisfactory yields, longer reaction times and poor catalyst recyclability.…”

The dual role of ammonium acetate as reagent and catalyst in the synthesis of 2, 4, 5-triaryl-1H-imidazoles

“…In connection with our ongoing work on the synthesis of various heterocyclic compounds [22][23][24][25][26][27][28][29], we wish to report a facile procedure for preparation of imidazole derivatives without addition of any specific catalyst. As mentioned above, several methods are introduced for the synthesis of trisubstitutedimidazoles and their derivatives.…”

Pd(0)‐guanidine@MCM‐41: a very effective catalyst for rapid production of bis (pyrazolyl)methanes

“…Environmental friendly operation via reducing the number of synthetic steps and work up, the energy consumption, reaction time, waste production, and eliminating the isolation of unstable intermediates are among the advantages of MCRs . Over the last few decades, with increasing environmental concerns, the design of new MCRs with ecofriendly, green procedures have become increasingly useful tools, especially in the fields of drug discovery, organic synthesis and material science . Because of the increasing concern of the harmful effects of organic solvents on the environment and human body, organic reactions that are operated with green solvents or without conventional organic solvents have aroused the attention of organic and medicinal chemists .…”