Synthesis and Catalytic Activity of Coumarin‐ and Chrysin‐Tethered Triazolylidene Gold(I) Complexes

Abstract

A series sterically-encumbered coumarin-(1) and chrysin-functionalized triazolium salts (2,3) have been synthesized stepwise via copper catalyzed alkyne-azide cycloaddition and N-alkylation procedures. Their one-pot deprotonation with KHMDS in presence of AuCl(SMe 2 ) allowed for the preparation of the corresponding triazolylidene gold(I) complexes (4-6) in high yields (75-92 %). All new compounds were fully character- [a] 4622 Scheme 2. Synthesis of coumarin-functionalized salt 1.Scheme 3. Synthesis of chrysin-functionalized mono-triazolium 2. Figure 2. Molecular structure of coumarin-functionalized MIC-gold complex 4. Ellipsoids are shown at 50 % probability.Scheme 6. Synthesis of the chrysin-derived dinuclear complex 6.

Spotlight on Ligand Effects in 1,2,3-Triazolylidene Gold Complexes for Hydroamination Catalysis: Synthesis and Catalytic Application of an Activated MIC Gold Triflimide Complex and Various MIC Gold Chloride Complexes

“…Triazolylidenes have proven to be powerful and versatile ligands in transition-metal coordination chemistry. − Their organic precursors are readily synthesized, and their electronic and steric properties are easily modified. In particularly, Au-MIC complexes have been applied as homogeneous catalysts for several reactions, and such complexes also display excellent photophysical and photochemical properties. − ,− In this contribution, we report on the synthesis (silver-free) and characterization of five differently substituted MIC gold­(I) chloride complexes, four of them being novel, to analyze how different electronic properties and steric demands of the ligand influence the catalytic activity of the MIC gold species in the hydroamination reaction. In addition, we present a fully characterized “activated” MIC gold complex by substituting the chloride ligand with a weakly coordinating bistriflimide.…”

An environmentally responsible route to tezacaftor, a drug for treatment of cystic fibrosis prepared in water via ppm Au catalysis as entry to 2-substituted indoles

“…13 Aiming to decrease the required amount of gold, Ruiz-Mendoza et al utilized a 0.5 mol% of a customized mesoisonic gold( i )-carbene complex in toluene at 25 °C and obtained simple indoles in good yields for nine examples. 14 Michalska et al utilized 0.25 mol% of a gold( i )-NHC complex in hexane at 40 °C that yielded the indoles in good yields for eight examples. 15 However, the cited examples apparently lack the applicability to more complex entities and are, obviously, conducted in organic solvents.…”

Preparation of Mixed Bis-N-Heterocyclic Carbene Rhodium(I) Complexes

“…Wingtip functionalized NHCs ligands can also participate in the formation of mixed bis-NHC rhodium(I) complexes. In this context, coumarin-functionalized-NHC metal complexes display interesting catalytic and luminescence properties [ 62 , 63 , 64 , 65 , 66 ]. In particular, we have prepared coumarin-NHC derivatives of type RhCl(NHC-Cou)(η 2 ,η 2 -cod) ( 5 ) in which, in contrast to the behavior observed for related IPr- or IMes-cod compounds, the diolefin ligand can be replaced in the presence of an excess of carbene to yield bis-NHC complexes [ 53 ].…”