Cerium (IV) sulfate tetrahydrate as a reusable heterogeneous Lewis acid catalyst: solvent-free and green synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione scaffolds

A convenient and efficient procedure is presented for the one‐pot synthesis of N‐substituted pyrroles by condensation of 2,5‐hexandione and amines or diamines in the presence of cross‐linked polystyrene‐supported aluminum chloride (PS/AlCl3) as a highly active and reusable heterogeneous Lewis acid catalyst. This polymeric solid acid catalyst is stable and can be easily recovered and reused without appreciable change in its efficiency. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:85–90, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20661

A new and environmentally benign protocol for the synthesis of quinoxaline derivatives through the condensation reactions of 1,2‐diketones and 1,2‐phenylenediamines using cross‐linked polystyrene‐supported aluminum chloride (PS/AlCl3) as a highly active and reusable heterogeneous Lewis acid catalyst is described. This polymeric catalyst is stable and can be easily recovered and reused without appreciable change in its efficiency. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:472–477, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.21039

Polystyrene-supported GaCl3: A new, highly efficient and recyclable heterogeneous Lewis acid catalyst for acetylation and benzoylation of alcohols and phenols

Polystyrene-supported GaCl3: A new, highly efficient and recyclable heterogeneous Lewis acid catalyst for tetrahydropyranylation of alcohols and phenols

Naphthoquinone-based xanthenes, specifically 14-aryl-13H-dibenzo[a,i]xanthene-8,13(14H)-diones and 12-aryl-2,3,4,12-tetrahydro-1H-benzo[b]xanthene-1,6,11-triones, were obtained in good to excellent yields by a simple, mild, and efficient three-component coupling procedure utilizing polystyrene-supported gallium trichloride as a highly active and eco-friendly heterogeneous Lewis acid catalyst. This reaction was also extended to the preparation of 14-aryl-2-hydroxy-13H-dibenzo[a,i]xanthene-8,13(14H)-diones. The experimental and work-up procedure is very simple and the catalyst can be easily separated from the reaction mixture and reused several times in subsequent reactions.

Polystyrene-supported GaCl3 as a highly efficient and recyclable heterogeneous Lewis acid catalyst for one-pot synthesis of N-substituted pyrroles

An environmentally friendly, chemoselective, and efficient protocol for the preparation of coumarin derivatives by Pechman condensation reaction using new and reusable heterogeneous Lewis acid catalyst polystyrene-supported GaCl3

Ethyl-4-(aryl)-6-methyl-2-(oxo/thio)-3,4-dihydro-1H-pyrimidine-5-carboxylates: Silica supported bismuth(III)triflate catalyzed synthesis and antioxidant activity

Arylaminotetrazoles were efficiently synthesized from secondary arylcyanamides by application of ZnCl2/AlCl3/silica as a reusable heterogeneous Lewis acid catalyst. 5-Arylamino-1H-tetrazoles can be obtained from arylcyanamides carrying electron-withdrawing substituents on the aryl ring, while with electron-releasing groups 1-aryl-5-amino-1H-tetrazoles will be produced. The former isomer is also produced within longer reaction times (~20 h) even with electron-releasing groups.

Synthesis of 2, 3-dihydroquinazolin-4(1H)-ones promoted by an efficient, inexpensive and reusable heterogeneous Lewis acid catalyst

Polystyrene‐supported aluminum chloride is used as catalyst in Paal‐Knorr pyrrole synthesis for the first time.

The optimized conditions allow the preparation of the parent system (Va) and various functionalized derivatives for organic and drug synthesis.

A novel, general, mild, and eco‐friendly one‐pot method for the synthesis of the title compounds is presented including a simple work‐up procedure.

Multi-walled carbon nanotubes sulfuric acid as a reusable heterogeneous stable solid acid catalyst was synthesized from a facile sulfonation of hydroxyl multi-walled carbon nanotubes with chlorosulfonic acid at 0 °C during 2 h. The synthesized catalyst was found to be a highly efficient heterogeneous catalyst for the Groebke-type synthesis of imidazo[1,2-a]pyridines through a condensation reaction of an aldehyde, a 2-aminopyridine, and an isocyanide in methanol in excellent yields with short reaction times at room temperature. The catalyst could be easily recovered by simple filtration and reused without losing its activity. Multi-walled carbon nanotubes sulfuric acid as a reusable heterogeneous solid acid catalyst for the rapid synthesis of imidazo[1,2-a]pyridines .

An environmentally benign method for the synthesis of N -substituted pyrroles from one-pot solvent-free condensation reaction of 2,5-hexanedione with various primary amines (Paal-Knorr pyrrole synthesis) on smectite clays as green and reusable heterogeneous Lewis acid catalysts is presented. The use of nontoxic, inexpensive, easily available and reusable catalysts under solvent-free conditions make this protocol practical, environmentally friendly and economically attractive. KEY WORDS : Paal-Knorr, Smectites, Pyrrole, Solvent-free, Grinding Bull. Chem. Soc. Ethiop. 2018 , 32(1), 139-147 DOI: https://dx.doi.org/10.4314/bcse.v32i1.13