Iron Nanoparticles Embedded in Graphitic Carbon Matrix as Heterogeneous Catalysts for the Oxidative C−N Coupling of Aromatic N−H Compounds and Amides

Abstract

Fe or Co nanoparticles (NPs) and two nanoparticulate Fe‐Co alloys having different Fe/Co atomic ratio with average particle size ranging from 10.9 to 26.5 nm embedded in turbostratic graphitic carbon matrix have been prepared by pyrolysis at 900 °C under inert atmosphere of chitosan powders containing Fe2+ and Co2+ ions in various proportions. The resulting Fe/Co NP@C samples have been evaluated as heterogeneous catalysts for the oxidative C−N coupling of amides and aromatic N−H compounds. It was observed that sequential addition of two aliquots of tert‐butyl hydroperoxide (TBHP) in an excess of N,N‐dimethylacetamide (DMA) as solvent affords the corresponding coupling product in high yields, and the most efficient catalyst was Fe NP@C. Fe NP@C is reusable and exhibits a wide scope. The catalytic activity of Fe is supported by using highly pure Fe salt and by the observation that purposely addition of Cu2+ impurities even plays a detrimental effect on the catalytic activity. Mechanistic studies by quenching with 2,2,6,6‐tetramethylpiperidyl‐1‐oxyl (TEMPO) have shown that the amide radical is the key reaction intermediate, and the role of Fe NP@C is to generate the first radicals by TBHP decomposition.

Co–Fe Nanoparticles Wrapped on N-Doped Graphitic Carbons as Highly Selective CO2 Methanation Catalysts

“…Previous studies have widely documented that the pyrolysis of carbon precursors results in the chemical reduction of transition metals, 27 − 30 including Fe. 31 To determine if the Co and Fe elements present in the samples are independent Co and Fe particles or if they are alloyed, experimental XRD data were analyzed by Rietveld refinement.…”

Synthesis of Novel 2-(Het)arylpyrrolidine Derivatives and Evaluation of Their Anticancer and Anti-Biofilm Activity

“…The first one includes the modification of an existing pyrrolidine fragment. Various cross-coupling reactions of (hetero)aromatics with appropriately substituted pyrrolidine derivatives [12,13,14,15,16,17], including oxidative [18,19,20] and photooxidative ones [21,22,23,24], are the most often used within this pathway. In several cases, the synthesis of enantiomerically pure 2-(het)arylpyrrolidines has been also accomplished by decarboxylative (hetero)arylation of proline derivatives [25,26,27,28,29,30,31].…”

Acid‐Catalyzed Intramolecular Imination / Nucleophilic Trapping of 4‐Aminobutanal Derivatives: One‐Pot Access to 2‐(Pyrazolyl)pyrrolidines

“…The first one includes the modification of an existing pyrrolidine fragment. Various cross‐coupling reactions of heteroaromatics with appropriately substituted pyrrolidine derivatives, including oxidative and photooxidative ones, are the most often used within this pathway. Synthesis of enantiomerically pure 2‐(hetaryl)pyrrolidines in several cases has also been accomplished by decarboxylative heteroarylation of proline derivatives …”