Gold‐Katalyse: Isolierung von Vinylgold‐Komplexen ausgehend von Alkinen

Hashmi, A. Stephen K.; Schuster, Andreas; Röminger, Frank

doi:10.1002/ange.200903134

Cited by 126 publications

(34 citation statements)

References 45 publications

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“…The selectivity-determining step of the reaction is most probably the initial attack of the tethered oxygen, which in the non-terminal case delivers intermediates III and IV derived from a 5-exo-dig or 6-endo-dig [16] cyclisation (Scheme 6). Intermediate III now once again favours the 5-exo-dig process versus the 4-exo-trig enol ether attack, which results in the formation of product 9.…”

Section: Full Papermentioning

confidence: 99%

Gold Catalysis: Tandem Reactions of Diyne–Diols and External Nucleophiles as an Easy Access to Tricyclic Cage‐Like Structures

Hashmi

Bührle

Wölfle

et al. 2010

Chemistry A European J

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131

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Different diyne-diols composed of two terminal homopropargylic alcohol groups were prepared by bi-directional synthesis. Subjection of the syn diastereomers to NAC-gold catalysts (NAC=nitrogen acyclic carbene) in the presence of external nucleophiles such as water or anilines provided substituted and highly rigid heterocyclic cages. The corresponding anti disastereomers polymerised. An intermediate of the reactions of the syn diastereomers could be isolated and even be characterised by crystal structure analysis. Overall, eight new bonds are formed in the reaction, which proceeds by a multistep sequence of highly selective hydroalkoxylations and hydrohydroxylation or hydroaminations. For furyl substituents and for internal alkynes competing reaction pathways could be identified. By the cross-coupling of a product with an iodoaryl substituent, the use of these cage compounds as geometrically defined linking groups by using orthogonal transition-metal-catalysed methodology, namely, gold and palladium catalysis, could be demonstrated.

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Section: Full Papermentioning

confidence: 99%

Gold Catalysis: Tandem Reactions of Diyne–Diols and External Nucleophiles as an Easy Access to Tricyclic Cage‐Like Structures

Hashmi

Bührle

Wölfle

et al. 2010

Chemistry A European J

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131

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“…[9] Other alkenylgold(I) species obtained recently from allenes [10] or alkynes were less stable. [11] A new dimension for gold catalysis would be the use of alkenylgold intermediates for a transmetalation to different transition metals like palladium, linking two catalytic cycles. The reluctance of gold to undergo a change in oxidation state would then become an advantage as the orthogonal reactivity of both metals should guarantee highly selective conversions.…”

Section: Introductionmentioning

confidence: 99%

Scope and Limitations of Palladium‐Catalyzed Cross‐Coupling Reactions with Organogold Compounds

et al. 2010

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Five different alkenylgold(I) phosphane complexes were prepared and then investigated in [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride-catalyzed cross-coupling reactions with different aryl halides, heterocyclic halides, an alkenyl halide, an alkynyl halide, allylic substrates, benzyl bromide and an acid chloride. With regard to the halides, the iodides were highly reactive, bromides or chlorides gave significantly reduced yields or failed, allylic acetates failed, too. The cross-coupling partners contained a number of different functional groups, while free carboxylic acids did not deliver cross-coupling products and o,o-disubstituted arenes failed as well, a broad range of other functional groups like nitro groups, nitrile groups, ester groups, a,b-unsaturated ester groups and lactones, aldehydes, alkoxy groups, pyridyl groups, thienyl groups, unprotected phenols and anilines, even aryl azides were tolerated. The structures of one alkenylgold(I) species and of four of the cross-coupling products were proved by crystal structure analyses.

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“…[8] Path d has not yet been observed, but with a shorter tether between the nucleophile and allene the distal carbon atom of the allene has also been reported to participate in such a gold-catalysed endo-trig cyclization. [9] In continuation of our work on cyclisations of propargylamides to oxazoles, methyleneoxazolines and oxazines, [10,11,12] which have also been used in industry, [13] we were now interested in studying the reactivities of the corresponding allenylamides.…”

Section: Introductionmentioning

confidence: 99%

Gold Catalysis: 1,3‐Oxazines by Cyclisation of Allene Amides

Hashmi

Schuster

Litters

et al. 2011

Chemistry A European J

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A series of allene amides was prepared and their gold-catalysed cyclisation was investigated. The formation of six-membered rings, 1,3-oxazines, was observed. Dihydropyrroles originating from intramolecular hydroamination of the distal C=C double bonds of the allenes were minor side products. Mechanistic studies by in situ (31)P NMR spectroscopy showed only one additional species during the conversion in each case; a computational study of the different allyl gold(I) species involved allowed this to be assigned as the σ-allyl gold species bearing the gold catalyst at the sterically less hindered methylene end. The regiospecific deuterodeauration of this intermediate confirmed a S(E) '-type mechanism for this last step of the catalytic cycle.

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Gold‐Katalyse: Isolierung von Vinylgold‐Komplexen ausgehend von Alkinen

Cited by 126 publications

References 45 publications

Gold Catalysis: Tandem Reactions of Diyne–Diols and External Nucleophiles as an Easy Access to Tricyclic Cage‐Like Structures

Gold Catalysis: Tandem Reactions of Diyne–Diols and External Nucleophiles as an Easy Access to Tricyclic Cage‐Like Structures

Scope and Limitations of Palladium‐Catalyzed Cross‐Coupling Reactions with Organogold Compounds

Gold Catalysis: 1,3‐Oxazines by Cyclisation of Allene Amides

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