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

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.

Gold‐Catalyzed Cross‐Coupling Reactions: An Overview of Design Strategies, Mechanistic Studies, and Applications

“…Alternatively,afew investigations have indicated that even in the absence of activation by light and external oxidants, aryl diazonium salts can be used as the coupling partners to perform certain CÀCc ross-coupling reactions. [233] Chem.E ur.J.2020, 26,1442 -1487 www.chemeurj.org Extending the scope of Au redox catalysis with aryl diazonium salts, Shi'sg roup have developed Sandmeyer-type reactions for the generationo fC ÀY( Y = Br,S ,a nd P) bonds (Scheme 40). [237] Pivotal to the successo ft he reactions was the use of 2,2'-bipyridine (bpy) ligand and the base Na 2 CO 3 .T he mechanistic studies revealed that Na 2 CO 3 assists the formation of an initial alkynyl or arylgold complex.T his Au complex bonds to the aryl-diazonium salts to produce an Au III intermediate.…”

“…[233] They used Me-Dalphos ligands containing Pa nd Ng roups, which can assist the oxidative addition process, as hasb een revealed from DFT studies (Scheme 38). [233] They used Me-Dalphos ligands containing Pa nd Ng roups, which can assist the oxidative addition process, as hasb een revealed from DFT studies (Scheme 38).…”

“…[146] In section 5o ft his review,w ehave discussed this topic. [233] Scheme38. In 2015, Shi and co-workers demonstrated facile C(sp)ÀC(sp 2 )a nd C(sp 2 )ÀC(sp 2 )c ross-coupling reactionso fa ryl diazonium salts with terminal alkynes and aryl boronic acids, respectively (Scheme 39).…”

Gold‐Catalyzed C–S Aryl‐Group Transfer in Zinc Finger Proteins

“…[33] Gold(III) intermediates generated after oxidative addition of arylÀXt oA u I /phosphine compounds are also widely used for aryl transfer and C À Cc oupling, [34] while gold(I)-catalyzed oxidative allene-thiol coupling leads to the formation of vinyl sulfide alcohols. [33] Gold(III) intermediates generated after oxidative addition of arylÀXt oA u I /phosphine compounds are also widely used for aryl transfer and C À Cc oupling, [34] while gold(I)-catalyzed oxidative allene-thiol coupling leads to the formation of vinyl sulfide alcohols.…”

Gold‐Catalyzed C(sp2)−C(sp) Coupling by Alkynylation through Oxidative Addition of Bromoalkynes

“…Second, in 2013, Glorious and co‐workers reported the Au I oxidation with aryldiazonium salts combined with a Ru photoredox catalyst, leading to the development of new methodologies for gold‐catalyzed arylation (Scheme b) . Third, in 2017, in Bourissou's group, aryl halides were used in the gold‐catalyzed arylation of electron‐rich arenes by hemilabile P,N ligand‐promoted oxidative addition of gold(I) (Scheme c) . However, these strategies suffered from some drawbacks, for example the steps for the synthesis of the hypervalent iodine reagents, the low atom efficiency (only a small part of the reagent is transferred or more than one equivalent of silver is required) and the need of complicated bidentate ligands.…”