Synthesis of Dihydropyrans <i>via</i> Pd-Catalyzed Cyclization of 2-Allyl-1,3-dicarbonyl Compounds and Vinylic Triflates or Halides

Cacchi, Sandro; Fabrizi, Giancarlo; Larock, Richard C.; Pace, Paola; Reddy, V. Vikram

doi:10.1055/s-1998-1788

Cited by 11 publications

(1 citation statement)

References 3 publications

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“…In a similar manner, the intermolecular palladium-catalyzed cross-coupling of 2-allyl-1,3-dicarbonyl compounds 214 with vinylic halides or triflates 215 generates dihydropyran derivatives 216 in good yields (Scheme ) 81 …”

Section: 4 Heterocycles Via Intermolecular Annulationmentioning

confidence: 99%

Synthesis of Heterocycles via Palladium-Catalyzed Oxidative Addition

2006

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Section: 4 Heterocycles Via Intermolecular Annulationmentioning

confidence: 99%

Synthesis of Heterocycles via Palladium-Catalyzed Oxidative Addition

2006

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An Expedient Variant of Heck Reaction of Alkenyl Nonaflates: Homogeneous Ligand‐Free Palladium Catalysis at Room Temperature

2007

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A mechanistic study on the ligand-free room-temperature Heck reaction of alkenyl nonafluorobutanesulfonates (nonaflates) is described. Kinetic data obtained from poisoning experiments, centrifugation and variation of catalyst loading consistently provide evidence for a homogeneous palladium catalysis unprecedented in Heck chemistry. The Heck reaction of alkenyl perfluorobutanesulfonates represents a remarkably robust, active and efficient catalytic system generally applicable to the coupling with a broad range of terminal olefins including non-activated ones under ambient conditions. It features insensitivity towards atmospheric oxygen and moisture, furnishing uniformly high yields of the anticipated coupling products without the necessity to purify commercial reagents and solvents.Keywords: alkenyl nonaflates; catalyst poisoning; Heck reaction; homogeneous catalysis; kinetics; ligand-free catalysis Coupling of olefins with aryl/alkenyl halides, commonly known as the Heck reaction, represents one of the basic tools in contemporary organic synthesis.[1]The existing vast realm of the Heck chemistry can conventionally be subdivided to ligand-assisted and ligand-free catalysis. Ligands at palladium play a different role depending on the application. While the ligation is crucially important for enantioselective variants of the Heck reaction [2] or activation of otherwise unreactive aryl chlorides, [3] it often tends to deteriorate the desired coupling, causes side reactions and deactivates the catalyst, [4] in particular, when aryl iodides are used as substrates.[5] From this standpoint, it is of no surprise that the fastest versions of Heck reaction known so far are described for ligand-free systems containing free halides (Cl À or Br À added as quaternary ammonium salts) which are believed to stabilize Pd(0)-species.[1d]Later on, it was shown that intermediary Pd nanoparticles as colloids are likely to be the true catalytic species in such systems. [6] Owing to the recent advancements in the mechanistic study and design of robust and efficient low Pd-loading systems, [7] the ligand-free Heck reaction became an emerging trend with particular promise for industrial applications. [8] On the other hand, it was demonstrated in a number of well-documented cases that palladacycles [7a,9] and pincer Pd(II) complexes [10] are pre-catalysts and not the actual active species catalyzing the Heck reaction of aryl halides as it was believed earlier.[11] Compelling evidence based on kinetic studies [10,12] and quantitative poisoning experiments [10] was obtained that the above complexes decompose under the reaction conditions to generate the actual catalytic species, Pd nanoparticles.The above breakthroughs in understanding the nature of catalysis in the Heck chemistry of aryl halides [13] and a lack of mechanistic insight in the underligated Heck reaction of aryl and alkenyl perfluoroalkanesulfonates [14] prompted us to investigate the nature of Pd-catalysis for the latter substrates.Herein, we report on the nat...

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Trapping of Active Methylene Intermediates with Alkenes, Indoles or Thiols: Towards Highly Selective Multicomponent Reactions

Barrault

Jérôme³

2009

Adv Synth Catal

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In this paper, a basic method to access new multicomponent reactions (MCRs) is reported. The mechanism of these MCRs is based on the trapping of methylene intermediates, formed in situ by reaction of formaldehyde with electron-rich carbons, with alkene, thiol or indole derivatives. According to our strategy, a wide range of valuable skeletons has been obtained in a one-pot reaction, thus allowing a minimization of waste, cost and labor. The presented methodology exhibits a broad substrate scope and electron-rich carbons in the a-position of a hydroxy or carbonyl group were found to be particularly efficient. More generally, this work offers new tools for creating molecular complexity and diversity from one of the simplest organic building blocks, formaldehyde.

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Synthesis of Dihydropyrans via Pd-Catalyzed Cyclization of 2-Allyl-1,3-dicarbonyl Compounds and Vinylic Triflates or Halides

Cited by 11 publications

References 3 publications

Synthesis of Heterocycles via Palladium-Catalyzed Oxidative Addition

Synthesis of Heterocycles via Palladium-Catalyzed Oxidative Addition

An Expedient Variant of Heck Reaction of Alkenyl Nonaflates: Homogeneous Ligand‐Free Palladium Catalysis at Room Temperature

Trapping of Active Methylene Intermediates with Alkenes, Indoles or Thiols: Towards Highly Selective Multicomponent Reactions

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