Dinuclear Gold Complexes Supported by Wide Bite Angle Diphosphines for Preorganization-Induced Selective Dual-Gold Catalysis

Marianne Lankelma,Maxime Siegler,Jarl Van Der Vlugt,Vincent Vreeken

doi:10.3390/inorganics7030028

Marianne Lankelma, Maxime Siegler + Show 2 more

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https://doi.org/10.3390/inorganics7030028

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Journal: Inorganics	Publication Date: Feb 26, 2019
Citations: 7	License type: CC BY 4.0

Affiliation: University of Amsterdam, Johns Hopkins University

Abstract

The synthesis, reactivity, and potential of well-defined dinuclear gold complexes as precursors for dual-gold catalysis is explored. Using the preorganizing abilities of well-known wide bite angle diphosphine ligands, DBFPhos and DPEPhos, dinuclear Au(I)–Au(I) complexes 1 and 2 are used as precursors to form well-defined monocationic species with either a chlorido- or acetylido-ligand bridging the two gold centers. These compounds are active catalysts for the dual-gold heterocycloaddition of a urea-functionalized alkyne, and the preorganization of both Au-centers affords efficient σ,π-activation of the substrate, even at high dilution, significantly outperforming benchmark mononuclear catalysts.

Highlights

The catalytic activation of substrates using two gold centers has proven to be a valuable strategy for a wide range of transformations in the broader context of gold-mediated catalysis [1,2,3,4,5,6,7,8,9,10,11,12,13,14].Commonly, mono-gold catalysis relies on π-activation of a substrate by a cationicAu(I) center
We have recently reported the catalytic competence of well-defined dinuclear σ,π-alkynide complexes in dual-gold catalysis, highlighting the importance of two preorganized Au centers with respect to regioselectivity and activity for intramolecular hydroamination [19,20]
In order to eliminate such ligand-centered chemistry leading to structural reorganization, and to exploit more readily available diphosphine ligands, we investigated wide bite angle diphosphine ligands with

Summary

Introduction

The catalytic activation of substrates using two gold centers has proven to be a valuable strategy for a wide range of transformations in the broader context of gold-mediated catalysis [1,2,3,4,5,6,7,8,9,10,11,12,13,14].Commonly, mono-gold catalysis relies on π-activation of a substrate (e.g., an alkene) by a cationicAu(I) center. Dual-gold catalysis, on the other hand, can lead to both σ- and π-activation (either of the same functional group within a substrate or of two separate functional groups) by two Au centers. We have recently reported the catalytic competence of well-defined dinuclear σ,π-alkynide complexes in dual-gold catalysis, highlighting the importance of two preorganized Au centers with respect to regioselectivity and activity for intramolecular hydroamination [19,20]. This was achieved using the ditopic tridentate ligand PNH PiPr (2,20 -bis(diisopropylphosphino)-4,40 -ditolylamine) (Figure 1). In order to eliminate such ligand-centered chemistry leading to structural reorganization, and to exploit more readily available diphosphine ligands, we investigated wide bite angle diphosphine ligands with

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Conclusion