Pt−Ag Catalyst System for Hydroarylations with Unactivated Arenes and Olefins

Karshtedt, Dmitry; Bell, Alexis T.; Tilley, T. Don

doi:10.1021/om0495325

Cited by 108 publications

(93 citation statements)

References 23 publications

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“…21 Tilley, Bell, and Karshtedt found that a PtÀAg catalyst system and Pt(II) catalysts supported by pyridylÀpyrrolyl ligands initiate norbornene hydroarylation, but the observed product selectivity suggests the possibility of a FriedelÀCrafts-type pathway. 22,29 Particularly germane is a recent study that reveals catalytic olefin hydroarylation using Pt(II) triflate salts likely proceeds by formation of triflic acid, which serves as the active catalyst. 30 Our groups reported a series of studies on TpRu(L)(NCMe)-(Ph) [Tp = hydridotris(pyrazolyl)borate, L = CO, PMe 3 , P(Npyrrolyl) 3 , or P(OCH 2 ) 3 CEt] catalysts for olefin hydroarylation.…”

Section: à26mentioning

confidence: 99%

Mechanistic Studies of Ethylene Hydrophenylation Catalyzed by Bipyridyl Pt(II) Complexes

et al. 2011

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Cationic platinum(II) complexes [( t bpy)Pt(Ph)(L)]+ [ t bpy =4,4′-di-tert-butyl-2,2′-bipyridyl; L = THF, NC5F5, or NCMe] catalyze the hydrophenylation of ethylene to generate ethylbenzene and isomers of diethylbenzene. Using ethylene as the limiting reagent, an 89% yield of alkyl arene products is achieved after 4 h at 120 °C. Catalyst efficiency for ethylene hydrophenylation is diminished only slightly under aerobic conditions. Mechanistic studies support a reaction pathway that involves ethylene coordination to Pt(II), insertion of ethylene into the Pt–phenyl bond, and subsequent metal-mediated benzene C–H activation. Studies of stoichiometric benzene (C6H6 or C6D6) C–H/C–D activation by [( t bpy)Pt(Ph-d n )(THF)]+ (n = 0 or 5) indicate a k H/k D = 1.4(1), while comparative rates of ethylene hydrophenylation using C6H6 and C6D6 reveal k H/k D = 1.8(4) for the overall catalytic reaction. DFT calculations suggest that the transition state for benzene C–H activation is the highest energy species along the catalytic cycle. In CD2Cl2, [( t bpy)Pt(Ph)(THF)][BAr′4] [Ar′ = 3,5-bis(trifluoromethyl)phenyl] reacts with ethylene to generate [( t bpy)Pt(CH2CH2Ph)(η2-C2H4)][BAr′4] with k obs = 1.05(4) × 10–3 s–1 (23 °C, [C2H4] = 0.10(1) M). In the catalytic hydrophenylation of ethylene, substantial amounts of diethylbenzenes are produced, and experimental studies suggest that the selectivity for the monoalkylated arene is diminished due to a second aromatic C–H activation competing with ethylbenzene dissociation.

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Section: à26mentioning

confidence: 99%

Mechanistic Studies of Ethylene Hydrophenylation Catalyzed by Bipyridyl Pt(II) Complexes

et al. 2011

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“…(28)]. [110] Both the Markovnikov selectivity for addition to propylene and the ortho/para selectivity observed for hydroarylation with toluene point to a Friedel-Crafts type of mechanism, which involves electrophilic activation of the olefin on coordination to platinum, and outer-sphere nucleophilic attack by the arene.…”

Section: Carbon Nucleophiles: Platinum-catalyzed Hydroarylation Of Almentioning

confidence: 99%

Electrophilic Activation of Alkenes by Platinum(II): So Much More Than a Slow Version of Palladium(II)

2007

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The electrophilic activation of alkenes by transition-metal catalysts is a fundamental step in a rapidly growing number of catalytic processes. Although palladium is the best known metal for this purpose, the special properties of its third-row cousin platinum (strong metal-ligand bonds and slow substitution kinetics) have enabled the development of transformations that are initiated by addition to the C=C bonds by protic carbon, nitrogen, oxygen, and phosphorus nucleophiles, as well as alkene or arene nucleophiles. Additionally, reactivity profiles, which are often unique to platinum, provide wholly new reaction products. This Review concerns platinum-catalyzed electrophilic alkene activation reactions, with a special emphasis on the mechanistic properties of known systems, on the differences between platinum and palladium catalysts, and on the prospects for the development of new systems.

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“…(28)]. [110] Die Markownikoff-Selektivität der Addition an Propylen und die ortho,para-Selektivität der Hydroarylierung mit Toluol deuten auf einen Friedel-Crafts-Mechanismus hin, der die elektrophile Aktivierung des Olefins bei Koordination zum Platin und den nucleophilen OuterSphere-Angriff durch das Aren einschließt. Widenhoefer et al haben über eine Methode zur Platinkatalysierten Hydroarylierung/Cyclisierung von Alkenylindolen zur Bildung von Tetrahydrocarbazolen berichtet [Gl.…”

Section: Kohlenstoff-nucleophile: Platin-katalysierte Hydroarylierungunclassified

Elektrophile Aktivierung von Alkenen mit Platin(II): sehr viel mehr als eine langsame Variante von Palladium(II)

2007

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Die elektrophile Aktivierung von Alkenen durch Übergangsmetallkatalysatoren ist die erste Reaktionsstufe bei einer Vielzahl von katalytischen Prozessen. Das bekannteste Metall für diesen Zweck ist Palladium, in jüngerer Zeit konnten aber auch die besonderen Eigenschaften des verwandten Platins (starke Metall‐Ligand‐Bindungen, langsame Substitutionen) genutzt werden, um häufig komplementäre Umsetzungen zu entwickeln, die durch Addition von protischen Kohlenstoff‐, Stickstoff‐, Sauerstoff‐, Phosphor‐ sowie Alken‐ und Aren‐Nucleophilen an eine CC‐Bindung eingeleitet werden. Die Umsetzungen mit Platinreagentien zeigen oft sehr charakteristische Reaktivitätsprofile, die zu gänzlich neuen Reaktionsprodukten führen. Dieser Aufsatz gibt einen Überblick über Platin‐katalysierte elektrophile Aktivierungen von Alkenen, wobei die Beschreibung von Reaktionsmechanismen, die Unterschiede zwischen Platin‐ und Palladiumkatalysatoren und die Aussichten für die Entwicklung neuer Systeme im Mittelpunkt stehen.

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Pt−Ag Catalyst System for Hydroarylations with Unactivated Arenes and Olefins

Abstract: A series of Pt complexes activated by Ag(I) salts have been shown to catalyze Markovnikov hydroarylations of unactivated olefins under mild conditions.

Cited by 108 publications

References 23 publications

Mechanistic Studies of Ethylene Hydrophenylation Catalyzed by Bipyridyl Pt(II) Complexes

Mechanistic Studies of Ethylene Hydrophenylation Catalyzed by Bipyridyl Pt(II) Complexes

Electrophilic Activation of Alkenes by Platinum(II): So Much More Than a Slow Version of Palladium(II)

Elektrophile Aktivierung von Alkenen mit Platin(II): sehr viel mehr als eine langsame Variante von Palladium(II)

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