N‐Heterocyclic Carbenes and Imidazole‐2‐thiones as Ligands for the Gold(I)‐Catalysed Hydroamination of Phenylacetylene

Abstract

Gold(I) complexes of 1-[1-(2,6-dimethylphenylimino)alkyl]-3-(mesityl)imidazol-2-ylidene (C^Imine(R)), 1,3-dimesitylimidazol-2-ylidene (IMes) and of the corresponding thione derivatives (S^Imine(R) and IMesS) were prepared and structurally characterised. The solid-state structure of the C^Imine(R) and S^Imine(R) gold(I) complexes showed monodentate coordination of the ligand and a dangling imine group that could bind reversibly to the metal centre to stabilise otherwise unstable catalytic intermediates. Interestingly, reaction of C^Imine(tBu) with [AuCl(SMe(2))] led to the formation of [(C^Imine(tBu))AuCl], which rearranges upon crystallisation into the unusual complex cation [(C^Imine(tBu))(2)Au](+), with AuCl(2)(-) as the counterion. The activity of the gold complexes in the hydroamination of phenylacetylene with substituted anilines was tested and compared to control catalyst systems. The best catalytic performance was obtained with [(C^Imine(tBu))AuCl], with the exclusive formation of the Markovnikov addition product in excellent yield (>95 %) regardless of the substituents on aniline.

Retraction: Synthesis and Characterization of Sterically Congested Mesityltris(imidazolium) Salts and the Corresponding Highly Crystalline Tris‐selone Derivatives

“…[13,25] Imidazole selones, as pecial class of heteroketones, have gained increasing interest in recenty ears as efficient ligating agents in lieu of traditional N-heterocyclic carbenes. In fact, mono-and bis-imidazole selones have been extensively used to generate transitionmetal-based complexes [26][27][28][29][30][31][32][33][34][35][36][37][38] and have furtherb een employed in versatile catalytic applications, such as polymerization [39] and the reduction of nitrobenzenes. [40] Moreover,s uch selenoketones have been used as inhibitors of lactoperoxidase-catalyzed oxidation and tyrosine nitration, [41][42][43] as an analogue of the antithyroidd rug methimazole, [44][45][46] in optoelectronics, [47] as chemicals ensors, [48] and also as ac hemical tool for Pd II extraction from water.…”

Synthesis and Characterization of Sterically Congested Mesityltris(imidazolium) Salts and the Corresponding Highly Crystalline Tris-selone Derivatives

“…[13,25] Imidazole selones, as pecial class of heteroketones, have gained increasing interest in recenty ears as efficient ligating agents in lieu of traditional N-heterocyclic carbenes. In fact, mono-and bis-imidazole selones have been extensively used to generate transitionmetal-based complexes [26][27][28][29][30][31][32][33][34][35][36][37][38] and have furtherb een employed in versatile catalytic applications, such as polymerization [39] and the reduction of nitrobenzenes. [40] Moreover,s uch selenoketones have been used as inhibitors of lactoperoxidase-catalyzed oxidation and tyrosine nitration, [41][42][43] as an analogue of the antithyroidd rug methimazole, [44][45][46] in optoelectronics, [47] as chemicals ensors, [48] and also as ac hemical tool for Pd II extraction from water.…”

Synthesis, characterization, photophysical properties, and catalytic activity of an SCS bis(N-heterocyclic thione) (SCS-NHT) Pd pincer complex

“…[29][30][31] Although the chemistry of SCS pincer complexes is not as developed as that of the related PCP and NCN derivatives, they have been found to exhibit interesting photophysical properties [22][23][24]26,30,32 and catalytic applications ranging from the borylation of allylic alcohols 33 to a variety of cross-coupling reactions. 36,37 It is noteworthy that pincer complexes incorporating N-heterocyclic thione (NHT) donor groups are virtually unknown even though the coordination chemistry of simple monodentate NHTs has been extensively investigated. 36,37 It is noteworthy that pincer complexes incorporating N-heterocyclic thione (NHT) donor groups are virtually unknown even though the coordination chemistry of simple monodentate NHTs has been extensively investigated.…”