Highly Enantioselective Hydrogenation of Steric Hindrance Enones Catalyzed by Ru Complexes with Chiral Diamine and Achiral Phosphane

2014 ◽  
Vol 16 (15) ◽  
pp. 3912-3915 ◽  
Author(s):  
Xiangning Chen ◽  
Han Zhou ◽  
Kunyu Zhang ◽  
Jiawen Li ◽  
Hanmin Huang
Keyword(s):  
Steric Hindrance ◽  
Enantioselective Hydrogenation ◽  
Chiral Diamine ◽  
Ru Complexes

Enantioselective Hydrogenation of Aromatic Ketones Catalyzed by Ru Complexes of Goodwin−Lions-type sp2N/sp3N Hybrid Ligands R-BINAN-R‘-Py

2006 ◽  
Vol 128 (27) ◽  
pp. 8716-8717 ◽  
Author(s):  
Hanmin Huang ◽  
Tomoko Okuno ◽  
Kazuomi Tsuda ◽  
Masahiro Yoshimura ◽  
Masato Kitamura
Keyword(s):  
Enantioselective Hydrogenation ◽  
Aromatic Ketones ◽  
Ru Complexes ◽  
Hybrid Ligands

scholarly journals Enantioselective Hydrogenation of Aromatic Ketones Catalyzed by Ru Complexes of Goodwin—Lions-Type sp2N/sp3N Hybrid Ligands R-BINAN-R′-Py.

ChemInform ◽  
2006 ◽  
Vol 37 (46) ◽  
Author(s):  
Hanmin Huang ◽  
Tomoko Okuno ◽  
Kazuomi Tsuda ◽  
Masahiro Yoshimura ◽  
Masato Kitamura
Keyword(s):  
Enantioselective Hydrogenation ◽  
Aromatic Ketones ◽  
Ru Complexes ◽  
Hybrid Ligands

Steric hindrance influence of a diazo link upon mesogenic properties of some ligands and related copper complexes

1997 ◽  
Vol 94 ◽  
pp. 1695-1714 ◽  
Author(s):  
P Lesot ◽  
F Perez ◽  
P Judeinstein ◽  
JP Bayle ◽  
H Allouchi ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Copper Complexes

METABOLISM OF 17α-HYDROXYPROGESTERONE-4-14C-17α-CAPROATE BY HOMOGENATES OF RAT LIVER AND HUMAN PLACENTA

1961 ◽  
Vol 36 (4) ◽  
pp. 511-519 ◽  
Author(s):  
Margaret Wiener ◽  
Charles I. Lupa ◽  
E. Jürgen Plotz
Keyword(s):  
Rat Liver ◽  
Human Placenta ◽  
Steric Hindrance ◽  
Placental Tissue ◽  
Caproic Acid ◽  
Major Product ◽  
Side Chain ◽  
Anaerobic Conditions ◽  
Prolonged Action ◽  
Long Acting

ABSTRACT 17α-hydroxyprogesterone-4-14C-17α-caproate (HPC), a long-acting progestational agent, was incubated with homogenates of rat liver and human placenta. The rat liver was found to reduce Ring A of HPC under anaerobic conditions to form allopregnane-3β,17α-diol-20-one-17α-caproate and pregnane-3β,17α-diol-20-one-17α-caproate, the allopregnane isomer being the major product. The caproic acid ester was neither removed nor altered during the incubation. Placental tissue did not attack HPC under conditions where the 20-ketone of progesterone was reduced. It is postulated that this absence of attack on the side chain is due to steric hindrance from the caproate ester, and that this may account for the prolonged action of HPC.

Tyrosine-Selective Bioconjugation with Iminoxyl Radicals

2020 ◽  
Author(s):  
Katsuya Maruyama ◽  
Takashi Ishiyama ◽  
Yohei Seki ◽  
Kounosuke Oisaki ◽  
Motomu Kanai
Keyword(s):  
Reaction Time ◽  
Steric Hindrance ◽  
Room Temperature ◽  
Water Soluble ◽  
Light Irradiation ◽  
Sodium Ascorbate ◽  
Iminoxyl Radical ◽  
Short Reaction Time ◽  
Modified Peptides ◽  
The Stability

A novel Tyr-selective protein bioconjugation using the water-soluble persistent iminoxyl radical is described. The conjugation proceeded with high Tyr-selectivity and short reaction time under biocompatible conditions (room temperature in buffered media under air). The stability of the conjugates was tunable depending on the steric hindrance of iminoxyl. The presence of sodium ascorbate and/or light irradiation promoted traceless deconjugation, restoring the native Tyr structure. The method is applied to the synthesis of a protein-dye conjugate and further derivatization to azobenzene-modified peptides.

Synthesis of Conjugated Triynes via Alkyne Metathesis

2019 ◽  
Author(s):  
Idriss Curbet ◽  
Sophie Colombel-Rouen ◽  
Romane Manguin ◽  
Anthony Clermont ◽  
Alexandre Quelhas ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
High Selectivity ◽  
Alkyne Metathesis ◽  
Cross Metathesis ◽  
Synthetic Strategy ◽  
Sterically Hindered ◽  
Site Selective

<div> <div> <div> <div> <p>The synthesis of conjugated triynes by molybdenum-catalyzed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed for the site- selective alkyne metathesis to produce the desired con- jugated triyne products. The steric hindrance of alkyne moiety was found to be crucial in preventing the for- mation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity. </p> </div> </div> </div> </div>

Ruthenium(II) Complexes Bearing Thioether-Appended α- Iminopyridine Ligands: Arene Precursors Permit Access to K2-N,N and K3-N,N,S Complexes

2019 ◽  
Author(s):  
Victoria A. Ternes ◽  
Hannah A. Morgan ◽  
Austin P. Lanquist ◽  
Michael P. Murray ◽  
Bradley Wile
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Strong Field ◽  
Active Role ◽  
Binding Mode ◽  
Phenethyl Alcohol ◽  
Ru Complexes

Herein we report the preparation of a series of Ru(II) complexes featuring alpha-iminopyridine ligands bearing thioether functionality (NNS<sup>R</sup>, where R = Me, CH<sub>2</sub>Ph, Ph). Metallation using (<i>p</i> cymene)RuCl dimer permits access to (k<sup>2</sup>-N,N)Ru complexes in which the thioether moiety remains uncoordinated. In the presence of a strong field ligand such as acetonitrile or triphenylphosphine, the p-cymene moiety is displaced, and the ligand adopts a k<sup>3</sup>-N,N,S binding mode. These complexes are characterized using a combination of solution and solid state methods, including the crystal structure of [(NNS<sup>Me</sup>)Ru(NCMe)<sub>2</sub>Cl]Cl. The k<sup>2</sup>-N,N Ru(II) complexes are shown to serve as efficient precatalysts for the oxidation of sec-phenethyl alcohol at 5 mol% loadings, using a variety of external oxidants and solvents. The complex bearing an S-Ph donor was found to be the most active of those surveyed, suggesting that the thioether donor plays an active role in catalyst speciation for this transformation.

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