Novel Phosphinite and Phosphonite Copper(I) Complexes: Efficient Catalysts for Click Azide–Alkyne Cycloaddition Reactions

Abstract

The preparation of novel phosphinite- and phosphonite-bearing copper(I) complexes of the general formula [CuX(L)] is reported. These compounds, which remain scarce in the literature, could be prepared using readily available starting materials and were spectroscopically and structurally characterized. These complexes, together with their known phosphine and phosphite analogues, were then applied to the 1,3-dipolar cycloaddition of azides and alkynes, to find that the new complexes displayed the best activities. Full optimization of the reaction conditions resulted in a noteworthy Click catalytic system, active under very mild reaction conditions in the absence of any additive and using low metal loadings.

Highly Active Dinuclear Copper Catalysts for Homogeneous Azide–Alkyne Cycloadditions

“…[65] In 2011, Díez-González et al introduced phosphinite and phosphonite copper(I) complexes ( Figure 9) as novel molecularly defined catalysts for CuAAC reactions under Click conditions. [66] Figure 9: Phosphinite and phosphonite copper(I) complexes presented by Díez-González. [66] These copper(I) complexes can be handled under aerobic conditions and have been fully characterized including single crystal X-ray structures, which show a cubane-like [Cu 4 Br 4 ] scaffold.…”

“…[66] Figure 9: Phosphinite and phosphonite copper(I) complexes presented by Díez-González. [66] These copper(I) complexes can be handled under aerobic conditions and have been fully characterized including single crystal X-ray structures, which show a cubane-like [Cu 4 Br 4 ] scaffold. Their main advantages are the ease of preparation, the tolerance towards water and air, and that they are molecularly defined so that their characteristics can be tuned according to specific demands.…”

Copper(I)–Phosphinite Complexes in Click Cycloadditions: Three‐Component Reactions and Preparation of 5‐Iodotriazoles

“…In a first step, we explored the three‐component reaction between boronic acids, NaN 3 , and terminal alkynes for the one‐pot preparation of 1,4‐disubstituted triazoles. Both steps of this transformation (azidonation and cycloaddition reactions) are copper(I)‐mediated, and therefore we chose {CuBr[PPh 2 (OPh‐2‐OMe)]} A for the initial screening, as it had previously shown the highest activity in CuAAC reactions . With para ‐ methoxyphenylboronic acid and phenylacetylene as model starting materials, different solvents were screened (Table ).…”

“…Unsurprisingly, phosphorous ligands, and PPh 3 in particular, were among the first ligands applied to the cycloaddition of azides and alkynes . We recently reported the excellent activity in copper‐catalyzed azide–alkyne cycloaddition (CuAAC) reactions of novel copper(I) complexes bearing phosphinite or phosphonite ligands . These complexes of general formula [CuBr(L)] are stable and can be handled with no particular precautions to exclude moisture or air.…”

Alkynyl Coinage Metal Clusters and Complexes–Syntheses, Structures, and Strategies

“…These are relatedt o[ CuX(PR 3 )] 4 systems (X = halide), which have been extensively studied in the past and are common motifs for halide incorporated Cu I -clusters. [46][47][48][49][50][51] In case of alkynyl clusters similar structures are adopted by replacing the anionic halides by an alkynide. The copper atoms form an (irregularly shaped) tetrahedron, with triangularf aces capped with the terminal alkynide carbonsi nb ridging coordination mode ( Figure 4a).…”