A hexafluorobenzene promoted ring-closing metathesis to form tetrasubstituted olefins

Rost, Daniel; Porta, Marta; Gessler, Simon; Blechert, Siegfried

doi:10.1016/j.tetlet.2008.07.161

Cited by 75 publications

(38 citation statements)

References 38 publications

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“…[41,42] The first strategy allows for the design of reactive pockets large enough to accommodate sterically demanding tetrasubstituted olefins, while the second strategy restricts rotation around the N-aryl bond, preventing catalyst decomposition. Complexes 7-10 incorporate key elements of these two www.chemeurj.org ligand-design strategies.…”

Section: Resultsmentioning

confidence: 99%

The Pivotal Role of Symmetry in the Ruthenium‐Catalyzed Ring‐Closing Metathesis of Olefins

Costabile

Mariconda

Cavallo

et al. 2011

Chemistry A European J

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The synthesis of Ru-based precatalysts with N-heterocyclic carbene (NHC) ligands bearing syn- and anti-methyl groups on the NHC backbone and aryl N-substituents with differing steric bulk was carried out. The catalytic behavior of the monophospine Ru precatalysts (7a, 7b, 8a, and 8b) was compared to the corresponding family of phosphine-free catalysts (9a, 9b, 10a and 10b) in the ring-closing metathesis (RCM) of olefins. These catalysts showed high efficiency in RCM reactions and the syn-isomers 7a and 9a, in particular, proved to be among the most active catalysts in the formation of tetrasubstituted olefins through RCM. DFT studies on the entire RCM catalytic cycle of hindered olefins were performed to rationalize the different behaviors of catalysts with syn- and anti-methyl groups on the NHC backbone. Theoretical results not only disclosed how NHC symmetry influences the overall activity of the catalyst, but also gave relevant and more general indications on the crucial steps of the RCM of olefins.

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Section: Resultsmentioning

confidence: 99%

The Pivotal Role of Symmetry in the Ruthenium‐Catalyzed Ring‐Closing Metathesis of Olefins

Costabile

Mariconda

Cavallo

et al. 2011

Chemistry A European J

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“…Diene ( R )- 9 was obtained by reduction of the epoxide 6 with LiAlH 4 to form alcohol ( R )- 7 , followed by esterification with 9-decenoic acid ( 8 ) using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 4-(dimethylamino)pyridine (DMAP) [24–25]. The following RCM was performed using Grubbs–Hoveyda II catalyst ( 11 ) and hexafluorobenzene as an additive [26]. During the reaction isomerization occurred, leading to a mixture of positional isomers and chain shortened as well as elongated products.…”

Section: Resultsmentioning

confidence: 99%

Identification, synthesis and mass spectrometry of a macrolide from the African reed frog Hyperolius cinnamomeoventris

Menke¹,

Peram²,

Starnberger³

et al. 2016

Beilstein J. Org. Chem.

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The contents of the gular glands of the male African reed frog Hyperolius cinnamomeoventris consist of a mixture of aliphatic macrolides and sesquiterpenes. While the known macrolide gephyromantolide A was readily identified, the structure of another major component was suggested to be a tetradecen-13-olide. The synthesis of the two candidate compounds (Z)-5- and (Z)-9-tetradecen-13-olide revealed the former to be the naturally occurring compound. The synthesis used ring-closing metathesis as key step. While the Hoveyda–Grubbs catalyst furnished a broad range of isomeric products, the (Z)-selective Grubbs catalyst lead to pure (Z)-products. Analysis by chiral GC revealed the natural frog compound to be (5Z,13S)-5-tetradecen-13-olide (1). This compound is also present in the secretion of other hyperoliid frogs as well as in femoral glands of male mantellid frogs such as Spinomantis aglavei. The mass spectra of the synthesized macrolides as well as their rearranged isomers obtained during ring-closing metathesis showed that it is possible to assign the location of the double bond in an unsaturated macrolide on the basis of its EI mass spectrum. The occurrence of characteristic ions can be explained by the fragmentation pathway proposed in the article. In contrast, the localization of a double bond in many aliphatic open-chain compounds like alkenes, alcohols or acetates, important structural classes of pheromones, is usually not possible from an EI mass spectrum. In the article, we present the synthesis and for the first time elucidate the structure of macrolides from the frog family Hyperoliidae.

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“…However, only low conversions of the starting material to the corresponding products were observed (isolated yields were with the range of 12-23%) and the starting material remained mostly unreacted. Addition of fluorinated solvents such as octafluorotoluene, which was shown to have a positive effect on the course of cross-metathesis reaction [22,23], or sequential addition of additional amounts of the catalyst did not result in better overall yields. Nonetheless, after much experimental work, reasonable conversions of the starting material to the desired products were achieved when the reactions were carried out under microwave irradiation [24] in a microwave reactor and the catalyst together with the perfluoroalkylpropenes were added in two portions during the course of the reaction.…”

Section: Resultsmentioning

confidence: 99%

Sphingosine and clavaminol H derivatives bearing fluorinated chains and their cytotoxic activity

Prchalová

Votruba

Kotora

2012

Journal of Fluorine Chemistry

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A hexafluorobenzene promoted ring-closing metathesis to form tetrasubstituted olefins

Cited by 75 publications

References 38 publications

The Pivotal Role of Symmetry in the Ruthenium‐Catalyzed Ring‐Closing Metathesis of Olefins

The Pivotal Role of Symmetry in the Ruthenium‐Catalyzed Ring‐Closing Metathesis of Olefins

Identification, synthesis and mass spectrometry of a macrolide from the African reed frog Hyperolius cinnamomeoventris

Sphingosine and clavaminol H derivatives bearing fluorinated chains and their cytotoxic activity

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