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We recently reported the gold‐catalyzed Heck and chain‐walking reactions, which utilize migratory insertion, β‐hydride elimination steps in a catalytic fashion. Budzelaar et al. in their correspondence state that these reactions proceed through gold‐catalyzed alkene heteroarylation followed by acid‐mediated elimination and cyclization sequence. In response to this correspondence, we have conducted some experiments which convinced us that the product formation solely can not be rationalized based on hetero‐arylation of alkenes under ligand‐enabled Au(I)/Au(III) catalysis. [ABSTRACT FROM AUTHOR]

The successful realization of gold‐catalyzed chain‐walking reactions, facilitated by ligand‐enabled Au(I)/Au(III) redox catalysis, has been reported for the first time. This breakthrough has led to the development of gold‐catalyzed annulation reaction of alkenes with iodoarenes by leveraging the interplay of chain‐walking and π‐activation reactivity mode. The reaction mechanism has been elucidated through comprehensive experimental and computational studies. [ABSTRACT FROM AUTHOR]

A series of enantioenriched substituted tetrahydropyrrolo[3,2‐c]azepine products possessing an axial chirality were synthesized in 63–99% yield through a gold(I)‐catalyzed hydroarylation. DFT calculations rationalized the reactivity observed for the formation of such complex molecular frameworks and guided our choice in the pyrrole N‐substituent to isolate configurationally stable compounds. [ABSTRACT FROM AUTHOR]

Cycloisomerization of N-tethered indole- and dihydropyrrole-arylpropargyl substrates into complex polycycles was investigated by using gold(I) catalysis. Enantioselectivities up to 93% ee were obtained in the asymmetric version of this process. DFT calculations rationalized the reactivity observed for the formation of such complex molecular frameworks. [ABSTRACT FROM AUTHOR]

Presented herein is a gold(I) catalyzed intramolecular tetradehydro‐Diels‐Alder (TDDA) reaction of alkyne‐tethered‐ynamides for the construction of structurally complex 2,3‐dihydrobenzo[f]indole derivatives. The mechanism of the regioselective benzannulation reaction was rationalized by means of density functional theory (DFT) calculations. Substrates having an aryl group at the ynamide terminus are exclusively participating in this TDDA reaction under gold catalysis. [ABSTRACT FROM AUTHOR]

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Two new cationic dinuclear gold(I) complexes, [Au2{μ(P,N)-5}2]X2--in which X=NTf2 (7; Tf=trifluoromethanesulfonate) or SbF6 (8) and 2-(diphenylphosphanyl)benzonitrile (5) is a P,N-bridging donor--have been synthesized and structurally characterized. These air-stable species and their dimeric and polymeric analogues possessing 1'-(diphenylphosphanyl)-1-cyanoferrocene (1) as the bridging ligand, [Au2{μ(P,N)-1}2](NTf2)2 and [Au{μ(P,N)-1}]n[SbF6]n, were used as precatalysts in various Au-mediated C-C and C-O bond-forming reactions. The reactivity of these complexes revealed the hemilabile nature of their P,N ligands. In the series of tested precatalysts, complex 8 exerted particularly high catalytic activity at low Au loading, even in reactions that usually require high amounts of gold catalyst to proceed efficiently under standard reaction conditions. [ABSTRACT FROM AUTHOR]

N-Allyltetrahydro-β-carbolines bearing a pendant allene undergo unprecedented gold(I)-catalyzed cyclizations proceeding with an allyl migration from the nitrogen to the allene moiety. The initial product of the gold-catalyzed cyclization evolves either via isomerization or Cope rearrangement, leading to different scaffolds. Density function theory (DFT) calculations established that the allyl migration occurs in an asynchronous suprafacial manner. [ABSTRACT FROM AUTHOR]

Chiral monodentate phosphines based on ortho-disubstituted ferrocene units have been prepared and used for the synthesis of gold(I) complexes. These complexes are highly active catalysts for the cycloisomerization of 3-hydroxy-1,5-enynes into bicyclo[3.1.0]hexanones. Their high catalytic activity is ascribed to their structural analogy to the biaryl-based Buchwald phosphines. This paper discloses the first enantioselective variant of these reactions based on gold catalysis ( ee's up to 80 %). [ABSTRACT FROM AUTHOR]

Cationic gold(I) complexes are soft Lewis acids that are able to trigger numerous types of nucleophilic attack onto alkenes, allenes, and alkynes (π-acid catalysis). In this account, we initially summarize the novel methods that we have developed to generate such catalysts by silver-free activation of ligated gold(I) chlorides. The advantages of this approach are the use of lower quantities of gold and the ability to scale-up transformations during which the standard gold/silver catalytic system is rapidly decomposed. In the second part, the synthesis and catalytic activity of original organogallium compounds is described. We have shown that (NHC)GaCl2 +-type complexes display a high affinity for alkenes and alkynes, and trigger tandem C–C/C–C or C–C/C–H bond formation processes. Thus, they also behave as π-acids. Practical applications of these different gold- and gallium-based catalytic systems for the synthesis of cyclic compounds are presented. 1 Introduction 2 Silver-Free Two-Component Approaches in Gold Catalysis 2.1 The Gold/Copper Catalytic System 2.2 Other Applications with Gold/Lewis Acid Systems 3 Gallium Catalysis 3.1 Cationic Gallium Complexes Supported by N-Heterocyclic Carbene Ligands 3.2 Catalytic Applications 4 Conclusions [ABSTRACT FROM AUTHOR]

Complexes of type [LAuCl] (L=phosphine, phosphite, NHC and others) are widely employed in homogeneous catalysis, however, they are usually inactive as such and must be used jointly with a halide scavenger. To date, this role has mostly been entrusted to silver salts (AgSbF6, AgPF6, AgBF4, AgOTf, etc.). However, silver salts can be the source of deactivation processes or side reactions, so it is sometimes advisable to use silver-free cationic gold complexes, which can be difficult to synthesize and to handle compared with the more robust chloride. We show in this study that various Lewis acids of the transition and main group metal families are expedient substitutes to silver salts. We have tested CuI, CuII, ZnII, InIII, SiIV, BiIII, and other salts in a variety of typical AuI-catalyzed transformations, and the results have revealed that [LAuCl] can form active species in their presence. [ABSTRACT FROM AUTHOR]

1,6-Enynes can be transformed into vinylidenecyclopentanes viagold-promoted 5-exodig cyclisation followed by 1,5-hydride or -alkoxide shift. [ABSTRACT FROM AUTHOR]

Abstract: The gold-catalyzed cycloisomerization of enynyl esters bearing a cyclohexyl template has been studied and has been shown to lead to two types of products arising from 1,2- vs. 1,3-O-acyl-migration. Results have shown to be dependent on the nature of the solvent, the catalysts, the migrating group, the stereochemistry of the starting diastereomer as well as the alkene partner. This set of findings confirms the intricate nature of the “golden carousel” of propargylic acetates. [ABSTRACT FROM AUTHOR]