Reusable ammonium salt-tagged NHC–Cu(i) complexes: preparation and catalytic application in the three component click reaction

Abstract

A series of ammonium salt-tagged SIPr-Cu(I) complexes have been conveniently synthesized and characterized by NMR and HRMS. They are highly active toward the three component click reaction of benzyl bromide, NaN 3 and alkyne with water as solvent at rt. Current water soluble NHC-Cu(I) catalyst could be efficiently used at least four times with an 84% isolated yield of the desired triazole in the last run.

Ammonium‐Salt‐Tagged IMesAuCl Complexes and Their Application in Gold‐Catalyzed Cycloisomerization Reactions in Water

“…Due to the low solubility of 6a and 6b in organic solvents like dichloromethane or acetone, in which the auration is usually performed, we used the procedure of Wang et al, [19] who carried out similar reactions with CuCl in methanol. Thus, treatment of the imidazolium salts with gold(I) chloride dimethylsulfide complex and potassium tert-butoxide in MeOH gave the desired ammonium-salt-tagged Au I complexes (i.e., 7a and 7b) in 44 and 87 % yields, respectively (Scheme 2).…”

“…[16][17][18] As SIPr, SIMes, IPr, and IMes ligands are the most common ligands in NHC-based catalysis, Wang et al described ammonium-salt-tagged SIPr-Cu I complexes with different alkyl residues on the ammonium group, and different counterions. [19] Zwitterionic gold-NHC complexes bearing sulfonate and pyridinium groups were found to catalyze the cyclization of alkynoic acids. [20,21] To enable access to ammonium-salt-tagged unsaturated NHC ligands, in this paper we present a synthetic pathway to water-soluble IMes derivatives and their conversion into recyclable gold catalysts that activate allenes or alkynes for intramolecular nucleophilic attack in water.…”

Copper-catalysed azide–alkyne cycloadditions (CuAAC): an update

“…56,57 Taking into consideration the potential of dinuclear copper complexes as pre-catalysts in CuAAC reaction, 22a,50 Straub and co-workers prepared and structurally characterized two bis-NHC-dicopper complexes 59 ( Figure 5). The catalytic activity of both dinuclear complexes surpassed significantly that of the mononuclear [(ICy)2Cu]PF6 derivative in dichloromethane at room temperature.…”

Synthese und Anwendung wasserlöslicher NHC‐Übergangsmetall‐Komplexe

“…Grubbs und Mitarbeiter präsentierten einen neuen Ansatz zur Verstärkung der Lçslichkeit in polaren Lçsungsmitteln durch Substitution des Rückgrats der NHCs, anstelle der üblichen Funktionalisierung Stickstoff-gebundener Liganden (L34). [57] Durch eine anspruchsvolle Klick-Reaktionsführung synthetisierten Gaulier et al triazolverbrückte Ammoniumiodide (L38). Diese einzigartige Methode ermçglicht die elektronische und sterische Feinabstimmung des Metallzentrums mit unveränderten N-Substituenten, während die Verstärkung der Lçslichkeit praktisch nur in der äußeren Koordinationssphäre erfolgt.…”