193354-06-2Relevant academic research and scientific papers
Second-coordination sphere effects on the reactivities of Hoveyda-Grubbs-type catalysts: A ligand exchange study using phenolic moiety-functionalized ligands
Akiyama, Naoki,Goshima, Kenta,Hirota, Shun,Jatmika, Catur,Matsuo, Takashi,Wakabayashi, Kazumo
supporting information, p. 11618 - 11627 (2020/09/09)
The Hoveyda-Grubbs (HG) second-generation catalyst (HG-II), a Ru complex with a 2-isopropoxybenzylidene ligand, is extensively used for olefin metathesis, the rearrangement of carbon-carbon double bonds. A well-known strategy to control its complex reactivity is to modify the phenyl ring in the ligand, thereby directly influencing the coordination of the phenolic oxygen to the metal center. We, herein, report that a functional group attached to the phenolic moiety in the 2-alkoxybenzylidene ligand can indirectly affect the reactivities of HG-type complexes. In this work, the ligand exchange reactions between HG-II and phenolic moiety-modified 2-alkoxybenzylidene ligands are useful for evaluating the structural effects of the ligands. Specifically, an ethylene amide or an ester group at the terminal phenolic moiety in the benzylidene ligand was found to influence the relative stabilities of HG-type complexes compared to that of the HG-II complex. The structural analyses proved that the observed effects of the functional groups on the complex stabilities originate from the interactions with a chlorido ligand in HG-type complexes without changes in coordination fashions at the metal centers. It was found that the outer-sphere interactions also influence the catalytic activities of HG-type complexes, namely, the properties of HG-type complexes can be controlled by outer-sphere structural factors toward the metal center (i.e., "the second-coordination sphere effect"). In the design of functionalized HG-type complexes, the outer-sphere structural effects need to be considered in addition to the optimization of the metal coordination site.
Synthesis of 1,3-Cycloalkadienes from Cycloalkenes: Unprecedented Reactivity of Oxoammonium Salts
Nagasawa, Shota,Sasano, Yusuke,Iwabuchi, Yoshiharu
supporting information, p. 13189 - 13194 (2016/10/30)
Few methods allow for the direct conversion of cycloalkenes into cycloalkadienes with high chemo- and regioselectivity. Herein, we report a convenient one-pot process for this transformation that involves the unprecedented N-preferential group transfer of N-oxoammonium salts to cycloalkenes, followed by Cope elimination, to afford cycloalkadienes at room temperature and pressure.
Evaluation of an olefin metathesis pre-catalyst with a bulky and electron-rich N-heterocyclic carbene
Manzini, Simone,Urbina Blanco, César A.,Nelson, David J.,Poater, Albert,Lebl, Tomas,Meiries, Sébastien,Slawin, Alexandra M.Z.,Falivene, Laura,Cavallo, Luigi,Nolan, Steven P.
, p. 43 - 48 (2015/01/30)
The commercially-available metathesis pre-catalyst M23 has been evaluated alongside new complex [RuCl2((3-phenyl)indenylidene)(PPh3)(SIPrOMe)] (1), which bears a para-methoxy-substituted N-heterocyclic carbene ligand. Several model metathesis reactions could be conducted using only parts-per-million levels of ruthenium catalyst. The effects of the different NHC ligands on reactivity have been explored.
Towards long-living metathesis catalysts by tuning the N-heterocyclic carbene (NHC) ligand on trifluoroacetamide-activated boomerang ru complexes
Clavier, Herve,Caijo, Frederic,Borre, Etienne,Rix, Diane,Boeda, Fabien,Nolan, Steven P.,Mauduit, Marc
experimental part, p. 4254 - 4265 (2011/02/24)
The synthesis and characterization of three novel trifluoromethylamido- containing "boomerang" precatalysts bearing various N-heterocyclic carbene (NHC) ligands are reported. Comparative kinetic and stability studies show the significant effect of the NHC on the catalyst reaction profile. An investigation of the reaction scope for diverse metathesis transformations has allowed us to establish the influence of the NHC on catalyst activity, especially as a function of substrate steric bulk. The excellent stability of one of the novel precatalysts is disclosed, and allowed for its recovery at the end of catalytic reactions. Large-scale ring-closing metathesis, enyne-metathesis and cross-metathesis experiments have revealed the recoverability of the catalyst. ICP-MS analyses of the synthesized products reveal Ru contamination levels of less than 2.5 ppm.
Stereoselective synthesis of (-)-jimenezin
Hwang, Cheol Hee,Keum, Gyochang,Sohn, Kyoung Il,Lee, Dong Hoon,Lee, Eun
, p. 6621 - 6623 (2007/10/03)
Total synthesis of jimenezin was achieved via radical cyclization of β-alkoxyacrylate and β-alkoxyvinyl sulfoxide intermediates and intramolecular olefin metathesis reaction.
A modular approach to nonracemic cyclo-BINOLs. Preparation of symmetrically and unsymmetrically substituted ligands
Lipshutz, Bruce H.,Shin, Young-Jun
, p. 7017 - 7020 (2007/10/03)
A new series of substituted cyclo-BINOLs is described, constructed using individually fashioned naphthol units which are tethered and oxidized to arrive at nonracemic materials.
Simple synthetic receptors that bind peptides in water
Torneiro, Mercedes,Still, W. Clark
, p. 8739 - 8750 (2007/10/03)
A simple two-armed receptor has been prepared that binds certain peptides sequence-selectively in water at pH 4.
