Rational development of catalytic Au(I)/Au(III) arylation involving mild oxidative addition of aryl halides

Abdallah Zeineddine,Sonia Mallet-Ladeira,Karinne Miqueu,Laura Estévez,Didier Bourissou,Abderrahmane Amgoune

doi:10.1038/s41467-017-00672-8

Abstract

The reluctance of gold to achieve oxidative addition reaction is considered as an intrinsic limitation for the development of gold-catalyzed cross-coupling reactions with simple and ubiquitous aryl halide electrophiles. Here, we report the rational construction of a Au(I)/Au(III) catalytic cycle involving a sequence of Csp2–X oxidative addition, Csp2–H auration and reductive elimination, allowing a gold-catalyzed direct arylation of arenes with aryl halides. Key to this discovery is the use of Me-Dalphos, a simple ancillary (P,N) ligand, that allows the bottleneck oxidative addition of aryl iodides and bromides to readily proceed under mild conditions. The hemilabile character of the amino group plays a crucial role in this transformation, as substantiated by density functional theory calculations.

Highlights

The reluctance of gold to achieve oxidative addition reaction is considered as an intrinsic limitation for the development of gold-catalyzed cross-coupling reactions with simple and ubiquitous aryl halide electrophiles
Transition metal catalysis has spectacularly progressed over the past century and nowadays occupies a forefront position in organic synthesis
Recent studies have shown that this limitation can be circumvented using strong external oxidants such as hypervalent iodine or electrophilic fluorinating reagents, which give access to the Au(III) oxidation state and enable turnover in so-called oxidative cross-couplings[12,13,14,15,16,17,18,19,20]. Strong electrophiles such as aryl diazonium or diaryliodonium salts can be used to oxidize gold under thermal or photochemical conditions[21,22,23]. This approach has been successfully applied to the cross-coupling of aryl diazonium salts with aryl boronic acids or alkynes merging photoredox and gold catalysis[24,25,26,27,28]

Summary

Introduction

The reluctance of gold to achieve oxidative addition reaction is considered as an intrinsic limitation for the development of gold-catalyzed cross-coupling reactions with simple and ubiquitous aryl halide electrophiles. The paucity of gold-catalyzed cross-coupling reactions has to do with the reluctance of gold to cycle between its I and III oxidation states. Oxidative addition step is the bottleneck to achieve and develop cross-coupling reactions with simple and ubiquitous electrophiles such as aryl halides.

Results

Conclusion