Homogeneous and Semi‐Heterogeneous Magnetically Retrievable Bis‐N‐Heterocyclic Carbene Rhodium(I) Based Catalysts for Selective Hydroaminomethylation Reactions

Abstract

The preparation of various bis‐N‐heterocyclic carbene (bis‐NHC) complexes of rhodium and their application in the hydroaminomethylation of vinyl arenes was investigated. Various reaction parameters such as solvent, temperature, and pressure were tested, and the optimized protocol was applied to a wide variety of vinyl arenes and amines to afford the corresponding amines in good yields with high selectivity towards the branched product. The bis‐NHC‐based catalyst demonstrated superior reactivity and selectivity compared to catalysts containing bidentate phosphine or monodentate NHC ligands. A triethoxysilyl‐functionalized bis‐NHC ligand was immobilized on magnetic nanoparticles and then utilized to bind a rhodium catalyst. The resulting catalytic system was successfully employed in hydroaminomethylation reactions. The catalyst exhibited excellent reactivity, high selectivity, and was simply recovered from the reaction medium by applying an external magnetic field.

Recent Advances in Catalysis Involving Bidentate N-Heterocyclic Carbene Ligands

“…Research areas where metal mediated organic molecule transformations were conducted using bidentate NHC ligands to a lesser degree include reduction of carbonyl compounds using hydrosilylation process [ 209 , 214 , 215 , 216 , 217 , 218 , 219 ], isomerization of allylic alcohols [ 220 ], cross metathesis [ 221 ], arene borylation [ 222 , 223 ], amination [ 224 ], reduction of sulfoxides [ 225 ], alcohol oxidation [ 132 , 226 , 227 ], CO 2 reduction [ 228 , 229 , 230 , 231 ], norbornene polymerization [ 232 , 233 , 234 ], alkylation of amines [ 235 ], C-H borylation [ 236 ], CO 2 activation [ 237 ], hydroamination [ 238 ], functionalization of propane [ 239 , 240 ], ylide cycloaddition [ 74 ], three component coupling [ 241 ], hydroxylation of benzene [ 242 ], hydroaminoethlyation [ 243 ], water oxidation [ 244 ], amine alkylation [ 245 ], homopolymerization of ethylene [ 246 ], destruction of chemical warfare [ 247 ], Friedel-Crafts alkylation [ 248 ], C–H arylation [ 249 ], C–H oxidation [ 250 ], SABRE catalyst [ 251 ], and alcohol amidation reactions [ 211 ]. S...…”

Reusable Catalysts for Hydroformylation‐Based Reactions

“…An efficient catalytic system was developed by Abu-Reziq et al [165] through immobilization of a bis-NHC ligand functionalized with silane groups on magnetic nanoparticles and subsequent coordination with rhodium. The immobilization of bis-imidazolium salts on magnetite nanoparticles was performed through its previous functionalization with trialkoxysilane groups, which reacted with the hydroxy groups on the surface of Fe 3 O 4 nanoparticles.…”

“…Bhanage [164] Eugenol (T = 80°C, P = 30 bar) (CO/H 2 ), 8 h 4Abu-Reziq [165] Styrene (T = 80°C, P = 70 bar) (CO/H 2 1 : 1), 16 h)…”

“…An efficient catalytic system was developed by Abu‐Reziq et al [165] . through immobilization of a bis ‐NHC ligand functionalized with silane groups on magnetic nanoparticles and subsequent coordination with rhodium.…”

Ultrasound-assisted and Efficient Knoevenagel Condensation Reaction Catalyzed by Silica Sodium Carbonate Nanoparticles

“…These disclosed properties encourage chemists and pharmacologists to design and synthesize of newly prepared molecules exhibiting pharmacological and biological activities which may be applied in treatment of human diseases as new medicines in the future. [9,10,36] Recently, solid supported catalysts have attracted significant interest because of their unique advantages including easy separation from the reaction mixture and reusability, [37][38][39] easy handling and storing, avoiding the generation of residual salts, nontoxicity, low solubility, increasing selectivity of the reactions, and high stability. [40][41][42] Very recently a green and recyclable inexpensive Brønsted base prepared and called silica sodium carbonate (SSC) 3, [43] via a cascade two steps method from silica gel (1) and silica chloride 2 (Scheme 1).…”