Pd(0)/Au(i) redox incompatibilities as revealed by Pd-catalyzed homo-coupling of arylgold(i)-complexes

Weber, Dieter; Gagné, Michel R.

doi:10.1039/c1cc11055a

Cited by 54 publications

(59 citation statements)

References 40 publications

(23 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As mentioned in the introduction, at least five plausible mechanistic pathways match the previous data; these mechanistic pathways are considered plausible in part due to studies by our group 5f and others 10b on dual-metal systems after our original publication. Determination of the precise order and nature of steps informs on the activation chemistry uniquely available to dual-metal systems, as will now be described.…”

Section: Resultssupporting

confidence: 56%

“…We proposed a mechanism in which a carbophilic 17 gold Lewis acid first activated the C–C π system prior to involvement by palladium (Scheme 1). 5b Recent work by our group and others suggests that oxophilic 18 and azaphilic 17a,19–21 activation by gold and SET 10b mechanisms may also be possible. In this series of mechanistic studies, we investigated the precise order of steps and the possibility of these alternative activation pathways which will be called “palladium first,” “oxophilic,” “palladium π-allyl cation catalyzed,” and “SET” for clarity.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Mechanistic Studies of Gold and Palladium Cooperative Dual-Catalytic Cross-Coupling Systems

2014

View full text Add to dashboard Cite

Double-label crossover, modified-substrate, and catalyst comparison experiments in the gold and palladium dual-catalytic rearrangement/cross-coupling of allenoates were performed in order to probe the mechanism of this reaction. The results are consistent with a cooperative catalysis mechanism whereby 1) gold activates the substrate prior to oxidative addition by palladium, 2) gold acts as a carbophilic rather than oxophilic Lewis acid, 3) competing olefin isomerization is avoided, 4) gold participates beyond the first turnover and therefore does not serve simply to generate the active palladium catalyst, and 5) single-electron transfer is not involved. These experiments further demonstrate that the cooperativity of both gold and palladium in the reaction is essential because significantly lower to zero conversion is achieved with either metal alone in comparison studies that examined multiple potential gold, palladium, and silver catalysts and precatalysts. Notably, employment of the optimized cocatalysts, PPh3AuOTf and Pd2dba3, separately (i.e., only Au or only Pd) results in zero conversion to product at all monitored time points compared to quantitative conversion to product when both are present in cocatalytic reactions.

show abstract

Section: Resultssupporting

confidence: 56%

Section: Resultsmentioning

confidence: 99%

Mechanistic Studies of Gold and Palladium Cooperative Dual-Catalytic Cross-Coupling Systems

2014

View full text Add to dashboard Cite

show abstract

“…This first study of the retentive stereochemistry of transmetalation of chiral organogold(I) complexes to palladium and a successful strategy for avoiding competing redox quenching of gold(I) by palladium provide insight into this subset of dual-metal catalysis. 8b,18 …”

Section: Discussionmentioning

confidence: 99%

Mechanistic Studies of Azaphilic versus Carbophilic Activation by Gold(I) in the Gold/Palladium Dual-Catalyzed Rearrangement of Alkenyl Vinyl Aziridines

et al. 2012

View full text Add to dashboard Cite

A vinyl aziridine activation strategy cocatalyzed by palladium(0) and a gold(I) Lewis acid has been developed. This rearrangement installs a C–C and a C–N bond in one synthetic step to form pyrrolizidine and indolizidine products. Two proposed mechanistic roles for the gold cocatalyst were considered: (1) carbophilic gold catalysis or (2) azaphilic gold catalysis. Mechanistic studies support an azaphilic Lewis acid activation of the aziridine over a carbophilic Lewis acid activation of the alkene.

show abstract

“…of Au I to regenerate Pd II from Pd 0 . [74] Pre-formed Au I alkynyl complexes can be used to introduce alkynyl fragments into the Pd II/0 cycle, although in toluene the reaction conditions are quite forcing (130°C, 16-24 h). [75] Scheme 2.…”

Section: Metal-localised Redox Chemistrymentioning

confidence: 99%

Ligand Redox Non‐Innocence in Transition‐Metal σ‐Alkynyl and Related Complexes

Schauer

Low

2011

Eur J Inorg Chem

View full text Add to dashboard Cite

Transition-metal σ-alkynyl complexes are valuable functional materials that have found application as sructural units in the assembly of polymetallic arrays and large molecular structures, reagents for the transfer, oligomerisation or functionalisation of alkynes, magnetic or optical materials and putative components for use in a future molecular-based electronics platform. Many σ-alkynyl complexes are redoxactive, undergoing facile oxidation (reduction) at moderate potentials to generate radical cations (anions) in which the

show abstract

Pd(0)/Au(i) redox incompatibilities as revealed by Pd-catalyzed homo-coupling of arylgold(i)-complexes

Abstract: A Pd(ii)-catalyzed homo-coupling of Au(i)-aryls is reported. The reaction is driven by a Pd(0)/Au(i) redox reaction that generates a gold mirror and Pd(ii), and illustrates one of the challenges for developing dual catalytic Au–Pd systems.

Cited by 54 publications

References 40 publications

Mechanistic Studies of Gold and Palladium Cooperative Dual-Catalytic Cross-Coupling Systems

Mechanistic Studies of Gold and Palladium Cooperative Dual-Catalytic Cross-Coupling Systems

Mechanistic Studies of Azaphilic versus Carbophilic Activation by Gold(I) in the Gold/Palladium Dual-Catalyzed Rearrangement of Alkenyl Vinyl Aziridines

Ligand Redox Non‐Innocence in Transition‐Metal σ‐Alkynyl and Related Complexes

Contact Info

Product

Resources

About