Are Alkyne Reductions Chemo-, Regio-, and Stereoselective Enough To Provide Pure (<i>Z</i>)-Olefins in Polyfunctionalized Bioactive Molecules?

Oger, Camille; Balas, Laurence; Durand, Thierry; Galano, Jean‐Marie

doi:10.1021/cr3001753

Cited by 325 publications

(219 citation statements)

References 546 publications

(1,214 reference statements)

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“…565,566 Compound 179 containing zerovalent palladium was the first catalyst for stereoand chemoselective semihydrogenation of aromatic and aliphatic internal alkynes under TH conditions with formic acid/triethylamine. 188 A series of alkynes with a wide range of scope were employed in this catalytic system, and in most cases the desired Z alkenes were obtained with >99% conversions and >90% selectivities; meanwhile, both E alkenes and alkanes were found as side-products.…”

Section: Osmium-based Catalystsmentioning

confidence: 99%

The Golden Age of Transfer Hydrogenation

2015

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Section: Osmium-based Catalystsmentioning

confidence: 99%

The Golden Age of Transfer Hydrogenation

2015

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“…[45,50,51,[84][85][86][87][88][89] Our group has previouslyr eported ac atalytic system that was proposed to proceed via an in situ generated molecular [Pd 0 (IMes)] speciesa st he active catalyst( IMes = 1,3-bis-mesityl-imidazol-2-ylidene) (Scheme 5). [46,[90][91][92] Sprengers et al reported that the in situ generated catalyst is significantly more active than the isolated catalyst. [93] One explanation for this higher activity is that less maleic anhydride (MA) ligand is appliedf or the in situ generated species.…”

Section: Pdmentioning

confidence: 99%

“…[48][49][50][51][52] Chemo-a nd stereoselectivity of the catalyst system is crucial in this reaction that is applied from laboratory to bulk scale. [45,46,52,53] In such cases an understanding of the type of active speciesa nd the reaction mechanism are required to improve catalyst systemst hat meet the desired chemo-and stereo-selectivities. Therefore, our initial goal was to investigate the type of active catalyst for three catalyst systems; one system for the Pd 0 -catalyzed Z-selective semihydrogenation of alkynes that uses molecular hydrogen, and two catalyst systems for the Pd 0 -catalyzed Z-selective transfer semihydrogenation of alkynes using formic acid.…”

Section: Introductionmentioning

confidence: 99%

Pd‐Catalyzed Z‐Selective Semihydrogenation of Alkynes: Determining the Type of Active Species

et al. 2015

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A protocol was developed to distinguish between well‐defined molecular and nanoparticle‐based catalysts for the Pd‐catalyzed semihydrogenation reaction of alkynes to Z‐alkenes. The protocol applies quantitative partial poisoning and dynamic light scattering methods, which allow the institution of additional validation experiments. For the quantitative partial poisoning method, tetramethylthiourea (TMTU) was developed as an alternative for the standard poison ligand CS2, and was found to be superior in its applicability. The protocol and the TMTU poison ligand were validated using the well‐described [PdII(phenanthroline)]‐catalyzed copolymerization of styrene and CO, confirming that this system is clearly operating as a well‐defined molecular catalyst. The protocol was subsequently applied to three catalyst systems used for the semihydrogenation of alkynes. The first was proposed to be a molecular [Pd0(IMes)] catalyst that uses molecular hydrogen, but the data gathered for this system, following the new protocol, clearly showed that nanoparticles (NPs) are catalytically active. The second catalyst system studied was an N‐heterocyclic carbene (NHC) Pd system for transfer semihydrogenation using formic acid as the hydrogen source, which was proposed to operate through an in situ generated molecular [Pd0(IMes)] catalyst in earlier studies. The investigations showed that only a small fraction of the Pd added becomes active in the catalytic reaction and that NPs are formed. However, despite these findings, a clear distinction between catalytic activity of NPs versus a molecular catalyst could not be made. The third investigated system is based on a [PdII(IMes)(η3‐allyl)Cl] precatalyst with additive ligands. The combined data gathered for this system are multi‐interpretable, but suggest that a partially deactivated molecular catalyst dominates in this reaction.

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“…Further, our hydrogenation reactions were carried out in presence of quinolones which enhances selectivity for 9 Z , 12 Z alkene production. 15 HPLC analyses of the purified final products indicated only linoleic acid (C18:2 Δ 9,12 ) with no detectable amounts of oleic (C18:1 Δ 9 ) or stearic (C18:0) acids, consistent with no over-reduction. 1 H NMR spectra were consistent with cis , cis -9,12 isomer.…”

mentioning

confidence: 92%

Synthesis of site-specifically 13 C labeled linoleic acids

Offenbacher

Zhu

Klinman

2016

Tetrahedron Letters

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Soybean lipoxygenase-1 (SLO-1) catalyzes the C-H abstraction from the reactive carbon (C-11) in linoleic acid as the first and rate-determining step in the formation of alkylhydroperoxides. While previous labeling strategies have focused on deuterium labeling to ascertain the primary and secondary kinetic isotope effects for this reaction, there is an emerging interest and need for selectively enriched 13C isotopologues. In this report, we present synthetic strategies for site-specific 13C labeled linoleic acid substrates. We take advantage of a Corey-Fuchs formyl to terminal 13C-labeled alkyne conversion, using 13CBr4 as the labeling source, to reduce the number of steps from a previous fatty acid 13C synthetic labeling approach. The labeled linoleic acid substrates are useful as nuclear tunneling markers and for extracting active site geometries of the enzyme-substrate complex in lipoxygenase.

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Are Alkyne Reductions Chemo-, Regio-, and Stereoselective Enough To Provide Pure (Z)-Olefins in Polyfunctionalized Bioactive Molecules?

Cited by 325 publications

References 546 publications

The Golden Age of Transfer Hydrogenation

The Golden Age of Transfer Hydrogenation

Pd‐Catalyzed Z‐Selective Semihydrogenation of Alkynes: Determining the Type of Active Species

Synthesis of site-specifically 13 C labeled linoleic acids

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