Effect of Added Salt on Ring-Closing Metathesis Catalyzed by a Water-Soluble Hoveyda–Grubbs Type Complex To Form N-Containing Heterocycles in Aqueous Media
摘要:
The efficiency of ring-closing metathesis catalyzed by a Hoveyda-Grubbs type catalyst in water can be enhanced by addition of a chloride salt under neutral conditions. UV-vis spectroscopic study showed that a characteristic band of the catalyst around 380 nm remained over 16 h in the presence of KCl, whereas the band distinctly decreased in the absence of KCl. The disappearance of the band is ascribed to a displacement of a chloride ligand by a water molecule or a hydroxide anion. The spectral changes can be related to the metathesis activity. The experimental results indicate that avoidance of the chloride ligand loss is important to maintain the metathesis activity in water.
Fast Olefin Metathesis: Synthesis of 2-Aryloxy-Substituted Hoveyda-Type Complexes and Application in Ring-Closing Metathesis
作者:Pavlo Kos、Roman Savka、Herbert Plenio
DOI:10.1002/adsc.201200956
日期:2013.1.16
donation of the diaryl ether oxygen atoms in complexes 5 and 6 led to rapidly initiating precatalysts. The Ru(II/III) redox potentials of complexes 6 were determined (6a–d: ΔE=0.89–1.08 V). In the crystal structure of 5b two independent molecules were observed in the unit cell, displaying RuO distances of 226.6(4) and 230.5(3) pm. The catalytic performance of complexes 5 and 6 in various ring-closing metathesis
[EN] RUTHENIUM-BASED METATHESIS CATALYSTS, PRECURSORS FOR THEIR PREPARATION AND THEIR USE<br/>[FR] CATALYSEURS DE MÉTATHÈSE À BASE DE RUTHÉNIUM, PRÉCURSEURS POUR LEUR PRÉPARATION ET LEUR UTILISATION
申请人:UMICORE AG & CO KG
公开号:WO2014067767A1
公开(公告)日:2014-05-08
The invention is directed to ruthenium-based metathesis catalysts of the Grubbs-Hoveyda type. The new 2-aryloxy-substituted ruthenium catalysts described herein reveal rapid initiation behavior. Further, the corresponding styrene-based precursor compounds are disclosed. The catalysts are prepared in a cross-metathesis reaction starting from styrene-based precursors which can be prepared in a cost- effective manner. The new Grubbs-Hoveyda type catalysts are suitable to catalyze ring- closing metathesis (RCM), cross metathesis (CM) and ring- opening metathesis polymerization (ROMP). Low catalyst loadings are necessary to convert a wide range of substrates including more complex and critical substrates via metathesis reactions at low to moderate temperatures in high yields within short reaction times.
[RuCl2(NHC)(Ind)(Py)] (N‐heterocyclic carbene (NHC)=1,3‐bis(2,4,6‐trimethylphenylimidazolin)‐2‐ylidene (SIMes), 1,3‐bis(2,6‐diisopropylphenylimidazolin)‐2‐ylidene (SIPr), or 1,3‐bis(2,6‐diisopropylphenylimidazol)‐2‐ylidene (IPr); Ind=3‐phenylindenylid‐1‐ene, Py=pyridine) with 2‐ethenyl‐N‐alkylaniline (alkyl=Me, Et) result in the formation of the new N‐Grubbs–Hoveyda‐type complexes 5 (NHC=SIMes, alkyl=Me), 6 (SIMes
Ruthenium-based metathesis catalysts, precursors for their preparation and their use
申请人:Umicore AG & Co. KG
公开号:EP2725030A1
公开(公告)日:2014-04-30
The invention is directed to ruthenium-based metathesis catalysts of the Grubbs-Hoveyda type. The new 2-aryloxy-substituted ruthenium catalysts described herein reveal rapid initiation behavior. Further, the corresponding styrene-based precursor compounds are disclosed. The catalysts are prepared in a cross-metathesis reaction starting from styrene-based precursors which can be prepared in a cost-effective manner.
The new Grubbs-Hoveyda type catalysts are suitable to catalyze ring-closing metathesis (RCM), cross metathesis (CM) and ring-opening metathesis polymerization (ROMP). Low catalyst loadings are necessary to convert a wide range of substrates including more complex and critical substrates via metathesis reactions at low to moderate temperatures in high yields within short reaction times.
[EN] CHOLINE METABOLISM INHIBITORS<br/>[FR] INHIBITEURS DU MÉTABOLISME DE LA CHOLINE
申请人:HARVARD COLLEGE
公开号:WO2020117942A1
公开(公告)日:2020-06-11
The present disclosure relates to compounds, compositions and methods for inhibiting choline metabolism, e.g., conversion of choline to trimethylamine. Disclosed herein are compounds, compositions, and methods for inhibiting choline metabolism, e.g., conversion of choline to TMA. Also disclosed herein are compounds, methods and compositions for inhibiting choline metabolism by gut microbiota resulting in reduction in the formation of trimethylamine (TMA) and trimethylamine N-oxide (TMAO).