On homogeneous gold/palladium catalytic systems
Two substrates containing an aryl iodide and an allenoate ester were prepared and the gold-induced cycloisomerisation to vinylgold(I) species and their proto-deauration as well as the intramolecular palladium-catalysed cross-coupling reactions were investigated. Switching to catalytic amounts of gol...
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| Hauptverfasser: | , , , , , , , |
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| Dokumenttyp: | Article (Journal) |
| Sprache: | Englisch |
| Veröffentlicht: |
January 12, 2012
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| In: |
Advanced synthesis & catalysis
Year: 2012, Jahrgang: 354, Heft: 1, Pages: 133-147 |
| ISSN: | 1615-4169 |
| DOI: | 10.1002/adsc.201000044 |
| Online-Zugang: | Verlag, Volltext: http://dx.doi.org/10.1002/adsc.201000044 Verlag, Volltext: https://onlinelibrary.wiley.com/doi/abs/10.1002/adsc.201000044 
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| Verfasserangaben: | A. Stephen K. Hashmi, Christian Lothschütz, René Döpp, Martin Ackermann, Janosc De Buck Becker, Matthias Rudolph, Christian Scholz, and Frank Rominger |
| Zusammenfassung: | Two substrates containing an aryl iodide and an allenoate ester were prepared and the gold-induced cycloisomerisation to vinylgold(I) species and their proto-deauration as well as the intramolecular palladium-catalysed cross-coupling reactions were investigated. Switching to catalytic amounts of gold and palladium and stoichiometric amounts of silver did indeed furnish the product of a cycloisomerisation/intramolecular cross-coupling. Control experiments revealed that silver cannot substitute for gold or palladium in these reactions, but a different palladium catalyst in a different oxidation state also afforded the cycloisomerisation/intramolecular cross-coupling products in only slightly reduced yields. By ICP analysis the palladium was shown to contain gold only at the sub-ppm level. This shows how carefully results obtained with such systems have to be interpreted. Then a series of allylic and benzylic o-alkynylbenzoates were investigated in gold- and palladium-catalysed reactions. For esters of benzyl alcohol and cinnamyl alcohol no palladium co-catalyst was needed for the conversion. All reagents were thoroughly checked for palladium traces by ICP analysis in order to thoroughly exclude a gold/palladium co-catalysis. Optimisation of the gold complex, counter ion and solvent showed that gold(I) isonitrile pre-catalysts and silver triflate as activator in dioxane are suitable to convert a number of substrates with aryl, alkyl and even cyclopropyl substituents. Crossover experiments proved an intermolecular allyl transfer. |
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| Beschreibung: | Gesehen am 06.09.2018 |
| Beschreibung: | Online Resource |
| ISSN: | 1615-4169 |
| DOI: | 10.1002/adsc.201000044 |