Fe₃O₄@SiO₂/Schiff base/Pd complex as an efficient heterogeneous and recyclable nanocatalyst for chemoselective N-arylation of O-alkyl primary carbamates

Abstract

An Fe3O4@SiO2/Schiff base/Pd complex as an efficient, heterogeneous magnetically recoverable and reusable catalyst for the N-arylation of O-alkyl primary carbamates.

A Fe3O4@SiO2/Schiff Base/Pd Complex as an Efficient Heterogeneous and Recyclable Nanocatalyst for One‐Pot Domino Synthesis of Carbamates and Unsymmetrical Ureas

“…The retrievable palladium (II) based magnetic nanocatalyst (Fe 3 O 4 @SiO 2 /Pd(II)) was synthesized through the protocol had been used among recent years by our research group . Scheme concisely describes the synthetic procedure of the catalyst.…”

“…General Procedure for the Preparation of Fe 3 O 4 Nanoparticles: The naked Fe 3 O 4 nanoparticles were prepared according to the improved chemical coprecipitation method as previously reported. To the solution of 1.3 g FeCl 3 · 6H 2 O (4.8 mmol) in deionized water (15 mL), added a mixture of polyvinyl alcohol (PVA 15000) (1.0 g), as the surfactant, and 0.9 g FeCl 2 · 4H 2 O (4.5 mmol) in deionized water (15 mL).…”

“…General Procedure for the Preparation of Fe 3 O 4 @SiO 2 Core‐shell: For the preparation of Fe 3 O 4 @SiO 2 core‐shell, Fe 3 O 4 (0.5 g, 2.1 mmol) was dispersed in a solution of ethanol (50 mL), deionized water (5.0 mL) and tetraethoxysilane (TEOS) (0.2 mL), followed by the addition of 5.0 mL of NaOH (10 wt.‐%)under vigorous stirring. This mixture was left to be stirred for 30 min at room temperature.…”

“…General Procedure for Preparation of the Ligand: A solution of the stoichiometric amount of salicylaldehyde (1.0 mmol, 0.122 g) in ethanol (25 mL) was added dropwise to the 3‐aminopropyl (triethoxy) silane (1.0 mmol, 0.176 g) in 25 mL of ethanol. Then, the mixture was stirred at room temperature for 6 hours.…”

“…General Procedure for Preparation of the Pd(II) Complex: Pd(OAc) 2 (0.224 g, 1.0 mmol) was added to the solution of synthesized ligand (0.651 g, 2.0 mmol) in ethanol (25 mL). Then, the obtained mixture was allowed to proceed in reflux conditions.…”