- Towards Sustainable Catalysis – Highly Efficient Olefin Metathesis in Protic Media Using Phase Labelled Cyclic Alkyl Amino Carbene (CAAC) Ruthenium Catalysts
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New generations of Hoveyda and bis-carbene type of ruthenium-based olefin metathesis catalysts (10 and 12), containing cationic cyclic alkyl amino carbene (CAAC) ligands, have been synthetized. The catalysts show exceptional stability and activity in environmentally benign, protic media. Various olefin metatheses reactions of OH functionalized feedstock (e. g. RCM, ROMP CM) can be carried out at as low as 0.05 mol % catalyst loading in methanol, isopropanol, water or methanol/water solvent mixture, accomplishing the lowest applied catalyst loading reported so far in these media. The facile olefin metathesis of renewable feedstocks including phospholipids (23) and vegetable oils (20) in protic media has also been demonstrated.
- Nagyházi, Márton,Turczel, Gábor,Balla, áron,Szálas, Gábor,Tóth, Imre,Gál, Gyula Tamás,Petra, Bombicz,Anastas, Paul T.,Tuba, Róbert
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p. 1953 - 1957
(2020/02/15)
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- Cross metathesis of methyl oleate (MO) with terminal, internal olefins by ruthenium catalysts: Factors affecting the efficient MO conversion and the selectivity
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Cross metathesis (CM) reactions of methyl oleate (MO) with cis-4-octene (OC), cis-stilbene (CS) using RuCl2(PCy3)(IMesH2)(CHPh) [IMesH2 = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene; Cy = cyclohexyl] afforded CM products with high MO conversion and high selectivity under high molar (OC/MO, CS/MO) ratios; CM with cis-1,4-diacetoxy-2-butene also afforded metathesis products with high MO conversion under certain conditions. The efficient CM with allyltrimethylsilane proceeded with high activity, whereas the CM with glycidyl ether, β-pinene, and vanillylidenacetone proceeded with low MO conversion.
- Awang, Nor Wahida,Tsutsumi, Ken,Hu?táková, Barbora,Yusoff, Siti Fairus M.,Nomura, Kotohiro,Yamin, Bohari M.
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p. 100925 - 100930
(2016/11/09)
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- Comparison of reactivity in the cross metathesis of allyl acetate-derivatives with oleochemical compounds
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The metathesis of unsaturated oleochemicals is an excellent tool for generating α,ω-difunctional substrates, which are useful intermediates for polymer synthesis. This article describes the cross metathesis of allyl acetate and cis-1,4-diacetoxy-2-butene with methyl 10-undecenoate and methyl oleate, which are oleochemical key substrates. Detailed optimizations led to high conversion rates and yields of the desired products under mild reaction conditions by using a low concentration of commercially available homogeneous ruthenium catalysts.
- Behr, Arno,Toepell, Stephanie
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p. 603 - 611
(2015/03/04)
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- Highly Regioselective Palladium-Catalyzed Carboxylation of Allylic Alcohols with CO2
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Various allylic alcohols were carboxylated in the presence of a catalytic amount of PdCl2 and PPh3 using ZnEt2 as a stoichiometric transmetalation agent under a CO2 atmosphere (1atm). This carboxylation proceeded in a highly regioselective manner to afford branched carboxylic acids predominantly. The β,γ-unsaturated carboxylic acid thus obtained was successfully converted into an optically active γ-butyrolactone, a known intermediate of (R)-baclofen.
- Mita, Tsuyoshi,Higuchi, Yuki,Sato, Yoshihiro
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supporting information
p. 16391 - 16394
(2015/11/09)
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- Metathesis of renewable raw materials - Influence of ligands in the indenylidene type catalysts on self-metathesis of methyl oleate and cross-metathesis of methyl oleate with (Z)-2-butene-1,4-diol diacetate
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The influence of different N-heterocyclic carbene (NHC) and other neutral ligands on the outcome of the cross-metathesis reaction of methyl oleate with (Z)-2-butene-1,4-diol diacetate and self-metathesis of methyl oleate was studied for a series of indenylidene type Ru catalysts.
- Kajetanowicz, Anna,Sytniczuk, Adrian,Grela, Karol
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supporting information
p. 1579 - 1585
(2014/03/21)
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- The cross-metathesis of methyl oleate with c/s-2-butene-1,4-diyl diacetate and the influence of protecting groups
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Background: α,ω-Difunctional substrates are useful intermediates for polymer synthesis. An attractive, sustainable and selective (but as yet unused) method in the chemical industry is the oleochemical cross-metathesis with preferably symmetric functionalised substrates. The current study explores the cross-metathesis of methyl oleate (1) with cis-2-butene-1,4-diyl diacetate (2) starting from renewable resources and quite inexpensive base chemicals. Results: This cross-metathesis reaction was carried out with several phosphine and N-heterocyclic carbene ruthenium catalysts. The reaction conditions were optimised for high conversions in combination with high cross-metathesis selectivity. The influence of protecting groups present in the substrates on the necessary catalyst loading was also investigated. Conclusions: The value-added methyl 11-acetoxyundec-9-enoate (3) and undec-2-enyl acetate (4) are accessed with nearly quantitative oleochemical conversions and high cross-metathesis selectivity under mild reaction conditions. These two cross-metathesis products can be potentially used as functional monomers for diverse sustainable polymers.
- Behr, Arno,Gomes, Jessica Perez
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experimental part
p. 1 - 8
(2011/03/22)
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- A chiral Lewis acid strategy for enantioselective allylic C-H oxidation
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(Chemical Equation Presented) Skip the chiral ligand: A chiral Lewis acid strategy for effecting asymmetric induction in oxidative systems not amenable to strongly binding chiral ligands is disclosed and its mechanism investigated. The highest levels of enantioselectivity for allylic C-H oxidation of terminal olefins is reported (see scheme; BQ=1,4-benzoquinone, LA=chiral Lewis acid).
- Covell, Dustin J.,White, M. Christina
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supporting information; experimental part
p. 6448 - 6451
(2009/03/11)
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