Evaluation of the Catalytic Ability of Sulfocationites Based on Petroleum Asphaltenes in the Synthesis of Pyrazolidin-3-one

The feasibility of the room temperature catalytic cyclization of hydrazine hydrate and acrylic acid in the presence of an acidic catalyst containing petroleum asphaltenes was explored. The effect of sulfocationite on the synthesis of the target pyrazolidin-3-one was studied. Reaction masses and their distillation residues were analyzed. Gas chromatography–mass spectrometry and electrospray ionization were used to reveal different individual, oligomeric and polymeric products. The most probable structures of the obtained products were proposed.

Mechanistic investigations on C–H activated dealkylating cyclo-amination reactions of substituted triazenes, formamidines and amidines

Catalytic dealkylating cycloamination reactions of N1-methylated-N1,N3-diarylated triazenes proceed via two subsequent oxidative addition reactions, regioselectivity producing benzotriazoles by C–H and C–Br activation steps. Whereas palladium-based catalysis in the presence of dealkylating reagents and directing phosphane ligands leads to high yields, the homologous metals nickel and platinum as well as other 3d transition metals show only poor catalytic activity in similar procedures. Starting compounds have been widely varied to introduce potentially competing reaction sites and to investigate the reaction mechanism of the catalytic cyclization reactions. Yields of the benzotriazole synthesis strongly depend on the electronic and steric properties of the directing phosphane ligands, the nature of the dealkylating bases and the substitution pattern in 2- and 4-position of the aryl groups of the starting triazenes. In order to clarify the role of the catalyst, palladium-based intermediates were identified. Finally, formamidines and bulky amidines were tested in related C–H activated dealkylating cycloamination reactions.

Molecular Ionic Liquid Supported on Mesoporous Silica Nanoparticles-Imprinted Iron Metal: A Recyclable Heterogeneous Catalyst for One-Pot, Three-Component Synthesis of a Library of Benzodiazepines

Aim and Objective: A novel and convenient transformation for the synthesis of benzodiazepines has been developed via catalytic cyclization reaction using ionic liquid supported on mesoporous silica nanoparticles- imprinted iron metal (Fe-MCM-41-IL) as a recyclable catalyst under mild conditions. Materials and Methods: For preparation of Fe-MCM-41-IL, FeCl3·6H2O was added to a mixture of distilled water, CTAB and NaOH aqueous solution. The tetraethyl orthosilicate was dropped into the solution under stirring. The product was separated, washed, and dried. The solid product was collected and calcined. Then, to a solution of β-hydroxy-1,2,3-triazole in toluene, 3-chloropropyltrimethoxysilane was added and the mixture was refluxed. The Conc. H2SO4 was added dropwise into the above solution and stirred. For immobilization of IL onto Fe-MCM-41, the solution IL was added to Fe-MCM-41 and was refluxed for the production of the Fe- MCM-41. Following this, benzodiazepines were synthesized using Fe-MCM-41-IL as a catalyst. </P><P> Results: The Fe-MCM-41-IL was prepared and characterized by a different analysis. The activity of the prepared catalyst as the above described was tested in the model reaction of o-phenyldiamine, tetronic acid, and different aldehydes under room temperature in ethanol solvent. Also, the catalyst could be recovered for five cycles. Conclusion: We developed a novel nanocatalyst for the synthesis of benzodiazepines in excellent yields. Fe- MCM-41-IL as a catalyst has advantages such as: environmental friendliness, reusability and easy recovery of the catalyst using an external magnet.

Beyond sulfide-centric catalysis: recent advances in the catalytic cyclization reactions of sulfur ylides

This Tutorial Review highlighted recent achievements on the catalytic cyclization reactions of sulfur ylide reagents, especially the asymmetric processes avoiding the use of structurally complex chiral sulfides.