Gold(l)-catalyzed formation of furans by a Claisen type rearrangement of ynenyl allyl ethers

International audienceA series of ynenyl allyl ethers were rearranged into polysubstituted furans in the presence of a gold(I) catalyst. It is proposed that the transformation involves a Claisen-type rearrangement that allows the efficient creation of quaternary centers under mild experimental conditions. © 2011 Istrate and Gagosz

Structural Effects of Heat Treatment Holding-Time on Dynamic and Damping Behaviour of an Fe-28Mn-6Si-5Cr Shape Memory Alloy

The paper reports the structural effects of holding time period, during heat treatment, on the dynamic and damping behavior of a Fe-28Mn-6Si-5Cr (mass. %) shape memory alloy. After casting and hot rolling, solution treatment at 1050 oC was applied for five holding times, 2, 4, 6, 8 and 10 hours, followed by water quenching. The specimens were analyzed by scanning electron microscopy and X-ray diffraction which emphasized that only the 2-hours solution treated specimens contained ε-hexagonal close packed (hcp) martensite and experienced the highest internal friction value. These specimens were tested on a special device which transformed both tension and compression into tensile strain applied to the specimens and proved to be a promising solution for anti-seismic damper

Development of new transformations catalyzed by gold(I) complexes

Gold complexes have emerged in the last few years as excellent catalysts in numerous homogeneous transformations involving the activation of carbon-carbon multiple bonds towards the attack of a large variety of nucleophiles (Chapter 1). Following the discovery by Dr. Fabien L. Gagosz of a new type of air-stable, crystalline and highly reactive cationic gold(I)-catalysts possessing a triflimide counteranion (Chapter 2), our team took a keen interest in the development of new transformations catalyzed by these complexes. This manuscript presents some of the work carried out in this area, which led to the discovery of new methods for the synthesis of various heterocycle and carbocycle derivatives, such as 4-alkylidene-1,3-dioxolan-2-ones (Chapter 3), 4-oxazolin-2-ones (Chapter 4), 2,5-dihydrofurans (Chapter 5), pyrroles and furans (Chapter 6), 1,3-butadien-2-ol esters (Chapter 7), cyclopentenes (Chapter 8) and 1,3-oxazinan-2-ones (Chapter 9).Dans les dernières années, les complexes d'or se sont avérés des excellents catalyseurs pour des nombreuses transformations homogènes impliquant l'activation des liaisons carbon-carbon multiples vis-à-vis de l'attaque des différents nucléophiles (Chapitre 1). Suite à la découverte par le Dr. Fabien L. Gagosz d'une nouvelle classe de catalyseurs cationiques d'or(I), cristallins, stables à l'air et très réactifs, ayant un groupement triflimide comme contre-anion (Chapitre 2), notre équipe s'est intéressée au développement de nouvelles transformations catalysées par ces complexes. Ce manuscrit présente une partie du travail effectué dans ce domaine qui a mené à la découverte de nouvelles méthodes pour la synthèse des différents dérivés hétéro- et carbocycliques, tels que les 4-alkylidène-1,3-dioxolan-2-ones (Chapitre 3), les 4-oxazolin-2-ones (Chapitre 4), les 2,5-dihydrofuranes (Chapitre 5), les pyrroles et les furanes (Chapitre 6), les esters de 1,3-butadièn-2-ol (Chapitre 7), les cyclopentènes (Chapitre 8) ou bien les 1,3-oxazinan-2-ones (Chapitre 9)

Synthesis of functionalized pyrroles via Gold(I)-catalyzed aza-claisen-type rearrangement

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Synthesis of functionalized furans via gold(I)-catalyzed Claisen-type rearrangement

International audience(Chemical Equation Presented) Gold(I)-catalyzed cyclization of pentenynyl allyl ethers allows the rapid construction of functionalized furans. The concerted oxy-Claisen-type mechanism induces a complete selectivity of the process and allows the easy formation of quaternary centers. © 2008 American Chemical Society

Gold(I)-catalyzed 5-endo hydroxy- and alkoxycyclization of 1,5-enynes: Efficient access to functionalized cyclopentenes

International audienceThe rapid and stereoselective construction of highly functionalized cyclopentenes is possible through gold(I)-catalyzed 5-endo hydroxy- and methoxycyclizations of 1,5-enynes. More complex 5,7- and 5,8-fused bicyclic structures of a type found in many terpene natural products can be formed by combining the cyclization reaction with ring-closing metathesis (RCM; see scheme)

Gold(I)-catalyzed isomerization of allenyl carbinol esters: An efficient access to functionalized 1,3-butadien-2-ol esters

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Gold (I)-catalyzed stereoselective formation of functionalized 2,5-dihydrofurans

A study concerning the gold(I)-catalyzed rearrangement of butynediol monobenzoates into functionalized 2,5-dihydrofurans is described. The mild reaction conditions employed allow the efficient and rapid stereoselective synthesis of a variety of 2,5-dihydrofurans via a sequence of two gold(I)-catalyzed isomerization step

Développement de nouvelles transformations catalysées par des complexes d'or(I)

PALAISEAU-Polytechnique (914772301) / SudocSudocFranceF

Gold-catalyzed rearrangement of propargylic tert-butyl carbonates

International audienceDiversely substituted 4-alkylidene-1,3-dioxolan-2-ones are efficiently synthesized by a gold(I)-catalyzed rearrangement of propargylic tert-butyl carbonates. The substrates are readily accessible and the transformation, which is performed under mild reaction conditions using a low loading of catalyst, allows the synthesis of cyclic carbonates, which would be less efficiently obtained using traditional methods. This procedure has also been applied to the stereoselective synthesis of (E)- or (Z)-4-halomethylene-1,3-dioxolan-2-ones, which proved to be suitable substrates for palladium-catalyzed cross-coupling reactions. © 2008 Elsevier Ltd. All rights reserved