A [(NHC)CuCl] complex as a latent Click catalyst

Abstract

A latent catalyst for the [3+2] cycloaddition reaction of azides and alkynes has been developed in accordance with the principles of Click chemistry

Synthesis, Structural Characterization and Catalytic Activities of Sulfur‐Functionalized NHC–Copper(I) Complexes

“…The C–Cu and Cu–X bond lengths are in the range of 1.883(2)–1.893(6) and 2.098(2)–2.216(1) Å, respectively (Table ). These values correspond quite well with those observed in similar (NHC)CuX systems , …”

“…To compare the activity of the new copper catalysts with the standard NHC–copper catalytic systems, we also included data from previously published results (Entries 12–14). [5b], , The standard NHC–copper complexes were active in a mixture of polar solvents such as water/ t BuOH and DMSO/water. In some cases, high temperature and an extension of the reaction time were required to activate these catalysts to obtain the expected product P1 (Entry 12).…”

A general synthetic route to [Cu(X)(NHC)] (NHC = N-heterocyclic carbene, X = Cl, Br, I) complexes

“…In this context, N-heterocyclic carbene (NHC) copper species of the type [Cu(X)(NHC)] (X = Cl, Br, I) have shown to be efficient catalysts for several transformations, 3 such as the reduction of carbonyl compounds, 4 hydrosilylation 5 and [3+2] cycloaddition of alkynes and azides. 6 They can also be used as carbene transfer reagents to other transition metals such as gold or palladium. 7 In addition, these systems have exhibited interesting biological activity as antitumour agents.…”

The Use of Ligands in Copper-Catalyzed [3+2] Azide-Alkyne Cycloaddition: Clicker than Click Chemistry?

“…However, direct comparison of these results with the ones with 33 cannot be drawn at this point, since not only the halogen (Cl instead of Br) but also the solvent used (t-BuOH/water instead of pure water) were different in both studies. Even though mainly methodological studies have been carried out so far, a number of application are already known for neutral [(NHC)CuX] complexes, such as the development of a latent catalyst, 144 or the preparation of triazole-containing porphyrins, 145 carbanucleosides, 146 or chelators for platinum-based anticancer drugs. 147 Additionally, one major contribution of this family of complexes relies on the isolation of a NHC-Cu-triazolide complex, one of the postulated intermediates for this reaction.…”