Use of π-allylpalladium as a nucleophile via an alkyl-allyl exchange reaction with alkylzinc

Yasui, Kengo; Goto, Yoichi; Yajima, Takafumi; Taniseki, Y.; Fugami, Keigo; Tanaka, Akihiro; Tamaru, Yoshinao

doi:10.1016/s0040-4039(00)60415-x

Cited by 66 publications

(19 citation statements)

References 17 publications

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“…These reactions have been described for a successful synthesis of the 2 H ‐pyran‐2‐one system from pent‐2‐en‐5‐olide (R = H) 22. Aldehydes 17a – c were transformed into homoallyl alcohols 18a – c with allyl benzoate, diethylzinc, and [Pd(PPh 3 ) 4 ] 23. Treatment with acryloyl chloride in triethylamine gave acrylate esters 19a – c , which were converted into the α,β‐unsaturated lactones 20a , massoialactone ( 8 ), and 20c by subsequent ring closing metathesis using the second‐generation Grubbs' catalyst 24.…”

Section: Resultsmentioning

confidence: 99%

2H‐Pyran‐2‐ones from Trichoderma viride and Trichoderma asperellum

2013

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Volatiles emitted by the soil fungi Trichoderma viride 272 and Trichoderma asperellum 328 were collected by using the closed loop stripping analysis (CLSA) headspace technique, and the obtained extracts were analysed by GC/MS. Several alkyl‐ and alkenyl‐2H‐pyran‐2‐ones, including known compounds 6‐pentyl‐2H‐pyran‐2‐one and (E)‐6‐(pent‐1‐en‐1‐yl)‐2H‐pyran‐2‐one, and the new derivatives (E)‐6‐(pent‐2‐en‐1‐yl)‐2H‐pyran‐2‐one, 6‐propyl‐2H‐pyran‐2‐one, and 6‐heptyl‐2H‐pyran‐2‐one were found. The alkenyl derivative (E)‐6‐(hept‐1‐en‐1‐yl)‐2H‐pyran‐2‐one, previously tentatively identified from a marine Botrytis by MS analysis, was also detected. All alkenyl pyrones were synthesised by using a reported Stille coupling followed by lactonisation, whereas the alkylated pyrones were obtained through a reported synthetic approach by radical bromination of 5‐alkylpent‐2‐en‐5‐olides and dehydrobromination. Because the yields in both cases were not satisfactory and fell a long way short of the yields reported for similar compounds, all compounds were synthesised again using a gold‐catalysed coupling of terminal alkynes with propiolic acid recently developed by Schreiber and co‐workers, giving high yields in all cases. A comparison of the synthetic methods is given.

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Section: Resultsmentioning

confidence: 99%

2H‐Pyran‐2‐ones from Trichoderma viride and Trichoderma asperellum

2013

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“…The aforementioned palladium-catalyzed allylic substitution (see Section 4.3) formed the basis for a diethylzincmediated umpolung of palladium-allyl complexes. [356][357][358][359][360] Scheme 70. Desymmetrization based on palladium-catalyzed allylic substitution.…”

Section: Allylation and Related Metal-catalyzed Reactionsmentioning

confidence: 99%

Phosphoramidites: Privileged Ligands in Asymmetric Catalysis

Teichert¹,

Feringa²

2010

Angew Chem Int Ed

648

340

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Asymmetric catalysis with transition-metal complexes is the basis for a vast array of stereoselective transformations and has changed the face of modern synthetic chemistry. Key to this success has been the design of chiral ligands to control the regio-, diastereo-, and enantioselectivity. Phosphoramidites have emerged as a highly versatile and readily accessible class of chiral ligands. Their modular structure enables the formation of ligand libraries and easy fine-tuning for a specific catalytic reaction. Phosphoramidites frequently show exceptional levels of stereocontrol, and their monodentate nature is essential in combinatorial catalysis, where a ligand-mixture approach is used. In this Review, recent developments in asymmetric catalysis with phosphoramidites used as ligands are discussed, with a focus on the formation of carbon-carbon and carbon-heteroatom bonds.

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“…[356][357][358][359][360] Hierbei wurden die Aldehyde 234 mit Cyclohexylacetat 233 und Palladiumkatalysatoren auf der Basis von Phosphoramidit-Liganden (Schema 74) umgesetzt. [361] Die vermutlich intermediär aus dem Allylpalladiumkomplex entstehende Allylzinkverbindung wurde mit verschiedenen Aldehyden 234 abgefangen, wobei die syn-Homoallylalkohole 235 mit Ausbeuten bis 82 %, ee-Werten bis 81 % und in allen Fällen hervorragenden Diastereoselektivitäten (> 20:1) gebildet wurden.…”

Section: Allylierung Und Verwandte Metallkatalysierte Reaktionenunclassified

Phosphoramidite: privilegierte Liganden in der asymmetrischen Katalyse

2010

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Die asymmetrische Katalyse mit Übergangsmetallkomplexen ist die Grundlage unzähliger stereoselektiver Umwandlungen und hat damit das Bild der modernen Synthesechemie gewandelt. Der Schlüssel zum Erfolg war die Entwicklung chiraler Liganden zur Kontrolle der Regio‐, Diastereo‐ und Enantioselektivität. Dabei haben sich Phosphoramidite als eine äußerst vielseitige und leicht zugängliche Klasse von chiralen Liganden erwiesen. Ihre modulare Struktur ermöglicht die Herstellung von Ligandenbibliotheken und erleichtert die Feinabstimmung für eine bestimmte katalytische Reaktion. Phosphoramidite bewirken oft außerordentlich hohe Stereoselektivitäten, und ihre einzähnige Natur ist in der kombinatorischen Katalyse, die gemischte Liganden verwendet, unverzichtbar. In diesem Aufsatz werden neue Entwicklungen in der asymmetrischen Katalyse mit Phosphoramiditen diskutiert, wobei der Schwerpunkt auf der Bildung von Kohlenstoff‐ Kohlenstoff‐ und Kohlenstoff‐Heteroatom‐Bindungen liegt.

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Use of π-allylpalladium as a nucleophile via an alkyl-allyl exchange reaction with alkylzinc

Cited by 66 publications

References 17 publications

2H‐Pyran‐2‐ones from Trichoderma viride and Trichoderma asperellum

2H‐Pyran‐2‐ones from Trichoderma viride and Trichoderma asperellum

Phosphoramidites: Privileged Ligands in Asymmetric Catalysis

Phosphoramidite: privilegierte Liganden in der asymmetrischen Katalyse

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